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NeiAer die thesis nor substantial extracts from it may be printed or otherwise reproduced without the author’s permission. L’auteur conserve la propriété du droit d’auteur qui protège cette thèse. Ni la thèse ni des extraits substantiels de celle-ci ne doivent être imprimés ou autrement reproduits sans son autorisation. 0-612-62481-1 CanadS APPROVAL Name: Jacqueline S. Lee Degree: Master of Science Thesis Title: THE DISTRIBUTION AND ECOLOGY OF THE FRESHWATER MOLLUSCS OF NORTHERN BRITISH COLUMBIA Examining Committee: Dr. Keith Egger ihg Dean of the College of Science and Management _________ Supervisw^bn^hRgfDaniel Ackerman Associat^yrof^or Faculty m Natural Resources and Environmental Studies Member: Dr. Max Blouw Dean of Research and Graduate Studies Member: lember: Dr. Ellen Petticrew Associate Professor Faculty of Natural Resources and Environmental Studies Member: Dr. Roger Wheate Associate Professor Faculty of Natural Resources and Environmental Studies External Examiner: Dr. Andre li. Martel Research Scientist (Molluscs) Canadian Museum of Nature DATE APPR ABSTRACT Molluscs (i.e., snails, clams and mussels) are common inhabitants of freshwater habitats in northern British Columbia (north of approximately S4°N), yet little w o* has been done on these animals in this area. A large-scale study recorded 55 taxa of freshwater molluscs in northern EC comprising 32 snail, 2 mussel and 21 clam taxa. Some of the factors that appeared to affect the distribution of these molluscs were climate, dispersal barriers, glacial history and water chemistry. Comparisons of mollusc community structure were made between historic and contemporary collections to monitor habitat change over time. Diversity was generally found to be higher in contemporary collections, likely due to sampling bias, or incomplete processing and archiving of historic collections. This emphasizes the need for standardized collection and processing techniques in order to sustain conservation efforts. A small-scale study was undertaken in the Lower Torpy River watershed to assess the effects of forest practices on freshwater mollusc habitat. Lentic (standing water) habitats had similar clam densities (Pisidium casertamm), water conditions and mollusc community structure whether natural or created by forest practices (e.g., road building). The case was similar for lotie (flowing water) habitats, although lotie and lentic habitats were significantly different in several ways. Lentic habitats had higher densities of clams, higher water temperatures, lower dissolved oxygen levels and lower pH. Forest practices in this watershed are interpreted to have increased the abundance of Pisidium casertanum by the creation o f additional habitats. This w o* contributes to our ability to conserve the freshwater molluscs of northern British Columbia through better understanding of their diversity, distribution and ecology. u TABLE OF CONTENTS ABSTRACT__________________________________________________ ü TABLE OF CONTENTS________________________________________ Ui LIST OF TABLES______________________________________________v LISTO FnC U R ES____________________________________________vü CHAPTER 1 - INTRODUCTION AND OVERVIEW__________________1 Freshwater Molluscs....................................................................................1 Northern British Columbia Study..................................................................9 CHAPTER 2 - DIVERSITY, DISTRIBUTION AND ECOLOGY OF FRESHWATER MOLLUSC IN NORTHERN BRITISH COLUMBIA: CLIMATIC, GEOGRAPHIC, POST-GLACIAL AND OTHER ENVIRONMENTAL CONSH)ERATIONS__________________________12 Introduction........................................................................................................ 12 M aterials and Methods...................................................................................... 13 Study Area and Site Selection..................................................................... 13 Field Sampling........................................................................................... 14 Data Processing......................................................................................... 16 Environmental Data Analysis......................................................................17 Taxa Summaries........................................................................................ 23 Results and D iscussion....................................................................................... 24 Collection Records.................................................................................... 24 Site Locations............................................................................................26 Distribution............................................................................................... 26 Environmental Data................................................................................... 32 Summary .............................................................................................................59 CHAPTER 3 - COMPARISON OF CONTEMPORARY AND HISTORIC COLLECTIONS OF FRESHWATER MOLLUSCS AS A MEANS OF ASSESSING ENVIRONMENTAL QUALITY.______________________ 65 Introduction........................................................................................................ 65 M aterials and M ethods......................................................................................67 m Results ........................................................................................................... 68 Discussion....................................................................».........»......»»»»........»»* 75 Conclusions......................................................................................................... 79 CHAPTER 4 - THE EFFECTS OF FOREST PRACTICES ON FRESHWATER MOLLUSC HABITAT: A CASE STUDY FROM THE TORPY RIVER WATERSHED IN EAST-CENTRAL BRITISH COLUMBIA_________________________________________________ 81 Introdnction........................................................................................................81 M aterials and Methods...................................................................................... 83 Study Area................................................................................................ 83 Habitat Classification................................................................................ 84 Sampling................................................................................................... 85 Results............................................................................................................... 86 Lotie Habitats............................................................................................ 87 Lentic Habitats...........................................................................................89 Lotie vs. Lentic Habitats.............................................................................90 Community Composition...........................................................................91 Discussion............»....»».»....»..»..»».».»»..»...».....»»....»...»»»..»»...»..».....»».. 92 CHAPTER 5 - INTEGRATION AND CONCLUSIONS_______________ 95 LITERATURE CITED_________________________________________ 99 ACKNOWLEDGEMENTS_____________________________________ 106 APPENDIX I ________________________________________________ 107 IV LIST OF TABLES Table 1-1. Systematic listing of âesbwater mollusc found in northern British Columbia (according to Clarice 1981).......................................................................................... 2 Table 2-1. Group numbers, group composition, table of significant t-tests and figure numbers for range plots and Canonical Correspondence Analysis of the environmental data for the fi«shwater molluscs collected at ecological sites in northern British Columbia......................................................................................... 2 1 Table 2-2. Record types, location map figure number, number of records, number of collections and dates o f collection of freshwater molluscs fiom northern British Columbia................................................................................................................... 24 Table 2-3. Systematic list of the fi%shwater molluscs of northern British Columbia. indicates taxa not found at ecological sites.........................................................25 Table 2-4. Number of freshwater mollusc collection sites in the drainages, major watersheds and biogeoclimatic zones in northern British Columbia............................................ 26 Table 2-5. Summary o f altitude and climate information for the biogeoclimatic zones in northern British Columbia (Meidinger and Pojar 1991). BWBS = Boreal White and Black Spruce; CWH = Coastal Western Hemlock; ESSF = Engelmann Spruce - Subalpine Fir, ICH = Interior Cedar - Hemlock; SWB = Spruce Willow - Birch; SBS = Sub-Boreal Spruce............................................................... 27 Table 2-6. Sample size, mean, standard error and range for the environmental variables measured at the ecological sites in northern British Columbia...................................34 Table 2-7. Significant differences and degrees of fieedom (df) in means of environmental variables found within the groups or subgroups o f freshwater mollusc compared. Table 2-7 (cont.) Significant differences and degrees of fireedom (df) in means o f environmental variables found within the groups or subgroups o f fieshwater mollusc compared......................................................................................................36 Table 2-8. Summary of the distribution and ecology o f the freshwater molluscs from ecological sites in northern British Columbia............................................................60 Table 2-9. Proportions o f fireshwater molluscs from ecological sites in northern British Columbia as compared to the proportions of freshwater molluscs in Britain in relation to dissolved calcium content as described by Russell-Hunter (1978). Northern British Columbia freshwater molluscs used in this comparison were those with n >2 plus the endemic species, P f^ e lla wrighti...................................... 62 Table 3-1. Species lists for historical and contemporary collections made at sites in northern British Columbia. indicates collections that were made within the same water body but not at the same sites. Taxa found in both years are indicated in bold.......... 69 Table 3-2. Comparisons of collection times (i.e. person-hours) and results of Sorenson’s brdex o f Community Similarity made between (1) contemporary collections and (2) historic collections............................................................................................... 72 Table 3-3. Comparison of number of species and percentage of total number of species of the four functional feeding groups o f fireshwater molluscs. Group 1 - Grazers (snails); Group 2 = Suspension feeders (mussels and clams of the genera Sphaerium and Musculium)\ Group 3 - Deposit Feeders (clams of the genera Sphaerium and Musculium); Group 4 =Infiumal feeders (clams of the genus f W m m )............ 74 Table 3-5. Species noted by Clarke (1972,1973a) as occurring at sites listed that are not confirmed by voucher specimens at the Canadian Museum of Nature...................... 78 Table 4-1. Average clam density and environmental conditions (mean ± SE [standard error]) in all categories of habitat and riparian condition in the Lower Torpy River watershed.................................................................................................................... 88 Table 4-2. Culvert and upstream densities o f Pisidium casertanum. indicates density is significantly different than culvert density at P < 0.05............................................... 88 Table 4-3. Results of ANOVA of density o f Pisidium casertanum at culvert pools and various combinations of upstream riparian conditions in the Lower Torpy River watershed................................................................................................................... 89 Table 4-4. Comparison of lotie and lentic habitats (mean ± SB) in the Lower Torpy River Watershed and probability level of differences in means........................................... 90 Table 4-5. List of fi’eshwater molluscs and their habitats in the Torpy River watershed.............91 Table A-1. Site number, collection date, site description, NAD83 UTM coordinates and environmental variables for locations of fi’eshwater mollusc collection sites in northern British Columbia........................................................................................ 107 Table A-2. Systematic listing of the fireshwater mollusc taxa of northern British Columbia including figure number of distribution map in Appendix I, maximum shell size (fiom Clarke 1981), and occurrences out of 176 sites. Uncommon species were found at ^10 sites, common species were found at 11 to 50 sites, and very common species were found at >50 sites.................................................................. 115 VI LISTOFnCURES Figure 2-1. Northern British Columbia freshwater mollusc study area. indicates a sampling location (n = 176). Location of study area in British Columbia is evident on the map at the right................................................................................ 13 Figure 2-2. The biogeoclimatic zones of northern British Columbia. Those zones that apply to freshwater mollusc sites are; BWBS = Boreal White and Black Spruce; CWH = Coastal Western Hemlock; ESSF = Engelmann Spruce Subalpine Fir, ICH = Interior Cedar Hemlock; SWB = Spruce - Willow Birch; and SBS = Sub-Boreal Spruce. indicates a collection site...................... 18 Figure 2-3. Major watersheds occurring in northern British Columbia. The Coastal, Fraser, Nass, Skeena, Stikine, Taku and Yukon watersheds drain into the Pacific Ocean; the Liard, Mackenzie and Peace watersheds drain into the Arctic Ocean......................................................................................................19 Figure 2-4. Ecological sites of collections of freshwater molluscs in northern British Columbia (i.e., “N l” sites). indicates a collection site; n = 114........................ 19 Figure 2-5. Non-ecological sites of collections of freshwater molluscs in northern British Columbia (i.e., “NO” sites). indicates collection sites; n = 41.......................... 20 Figure 2-6. Clarke’s collections of freshwater molluscs in northern British Columbia (i.e., “CN” sites). indicates collection sites; n = 25........................................... 20 Figure 2-7. Miscellaneous collections of freshwater molluscs in northern British Columbia (i.e., “MN” sites). indicates collection sites; n = 15.......................................... 21 Figure 2-8. Dispersal routes of freshwater fishes firom the (a) Bering, (b) Pacific and (c) Mississippi réfugia. These patterns may also be reflected in dispersal patterns of freshwater molluscs. Area of refuge from the ice sheet is stippled. Dispersal routes are indicated by arrows. Dotted lines delineate major drainage areas.(From McPhail and Lindsey 1970.)................................................ 29 Figure 2-9. Group 1: Range and means of environmental variables measured for Family Valvatidae, Family Acroloxidae and Family Ancylidae. “ I” indicates mean. Minimum calcium concentration is indicated on plot (c)........................................ 37 Figure 2-10. Group 2: Range and means of environmental variables measured for Family Lymnaeidae. “ I” indicates mean. Minimum calcium concentration is indicated on plot (c)...............................................................................................................38 Figure 2-11. Group 3: Range and means of environmental variables measured for Family Physidae. “ | ” indicates mean. Minimum calcium concentration is indicated on plot (c).............................................................................................................. 40 Figure 2-12. Group 4: Range and means of environmental variables measured for Family Planoibidae. “ I” indicates mean. Minimum calcium concentration is indicated on plot (c).............................................................................................................. 41 Figure 2-13. Group 5: Range and means of environmental variables measured for Family Margaritiferidae, Family Unionidae and Family Sphaeriidae; genus Sphaerium and genus Musculium. “ I” indicates mean. Minimum calcium concentration is indicated on plot (c)........................................................ 43 Figure 2-14. Group 6. Range and means of environmental variables measured for Family Sphaeriidae, genus Pisu/iuin. “ I” indicates mean. Minimum calcium concentration is indicated on plot (c)..................................................................... 45 Figure 2-15. Canonical Correspondence Analysis o f environmental variables and taxa from Group 1 (Family Valvatidae, Family Acroloxidae and Family Ancylidae)............47 vu Figure 2-16. Canonical Correspondence Analysis of environmental variables and taxa from Group 2 ( Family Lymnaeidae)..............................................................................47 Figure 2-17. Canonical Correspondence Analysis of environmental variables and taxa from Group 3 (Family Physidae)....................................................................................48 Figure 2-18. Canonical Correspondence Analysis of environmental variables and taxa from Group 4 (Family Planorbidae)............................................................................... 48 Figure 2-19. Canonical Correspondence Analysis of environmental variables and taxa frx)m Group 5 (Family Margaritiferidae, Family Unionidae and genus Sphaerium and Musculium of Family Sphaeriidae)..................................................................49 Figure 2-20. Canonical Correspondence Analysis of environmental variables and taxa from Group 6 (genus Pisidium of Family Sphaeriidae).................................................. 49 Figure 3-1. Regional Districts of British Columbia and intercensal human population estimates in 1971 and 1996 for regional districts within northern British Columbia with percent change during this time period. (From British Columbia Statistics, Ministry of Finance and Corporate Relations, Victoria, BC.)................66 Figure 3-2. Vertical icicle plot of the cluster analysis of the contemporary and historic collection sites of freshwater molluscs o f northern British Columbia based on unweighted pair-group average o f the species lists in Table 3-1. indicates same-site pairs that join directly....................................................... 73 Figure 4-1. The Torpy River Watershed and its location in British Columbia......................... 83 Figure 4-2. Density of Pisidium casertanum along the Lower Torpy River Road. indicates area of high density (>10,000 m'^)....................................................87 Figure 5-1. (a) Number of species per site at ecological sites in northern British Columbia Oarge-scale study) with percentage of sites per species number and number of lentic and lotie sites per species number, (b) Number o f species per site in the Lower TorpyRiver watershed and Pass Lake (small-scale study)with percentage of sites per species number and number of lentic and lotie sites per species number...................................................................................................................96 Figures A-1 to A-63. Distribution maps of taxa o f freshwater molluscs collected in northern British Columbia.......................................................................... 117- 234 Figure A-64. Sites where freshwater molluscs were not collected . ..236 Figure A-6S. The ecoprovinces of northern British Columbia.”*” indicates a collection site... 238 vm CHAPTER 1 - INTRODUCTION AND OVERVIEW Environmental change may he reflected in changes to water quality. Freshwater molluscs may be excellent monitors of water quality because of their long life spans, feeding habits, and persistent shells (Strayer 1999a). Freshwater molluscs are common components of inland aquatic ecosystems, yet little is known about this group in northern British Columbia (BC). In this study, biodiversity, distribution and physico-chemical conditions of the habitats of fl-eshwater molluscs was examined on large and small spatial scales. In addition, contemporary and historical collection records were compared to assess whether temporal changes in mollusc biodiversity may reflect environmental change. Freshwater Molluscs Phylum Mollusca comprises invertebrate animals that are soft-bodied, non-segmented and have a mantle (an enveloping sheet of tissue that in most taxa secretes a calcareous shell) (Clarke 1981). In fireshwater, molluscs occur in habitats ranging firom large lakes and rivers to small, even temporary, ponds (Pennak 1989). Freshwater molluscs are primary consumers being surface or suspension feeders (Brown 1991, McMahon 1991) and are prey items for ecologically and economically important aquatic and terrestrial predators (Pennak 1989). Freshwater molluscs are firom Class Gastropoda and Class Bivalvia, and comprise nine families in northern BC (Table l-l). Class Gastropoda Gastropods, or snails, have a muscular foot on top of which sits a visceral mass commonly protected by a univalved diell that is typically coiled (Pechenik 1996). The fireshwater snails include the Subclass Piosobranchia (prosobranchs) and the Subclass Pulmonata (pulmonates). I Table l-l. Systematic listing of freshwater mollusc found in northern British Columbia (according to Clarice 1981). Class Gastropoda (Snails) Class Bivalvia (Mussels and Clams) Subclass Prosobranchia (Gilled snails) Order Mesogastropoda Family Valvatidae Subclass Pulmonata (Lunged snails) Order Basommotophora Family Acroloxidae Family Lymnaeidae Family Physidae Family Planorbidae Family Ancylidae Order Eulamellibranchia Superfamily Unionacea Family Margaritiferidae Family Unionidae Superfamily Sphaeriacea Family Sphaeriidae Subclass Prosobranchia hi North America (which herein refers to that area north of Mexico), there are 49 genera and -350 species of prosobranch snails (Burch 1989). These snails invaded river systems from estuaries and retain the true gills of their marine ancestors (Fuller 1974, McMahon 1983). Prosobranchs have an operculum, which is a rigid or leathery disc that seals the shell aperture when the snail’s body is withdrawn into the shell (Harman and Berg 1971). Most prosobranchs are dioecious (i.e., separate sexes) (Rupert and Barnes 1994). Prosobranchs tend have limited distributions because they tolerate only limited variations in environmental conditions (i.e., stenotopic; Boss 1978) or have limited abilities to disperse (Harman and Berg 1971). Prosobranchs tend to live in relatively deep water and so are less likely to disperse passively (i.e., dispersal due to the movement of other animals) than are pulmonates, which are often restricted to shallow water by their dependence on atmospheric air (Boss 1978). O f the ten families in the Subclass Prosobranchia in North America (Burch 1989), only members of the Family Valvatidae have been found in northern BC. Family Valvatidae There are 11 species in Family Valvatidae (valvatids) in North America (Turgeon et al. 1998). These snails are generally less than eight mm in diameter with dextral coiling (coiling from left to right, as seen from the apex) (Burch 1989). Valvatids are unique among the Subclass Prosobranchia in being monoecious (i.e., hermaphroditic; Heard 1963), and unique within the Order Mesogastropoda in possessing a bipectinate gill (Rupert and Barnes 1994). This gill is feather-like and external (Pennak 1989) and appears to allow valvatids to tolerate fine substrates by permitting good circulation for respiration without clogging the mantle cavity (Yonge 1947). Taxonomic issues within the Valvatidae Clarice (1981) identified two species of valvatids firom western Canada, Valvata sincera sincera and V. sincera helicoidea. The raised axial striae (i.e. spiral ridges) used by Clarice (1981, 1973b) as characteristic of V. sincera sincera is interpreted by Burch (1989) as characteristic of V. lewisi lewisi. The fine axial striae used by Clarke (1981) as characteristic of V. sincera helicoidea is interpreted by Burch (1989) as characteristic of V. sincera sincera. This study uses the identifying characteristics of Burch (1989) and Clarice’s records have been revised accordingly. Subclass Pulmonata There are 29 genera and -150 species of pulmonate snails in North America (Burch 1989). These snails do not have true gills or an operculum (Rupert and Barnes 1994). Pulmonates first invaded terrestrial habitats by losing their gills and developing a richly vascularized pulmonary cavity in the mantle used to extract oxygen firom the air (Brown 1991). Their subsequent invasion of fieshwater can be ranked in a series showing progressively greater degrees o f re-adaptation to aquatic life (Russell-Hunter 1978). At one end of the series are some species of Lymnaeidae that breath air primarily. Intermediate species (i.e., some species of Lymnaeidae and the Physidae) use the pulmonary cavity to exchange oxygen with air or with water. At the other end of the series are the truly aquatic species that have developed pseudobranchs, which are gill-lobes not homologous with any part of the true gills of other molluscs (McMahon 1983). These are the Planorbidae and the fireshwater limpets (Acroloxidae and Ancylidae). All pulmonate snails are monoecious (i.e., hermaphroditic; Brown 1991). Pulmonates usually have broad physiological and ecological tolerances (euryoecic) allowing them to be excellent colonizers of a wide range of habitats (Davis 1982). Reliance on atmospheric air restricts many pulmonates to shallow water where they can become affixed to other animals and passively dispersed (Boss 1978). Most post-glacially emerging fireshwater habitats were probably colonized by molluscs arriving via passive dispersal. This concurs with the observation that there are far more pulmonate than prosobranch snails in northern BC (Clarice 1981). All five families of North American pulmonates (Burch 1989) have been found in northern BC (Table 1-1). Family Acroloxidae Members of the Family Acroloxidae are small limpets that are truly aquatic (RussellHunter 1978). They occur mainly in Eurasia where there are six species (Clarke 1970). The one species in North America, Acroloxus coloradensis, displays a rare and disjunct distribution and has been considered for endangered species designation in both Canada and the USA (Lee and Ackerman 1999c). Acroloxidae have the apex of the shell tipped to the left so the aperture is considered to be on the right (Brown 1991). This is considered dextral body organization and the pseudobranch is on the right side of the animal’s body (Burch 1989). Family Lymnaeidae Family Lymnaeidae (lymnaeids) is the most diverse pulmonate group in the northern US and Canada (Brown 1991) with 57 species (Turgeon et al. 1998). Most lymnaeids are high spired and have dextral shell coiling although one western group has limpet-shaped shells (Burch 1989). The tentacles of lymnaeids are broad, flat and triangular rather than the long, thin, filamentous tentacles of other freshwater pulmonates (Burch 1989). Lymnaeids respire via their pulmonary cavity and primarily rely on aerial respiration (Burch 1989) making them somewhat amphibious (Brown et al. 1998). They are considered the most primitive of the freshwater pulmonate families, as they are unspecialized structurally for aquatic life (Russell-Hunter 1978). Family Physidae The 43 species of the Family Physidae (physids) in North America (Turgeon et al. 1998) are the most abundant and widespread of the freshwater gastropods (Burch 1989). Physids are high spired and have sinistral shell coiling (i.e., coiling from right to left, as seen fix>m the apex). Some physids rely on aerial respiration and are somewhat amphibious (Brown et al. 1998) whereas others fill the pulmonary cavity with water and use it as a derived gill (Russell-Hunter 1978). In these respects, physids are considered more advanced in their adaptation to aquatic life than the lymnaeids. Taxonomic issues within the Physidae Different authors use different generic names to describe species within the Family Physidae. The exception is the genus Aplexa, which has a distinct morphology. Prior to Te’s (1978) revision of the Family Physidae, most authors placed all other North American physids in the genus Physa (e.g., Clarice 1973b, 1981). Te’s (1978) study assigned the North American physids into the geaen Aplexa, Physa, and Physella based on detailed anatomical studies. While this classification is used by Burch (1989) and by Turgeon et al. (1998), Wu (1989) and Wu and Beetle (1995) used another system. Wu and co-woricers assign all North American physids (other than Aplexa) to the genus Physa, which was in turn subdivided into three subgenera based on the type of the terminal male genitalia (Physa, Physella or Physodon). For example, the species referred to as Physa gyrina by Clarke (1973b, 1981) is referred to as Physella gyrina by Burch (1989) and Turgeon et al. (1998), and as Physa (Physella) gyrina by Wu (1989) and Wu and Beetle (1995). Therefore, the generic name used depends on the date of the publication and/or on the taxonomic preference of the author. The nomenclature used in this study is according to Turgeon et al. (1998), which follows Te’s (1978) classification. Collections made in the course of this study were identified to species for the genera Aplexa and Physa, but not for the genus Physella. The exception was Physella wrighti, which was identified by its presence in its type locality, Liard River Hotsprings. Identification of other Physella species required anatomical expertise that was not available. Other members of the genus Physella that are identified to species in this study are from collections held at the Canadian Museum ofNattne. Family Planorbidae There are 48 species in Family Planorbidae (planorbids) in North America (Turgeon et al. 1998). With a few exceptions, planorbid shells are discoidal (i.e., coiled in one plane) and all are sinistral (Burch 1989). However, many species appear to be dextral because the shell tips to the left side, hence they are termed ’’pseudodextral” or “ultrasinistral” (Burch 1989). Planorbid snails are truly aquatic having a pseudobranch on the left side of the body (Burch 1989, Brown et al. 1998). The respiratory pigment of haemoglobin in this family gives the animals a reddish appearance (McMahon 1983). Family Ancylidae There are 13 species in Family Ancylidae (ancylids) in North America (Turgeon et al. 1998). These truly aquatic fieshwater limpets have small, cap-shaped shells with the apex tipped to the right so that the aperture is considered to be on the left (Brown 1991). This is considered sinistral body organization and the pseudobranch is on the left side of the txxly (Burch 1989). Class Bivalvia The fireshwater bivalves in northern BC are firom three families; Margaritiferidae and Unionidae, the fireshwater mussels, and Sphaeriidae, the fireshwater clams. All native Canadian fireshwater bivalves are in the Order Eulamellibranchia. This order is characterized by a hinge containing a few teeth of diverse shapes and sizes, two large adductor muscles of about the same size, one anterior and one posterior, a partly closed mantle with well-developed siphons, and leaf-like gills within the mantle cavity (Clarke 1981). Families Margaritiferidae and Family Unionidae - Freshwater Mussels Freshwater mussels may have first evolved in ihe Mississippi drainage basin where the greatest diversity o f species is found (Pennak 1989). There are five species of Margaritiferidae and 299 species o f Unionidae in North America (Turgeon et al. 1998). The Margaritiferidae and Unionidae are separated by soft tissue characteristics with the main differentiating feature being the lack of siphons in the Margaritiferidae (Burch 1975b). All native North American fireshwater mussels are associated with benthic sediments where they are suspension feeders. Dispersal occurs in the form of unique, glochidial larva that become temporary and obligatory parasites on fish (Pennak 1989). This reproductive method limits passive dispersal and is likely to have resulted in the evolution of the relatively large number o f genera and species (Buricy 1983). In the Pacific drainage of North America, the mussel fauna consists of genera Anodonta, Gonidea and Margaritifera (Pennak 1989). The range of A. kennerlyi and M. falcata includes parts of northern BC, whereas G. angulata and other species o f Anodonta occur only in southern BC. Family Sphaeriidae - Freshwater Clams The family Sphaeriidae (sphaeriids) has evolved along two major lines. The first, genera Sphaerium and Musculium, are associated with benthic surfaces (McMahon 1991) and the second, genus Pisidium, lives within organically rich sediments (Lopez and Holopainen 1987). Sphaeriids are able to disperse passively by clamping on to the limbs of aquatic insects, the feathers of water fowl, or even the limbs of salamanders, and some can survive ingestion and regurgitation by ducks (see review in McMahon 1991). Genus Sphaerium and Genus Muscuiium There are eight species in the genus Sphaerium and four species in the genus Muscuiium in North America (Turgeon et ai. 1998). Both genera have branchial and anal siphons but Sphaerium have these siphons fused only at their bases, whereas Muscuiium have them joined for most of their length. Both genera have the posterior end of the shell longer than the anterior end but the shell of Muscuiium differs firom that of Sphaerium in having raised umbonal (umbo = the apex of a valve) caps (Burch 1975a). Sphaerium and Muscuiium species can use their siphons in suspension or deposit feeding, or can use their ciliated foot epithelium to collect food in a method called pedal deposit feeding (Hombach et ai. 1984, Way 1989, McMahon 1991). Genus Pisidium Pisidium species are the most cosmopolitan, abundant and widely distributed family of fireshwater bivalves (Buricy 1983). There are 26 species of Pisidium described from North America (Turgeon et ai. 1998) plus at least one undescribed species (Frest and Johaimes 1995). Pisidium species have the anal siphon present but the branchial siphon is absent or represented by a slit in the mantle, and the shell has a longer posterior than anterior end (Burch 1975a). Pisidium species live in horizontal burrows within organically rich sediments where they 8 filter feed on interstitial bacteria (Meier-Brook 1969, Lopez and Holopainen 1987). Size may be a constraint of this mode of feeding and may explain the characteristically small shell size (1.7 to 12 mm long) of many Pisidium species (Lopez and Holopainen 1987). Northern British Columbia Study Northern BC, which in this study is defined as the region north of approximately S4°N latitude, has abundant fi-eshwater habitats. These habitats are relatively young geologically and are inhabited by a variety of organisms including fireshwater molluscs. Studies of fireshwater molluscs were undertaken to document their diversity, distribution and ecology. In general, the euryoecic nature of many pulmonate snails and sphaeriid clams has resulted in their widespread distribution, whereas the stenotopic nature of many prosobranch snails and reproductive characteristics of mussels has restricted their distributions. Within their range, the habitat requirements of individual taxa may restrict their distribution to certain water bodies. Water conditions, macro-vegetation, and substratum are associated with fiieshwater snail fauna (Harman 1972, Okland 1983). Trophic condition also seems to be of particular importance in detennining the presence of certain molluscs (Green 1971, Clarice 1979a, Clarice 1979b, Costil and Clement 1996, Dillon 1997). Lodge et al. (1987) and Brown et ai. (1998) noted the importance of disturbance, competition, food selection, predation and physiochemical regimes in structuring fieshwater snail assemblages. However, Haag and Warren (1998) found that the pattern of fieshwater mussel assemblages was better explained by the pattern of fish communities rather than by ecological factors. According to Lodge et al. (1987), biogeognqthic and evolutionary history determines the potential pool of snail colonizers, while abiotic Actors such as climate, chemistry and substrate, act as a filter for colonists. It is likely that the same can be said for fieshwater clams, while mussel distribution is linked to that of their fish hosts. These factors act on different spatial scales and vary in importance in different water bodies. Thus, it is likely that many processes may explain the heterogeneity of community structures in freshwater molluscs. The difficult issue will be to determine the relative importance of each of them for particular taxa. Chapter 2 presents the results of a large-scale spatial study based on new and existing collections, which were assembled to determine the diversity, distribution and ecology of freshwater molluscs in northern BC. The distribution of molluscs taxa were examined from the perspective of large-scale climatic differences, location of potential geographic barriers, hypothesized post-glacial dispersion routes, and measurements of selected environmental variables. Analyses of some of the putative factors that may be responsible for the current patterns of distribution are presented. It is reasonable to suggest that increased population and resource use in northern BC may have impacted aquatic ecosystems in a manner that may be reflected in the community structure of molluscs. Historical information on the freshwater molluscs of northern BC was available from collections made during the summers of 1972 and 1973 by Clarke (Lee and Ackerman 1999a). In Chapter 3, these data are compared to contemporary data observed at the same sites. Forest practices are causing landscape alterations in northern BC that have likely affected aquatic habitats through increased sediment deposition and changes in water temperature regimes. These changes are likely to affect freshwater molluscs. While several authors have attributed changes in freshwater mussel community structure to deforestation and loss of riparian vegetation (Neves 1992, Williams et al. 1993, Morris and Coricum 1996, Bogan 1998, Box and Mossa 1999), similar studies of the effects of such changes on freshwater snails or clams do not exist. Chapter 4 presents the results of a small-scale spatial study to assess the impact o f forest practices on freshwater snail and clam habitat in a northern boreal watershed. Both quantitative and qualitative assessments of freshwater habitats were made to track anthropogenic impacts within this watershed. The findings suggest that anthropogenic activities may be affecting the 10 abundance of certain taxa o f freshwater mollusc within this watershed. Chapter 5 presents a summary of the findings fi-om the perspective o f large and small spatial scales. This thesis contributes to our understanding o f the historical, geographical, ecological and anthropogenic processes that affect the distribution, ecology and community structure of fireshwater molluscs in northern BC. This provides a scientific basis upon which further research can be conducted to understand, conserve and protect our freshwater organisms and ecosystems. 11 CHAPTER 2 - DIVERSITY, DISTRIBUTION AND ECOLOGY OF FRESHWATER MOLLUSC IN NORTHERN BRITISH COLUMBIA: CLIMATIC, GEOGRAPHIC, POST-GLACIAL AND OTHER ENVIRONMENTAL CONSIDERATIONS. Introduction This study examines the diversity, distribution and ecology of freshwater molluscs in northern British Columbia (BC). This relatively large area (-550,000 km^; Figure 2-1) contains: (1) regions with mean annual temperature ranging from -2.9 to 8.7°C; (2) major drainages basins that lead into the Pacific and Arctic oceans; (3) is crossed by the Rocky Mountains in the northeast; and (4) has been ice fi%e since the retreat of glaciers about 10,000 years ago. This heterogeneous landscape contains abundant water bodies that are likely to have different histories and ecological characteristics. New and existing field data were used to examine distribution of freshwater mollusc taxa in northern BC. The following factors were examined in an effort to identify the likely causes of the present distributions of molluscs: (1) climatic effects - based on biogeoclimatic zones (Meidinger and Pojar 1991), as some climatic conditions may exclude molluscs; (2) post-glacial history, which influenced how molluscs were able to disperse in northern BC; (3) dispersal mechanisms, as some molluscs may be unable to cross geographic barriers; and (4) alien species (i.e., those carried outside their original ranges by human activities), which can affect the distribution of freshwater molluscs (Strayer 1999b). As freshwater molluscs respond to the characteristics of the water in which they live (Brown 1991, McMahon 1991), selected physico-chemical water conditions were measured to record possible ecological requirements of the mollusc taxa of northern BC. Throughout North America, many fieshwater molluscs are imperiled due to habitat alteration and the introduction of exotic species (Brown et al. 1998, Strayer 1999b). Conservation and rehabilitation efforts can only be based on existing information. The purpose 12 of this study is record some of the historical, geographic and ecological factors that may be responsible for the observed patterns of distribution of freshwater molluscs so that this information can act as a basis for the protection and conservation of the freshwater molluscs of northern BC. M aterials and Methods Study Area and Site Selection The study area (Figure 2-1) incorporated BC north of approximately S4"N latitude with the exception of the Queen Charlotte Islands and the extreme northwest of the province, which were not accessed during the course of the study. As the only access road between the west and east of the far north of BC requires incursion into the Yukon at two points, some collections were also made in the Yukon. Site selection was made in an attempt to maximize biodiversity information while including as much of northern BC as was allowed by accessibility, time and Figure 2-1. Northern British Columbia freshwater mollusc study area. indicates a sampling location (n = 176). Location of study area in British Columbia is evident on the map a tth e r i^ t 13 budgetary constraints. Sites tended to be large, vegetated, lentic (standing) water bodies, which provide habitats for larger number of molluscs than do lotie (flowing) or smaller lentic sites (Lassen 1975). Site selection also included sites collected historically by Clarke (1972,1973a). Field Sampling Most of the area was sampled August 6 - 26, 1997 with other collection dates noted in Table A-1 (Appendix I). Most sampling was done from road-accessible shore areas but if this did not appear to provide the best habitat to ensure adequate representation of the mollusc fauna, a canoe was used to access other areas. Molluscs were generally collected after entering the water wearing chest-waders. An 18 cm diameter stainless steel mesh net (nominal pore size of -1.5 mm) attached to a 1.5 m broom handle with hose clamps was used to sweep vegetation for snails and to dig into soft sediments for the collection of mussels, clams and sediment grazing snails to the maximum depth allowed by the waders (-1.5 m). Aquatic vegetation, such as lily pads (Nuphar sp.), was also examined for molluscs and submerged rock and wood, when present, were lifted off the bottom for examination to the maximum depth possible (-0.6 m). In some instances when the canoe was used, sampling was attempted in deeper water (maximum 5 m depth) with a PONAR grab (Wildco, Saginaw, MI, USA) with a 15 2 cm x 15.2 cm sampling area (0.231 m^). All molluscs collected were kept in water and put into an insulated container for later processing. Specimens were relaxed before preservation by sprinkling the surface o f the water in the collection container with granulated menthol (Brown 1991). The addition of a drop of propylene phenoxetol was made to help relax difficult taxa (McMahon 1991). Jars containing specimens and relaxants were left undisturbed ovem i^t. Water was then replaced with a solution of 5% formaldehyde in which specimens were left for 3-7 days to fix tissue. Specimens were then moved to a long-term preservative o f 70% ethanol containing 3-5% glycerin by volume to help keep tissues pliable (McMahon 1991). 14 All specimens were later sorted by taxa using criteria presented in Burch (1975a, 1975b, 1989), Clarke (1973b, 1981) and Herrington (1962,1965). Voucher specimens were established in a reference collections at the University of Northern EC and at the Royal British Columbia Museum. Water quality measurements were made once at each site, usually from an area close to shore and within the top 10 to 15 cm of water. The measurements made were: (1) water temperature (°C) with an alcohol thermometer; (2) dissolved oxygen (% saturation), and (3) conductivity (microSiemens - pS) with a Coming Checkmate Modular Meter System (Coming Inc., Coming, NY, USA) and; (4) pH with a Canlab (Mississauga, ON, Canada) portable digital pH meter Model 607. Rodhe (1949) found that the average proportions of the major dissolved mineral constituents of freshwater were about the same regardless of the absolute conductivity. Thus, the calcium concentration of freshwater can be approximated from the conductivity reading. The data presented in Table 2 o f Rodhe (1949) was used to produce a regression equation to convert conductivity measures into dissolved calcium levels (mg/1). The equation for this conversion is: mg Calcium/litre = (-1.3 ± 0.2) + (0.1491 ± 0.0008) x conductivity, n = 20, r^ = 0.9995, and p <0.001. Rhode (1949) based his studies on measurements taken from lakes. It was assumed that the relationship between conductivity and calcium held true in all systems sampled. The NAD83 (North American Datum 1983) UTM (Universal Transverse Mercator) coordinates for each field site were read with a Trimble Geo-Explorer (Trimble Navigation, Sunnyvale, CA, USA). Print and slide photographs were taken of each site with the compass direction of the angle of view noted. Some contemporary collections of freshwater molluscs were also made from sites where no ecological, UTM or photographic information was recorded. 15 Data Processing Contemporary collections of freshwater molluscs were classified as two types: (1) ecological sites, where samples were collected and environmental variables, NAD83 UTM and photographs were recorded. These sites were assigned record numbers preceded with “N l” and; (2) non-ecological sites, where samples were collected but only the locations were recorded. These sites were assigned record numbers preceded with ‘"NO”. A visit to the Canadian Museum of Nature (CMN) was made in December 1997 to obtain information on their collections of BC fireshwater molluscs. The collections made by Clarke in northern BC during 1972 and 1973 were combined with his field notes (Clarke 1972,1973a) into site summaries with record numbers preceded by "CN" (Clarke North). All other historic collections firom northern BC were made between 1875 and 1974 and these site summaries were assigned record numbers preceded by "MN" (Miscellaneous North). Royal British Columbia Museum (RBCM) holdings provided no additional information. However, RBCM staff provided an unpublished report by a fi%shwater malacologist. Dr. Dwight D. Taylor (Taylor 1993). This report included information on collections made in the Atlin area of northern BC and these have been included with other records preceded by “MhT’. For all sites without UTM coordinates, the site descriptions were used to find the location on 1:5(X)00 scale maps fix>m which the NAD27 UTM coordinate was recorded. These coordinates were converted to NAD83 using Arc/Info software (ESRI Incorporated, Redlands, CA,USA). Information on all of these four site types (i.e., N l, NO, CN and MN) was compiled into Lee and Ackerman (1999a) resulting in information on 195 sites. For mtytping purposes, collection sites that coincided were combined resulting in 176 sites fimm the original 195 records. The NAD83 coordinates and a taxa list for each of the 176 sites was supplied to the 16 Geographic Information Services technical staff at the Conservation Data Centre, a unit of the Resource and Inventory Branch of the Ministry of Environment in Victoria, BC. With their instruction and assistance, a map of all the sites was produced (Figure 2-1) and overlain with the theme layers of biogeoclimatic zone (Figure 2-2), watershed (Figure 2-3), and ecoprovince (Figure A-6S in Appendix I) and in order to assign these attributes to each site. Distribution maps were produced for each type of record classification (Nl - Figure 2-4; NO - Figure 2-5, CN - Figure 2-6; and MN - Figure 2-7), for each of the taxa recorded fi»m northern BC (Figures A1 - A-63 in Appendix I) and for the sites where no molluscs were collected (Figure A-64). Taxa were considered uncommon if they were recorded firom <10 sites, common if recorded firom 11 to 50 sites, and very common if recorded firom >50 sites (Table 2-8). Environmental Data Analysis T-tests, range plots and Canonical Correspondence Analysis (CCA) were used to examine environmental data. As CCA requires at least as many taxa as environmental variables, families represented by fewer than four taxa were combined with other families or genera. This resulted in six groups ranging in size fiorn four to 14 taxa (Table 2-1). Group 1 comprised gastropod families with one or two taxa (Valvatidae, Acroloxidae and Ancylidae). Group 2, 3 and 4 comprised Families Lymnaeidae, Physidae and Planorbidae, respectively. Group 5 comprised the two families of mussels plus the genera Musculium and Sphaerium of the Family Sphaeriidae, and Group 6 comprised the genus Pisidium of the Family Sphaeriidae. It was appropriate to divide the family Sphaeriidae in this matter based on functional differences. Species of the genera Sphaerium and Musculium are surface feeders (Way 1989), whereas species of the genus Pisidium are interstitial feeders (Lopez and Holopainen 1987). Results of these analyses are discussed by Amily for gastropods and mussels, and by genus for sphaeriids. 17 Figure 2-2. The biogeoclimatic zones of northern British Columbia. Those zones that apply to freshwater mollusc sites are: EWES = Boreal White and Black Spruce; CWH = Coastal Western Hemlock; ESSF = Engelmann Spruce - Subalpine Fir, ICH = hiterior Cedar Hemlock; SWB = Spruce - Willow - Birch; and SES = Sub-Boreal Spruce. indicates a collection site. 18 r m à w :6 ■ /(' ÿrh A 2 # Albers Equal Area Conic Prajection NAD 83 Datum Malor Watersheds 0 100 1 -------1 200km ÛTS Albefs EOual Aroa Conic Preiaction Figure 2-3. Major watersheds occurring in northern British Columbia. The Coastal, Fraser, Nass, Skeena, Stikine, Taku and Yukon watersheds drain into the Pacific Ocean; the Liard, Mackenzie and Peace watersheds drain into the Arctic Ocean. Ireshwatar Mollusc Ecological Sites NADKIOMwn Figure 2-4. Ecological sites of collections of freshwater molluscs in northern British Columbia (i.e., “N l” sites). indicates a collection site; n = 114. 19 I^hw ater Mollusc Non-Ecological Sites 6— lOiwCwitPwHdlow NAOnOWwn Figure 2>S. Non-ecological sites of collections of freshwater molluscs in northern British Columbia (i.e., “NO” sites). indicates collection sites; n = 41. FmhMMlw MoIIu k Coleciion SMas E»1<»iwCcwleW«Hclla> MODMDauwi Figure 2-6. Clarice’s collections o f freshwater molluscs in northern British Columbia (i.e., “CN” sites). “•” indicates collection sites; n = 25. 20 .MisceHarwous FfMtwwter MoHusc CoWedion Sites NWMOWwm Figure 2-7. Miscellaneous collections of freshwater molluscs in northern British Columbia (i.e., “MN” sites). indicates collection sites; n = 15. Table 2-1. Group numbers, group composition, table o f significant t-tests and figure numbers for range plots and Canonical Correspondence Analysis of the environmental data for the freshwater molluscs collected at ecological sites in northern British Columbia. 1 Family Valvatidae (2 taxa) Family Acroloxidae (1 taxa) Family Ancylidae (I taxa) Table 2-7 Figure 2-9 Canonical Correspondence Analysis Figure 2-15 2 Family Lymnaeidae (9 taxa, 1 generic identification) Table 2-7 Figure 2-10 Figure 2-16 3 Family Physidae (3 taxa, 1 generic identification) Table 2-7 Figure 2-11 Figure 2-17 4 Family Planorbidae (11 taxa) Table 2-7 Figure 2-12 Figure 2-18 5 Family Margaritiferidae (1 taxa) Family Unionidae (1 taxa) Family Sphaeriidae; Genus Sphaerium (3 taxa) Genus Musculium (2 taxa) Table 2-7 Figure 2-13 Figure 2-19 6 Family Sphaeriidae; Genus Pisùüum (13 taxa, 1 generic identification) Table 2-7 Figure 2-14 Figure 2-20 Group Group Composition No. Significant t-tests Range Plot 21 T-tests A t-test (Statistica 5.1, StatSoft, Inc. 1997) was used to evaluate the difference in mean between each environmental variable measured for each taxon in families or genera examined. A probability level (p-value) of 0.05 or less was accepted as indication that the two taxa being compared had significantly different means of the particular variable. Range Plots Plots of the range of each environmental variable measured for each taxon were produced for the six groups (Figures 2-9 to 2-14). The value measured for taxa found at single sites were indicated with a dot (“•”). The mean for each variable was mariced with a vertical line and the plots for conductivity included the minimum calcium concentration calculated. Canonical Correspondence Analysis Canonical Correspondence Analysis (CCA), which examines the relationship of taxa and environmental variables, was undertaken using CANOCO version 4.0 software (Microcomputer Power, Ithaca, NY, USA) on the six groups (Figures 2-15 to 2-20). Temperature and pH measures firom all the ecological sites displayed normal distributions (Shapiro-Wilks W test; W = 0.9854, p < 0.7909 and W = 0.9774, p < 0.3720 respectively). Dissolved oxygen and conductivity did not display normal distributions (Shapiro-Wilks W test; W = 0.9547, p < 0.0048 and W = 0.7404, p < 0.0001 respectively). To achieve normality, the two measures of dissolved oxygen >100% were reduced to 100% and the arc sine of the square root of all o f these values was calculated (Shrq)iro-Wilks W test; W = 0.9714, p < 0.1512). Conductivity was transformed to a log(10) value to achieve normality (Sh^iro-W ilks W test; W = 0.9774, p < 0.3720). All environmental variables, including the normalized dissolved oxygen and conductivity, were standardized by dividing the raw value minus the mean, by the standard deviation (i.e., standard deviates). These standardized values were the data used in the CCA analysis. 22 CCA supplies a probability value (p-value) of the relationship of the species data to the environmental variables and accounts for the amount of inter-community variation that is explained by these variables. This analysis assumes that taxa respond to environmental variables in a unimodal manner. The response of each taxon is compiled into a taxon score, which results in placement on a biplot (e.g.. Figure 2-IS). Each taxon appears on the plot nearest to the environmental variable to which it has the strongest unimodal response (ter Braak and Émilauer 1998). Attention must be paid to sample size when interpreting CCA plots as sample size may not be sufficient to produce the assumed unimodal response to the environmental variables. Taxa Summaries The taxonomy used in this study is according to Turgeon et al. (1998) for species and Burch (1989) for subspecies identifications. The common names for the taxa were taken from Turgeon et ai. (1998) unless otherwise indicated (Appendix I). The information obtained for each taxon identified from northern BC has been summarized and is discussed in Appendix I. Each summary includes a distribution map, collection site numbers, and a list of drainages/watersheds, ecoprovinces/ecoregions, and biogeoclimatic zones in which each taxon was found. For each taxon found at environmental sites, the mean, standard error, and minimum and maximum measure of each environmental variable have been tabulated. The illustrations accothpanying the gastropod summaries were taken from Burch (1989) with the exception o f Acroloxus coloradensis and Physella wrighti, which were provided by Trent Hoover (graduate student at UNBC), and Ferrissia parallelus and Planorbella binneyi, which were taken from Clarke (1981). The bivalve illustrations were taken from Clarice (1973b) with the exception o f Margaritifera falcata and Pisidium insigne, which were taken from Clarice (1981), and Anodonta kennerfyi. which was taken fiom Burch (1975b). All hinge illustrations for the genus Pisidium were taken fiom Herrington (1962). 23 Results and Discussion Collection Records Collections were made at 155 sites in northern BC, which when combined with historic records available from 40 sites provided a total of 195 sites. Total collections at these sites provided 1108 collections identified by taxa (Table 2-2). Table A-1 in Appendix I presents site descriptions and NAD83 coordinates for all sites. Table 2-2. Record types, location map figure number, number of records, number of collections and dates of collection of freshwater molluscs from northern British Columbia. Number of Number of Dates of Collection Collections Records Record numbers Location Map N1000-N1113 Figure 2-4 114 798 1997 and 1998 N0100-N0140 Figure 2-5 41 170 1997 and 1998 CN1000-CN1024 Figure 2-6 25 87 1972 and 1973 NM1000-MN1014 Figure 2-7 15 53 1875 to 1974 195 1108 Totals Clarice (1981) indicated that there were 29 taxa of freshwater gastropods in northern BC. However four of these, Valvata tricarinata, Fossaria truncatula, Stagnicola proximo and Physa gyrina were not found in field or museum collections and so have not been included in the synoptic listing of taxa confirmed to occur in northern BC. Seven additional taxa of gastropods were discovered in this study. The current study confirms the presence o f 32 taxa o f fi^shwater gastropods in northern BC (Table 2-3). Clarice (1981) indicated that there were 16 species of bivalves in northern BC including three species o f mussels and 13 species of sphaeriid clams. One of the mussels, Anodonta beringiana. and one of the clams, Pisidium subtruncatum, were not found in field or museum collections. Nine additional species of sphaeriid clams were discovered in this study. The current study confirms the presence o f 23 species freshwater bivalves in northern BC (two 24 Table 2-3. Systematic list of the freshwater molluscs of northern British Columbia, indicates taxa not found at ecological sites. Class Gastropoda Subclass Prosobrauchia * Family Valvatidae Valvata lewisi lewisi Currier, 1868 Valvata sincera sincera Say, 1824 Subclass Pulmonata * Family Acroloxidae Acroloxus coloradensis (J. Henderson, 1930) * Family Lymnaeidae Fossaria galbana (Say, 1825) Fossaria modicella {Say, 1825) Fossaria parva (Lea, 1841) Lymnaea atkaensis Dali, 1885 Lymnaea stagnalis appressa C^y, 1817) Stagnicola arctica (Lea, 1864) Stagnicola cty>erata {Say, 1829) Stagnicola catascopium catascopium (Say, 1817) Stagnicola elodes (Say, 1821) * Family Physidae Aplexa elongata {Say, 1821) PhysajennessiDaü, 1919* Physa skinneriTayloT, 1954 Physella lordi (Baird, 1863)* P a ella propinqua (Tryon, 1865) * Physella virpnea (Gould, 1847) Physella wighti Te and Clarice, 1985 Class Bivalvia * Family Margaritiferidae Margaritifera falcata (Gould. 1850) * Family Unionidae Anodonta kennerlyi Lea, 1860 * Family Sphaeriidae Sphaerium nitidum Westerlund,1876 Sphaerium rhomboideum (Say, 1822) Sphaerium simile {Say, 1817) Sphaerium striatinum (Lamarck, 1818) Musculium lacustre (Müller, 1774) Musculium securis (?nme, 1852) Musculium transversum (Say, 1829)* Pisidium casertanum (Poli, 1791) Pisidium compressum Prime, 1852 Pisidium conventus Clessin, 1877 Pisidiumfallax Stetki, 1896 Pisidiumferrugineum Prime, 1852 Pisidium idahoense Roper, 1890 Pisidium insigne Gabh, 1868 Pisidium lilljeborgi (Clessin, 1886) Pisidium milium Held, 1836 Pisidium nitidum Jeayns, 1832 Pisidium punctatumSteÂi, 1895 Pisidium rotundatum Prime, 1852* Pisidium variabUe Prime, 1852 Pisidium ventricosum Prime, 1851 * Family Planorbidae Gyraulus circumstriatus (Tryon, 1866) Gyraulus crista (Linnaeus, 1858) Gyraulus dtfiectus {Say, 1824) Gyraulus parvus (Say, 1817) Helisoma anceps anceps (Menke, 1930) Menetus opercularis (Gould, 1847) Plcmorbella binneyi Çïryon, 1867) Planorbella subcrenata{CatpaAer, 1856) Planorbula armigera (Say, 1821) Planorbula campestris Dawson, 1875 Promenetus exacuous exacuous {Say, 1821) * Family Ancylidae Ferrissiafragilis (Tryon, 1863)* Feirissia parallelus (Baldeam, 1841) 25 mussels and 21 sphaeriid clams; Table 2-3). No non-native taxa of freshwater molluscs were found in the course of this study. This precludes the evaluation of the hypothesis of alien species affecting the distribution of molluscs. A total of 55 taxa of freshwater molluscs are now recorded from northern BC (Table 2-3). O f these, 30 (55%) were uncommon (i.e., found at < 10 sites), 21 (38%) were common (i.e., found at 11 to 50 sites), and 4 (7%) were very common (i.e., found at >50 sites) (Table 2-8). Site Locations Freshwater molluscs were found in all of the biogeoclimatic zones (Figure 2-2) and in nine of the ten the major watersheds (Figure 2-3; no sites sampled in Taku watershed) in northern BC (Table 2-4). The number of sites within a particular region depended on the size of the region and on the accessibility of these areas for sampling. Biogeoclimatic Zones Drainages Major Watersheds Pacific Coastal n = 3 Boreal Black and White Sprace n = 84 Fraser n = 47 Coastal Western Hemlock Arctic n= 111 n = 94 n=9 Nass n = 5 Engelmann Spruce-Subalpine Fir n = 3 Skeena n = 20 hiterior Cedar - Hemlock n= 10 Stikine n= 8 Spruce - Willow - Burch n = 10 Yukon n= 1 Sub-Boreal Spruce n = 69 Liard n=58 Mackenzie n = 3 Peace n=195 n=50 n=195 n=195 Table 2-4. Number of freshwater mollusc collection sites in the drainages, major watersheds and biogeoclimatic zones in northern British Columbia. Distribution The distribution mtqss (Figures A-1 to A-63 in Appendix I) show that many of the 26 freshwater molluscs were not found throughout the study area (i.e., their distributions were nonrandom). Examination of the non-random distributions was made based on climate, glacial history and dispersal factors. Climate Climate conditions within the study area were available from the biogeoclimatic (BGC) zone classification system (Figure 2-2), which incorporates climate, soil and vegetation data into large-scale zones of similarity (Meidinger and Pojar 1991). The climate characteristics that distinguish the BGC zones within the study area are presented in Table 2-5. Months Months below 0*C above10*C annual precipitation (mm) amount of precipitation as snow (%) BGC Zone Elevation (m) Mean annnal temp. CQ BWBS 230-1300 -2.9 to +2.0 5 -7 2 -4 330- 570 35-55 CWH 0- 300 5.2 to 10.5 0 4 -6 1000-4400 40-50 ESSF 900-1700 -2.0 to +2.0 5 -7 0 -2 400 - 2200 50-70 ICH 100-1000 2.0 to 8.7 2 -5 3 -5 500-1200 25-50 SWB 900-1500 -0.7 to -3.0 valley bottoms 1.7 to 5.0 -1300 n/a 1 460 - 700 35-60 4 -5 2 -5 440 - 990 25-50 SBS Table 2-5. Summary o f altitude and climate information for the biogeoclimatic zones in northern British Columbia (Meidinger and Pojar 1991). BWBS = Boreal White and Black Spruce; CWH = Coastal Western Hemlock; ESSF = Engelmann Spruce Subalpine Fir, ICH = Interior Cedar - Hemlock; SWB = Spruce - Willow - Birch; SBS = Sub-Boreal Spruce. See Figure 2-2. Climate factors affect water temperature, which in turn affects life history traits such as growth rate, age of maturity, and fecundity levels in fi^shwater prosobranchs (Aldridge 1983), pulmonates (McMahon 1983) and bivalves (Buricy 1983). Some fireshwater mollusc taxa may be restricted to climatic regimes providing sufficient days of elevated water temperature for completion o f their life cycle. Families with taxon distributions that may have been influenced by climate were: 27 Family Acroloxidae - Acroloxus coloradensis (Figure A-4) was found only in the Sub-Boreal Spruce biogeoclimatic (BGC) zone in the southeast of the study area (Figure 2-2). This zone has a mean annual temperature above 0°C and more months above 10°C than do the more northerly BGC zones (Table 2-5). However, if A. coloradensis was restricted to the south of the study area by climatic requirements, it would be expected to also occur further south in the province but this has not been verified to date. Family Lymnaeidae - Fossaria parva (Figure A-7) and Stagnicola catascopium catascopium (Figure A-13) were found only in the south of the study area in a variety of BGC zones. However, both species occur elsewhere in Canada northerly latitudes (Clarice 1981). Family Sphaeriidae - Sphaerium rhomboideum (Figure A-43) was found only in the Sub-Boreal Spruce BGC zone in the south of the study as described for Family Acroloxidae above. As this distribution corresponds to the northern limit of its range elsewhere in Canada (Clarice 1981), it appears that the distribution of S. rhomboideum may be influenced by climate. Glacial Historv The last major glaciation began about 30,000 years ago and ended about 10,000 years ago (Cannings and Cannings 1996). Most of BC became covered by ice during this period as a result of the Cordilleran ice sheet spreading from the west and the Laurentide ice sheet spreading frrom the east. However, there were three large areas adjacent to these ice sheets that escaped glaciation (McPhail and Lindsey 1970) and probably acted a refuge for many aquatic organisms including frreshwater molluscs. These are: (1) the Bering Refuge (Figure 2-8a), which included a large part o f the Yukon River basin; (2) the Pacific Refuge (Figure 2-8b) along the coast o f what is now California, Oregon and southern Washington and; (3) the Mississippi Refuge (Figure 28c) in the northern tributaries o f the Gulf o f Mexico drainage. It is likely that organisms within the réfugia dispersed behind the melting ice sheets, as indicated by the arrows in Figure 2-8. 28 Stratigraphie evidence indicates the two ice sheets made contact in only a few places in the Liard Plateau in northern BC leaving some of this area unglaciated (Prest 1976). It is also possible that there were mountain summits (nunataks) protruding through the ice sheet (Pielou 1991) and some molluscs may have survived in high mountain lakes in these nunataks. (a) Bering Refuge and dispersal (b) Pacific Refuge and dispersal routes (c) Mississippi Refuge and dispersal routes Figure 2-8. Dispersal routes o f freshwater fishes firom the (a) Bering, (b) Pacific and (c) Mississippi réfugia. These patterns may also be reflected in dispersal patterns of fireshwater molluscs. Area of refuge firom the ice sheet is stippled. Dispersal routes are indicated by arrows. Dotted lines delineate major drainage areas. (From McPhail and Lindsey 1970.) Dispersal Passive dispersal of mollusc takes place when they are moved by mechanisms in which they play no active part. Occasional floodwaters may carry eggs or adults to new locations, and small snails and clams can become lodged in the feathers or in the mud on the feet of aquatic birds (Mackie 1979). Freshwater clams can also be transported by large aquatic insects (Clarke 29 1981) and salamanders (Davis and Gilhen 1982). While passive dispersal allows many molluscs to transcend geographic and drainage-system boundaries, there may be some barriers that present an insurmountable obstacle to some taxa. In northern BC, the most apparent geographic barrier is the Rocky Mountains. Patterns that may be indicative of glacial phenomena or obstruction by geographic barriers are apparent in seven of the nine families of freshwater molluscs in northern BC (not apparent in Valvatidae or Sphaeriidae). These families are; Family Acroloxidae - Fossil evidence indicates that A. coloradensis was once more widespread in North America (Bryce 1970). As it is currently most commonly known in western North America from disjimct locations in the Rocky Moimtains (i.e. northern BC, Montana and Colorado; Lee and Ackerman 1999c), it may have survived glaciation in lakes in nunataks. Its current limited distribution may reflect a limited capacity for post-glacial dispersal away from these small réfugia although the possible location of these réfugia has not been examined. Family Lymnaeidae - Of the nine taxa of lymnaeids collected in northern BC, five displayed distributions that were not interpretable based on hypothesized post-glacial dispersion routes. O f the remaining four taxa, L atkaensis (Figure A-8) is recognized as a Bering Refuge species (Clarke 1981), which concurs with the findings of this study. Fossaria galbana (Figure A-S) and Stagnicola caperata (Figure A-12) were found only east of the Rocky Mountains, suggesting their migration from the Mississippi Refuge may have been halted by the geographic barrier posed by these mountains. Fossaria parva (Figure A-7) was found only in the Pacific drainage but has been found elsewhere in Canada so its limited distribution in this study is not necessarily indicative of migration from the Pacific Refuge. Family Physidae - Aplexa elongata (Figure A-16) and Physa skinneri (Figure A-19) were found in both the Pacific and Arctic drainages displaying no interpretable patterns of distribution. As 30 most contemporary Physella collection were not identified to species, and historic Physella collections were sparse, no distribution patterns could be discerned for most of this genera. The exception was Physella wrighti, which is endemic to the Liard River hotsprings complex (Figure A-23). This hotsprings is in the area of the Liard plateau believed to have remained unglaciated during the last ice age. P. wrighti is believed to have survived glaciation and may have been present at this site for about 100,000 years (Te and Clarke 1985). Family Planorbidae - O f the 11 taxa of planorbids in northern BC, eight displayed distributions that were not interpretable based on hypothesized post-glacial dispersion routes. Of the remaining three species, Menetus opercularis (Figure A-29) and Planorbella binneyi (Figure A35) are confined to the Pacific drainage suggesting post-glacial dispersal firom the Pacific Refuge. Planorbula armigera (Figure A-31) was found only in the Arctic drainage east of the Rocky Mountains suggesting its migration firom the Mississippi Refuge was halted by the geographic barrier imposed by these mountains. Family Ancylidae - Ancylidae have not been previously recorded in northern BC (Clarice 1981) although this study fotmd F. parallelus to be common. F. parallelus (Figure A-38) was more common in the south o f the study area but was occasionally collected fiom large lakes in the north. Families Margaritiferidae and Unionidae - Both Margaritifera falcata (Figure A-40) and Anodonta kennerlyi (Figure A-41) were found in the Pacific drainage but A. kennerlyi was also found in the Arctic drainage in the upper Peace River watershed. Freshwater mussels owe their distributional patterns to the ranges of their fish hosts (Watters 1992) and it is believed Pacific fish species entered the upper Peace River watershed during a relatively recent minor headwater transfer, as few o f the fish species have dispersed much farther down the Peace than the Alberta/BC border (McPhail and Lindsey 1970). This is also the i^)parent distribution for A. 31 kennerlyi (Clarke 1981), and the headwater transfer may have included these mussels or fish carrying their glochidia. The post-glacial dispersal of M. falcata may have been slower in its northward movement so that it, or its fish host(s), may not have been available for headwater transfer. Af. falcata has still not been found as far north as has A kennerlyi. Environmental Data Water conditions may set limits on the distributions of freshwater molluscs (see review in Lodge et al. 1987). The environmental data collected in this study provides a basis for initiating further field and laboratory studies on the ecology of freshwater molluscs and should not be interpreted as definitive ecological requirements for any of the taxa found. The range plots (Figures 2-9 to 2-14) show that common taxa often tended to be found over a wide range of environmental conditions whereas less common taxa tended to be found within narrow ranges. This may be a consequence of sample size. Without further scientific testing, it cannot determined if these more limited ranges are artifacts o f fewer collections or if they are representative of true ecological requirements. The water conditions measured in this study and the relationship of these variables with the distribution and ecology of freshwater molluscs are as follows: (1) Water temperature: With the exception o f Physella wrighti. which lives in a hotsprings stream, the fi-eshwater molluscs of northern BC probably tolerate cold water temperatures for part of the year. However, there may be differences in their ability to tolerate higher temperatures. This may restrict some molluscs to running water or to large water bodies that are not as susceptible to the magnitude of ambient heating as are smaller water bodies. (2) Dissolved Oxygen: Two types o f respiratory mechanisms occur in truly aquatic fieshwater snails (Berg and Ockelmann 1959) and in sphaeriid clams (Burky 1983): (1) Oxygenindependent - these taxa tend to maintain a constant oxygen consumption, despite a lowering of 32 dissolved oxygen levels and so can maintain their physiological functions under reduced oxygen conditions. These taxa are tolerant of prolonged hypoxia and can live in a wide variety of habitats; and (2) Oxygen-dependent - these taxa exhibit a slow reduction in oxygen consumption as the dissolved oxygen levels decrease and so physiological functions are depressed under reduced oxygen conditions. These taxa are intolerant of prolonged hypoxia and are restricted to well-oxygenated habitats. (Î) Conductivity and Calcium Concentration: The concentration of dissolved calcium (which in this study was derived 6om the conductivity measure) is often considered a major factor determining the distribution of fireshwater molluscs (reviewed by Brown 1991 for snails, and by McMahon 1991 for bivalves). Calcium is an essential material for molluscan shell construction and egg development, and affects growth rate, survivorship, and fecundity rates in fireshwater pulmonate snails (McMahon 1983). (4) pH: The pH, which is a measure of acidity/alkalinity, is often considered a major factor determining the distributions of freshwater snails (Brown 1991), whereas McMahon (1991) states that ambient pH does not greatly limit the distribution of freshwater bivalves. Low pH is generally associated with low calcium concentration and with levels o f cartran dioxide that probably impede gas exchange (Fuller 1974). High pH is associated with high calcium levels and these habitats are usually associated with streams draining limestone catchments (Thorp and Covich 1991). As pH and calcium concentrations are linked, pH may be equally as important as calcium in determining the distribution of fireshwater molluscs. Measurements of the four water conditions discussed above were taken at 114 sites (113 sites for pH). These values plus the calcium concentration derived firom the conductivity measure are presented in Table A-1 (Appendix 1) and are summarized in Table 2-6. Molluscs were found at 108 of these sites. The environmental variables at these 108 sites differ firom the values for all 114 sites presented in Table 2-6 in that the range o f pH was less (range firom 5.15 33 to 9.25). The mean pH of the six sites where molluscs were not found (6.19 ± 0.63) was significantly lower than for the 108 positive sites (7.42 ± 0.08; p = 0.001). The dissolved oxygen saturation was above 100% in two large lakes with a dense floating algal blooms. Table 2-6. Sample size, mean, standard error and range for the environmental variables measured at the ecological sites in northern British Columbia. Environmental Variable Sample Size Mean Standard E rror Range Temperature (“C) 114 18.8 0.43 1.5-35.5 Dissolved Oxygen (% Saturation) 114 67.9 2.15 7.0-135 Conductivity (pSiemens) 114 280.8 23.95 19.7-1568 Dissolved calcium (mg/litre) 114 36.3 3.57 pH 113 7.35 0.08 3.95-9.25 1.2 - 209.3 T-tests The results of t-tests on the means of the environmental variables showed many significant differences between taxa in the families or genera «tamined (Table 2-7). However, it was not the mean that appeared to be the most important statistic. Maximum water temperature, minimum dissolved oxygen saturation, and minimum conductivity/calcium concentration provided better indications of environmental determinants of taxa occurrence than did the mean of these measurements. The mean pH was useful in determining if taxa appeared to prefer acidic (i.e., < 7) or alkaline (i.e., > 7) conditions but differences in mean pH that may reflect ecological differences were more easily assessed firom the range plots (see below). Range Plots The range plots of the environmental data collected for each taxon are shown for the six groups in Figures 2-9 to 2-14. These show that some molluscs were found over a wide range of the environmental variables whereas others seem more restricted in the range o f conditions under which they were found to occur. These plots Acilitated assessment of the possible ecological 34 Table 2-7. Significant differences and degrees of freedom (df) in means of environmental variables found within the groups or subgroups of fireshwater mollusc compared. Group Env. Variable Taxa compared p-value df I pH Valvata sincera sincera > V. lewisi lewisi p = 0.017 34 2 Temperature Fossaria galbana > Fossaria parva F. modicella > F. parva Lymnaea atkaensis > F parva Lymnaea stagnalis appressa > F. parva Stagnicola arctica > F. parva S. caperata > F. parva S. elodes > F. parva Stagnicola sp. juveniles > F. parva p = 0.005 p = 0.016 p = 0.054 p <0.001 p< 0.001 p = 0.003 p< 0.001 p = 0.003 16 20 14 37 27 15 58 16 p = 0.042 p = 0.033 p = 0.044 38 26 15 Dissolved Oxygen Lymnaea stagnalis appressa > S. arctica L. stagnalis appressa > S. caperata Staffiicola catascopium > Fossaria parva Conductivity Fossaria modicella > Lymnaea stagnalis appressa F. modicella > Stagnicola elodes S. caperata > L. stagnalis empressa S. caperata > s. elodes p = 0.038 p = 0.048 p = 0.024 p = 0.031 31 52 26 47 pH Fossaria galbana > Fossaria parva F. galbana > Stapiicola caperata F. modicella > F. parva p * 0.035 p = 0.014 p = 0.054 16 5 20 3 Temperature ) Conductivity Physella spp. > Physa skinneri Physella wrighti > Aplexa elongata P. wrighti > P. skinneri P. wrighti > Physella spp. Physella wrighti > Aplem elongata P. wrighti > Physella skinneri P. wrighti > P a ella sp. P = 0.042 p = 0.043 p = 0.003 p <0.001 p = 0.032 p = 0.018 p = 0.004 52 2 3 49 2 3 49 pH Physa skinneri > Aplexa elongata Physella spp. > A. elongata p = 0.015 p = 0.014 5 51 Temperature Planorbula armigera > Menetus opercularis P. subcrenata > Gyraulus circumstriatus P. subcrenata > G. parvus p = 0.016 p = 0.039 p = 0.013 9 98 53 Dissolved Oxygen Gyraulusparvus > G. crista M. opercularis > G. crista M. opercularis > Planorbella siAcrenata p = 0.047 p = 0.034 p = 0.052 22 12 43 Conductivity G. parvus > Helisoma anceps anceps G. parvus > M. opercularis P. exacuous exacuous > M. opercularis Planorbula armigera > Planoritella binneyi H. anceps anceps > M. opercularis Planorbella subcrenata > M. opercularis p = 0.038 p = 0.000 p * 0.016 p® 0.001 p® 0.009 p = 0.026 25 28 36 1 15 43 pH Gyraulus circumstriatus > Planorbula campestris p =0.051 67 4 1 . 35 Table 2-1 (cont.) Significant differences and degrees of fireedom (df) in means of environmental variables found within the groups or subgroups of freshwater mollusc compared. Group Env. Variable 5 Temperature Taxa compared Anodonta kennerlyi > Margaritiferafalcata p-value p = 0.028 df 14 6 P. lilljeborgi > P. idahoense P. ventricosum > P. idahoense p = 0.018 p = 0.036 23 33 Dissolved Oxygen P. compressum > P. ventricosum P. idahoense > P. ventricosum p = 0.022 p = 0.019 41 33 Conductivity Pisidium milium > P. compressum P. milium > P. idahoense P. nitidum > P. idahoense p = 0.030 p = 0.016 p = 0.045 35 27 19 pH P. compressum > P. ventricosum P. conventus > P.ferrugjneum P. conventus > P. insigne P. conventus > P. milium P. conventus > P. punctatum P. conventus > P. ventricosum P. conventus > Pisidium sp. P. idahoense > P.ferrugineum P. idahoense > P. milium P. idahoense > P. ventricosum P. idahoense > Pisidium sp. P. nitidum > P. ventricosum P. nitidum > Pisidium sp. p = 0.012 p = 0.040 p = 0.006 p = 0.029 p = 0.006 p = 0.019 p = 0.003 p = 0.024 p = 0.015 p = 0.004 p = 0.037 p = 0.055 p = 0.054 41 23 5 21 5 27 5 29 27 33 11 30 8 Temperature requirements of individual taxa as the minimum, maximum, mean and range of the variables could be easily read, and the differences in the range of conditions measured between taxa could be readily compared. Canonical Correspondence Analysis (CCA) The CCA plots, significance level (p-value) of the first canonical axis (i.e., relationship of the taxa to the environmental variables) and cumulative percent variance of the taxa data are shown for each of the six groups in Figures 2-15 to 2-20. These analyses show that for all of the gastropod groups (Groups 1 - 4 ; Figures 2-15 to 2-18), the environmental variables significantly affected the presence o f snails ^ < 0.05) whereas this was not the case for the bivalves (Groups 5 and 6; Figures 2-19 and 2-20; p > 0.05). For those taxa that had sample sizes adequate to show a unimodal response (i.e, n > 4), very few showed any strong responses to 36 Figure 2-9. Group 1: Range and means of environmental variables measured for Family Valvatidae, Family Acroloxidae and Family Ancylidae. “ I ” indicates mean. Minimum calcium concentration is indicated on plot (c). Temperature 0 5 15 20 1 T Valvata lewisi lewisi (n = "il) 25 330 “C 1 1 1 1 Valvata sincera sincera (n = 29) Acroloxus coloradensis (n = 1) 1 Ferrissia parallelus (n = 23) fbl Dissolved Oxygen 20 40 60 80 100% 200 29 400 58 600 800 1000 pS 148 mg/1 Valvata lewisi lewisi (n = 32) Valvata sincera sincera (n = 29) Acroloxus coloradensis (n = 7) Ferrissia parallelus (n = 23) (c) Conductivity and Calcium 0 0 Valvata lewisi lewisi (n = 32) 9.6mg/l Valvata sincera sincera (n = 29) -^1 99 12.8 Acroloxus coloradensis (n = 7) 10.1 Ferrissia parallelus (n = 23) (d)pH Valvata lewisi lewisi (n - 32) 88 "^1199 cr 5 5 7 Valvata sincera sincera (n = 29^ Acroloxus coloradensis (n = 7) Ferrissia parallelus (n = 23) \ 1 1 1 1 1 1 37 Figure 2-10. Group 2; Range and means of environmental variables measured for Family Lymnaeidae. “ I ” indicates mean. Minimum calcium concentration is indicated on plot (c). («1 Temperature 10 20 25 30 “C 60 80 100% Fossaria galbana (n = 4) Fossaria modicella (n = 8) 1.5 4 Fossaria parva (n = 14) Lymnea atkaensis (n = 2) Lymnaea stagnalis oppressa (n = 25) Stagnicola arctica (n = 15) Stagnicola caperata (n = 3) Stagnicola catascopium (n = 3) Stagnicola elodes (n = 46) Stagnicola sp. - Juveniles (n = 4) fb) Dissolved Oxvzem 20 40 Fossaria galbana (n = 4) — Fossaria modicella (n - 8) 1 h 1 1 Fossaria parva (n = 14) Lymnea atkaensis (n = 2) ■ 1 1 Lymnaea stagnalis oppressa (n = 25) Stagnicola arctica (n - 15) Stagnicola caperata (n = 3) 1 1 1 -1 — Stagnicola catascopium (n = 3) Stagnicola elodes (n = 46) 1 i^ l2 5 Stagnicola sp. - Juveniles (n =4) 38 Figure 2-10 (cont.). Group 2: Range and means of environmental variables measured for Family Lymnaeidae. “ ” indicates mean. Minimum calcium concentration is indicated on plot (c). I (cl Conductivitv and Calcium 0 0 400 58 200 29 Fossaria galbana (n = 4) 600 88 800 1000 pS 148 mg/1 25.3 mg/1 1^568 Fossaria modicella (n = 8) 22.8 Fossaria parva (n = 14) 11.5 Lymnea atkaensis (n = 2) Lymnaea stagnalis appressa (n = 25) Stagnicola arctica (n = 15) 35.2 12.1 1.6 1^568 Stagnicola caperata (n = 3) 24.9 Stagnicola catascopium (n = 3) Stagnicola elodes (n = 46) Stagnicola sp. - juveniles (n = 4) 16.6 1^1199 10.1 16.4 (dlpH 10 Fossaria galbana (n = 4) Fossaria modicella (n = 8) Fossaria parva (n = 14) — 1 1 Lymnea atkaensis (n = 2) —H" 1 Lymnaea stagnalis appressa (n = 25) Stagnicola arctica (n= 15) H 1 Stagnicola caperata (n = 3) 1 1 Stagnicola catascopium (n = 3) Stagnicola elodes (n = 46) Stagnicola sp. - juveniles (n =4) 1 1 39 Figure 2-11. Group 3: Range and means of environmental variables measured for Family Physidae. “ I " indicates mean. Minimum calcium concentration is indicated on plot (c). fa) Temperature 20 10 25 0 “C Aplexa elongata (n = Z) Physa skinneri (n = 4) Physella wrighti (n = 1) 36.5 Physella spp. (n = 50) fb) Dissolved Oivuen 20 60 40 80 100 % Aplexa elongata (n = 3) Physa skinneri (n = 4) Physella wrighti (n = 1) >135 Physella spp. (n = 50) fa) Conductivitv and Calcium 200 29 0 0 Aplexa elongata (n = 3) 400 58 600 88 800 18 12.1 m p Physa skinneri (n = 4) 27.4 - > • 1155nS 171mg/l Physella wrighti (n = 1) Physella spp. (n = 50) fd)pH 1000 pS M8 mg/1 lOT 5 ^^568 5 7 8 Î 10 Aplexa elongata (n = 3) Physa skinneri (n = 4) • Physella wrighti (n = 1) Physella spp. (n = 50) 1 40 Figure 2-12. Group 4: Range and means of environmental variables measured for Family Planorbidae. “ I ” indicates mean. Minimum calcium concentration is indicated on plot (c). (àï Température 5 Gyrauhis circumstriatus (n = 65) 1.5 ^ 10 20 25 60 80 0 ”C Gyraulus crista (n = 4) Gyraulus deflectus (n = 26) Gyraulus parvus (n = 20) Menetus opercularis (n = 10) Promenetus exacuous (n = 28) Planorbuia armigera (n = 1) Planorbula campestris (n = 4) Helisoma anceps anceps (n = 7) Planorbella binneyi (n = 2) Planorbella subcrenata (n = 35) (b) Dissolved Oxygen 0 20 40 100 Gyraulus circumstriatus (n = 65) Gyraulus crista (n = 4) 1 1 Gyraulus d ^ectu s (n = 26) 1 Gyraulus parvus (n = 20) 1 1 Menetus opercularis (n = 10) 1 1 Promenetus acacuous{n = 28) • Planorbula armigera (n= 1) Planorbula campestris (n = 4) 1^3 5 1 1 1 Helisoma ancqts anceps (n = 7) Planorbella binneyi (n = 2) Planorbella subcrenata (n = 35) ! 41 Figure 2-12 (cont.). Group 4; Range and means of environmental variables measured for Family Planorbidae. “ I ” indicates mean. Minimum calcium concentration is indicated on plot (c). fa) Conductivitv and Calcium 0 0 200 29 Gyraulus circumstriatus (n = 65) 600 400 58 88 800 118 5.7mg/l Gyraulus crista (n = 4) 1000 pS _148 mg/1 ^199 1^199 i6.r Gyraulus deflectus (n = 26) 10.1 Gyraulus parvus (n = 20) 12.0 Menetus opercularis (n = 10) TTr* Promenetus exacuous(xi = 28) 10.1 Planorbula armigera (n = 1) 26.1 • Planorbula campestris (n = 4) 12T Helisoma anceps anceps (n = 7) 16.6 Planorbella binneyi (n = 2) 16.5 -^199 1^199 Planorbella subcrenata (n = 35) (d)pH 5 5 7 8 S 10 Gyraulus circumstriatus (n = 65) Gyraulus crista (n = 4) - 4 — 1 Gyraulus deflectus (n = 26) 1 1 Gyraulus parvus (n = 20) 1 Menetus opercularis (n = 10) 1 Promenetus exacuous (n = 28) • Planorbula armigera (n= 1) Planorbula campestris (n = 4) Helisoma a n c^s anceps (n = 7) 1 1 1 1 Planorbella binneyi (n = 2) Planorbella subcrenata (n - 34) 1 I 42 Figure 2-13. Group S: Range and means of environmental variables measured for Family Margaritiferidae, Family Unionidae and Family Sphaeriidae; genus Sphaerium and genus Musculium. “ | " indicates mean. Minimum calcium concentration is indicated on plot (c). fal Tem neniture 30 “C 20 25 0 Margaritifera falcata (n = 4) Anodonta kennerlyi (n = 12> Sphaerium nitidum (n = 14) Sphaerium rhomboideum (n = 1) Sphaerium simile (n = 8) Sphaerium striatinum (n = 1) Musculium lacustre (n = 33) Musculium securis (n = 36) fb) Dissolved Oivgen 20 40 60 80 100 % 200 29 400 58 600 800 118 1000 pS 148 mg/1 Margaritifera falcata (n = 4) Anodonta kennerlyi (n = 12> Sphaerium nitidum (n = 14) Sphaerium rhomboideum (n = 1) Sphaerium simile (n = 8) Sphaerium striatinum (n = 1) Musculium lacustre (n = 33) Musculium securis (n = 36) Conductivity and Calcium Margaritifera falcata (n = 4) 0 0 88 8 .8 n î Anodonta kennerlyi (n = 12) Sphaerium nitidum (n = 14) 1^1199 L6 Sphaerium rhomboideum (n = 1) 39.7 Sphaerium simile (n = 8) 16.6 Sphaerium striatinum (n = 1) 16.6 • Musculium lacustre (n = 33> 1.7 Musculium securis (n = 36) ITT ^1199 43 Figure 2-13 (cont.). Group S: Range and means of environmental variables measured for Family Margaritiferidae, Family Unionidae and Family Sphaeriidae; genus Sphaerium and genus Musculium. “ I ” indicates mean. Minimum calcium concentration is indicated on plot (c). fd^pH 10 Margaritifera falcata (n = 4) Anodonta kennerlyi (n = 12) Sphaerium nitidum (n = 14) Sphaerium rhomboideum (n= 1) Sphaerium simile (n = 8) Sphaerium striatinum (n = 1) Musculium lacustre (n = 33) Musculium securis (n = 36) 44 Figure 2-14. Group 6. Range and means of environmental variables measured for Family Sphaeriidae, genus Pisidium. “ I” indicates mean. Minimum calcium concentration is indicated on plot (c). fml Temperature 20 25 0 “C 10 5 15 Pisidium casertanum (n = 61) ; g 4-----— h 1 1 Pisidium compressum (n = 20) Pisidium conventus (n = 6) Pisidium fallax (n = 2) f 11 Pisidium ferrugineum (n = 19) 1 Pisidium idahoense (n= 12) |i 1 1 • Pisidium insigne (n = 1) 1 Pisidium liUjeborgi (n= 13) 1 Pisidium milium (n = 17) 1 Pisidium nitidum (n = 9) • Pisidium punctatum (n= 1) 1 Pisidium variabile (n = 36) Pisidium ventricosum (n = 23) # Pisidium sp. (n= 1) fb) Dissolved Oivgen 20 60 40 Pisidium casertanum (n = 61) 80 100% H — Pisidium compressum (n = 20) Pisidium conventus (n = 6) Pisidium fallax (n = 2) — 1- Pisidium ferrugineum (n = 19) 1 1 Pisidium idahoense (n = 12) • Pisidium insigne (n = 1) 1 1 Pisidium liUjeborgi (n = 13) Pisidium milium (n = 17) 1 Pisidium nitidum (n = 9) — h # Pisidium punctatum (n = 1) Pisidium variabile (n = 36) Pisidium ventricosum (n = 23) Pisidium sp. (n = 1) _ 1 1 1 1 _ # 45 Figure 2-14 (cont.). Group 6. Range and means of environmental variables measured for Family Sphaeriidae, genus Pisidium. “ I " indicates mean. Minimum calcium concentration is indicated on plot (c). (c) Conductivitv and Calcium 200 29 0 0 Pisidium casertanum (n = 61) J.7mg/1 Pisidium compressum (n = 20) I2.f“ Pisidium conventus (n = 6) 1 2 .f 400 58 600 88 800 118 1000 pS 148 mg/1 28.9 Pisidium faiiax (n = 2) Pisidium ferrugineum (n = 19) 9 .r Pisidium idahoense (n = 12) i2 .r Pisidium insigne (n = 1) 12* Pisidium liUjeborgi (n = 13) lo.r Pisidium milium (n = 17) 8.5 Pisidium nitidum (n = 9) 20.6 . 45.3 Pisidium punctatum (n = 1) Pisidium variabile (n = 36) Pisidium ventricosum (n = 23) Pisidium sp. (n = 1) fd)pH To • 12.6 10 Pisidium casertanum (n = 61) Pisidium compressum (n = 20) Pisidium conventus (n = 6) Pisidium fallax (n = 2) Pisidium ferrugineum (n = 19) Pisidium idahoense (n = 12) Pisidium insigne (n = 1) Pisidium liUjeborgi (n = 13) Pisidium milium (n = 17) Pisidium nitidum (n = 9) Pisidium punctatum (n = 1) Pisidium variabile (n = 36) Pisidium ventricosum (n = 23) Pisidium sp. (n = 1) 46 Figure 2-lS. Canonical Correspondence Analysis of environmental variables and taxa from Group 1 (Family Valvatidae, Family Acroloxidae and Family Ancylidae). TEMP = température DO= dissolved oxygen COND= conductivity Test of significance of first canonical axis: F-ratio = 5.574 p-value = 0.040 Cumulative percent variance of species data: 13.2% Legend VALL = Valvata lewisi lewisi (n = 32) VASS = Valvata sincera sincera (n = 29) ACCO = Acroloxus coioradensis (n = 7) FEPA = Ferrissia paralleius (n = 23) • VALL • FEPA - ACCO ♦i.o 1.0 Figure 2-16. Canonical Correspondence Analysis of environmental variables and taxa from Group 2 ( Family Lymnaeidae). *1 TEMP - tempeiiture DO ■ dissolved oxygen COND - conductivity .0 Cumulative percent variance of species data: 6.3% LsSËOâ FOGA= Fossaria galbana (n = 4) FOMO = Fossaria modicella (n = 8) FOPA = Fossaria parva (n=14) LYAT= Lymnaea atkaensis (n=2) LYSA=Lymnaea stagmdis appressa (n - 25) STAR= Stagnicola arctica (n = IS) STCA = Stagydcola caperata (n = 3) STCC = Stagnicola catascopium (n = 3) STEL = Stagnicola elodes (n=4Q STSP-J= Stagnicola sp. juveniles (n = 4) COND IM P STCA ♦ • I •ST A R LŸSÀ "F O P A FOGA y é j sTSpy* 7 YAT •S T C C PM 1 1. -1.0 Test o f significance of first canonical axis: F-ratio = 3.669 p-value = 0.010 . 1 ♦1.0 47 Figure 2-17. Canonical Correspondence Analysis of environmental variables and taxa from Group 3 (Family Physidae). Test of significance o f first canonical axis: F-ratio =10.152 p-value = 0.005 TEMP = letnperamrc DO = dissolved oxygen COND= conductivity Cumulative percent variance of species data: 23.6% APEL* Legend APEL = Aplexa elongata (n = 3) PHSK = Physa skinneri (n = 4) PHWR = Physella wrighti (n = 1) PHSP = Physella spp. (n = 50) - 1.0 * 1.0 Figure 2-18. Canonical Correspondence Analysis of environmental variables and taxa fix>m Group 4 (Family Planorbidae). Test of significance of first canonical axis: F-ratio = 5.159 p-value = 0.005 TEMP - tengtenture DO “ dissolved oxygen COND > conductivity Cumulative percent variance of species data: 8.8% Lfigaad GYCI= Gyraulus circumstriatus (n = 65) GYCR = Gyraulus crista (n = 4) GYDE = Gyraulus deflectus (a = 26) GYPA = Gyraulus parvus (n=20) MEOP = Menetus opercularis (a = 10) PREE= Promenetus exacuous (a=28) PLAR=Planorbula armigera (a = 1) PLCA = Planorbula campestris (a =4) HEAA = Helisoma anceps anceps (a =7) PLBI=Planorbella binneyi (a=2) PLSU= Planorbella subcrenata (a = 35) 00 \ COND . f ______ . >LBe ^ GY PA.e . G V C Ie / Kmc i \ «H E A A PLAR - 1.0 + 1.0 48 Figure 2-19. Canonical Correspondence Analysis of environmental variables and taxa from Group 5 (Family Margaritiferidae, Family Unionidae and genus Sphaerium and Musculium of Family Sphaeriidae). TEMP = tempeiitiiR DO= dissolved oxygen COND = conductivity Cumulative percent variance of species data: 5.1% Legend MAFA = Margaritiferafalcata (n = 4) ANKE= Anodonta kennerlyi (n = 12) SPNI = Sphaerium nitidum (n = 14) SPRH = Sphaerium rhomboideum (n = 1) SPSI = Sphaerium simile (n = 8) SPST = Sphaerium striatinum (n = 1) MULA = Musculium lacustre (n = 33) MUSE = Musculium securis (n = 36) •SPST MAFA COND Test of significance of first canonical axis: F-ratio = 2.123 p-value = 0.480 SPRH DO ♦ 1.0 1 .0 - Figure 2-20. Canonical Correspondence Analysis of environmental variables and taxa from Group 6 (genus Pisidium of Family Sphaeriidae). TEMP«tempenture DO • disiotwgd oxygen COND • conductivity ICA - 1.0 Test of significance of first canonical axis: F-ratio = 2.271 p-value = 0.225 Cumulative percent variance of species data: 3.7% Lsggnd PICA = Pisidium casertanum (n = 61) PICO = Pisidium compressum (n=20) PICN = Pisidium conventus (n = 6) fW A - Pisidiumfallax (n = 2) PIPE = Pisidiumferrugineum (n = 19) PUD = Pisidium idahoense (n = 12) PUN = Pisidium insigne (n = 1) PDLI=Pisidium liUjeborgi (n = 13) PIMI =Pisi(Hum milium (n = 17) PINT=Pisidium nitidum (n = 9) PIPU =Pisidium punctatum (n = 1) PIVA =Pisidium variabile (a =36) PIVE =Pisidium ventricosum (n=23) PISP =Pisidium sp. (n = 1) pipu ♦ 1 .0 49 single or combinations of environmental variables (i.e., they were located near the origin on the plots or between environmental variable arrows). In some cases (e.g., Valvata sincera sincera, Margaritifera falcata and Anodonta kennerlyi) these responses concurred with data extrapolated from the range plots. The responses are discussed in the group analyses that follow. Analysis of the environmental data yielded the following information for each family or genera examined: Family Valvatidae - The plots in Figure 2-9a indicate that neither of the Valvata taxa appears to be restricted to cool water temperatures (i.e., < 25“C). The two Valvata taxa occurred at very similar ranges of dissolved oxygen and had very similar means (Figure 2-9b). While prosobranchs are generally described as less hypoxia tolerant than pulmonates (Boycott 1936), this may not be the case for these valvatids as they were found at very low levels of dissolved oxygen (< 15% saturation) and, therefore, may be oxygen-independent. The two Valvata taxa were found over broad ranges of conductivity/calcium concentration, but they were not collected at the sites with the lowest values measured in this study (Figure 2-9c). It may be that these taxa are physiologically prohibited from inhabiting habitats with very low levels of calcium and that this may be a limiting factor in the number of habitats available to them in northern EC. Pennak (1989) states that all Valvatidae are confined to waters having pH readings o f 7.0 or above. However, in this study, V. lewisi lewisi was found at pH as low as 5.6 and V. sincera sincera as low as 6.5 (Figure 2-9d). The lower pH tolerance of V. lewisi lewisi may allow it to occupy a wider range of habitats than V. sincera sincera. Three families were included in the CCA analysis that includes the Valvata taxa (Group 1; Table 2-1). The results (Figure 2-15) were that these frunilies responded significantly to environmental variables (p - 0.04), and the variables accounted for 13.2% of the variance in taxa 50 presence at the sites examined. The plot shows that the presence of K lewisi lewisi corresponded to lower than average temperature and dissolved oxygen, neither of which appeared to be particularly important in its ecology as extrapolated from the range plots. However, V. sincera sincera presence corresponded to higher than average pH, which may be an ecological factor for this species as discussed above. Family Acroloxidae - Acroloxis coioradensis was found only in habitats with water temperature < 24.5“ (Figure 2-9a). Other factors suggest that A. coioradensis may be restricted to stable, perennial habitats (see below) and lower temperatures may be characteristic of these types of habitats. A. coioradensis was only collected from habitats of relatively high dissolved oxygen saturation (> 40%; Figure 2-9b). Eurasian species of Acroloxus are oxygen*dependent (RussellHunter 1978) and A. coioradensis may also be limited to well-oxygenated habitats. This may restrict the its distribution to perennial habitats with relatively stable conditions. A. coioradensis was collected at a minimum calcium concentration of ~10.1 mg/1 calcium (Figure 2-9c). However, sites with lower measures occurred only outside of the physical distribution range for A. coioradensis. Thus, it cannot be discerned if this calcium level is a minimum requirement for A. coioradensis, if it is a result of a range restricted by other factors, or if it is an artifact of small sample size (n = 7). A. coioradensis is one of the few molluscs in this study found in habitats with acidic mean pH, although it was also found in alkaline conditions (Figure 2-9d). It may be that perennial, stable habitats within the range of A. coioradensis tend to be acidic and that a preference for acidic water is not a distinctive characteristic of the species. Three families were included in the CCA analysis that included A. coioradensis, as described for Valvatidae (Figure 2-15). A. coioradensis occurs on the plot most closely 51 corresponding to lower than average pH, which is consistent with the observations from the range plot o f pH (Figure 2-9d). Family Lynuiaeidae • Fossaria galbana, F. parva, Lymnaea atkaensis and Stagnicola catascopium catascopium were found only at water temperatures < 2S°C (Figure 2-10a). Both F. galbana and L. atkaensis are cold-water species (Clarice 1981) and were only collected from large lakes, as was S. catascopium catascopium. The collections o f F. parva were often associated with small streams with relatively low temperatures (see Chapter 4) but as this species is amphibious (Clarice 1981), it may have a broader tolerance for temperature variation than indicated by water temperature. All other lymnaeids were collected at temperatures > 2S°C (Figure 2-10a) and so do not appear to have their distributions limited by temperature in northern EC. As lymnaeids retain dependence on atmospheric air, the dissolved oxygen content of the water should not be a limiting factor in distribution. The relatively large amount of variability in the minimum for dissolved oxygen levels (Figure 2-10b) may be indicative o f other factors. For example, lake species were found in habitats of relatively high dissolved oxygen. Fossaria galbana (n = 4), F. modicella (n = 8), Lymnaea atkaensis (n = 2) and Stagnicola caperata (n = 3) were found at sites with calcium concentration > 20 mg/1 (Figure 2-lOc). These species may be restricted to h i^ calcium habitats however, the sample size of these snails was small and may not represent their full range of tolerance. Pennak (1989) states that nearly all Lymnaeidae are confined to waters having neutral pH readings (i.e., 7.0) or above. Figure 2-lOd shows that while this was true for some of the lymnaeids in this study (i.e., Fossaria galbana, F. modicella, Lymnaea atkaensis and Stagnicola caperata, in keeping with their putative high calcium requirement), all other taxa were found in acidic waters as well. 52 The CCA results showed the lymnaeid taxa to respond significantly to the environmental variables (p = 0.01) and that these variables account for 6.3% of the variance in taxa presence at the sites examined (Figure 2-16). The plot shows few taxa to correspond to any particular environmental variable with most appearing near the origin of the plot. For taxa with larger sample sizes (n > 4), only S. arctica appears to correspond to lower than average dissolved oxygen but this may be of limited ecological consequence to an air-breathing snail. Family Physidae - The unusual habitat of Physella wrighti separates it fiom other members of this family in temperature and conductivity (Figures 2-1 la,c and Figure 2-17). Physa skinneri was found only at relatively low temperatures (Figure 2-1 Ic) but given the wide range of habitats described for this species in western North America (Taylor 1988), it seems unlikely that high temperature would be a limiting factor for this species. Physidae collected in this study were assumed to retain dependence on atmospheric air. The three identified taxa at ecological sites were found in habitats of relatively high dissolved oxygen (Figure 2-17b) but there may be other factors that limit them to these sites. Physidae were not collected from sites with low conductivity/calcium concentrations (i.e., < 10.1 mg/1; Figure 2-17c). This suggests that these physids may have a minimum calcium requirement that would restrict them to certain habitats within their range. P. skinneri was only found at calcium concentration > 20 mg/1 although sample size was small (n = 4). The plots in Figure 2-17d suggest that A. elongata and P. skinneri may be separated ecologically by pH requirements, with A. elongata occurring in acidic and P. sldnneri occurring in alkaline habitats, whereas the Physella spp. displayed a wide range of tolerance to pH. The CCA results are that the physids responded significantly to the environmental variables (p = 0.005) and that these variables account for 23.6% o f the variance in taxa presence at the sites examined (Figure 2-17). A. elongata corresponded to lower than average pH, which 53 may be an important ecological factor for this species. The sample size for P. skinneri and P. wrighti are small, prohibiting the development of a unimodal response, however, the latter is associated with high temperature and conductivity in accordance with its apparent ecology. Family Planorbidae - Menetus opercularis was found at lower water temperatures (max. 22.9°C) than most taxa in this family (Figure 2-12a). As it was only collected firom large, permanent water habitats, water temperature may be an ecological factor for this taxon although it may be restricted to these habitats by other factors. Planorbella binneyi was also found only at relatively low water temperature but the small sample size (n = 2) is not representative of its range of tolerance. The minimum dissolved oxygen levels at which planorbid taxa with sufficient sample size (i.e., n > 4) were found (Figure 2-12b) might be useful to identify oxygen-dependent and oxygen-independent taxa within this family. Oxygen dependent taxa, found only above 40% saturation, may be Gyraulus parvus, Helisoma anceps anceps, and Menetus opercularis. Oxygen-independent taxa, found at lower than 40% saturation, may be G. circumstriatus, G. crista, G. deflectus, Promenetus exacuous exacuous, Planorbula campestris and Planorbella subcrenatum. Menetus opercularis was found at the lowest measured conductivity/calcium concentrations and is different fiom the remaining taxa, which occurred in habitats with higher conductivity/calcium levels. It may be that these planorbids are physiologically prohibited fiom inhabiting habitats with very low levels of calcium and that this may be a limiting factor in the number of habitats available to them in northern BC. Planorbula campestris (n = 4) was the only planorbid found in habitats with acidic mean pH (Figure 2-12d). Planorbula armigera (n = 1), Planorbella binneyi (n = 2). and perhaps Gyraulus crista (only collected at pH > 6.85; n - 4) were found in alkaline conditions. All of 54 these taxa have small sample sizes. The CCA results indicate that the planorbids responded significantly to the environmental variables (p = 0.005) and that these variables account for 8.8% of the variance in taxa presence at the sites examined (Figure 2-18). However, none of the taxa with large sample sizes appeared to associate with environmental variables of particular importance to their ecology as assessed from the range plots. Family Ancylidae - The range of water temperature shown in Figure 2-9a suggests that Ferrissia paralleius can tolerate relatively high water temperatures (i.e. > 2S°C). F. paralleius was not collected from habitats of extremely low dissolved oxygen (Figure 2-9b). At sites where oxygen levels were < 50%, it was generally collected fix>m the undersides of lily pads where the dissolved oxygen saturation may have been higher than in the near-shore water where measurements were taken. It may be that F. paralleius selects an appropriate microhabitat within a water body to ensure an adequate supply of oxygen suggesting that it may be oxygen-dependent. The low minimum level of conductivity/calcium concentration (1.7 mg/1) measured for F. paralleius (Figure 2-9c) indicates that the level of dissolved calcium in the water is probably not a limiting fitctor in the distribution of this taxa in northern BC. Pennak (1989) identified F. paralleius as exceptional among freshwater gastropods in having being recorded from pH ranging from 6.0 to 8.4. hi this study, F. paralleius was found at pH ranging from 5.25 to 8.75 (Figure 2-9d), an even wider range than described previously. This suggests that in all but the most extreme habitats, pH would probably not be limiting factor in the distribution of this species in northern BC. Three families were included in the CCA analysis that includes F. paralleius, as described for Valvatidae (Figure 2-15). F. paralleius occurs on the plot most closely 55 corresponding to lower than average conductivity. As F. paralleius displayed no minimum tolerance for conductivity/ calcium concentration (Figure 2-9d), this factor may be of limited ecological importance to this species in northern BC. Family M argaritiferidae and Unionidae - fai Canada, Margaritiferidae are always found in running streams (Clarice 1981). Unionidae are found in both lotie and lentic habitats (Clarice 1981), but Anodonta kennerlyi was found only in lakes in northern BC. The temperature of the habitats of these two mussels differed significantly (Table 2-7) with the running water habitat of M. falcata being significantly colder (Figure 2-13a). Both mussel species were collected in habitats of relatively high dissolved oxygen saturation (Figure 2-13b). However, the results of a study on another Anodonta species, A. grandis, found it to be oxygen-independent (Lewis 1984). If this is also the case for A. kennerlyi, it is not consistent with the findings of this study. A. kennerlyi was collected from habitats with the lowest level of conductivity/calcium concentration measured in this study (Figure 2-13c). The higher level measured for M. falcata may be characteristic of northern Pacific drainage rivers or M falcata may be restricted to streams providing this minimum level. While Pennak (1989) states that members of the subfamily Anodontinae, which includes A. kennerlyi, are rarely found in acid waters, McMahon (1991) states that member of the Family Unionidae can grow and reproduce over a pH range of 5.6 to 8.3, with a pH of less than 4.7 to 5.0 being the absolute lower limit, h this study, A. kennerlyi was collected in waters where the pH ranged from 5.25 to 8.55 (Figure 2-13d), which concurs reasonably closely to the range indicated by McMahon (1991) for the Unionidae in general. M falcata was found within a more limited range of pH but was found in both acidic and alkaline conditions. CCA analysis o f Af. falcata and A. kennerlyi required combination with other fireshwater 56 bivalves (Table 2-1). The results show that these bivalves did not respond significantly to the environmental variables (p = 0.48), and accounted for only 5.1% of the variance in taxa presence at the sites examined (Figure 2-19). However, the plot shows M. falcata to correspond to lower than average temperature and A. kennerlyi to correspond to higher than average dissolved oxygen, which concur with ecological information extracted fi"om the range plots. Family Sphaeriidae - Genera Sphaerium and Musculium - The plots in Figure 2-13a show that Sphaerium and Musculium species collected more than once were found in habitats of relatively high temperature (> 2S°C) suggesting that high water temperature may not be a limiting factor for these taxa in northern BC. According to Burky (1983), Sphaerium and Musculium species are oxygen-dependent. In this study, Sphaerium and Musculium species were found in some habitats of low oxygen (23%; Figure 2-13b), but they were never collected fix)m habitats of extremely low dissolved oxygen (as compare to some Pisidium species Figure 2-14b) and the means are skewed to the high end of the range. Thus, these findings generally concur with the oxygen-dependence designation, which may be a limiting factor in the distribution of Sphaerium and Musculium species in northern BC. Sphaerium simile was the only species in this group with a sample size > 1 (n = 8) that was found at relatively high conductivity/calcium concentration levels (Figure 2-13c). This suggests that this species may have a higher calcium requirement and, therefore, be more restricted in distribution. According to Pennak (1989) and McMahon (1991), some sphaeriids species are relatively insensitive to pH and are common in lakes having a pH as low as 6.0. Sphaerium nitidum, and both Musculium species were collected from both acidic and alkaline conditions, with pH as low as 5.25 (Figure 2-13d). S. simile was not found at low pH and its putative h i^ e r calcium 57 requirement may limit it to habitats of higher pH. The CCA results shows that the bivalves in Group 5 did not respond significantly to the environmental variables measured (p = 0.48) and accounted for only S. 1% of the variance in taxa presence at the sites examined (Figure 2-19). This is also the case if the freshwater mussels are removed from the analysis (p = 0.62 and 6.3% of the variance in taxa presence at the sites examined explained). All Sphaerium and Musculium species with sample size >1 appeared near the origin o f the plot. Family Sphaerium - Genus Pisidium - Most species o f Pisidium that were collected more than once were found in habitats where the water temperature was >25°C indicating that high temperature may not be a limiting factor for most Pisidium species in northern BC (Figure 214a). The exceptions were P. conventus, which is a cold water species (Clarice 1981), and P. idahoense which was only collected from lakes, rivers and streams where the temperature was generally lower than in smaller, more ephemeral habitats. The minimum dissolved oxygen levels at which Pisidium species with sufficient sample size (i.e., n Z 6) were found (Figure 2-14b) might be useful to identify oxygen-dependent and oxygen-independent taxa within this genus. Oxygen-independent species, found at < 40% oxygen saturation, may be P. casertanum, P. compressum, P. ferrugineum, P. milium and P. ventricosum. All others were found at oxygen saturations >40%, and so may be oxygendependent. Thus, the level of dissolved oxygen in a habitat may be a factor in determining the distribution of some Pisidium species in northern BC. Pisidium species seemed to vary greatly in their minimum requirements for calcium with only P. casertanum, P. variabile and P. ventricosum found at the lowest levels measured in this study (Figure 2-14c). It may be that many Pisidium species are restricted to habitats supplying their minimum calcium requirements. 58 McMahon (1991) states that ambient pH does not greatly limit the distribution of freshwater bivalves and that some sphaeriids species are relatively insensitive to pH. However, in this study, members of the genus Pisidium were more commonly collected from habitats of neutral to alkaline pH (Figure 2-14d) than were most of the other groups of freshwater molluscs examined. This may be due to their putative relatively high calcium requirements as mentioned above. The CCA results were that the Pisidium species did not respond significantly to the environmental variables (p = 0.225) and accounted for only 3.7% of the variance in taxa presence at the sites examined (Figure 2-20). The CCA plot shows that most species tended to occur near the origin and to correspond to a combination of variables. Summary Fifty-five taxa of freshwater molluscs are now recorded fix)m northern BC comprising two prosobranch snails, 30 pulmonate snails, two mussels and 21 clams. The relatively low number of prosobranchs and mussels found is probably because of their limited abilities to disperse due to their stenotopic nature and restrictive reproductive characteristics. Forty-nine of these 55 taxa were collected along with ecological information. The distribution patterns and ecological factors that may be important in determining the present distributions of these 49 taxa are summarized in Table 2-8. Only Sphaerium rhomboideum appears to have a distribution that may be limited by climate. Lymnaea atkaensis appears to be a Bering Refuge species and Menetus opercularis, Planorbella binneyi, Anodonta kennerlyi and Margaritifera falcata appear to be Pacific Refuge species. The most apparent Mississippi Refuge species are those that appear to have had their migration halted by the geographic barrier of the Rocky Mountains. These are Fossaria galbana, Stagnicola caperata and Planorbula armigera. The hot springs snail, Physella wrighti, may have survived glaciation and is known 59 Table 2-8. Summary o f the distribution and ecology o f the freshwater molluscs from ecological sites in northern British Columbia, n = number o f sites. Unconunon = ^ 10, common = 1 1 - SO, and very common = > 5 0 occurrences. Class Gastropoda Subclass Prosobranchia ^ Family Valvatidae Valvata lewisi lewisi (n = 32) Valvata sincera sincera (n = 29) Subclass Pulmonata ^ Family Acroloxidae 1 Acroloxus coioradensis (n = 7) ^ Family Lymnaeidae Fossaria galbana (n = 4) Fossaria modicella (n = 8) Fossaria parva (n = 14) Lymnaea atkaensis (n = 2) Lymnaea stagnalis appressa (n = 25) Stagnicola arctica (n = 15) Stagnicola caperata (n = 3) Stagnicola catascopium catascopium (n=3) Stagnicola elodes (n = 46) Aplexa elongata (n = 3) Physa skinneri (n = 4) Physella spp. (n = 50) Physella wrighti (n = 1) * Family Planorbidae Gyraulus circumstriatus (n = 65) Gyraulus crista (n = 4) Gyraulus deflectus (n = 26) Gyraulus parvus (n = 20) Menetus opercularis (n = 10) Promenetus exacuous exacuous (n=28) Planorbula armigera (n = 1) Distribution common; widespread common; widespread Ecological Factors Related to Distribution oxygen-independent; minimum 9.6 mg/1 calcium oxygen-independent; minimum 12.8 mg/l calcium iuicommon;south-centiaI area oxygen-dependent; minimum 10.1 mg/l calcium; acidic mean pH uncommon;east of Rocky Mts: Mississippi Refuse uncommon; widespread uncommon; southeast area uncommon; Bering Refuge common; widespread common; widespread uncommon;east of Rocky Mts; Mississippi Refuse uncommon; south-east area very common; widespread minimum 25.3 mg/l calcium; alkaline pH only minimum 16.6 mg/l calcium minimum 10.1 mg/l calcium uncommon; non-coastal areas uncommon; non-coastal areas very common; widespread uncommon; endemic minimum 12.1 mg/l calcium; acidic mean pH minimum 27.4 mg/l calcium; alkaline pH only minimum 10.1 mg/l calcium high temperature and conductivity/calcium very common; widespread uncommon; widespread common; widespread common; widespread uncommon; Pacific Refuge conunon; widespread uncommon;east of Rocky Mts; Mississippi Refuge oxygen-independent; minimum 5.7 mg/l calcium oxygen-indetiendent; minimum 16.5 mg/l calcium; alkaline pH only oxygen-independent; minimum 10.1 mg/l calcium oxygen-dependent; minimum 12.0 mg/l calcium oxygen-dependent; minimum 1.7 mg/l calcium oxygen-independent; minimum 10.1 mg/l calcium insufficient sample size minimum 22.8 mg/l calcium; alkaline pH only minimum 11.0 mg/l calcium insufficient sample size minimum 12.1 m ^ calcium minimum 1.6 mg/l calcium minimum 24.9 mg/l calcium; alkaline pH only 60 Table 2-8 (cont.). Summary o f the distribution and ecology o f the freshwater molluscs from ecological sites in northern British Columbia, n = number o f sites. Uncommon = ^ 10, conunon = 11 - 50, and very common = > 50 occurrences. ^ Family Planorbidae (continued) Distribution unconunon: widespread Planorbula campestris (n = 4) unconunon; widespread Helisoma anceps anceps (n = 7) unconunon: Pacific Refuge Planorbella binn^i (n = 2) common; widespread Planorbella subcrenata (n = 35) *' Family Ancylidae 1 Ferrissia paralleius (n = 23) | common; widespread Class BivaMa * Family Margaritiferidae 1unconunon; Pacific Refuge 1 Margaritifera iaicata (n = 4) * Family Unionidae 1conunon; Pacific Refuge 1 Anodonta kennerlyi (n= 12) * Family Sphaeriidae common; widespread Sphaerium nitidum (n = 14) unconunon; south area Sphaerium rhomboideum (n = 1) Sphaerium simile (n = 8) uncommon; widespread uncommon; south area Sphaerium striatinum (n = 1) conunon; widespread Musculium lacustre (n = 33) common; widespread Musculium securis (n = 36) conunon; widespread Pisidium casertanum (n = 61) conunon; widespread Pisidium compressum (n = 20) uncommon; widespread Pisidium conventus (n = 6) unconunon; southeast area Pisidium fallax (n = 2) common; widespread Pisidium ferrugineum (n= 19) conunon; widespread Pisidium idahoense (n = 12) uncommon; west area Pisidium irusigne (n = 1) conunon; widespread Pisidium lillteborgi (n = 13) conunon; widespread Pisidium milium (n = 17) uncommon; widespread Pisidium nitidum (n = 9) tmcommon; east area Pisidium punctatum (n = 1) conunon; widespread Pisidium variabile (n = 36) conunon; widespread Pisidium ventricosum (n = 23) Ecological Factors Related to Distribution oxygen-independent; minimum 12.1 mg/l calcium; acidic mean pH oxygen-dependent; minimum 16.6 mg/l calcium insufficient sample size oxygen-independent; minimum 2.7 mg/l calcium oxygen-dependent; minimum 1.7 mg/l calcium | oxygen use type unknown; minimum 8.8 mg^! calcium oxygen use type unknown; minimum 1.7 mg/l calcium oxygen-dependent; minimum 1.6 mg/l calcium insufficient sample size; possible climatic restriction oxygen-dependent; minimum 16.6 mg/l calcium insufficient sample size oxygen-dependent; minimum 1.7 mg/l calcium oxygen-dependent; minimum 1.7 mg/l calcium oxygen-independent; minimum 1.7 mg/l calcium oxygen-dependent; minimum 12.8 mg/l calcium oxygen-inde|)endent; minimum 12.8 mg/l calcium; alkaline pH only insufficient sample size oxygen-independent; minimum 9.6 mg/l calcium oxygen-dependent; minimum 12.8 mg/l calcium; alkaline pH only insufficient sample size oxygen-dependent; minimum 10.1 mg/l calcium; alkaline pH only oxygen-independent; minimum 8.6 mg/l calcium oxygen-dependent; minimum 20.6 mg/l calcium ; alkaline pH only insufficient sample size oxygen-dependent; minimum 1.6 mg/l calcium oxygen-independent; minimum 1.6 mg/l calcium 61 globally only 6om one location in northern BC (Te and Clarke 1985). Water temperature appears to be the least important of the four environmental variables measured, in determining molluscan distribution. Taxa found at low water temperatures were generally found in large, perennial water bodies and these species may be restricted to these habitats for other reasons. Five of the nine families of freshwater molluscs in northern BC could be categorized as either oxygen-independent or oxygen-dependent (Table 2-8). Oxygen-independent taxa were generally found more often as they may be able to survive in a wider range of habitats than can the oxygen-dependent taxa, which are obviously restricted to well-oxygenated habitats. Russell-Hunter (1978) categorized freshwater molluscs in Britain according to their calcium requirements (Table 2-9). The 49 taxa found at the ecological sites in this study were similarly categorized and compared to the British categories (Table 2-9). Table 2-9. Proportions of freshwater molluscs from ecological sites in northern British Columbia as compared to the proportions of freshwater molluscs in Britain in relation to dissolved calcium content as described by Russell-Hunter (1978). Northern British Columbia freshwater molluscs used in this comparison were those with n >2 plus the endemic species, Physella wrighti. Minimum calcium requirement (mg/l) Number of taxa and percent of total taxa in northern BC Number of taxa and percent of total taxa in Britain Low : <3 11 27% 7 11% Intermediate; 3 to 10 11 27% 19 31% Moderate: >10 to 20 13 32% 6 10% Calciphilic: > 20 6 14% 30 48% 41 100% 62 100% Totals This comparison shows that northern BC has far fewer calciphilic molluscs than does Britain (i.e., 14% vs. 48%, respectively). This is not a function of a limited number of highcalcium concentration sites, as -75% of the ecological sites examined had calcium 62 concentrations > 20 mg/1 (Table A-1). The proportion of molluscs found in habitats with intermediate (i.e., 3 to 10 mg/1) calcium concentration was similar between the two areas (27% vs. 31%, respectively for BC and Britain), but BC had a much higher proportion of molluscs able to tolerate low (i.e., <3 mg/1; 27% vs. 11%, respectively), and moderate (i.e., >10 to 20 mg/1; 32% vs. 10%, respectively) calcium concentration. Thus, BC has a higher proportion of noncalciphilic taxa than does Britain (86% vs. 52%, respectively). The high proportion of noncalciphilic taxa in the geologically young habitats of northern BC may be indicative o f the ability of these more euryoecic taxa to be successfully passively dispersed and inhabit new areas. Many freshwater molluscs were found in both alkaline and acidic habitats but most had an alkaline mean pH (> 7). The exceptions having acidic mean pH (< 7) were Acroloxus coloradensis (n = 7). Aplexa elongata (n = 4), and Planorbula campestris (n = 4). Molluscs found only in alkaline habitats (> 6.85) were Fossaria galbana (n = 4), F. modicella (n = 8), Gyraulus crista (n = 4), Pisidium conventus (n = 6), P. idahoense (n = 12), P. lilljeborgi (n = 13) and P. nitidum (n = 9), which may be linked to their putative high calcium requirements. Many of these taxa had relatively small sample sizes. This highlights the conundrum as to whether uncommon taxa appear to have limited ranges because they are collected less often or are they collected less often because they have limited ranges. This study hypothesized that the freshwater molluscs in northern BC would be randomly distributed. However, of the 49 taxa of molluscs found at the ecological sites, one species (2%) displayed distribution consistent with the climatic-limitation hypothesis in that it reached the northernmost limit of its range in northern BC, and nine species (4 Pacific, 1 Bering and 3 Mississippi plus P. wrighti', 18%) displayed distributions consistent with glacial phenomena. The three Mississippi refuge species (6%) appear to have been unable to overcome the geographic barrier of the Rocky Mountains. Harman (1974) cites several authors who found little or no correlation between species 63 presence/absence and water chemistry. The results of this study suggest otherwise for 36 of the 40 taxa collected from more than two ecological sites plus the endemic species P. wrighti. Specifically, dissolved oxygen, conductivity/calcium concentration and pH appear to affect the distributions of 14, 30 and 10 taxa, respectively, with a combination of these factors evident for some taxa. In the five families of freshwater molluscs where dissolved oxygen use could be examined, 27 taxa were collected more than twice at ecological sites. Of these, 14 taxa (52%) appeared to be oxygen-dependent and so restricted to well-oxygenated habitats. Of the 40 taxa collected from more than two ecological sites plus P. wrighti, 30 taxa (75%) were collected at sites where the calcium concentration was > 3 mg/1, and 6 of these (15%) were found only in habitats with calcium concentration > 20 mg/1. Of these same 40 taxa, only three (7%) had an acidic mean pH and seven taxa (17%) appeared to be restricted to habitats o f alkaline conditions. The taxa Stagnicola arctica, Planorbella subcrenata, Anodonta kennerlyi, Pisidium casertanum and P. ventricosum showed no discernable responses to any of the environmental variables measured. Climate, history and geography appear to affect the distribution of some fireshwater molluscs, and physico-chemical factors may also be important determinants of the habitats occupied by many taxa in northern BC. Realistically, it is likely that combinations of many factors have shaped the present distribution and ecology of the freshwater molluscs of northern British Columbia. 64 CHAPTER 3 - COMPARISON OF CONTEMPORARY AND HISTORIC COLLECTIONS OF FRESHWATER MOLLUSCS AS A MEANS OF ASSESSING ENVIRONMENTAL QUALITY. Introduction Assessments of the conservation status of organisms are important guides for the allocation of conservation resources and are best made when based on detailed historical information. One of the key uses of historical information is to help calibrate present expectations regarding the productivity, diversity, and stability of natural systems upon which humans depend (Steedman et al. 1996). Most available historic information on organisms is in the form of taxonomic collections. As changes in community structure are generally accepted as indicative of changes in environmental quality (Norris and Georges 1993), it should be possible to examine temporal changes to habitats by comparing contemporary and historic taxonomic collections (Steedmanera/. 1996, McCarthy 1998). Contemporary and historic collections of freshwater molluscs have been made in northern BC. Much of the historic information dates to collections made by Dr. A. H. Clarice and assistants for the National Museums of Canada (now the Canadian Museum o f Nature) during the summers of 1972 and 1973 (Clarice 1972, 1973a). Many changes have occurred in northern BC since that time. For example, the human population in the six regional districts that are entirely or partially within northern BC increased by 48% in the 25 years from 1971 to 1996 (Figure 3-1). As the economy of northern BC is based primarily on natural resource utilization, it can be assumed that the increased human population reflects an increase in the use o f northern resources, especially forests. Increased population and resource use may have impacted aquatic ecosystems in a manner reflected in temporal changes in freshwater mollusc conununities. A direct comparison of communities using historic (i.e., 1972/1973) and contemporary (i.e., 1997) data may give an indication of historic and potential future impacts on aquatic ecosystems. 65 District Population Estimates Intercensal 1971 %Chmnge Reyinnal 1996 Stikine 57-Sdkine 59 - Ft Nelson/Liard 49 - Kitimat/Stildne 55-PeaceRiver 51 - BuUdly/Nechako 53 - Fraser/Ft George 1,470 1,450 -1% Fort Nelson/Liard and Peace River (formerly Peace River /Liard) +48% 43,996 6,127 58,887 Kitimat/Stildne 37,326 45,457 +22% Bulkley/Nechako +60% 27,145 43,383 Fraser/Fort George 64,364 103,202 +60% Total +48% 174,301 258,506 Figure 3-1. Regional Districts o f British Columbia and intercensal human population estimates in 1971 and 1996 for regional districts within northern British Columbia with percent change during this time period. (From British Columbia Statistics, Ministry of Finance and Corporate Relations, Victoria, BC.) Comparisons of floral and faunal community composition may provide important insights into environmental quality and similarity indices can be used to quantify similarities between communities (Spellerberg 1991). Other measures, such as functional-feeding guilds, can provide insight into the ecology and functioning of the ecosystems by elucidating differences in food acquisition (Resh and Jackson 1993). Changes in the relative proportions of feeding guilds are generally interpreted as "stress" to the community (Lenat and Barbour 1993) and these may provide a measure o f the natural and anthropogenically driven changes in aquatic ecosystems (Cummings 1993). This tqiproach is often used in studies of aquatic insect larvae in which species are categorized by their eating habits as shredders, gathering collectors, filtering collectors, scnqiers, predators and plant piercers (Cummins 1993). The use of freshwater molluscs in water quality studies has lagged behind that of other aquatic organisms such as insects (Strayer 1999a). However, an analogous guild {qjproach may be possible for freshwater molluscs, which can be assigned to four feeding guilds based on their generalized method of 66 food acquisition. These guilds are: (1) grazers - gastropods are generally grazers on awfwuchs (organisms forming a living film on aquatic substrata) that grow on solid surfaces in aquatic habitats (Brown 1991); (2) suspension feeders - mussels, and clams of the genera Sphaerium and Musculium, may remain relatively sedentary in soft sediments, obtaining food by drawing surrounding water over their ciliated gills (McMahon 1991); (3) deposit feeders - clams of the genera Sphaerium and Musculium may supplement suspension feeding by using their inhalant siphon to draw in food fit>m the sediment surface (Way 1989); and (4) infaunal feeders - clams of the genus Pisidium actively crawl through soft substrates, feeding on organic material that becomes available through their burrowing activities (Lopez and Holopainen, 1987). Materials and Methods Historic and contemporary species lists and person-hours spent on collection at appropriate sites were taken from Lee and Ackerman (1999a). Contemporary collections were made by the methods described in Cluqster 2. Sorenson’s Community Comparison Index, a binary (i.e. presence/absence) community similarity index, was used to quantify differences between the species assemblages found contemporarily and historically at the same sites. The formula for this index is: C = ^ .1 0 0 where C is the index of similarity, w is the number of species common to both samples, A is the number of species in sample one, and B is the number of species in sample two. The scores are multiplied by 100 to give a percent scale. A value o f 100% indicates complete similarity and a value of 0% indicates complete dissimilarity between samples (Spellerberg 1991). The similarity of contemporary and historic mollusc community structure was also examined by cluster analysis with Statistica 5.1 software (StatSoft, b e. 1997). 67 Species lists were categorized according to feeding guild. As species o f the genera Sphaerium and Musculium are believed to both suspension and deposit feed (Way 1989), these species were divided evenly between the two groups. Results There were sixteen sites in northern BC for which historic and contemporary collections of fireshwater molluscs could be compared (Table 3-1). Tables 3-1 and 3-2 show that at all but the single species sites, contemporary collections contained more species than did historic ones. At two sites, the same single species was collected resulting in similarity indices of 100%. At another two sites, the contemporary and historic collections contained dissimilar species resulting in similarity indices of 0%. For the remaining 12 sites, the community similarity indices were quite low (Table 3-2) with results exceeded 50% for only three sites. Time-search effort was generally h i^ e r in the contemporary study (Table 3-2) during which 29.8 hours were spent on collection whereas the total historic collection time was 18.7 hours. A total of 126 collections of taxa were recorded contemporarily compared to 53 recorded historically. Thus, the contemporary study expended 1.6 times more search-effort resulting in 2.4 times as many collections of taxa. Cluster analysis produced a vertical icicle plot (Figure 3-2) that resulted in only three of the contemporary and historic site-pairs forming direct groups (indicated by on Figure 3-2). Two of these were single species sites (Alpha Stream - N1108/CN1023 and Lakelse River N1083/CN1022), which join at a Euclidean distance of 0 as the communities were identical and so had similarity indices of 100%, and the third was Azouzetta Lake (N100S/CN1013), which had the next h ip est similarity index of 67%. In general, the cluster analysis failed to identify patterns among or between sites. The categorization of functional feeding groups (Table 3-3) showed that contemporary 68 Table 3-1. Species lists for historical and contemporary collections made at sites in northern British Columbia. indicates collections diat were made within the same water body but not at the same sites. Taxa found in both years are indicated in bold. 1. McLeod Lake N1003 (1997) Valvata sincera sincera StagHicola elodea PhyseUa tp. Gyraulus circumstriatus HeUsoma anceps aneeps PtoHorbeUa subcrenata Ferrissia parallela Anodonta kennerfyt Sphaerium simile Pisidium compressum Pisidium nitidum 2. Azouzetta Lake N1008(1997) Stagnicola elodea Gyraulus circumstriatus Gyraulus parvus Iridium compressum Pisidium lilljeborgi Pisidium variabile 3. Tate Creek N1016(1997) Stagnicola caperata Physella sp. Sphaerium simile Pisidium compressum CN1012(1972) Lymnaea stagpalis oppressa Stagnicola elodea Physella lordi Helisoma anceps anceps Planorbella subcrenata Anodonta kennerfyi CN1013 (1972) Stagnicola elodes Pisidium compressum Pisidium variabile CN1014(1972) Gyraulus circumstriatus Musculium lacustre Pisidium nitidum 4. Dease Lake* N1068 (1997) Valvata lewisi lewisi Valvata sincera sincera Lymnaea atkaensis Stagnicola arctica Staffucola elodes Physa skinneri Gyraulus circumstriatus PisbUum casertanum Pisidium idahoense Pisidium milium Pisidium variabile CN1005(1972) Lymnaea atkaensis Stagnicola arctica Physa jennessi Jennessi Gyraulus vermicularis Pisidium casertanum Pisidium variabile 5. Eddontenajon Lake* N1073(1997) Valvata lewisi lewisi Stagnicola elodes Gyraulus circumstriatus Pisidium casertanum Pisidium idahoense Pisidium variabile CN1004 (1972) Gyraulus vermicularis Sphaerium nitidum Pisidium casertanum Pisidium compressum Pisidium idahoense Pisidium lilljeborgi 6. Lakelse River N1083(1997) Margaritifera falcata CN1022(1973) Margaritifera falcata 69 Table 3~l (cont.). Species lists for historical and contemporary collections made at sites in northern British Columbia. indicates collections that were made within the same water body but not at the same sites. Taxa found in both years are indicated in bold. 7. Seeley Lake NI091 (1997) Valvata sincera sincera Lymnaea stagnalis appressa PhyseUa sp. Gyraulus circumstriatus Pmmenetus exacuous exacuous Planorbella subcrenata Ferrissia paraUela Musculium lacustre Musculium securis Pisidium compressum 8. Decker Lake NI 100(1997) Valvata sincera sincera Physella sp, Acroloxus coloradensis Gyraulus deflectus Promenetus exacuous exacuous Menetus opercularis Ferrissia parallela Anodonta kennerfyi Musculium securis Pisidiumferrugineum CN1021 (1973) PhyseUa propinqua FerrissiafragiUs CN1020(1973) Planorbella subcrenata Anodonta kennerfyi 9. Steiiako River N1102 (1997) Vafvata lewisi iewisi Valvata sincera sincera Stagnicola elodes Physella sp. Gyraulus circumstriatus Promenetus exacuous exacuous Menetus opercularis Musculium lacustre Pisidium casertanum Pisidium compressum Pisidium conventus Pisidium idahoense 10. slough o f Nechako River N1103 (1997) Valvata lewisi lewisi Stagnicola arctica Physella sp. Gyraulus circumstriatus Promenetus exacuous exacuous Pisidium casertanum CN1019(1973) Valvata lewisi lewisi CN 1018 (1973) Valvata sincera Stagnicola elodes Planorbella subcrenata Anodonta kennerlyi Musculium lacustre 11. Alpha Stream - Liard River Hotsprings CN1023(1973) N1108 (1997) PhyseUa wrighti PhyseUa wrighti 12. Warm Swamp - Liard River Hotsprings CN1023(1973) N1109 (1997) Physa virginea Gyraulus circumstriatus Gyraulus circumstriatus Pisidium casertanum 70 Table 3-1 (cont.). Species lists for historical and contemporary collections made at sites in northern British Columbia. indicates collections that were made within the same water body but not at the same sites. Taxa found in both years are indicated in bold. 13. Stuart Lake* NI 105 (1997) Valvata lewisi lewisi Valvata sincera sincera Lymnaea stagnalis appressa Stagnicola elodes Physella sp. Gyraulus circumstriatus Promenetus exacuous exacuous Planorbula campestris Anodonta kennerlyi Musculium lacustre Pisidium casertanum 14. Purden Lake N1107 (1997) Valvata lewisi lewisi Lymnaea stagnalis appressa Stagnicola catascopium catascopium PhyseUa sp. Acroloxus coloradensis Gyraulus deflectus Promenetus exacuous exacuous Helisoma anceps anceps Planorbella subcrenata Ferrissia parallela Sphaerium simile Sphaerium striatinum Musculium securis Pisidium casertanum Pisidium compressum CN1000(1972) Stagnicola elodes Gyraulus vermicularis Pm m enetus exacuous exacuous Musculium transversum Pisidium compressum Pisidium nitidum Pisidium variabile CN1015(1073) Acroloxus coloradensis Physa sp. 15. Ciuculz Creek N0108(1997) Planorbella subcrenata Ferrissia parallela Sphaerium simile Musculium lacustre Musculium securis Pisidium casertanum Pisidium compressum 16. Summit Lake N0113(1997) Valvata sincera sincera PhyseUa sp. Helisoma anceps anceps Planorbella subcrenata Gyraulus circumstriatus Gyraulus parvus Promenetus exacuous exacuous Ferrissia parallela Anodonta kennerlyi Sphaerium simile Musculium securis Pisidium casertanum Pisidium milium CN1017(1973) Valvata sincera PhyseUa propinqua Planorbella binneyi Anodonta kennerlyi Sphaerium simUe CNlOll (1972) Anodonta kennerlyi 71 Table 3-2. Comparisons o f collection times (i.e. person-hours) and results of Sorenson’s Index o f Community Similarity made between (1) contemporary collections and (2) historic collections. A = number o f species found during contemporary collections. B = number o f species found during historic collections, w = number o f species common to both collections. C = similarity index, indicates collections that were made within the same water body but not at the same sites within those water bodies. # 1 2 3 4 5 6 7 8 9 10 (1) Contemp­ orary NI003 N1008 N1016 N1068 NI073 N1083 N1091 NllOO N1102 11 12 N1103 N1108 N1109 13 N1105 14 IS N1107 N0108 16 N0113 Total Average Collect, time Person Hours 1.0 hr 1.4 hr 0.8 hr (2) Historic CN1012 CN10I3 CN1014 Collect, time Person Hours 2.0 hr 1.2 hr 0.6 hr 3.5 hr Location McLeod Lake Azouzetta Lake Tate Creek "'Dease Lake *Eddontenajon Lake Time t|/l2 0.5 1.2 1.3 0.9 7.5 1.5 3.0 hr 3.0 hr 0.6 hr CNI005 CN1004 1.4 hr 1.0 hr 0.8 hr 0.8 hr CN1021 CNI020 CN1019 CN1018 0.4 hr 0.4 hr 2.0 hr CN1023 CNI023 CNIOOO 0.8 hr Alpha Steam, Liard Hotsprings Warm Swamp, Liard Hotsprings 1.0 1.6 hr *Stuart Lake 8.0 hr 0.2 hr 5.0 hr CN1015 CN1017 C N lO ll 1.4 hr 1.2 hr 2.0 hr Purden Lake Ciuculz Creek Summit Lake 29.8 hr 1.9 hr CN1022 0.4 hr 0.4 hr 1.0 hr 0.8 hr l.Ohr 0.8 hr 18.7 hr 1.2 hr Lakelse River Seeley Lake Decker Lake Steiiako River slough o f Nechako River 1.4 1.3 0.8 1.0 A B w 11 6 4 11 6 6 3 3 6 6 1 2 5 3 0 5 3 1 10 10 12 6 2 1 0.5 I 2 11 5.7 0.6 2.5 15 7 13 1 2 7 2 5 1 126 53 1.6 5 1 2 1 1 0 C % 59 67 0 59 50 100 33 17 15 0 1 1 100 50 33 1 1 1 12 17 14 1.8 39 72 Figure 3-2. Vertical icicle plot o f the cluster analysis o f the contemporary and historic collection sites o f freshwater molluscs o f northern British Columbia based on unweighted pair-group average of the species lists in Table 3-1. indicates same-site pairs that join _______________________________________________ directly. Contem porary and H istoric C ollection Sites o f Freshw ater M olluscs in N orthern B ritish Colum bia 4.0 3.5 I f : ■ ■ » I I I I ■ ........................ 3.0 2.5 2.0 1 1.5 I tS 1.0 0.5 0.0 P CS < C/Î t/5 W W c/3 C/3 ill 73 Table 3-3. Comparison o f number o f species and percentage o f total number o f species o f the four functional feeding groups o f freshwater molluscs. Group 1 - Grazers (snails); Group 2 = Suspension feeders (mussels and clams o f the genera Sphaerium and Afusculium); Group 3 - Deposit Feeders (clams o f the genera Sphaerium and Musculium); Group 4 =Infaunal feeders (clams o f the genus Pisidium). Clams o f the genera Sphaerium and Musculium have been divided equally between Groups 2 and 3. Number and Percent of Specie# per Group No. Contemporary 1 N1003 2 N1008 3 N1016 4 N1068 5 N1073 6 N1083 Number and Percent of Specie# per Group Croup 1 Group 2 Croup3 Croup 4 Total Hbtork Croup 1 Croup 2 7:64% 3:50% 1.5:14% 0.5: 4% 5:83% 1 : 17% - 2 ; 50% 0.5:12% 0.5:13% 11 6 4 CN1012 - 2 : 18% 3:50% CN1013 CN1014 7:64% 3:50% - - 1 :33% 1 : 33% 4:67% . - - 1 :100% - - 2:67% 0.5: 16% 0.5: 17% 1 : 33% 2:33% 0.5: 8% 0.5: 8% 4:67% 1 :100% 1: 10% 1 : 10% 1 :25% 4:36% 3:50% 11 6 1 10 CN1005 CN1004 10 CN1020 12 6 CN1019 CN1018 1 CN1023 2 11 15 CNI023 CNIOOO 7 13 CN1017 CNlOll 28:22% 126 Total 1.8 7.9 Average 7 N1091 8 NllOO 7:70% 1 : 10% 1 :10% 7:70% 1.5:15% 9 N1102 10 N1103 11 N1108 7:58% 5:83% 1:100% 0.5: 4% 0.5: 5% 0.5: 4% - - - . - 12 N1009 13 N1105 1 :50% 8:73% - - 1 :50% 1 : 9% 14 N1107 IS NO108 16 N0113 10: 67% 2:29% 1.5:10% 8:62% 2:15% Total 78: 62% 12.5:10% 7.5: 6% Average 4.9 1.5:14% 0.5:4% 1.5:21% 0.8 4 :33% 1 : 17% 1.5:10% 2: 13% 1.5:21% 2:29% 1 : 8% 2: 15% 0.5 CN1022 CN1021 CN1015 1 : 17% - 2:100% 1 : 50% 1:100% 3:60% 1:100% 2:100% Croup 3 Croup 4 - - - - 1 :50% - - - 1.5:30% 0.5: 10% - - - 3 :43% 2:100% 0.5 : 7% 3:60% 1.5:30% 1 :100% 0.5: 10% 30:56% 8.5:16% 2.5: 5% 12: 23% 53 1.9 0.5 0.2 0.7 3.3 - 0.5: 7% 6 3 3 6 6 I 2 2 1 5 1 2 - - Total - 3 : 43% - 7 2 5 1 - - 74 collections comprised 62% grazers, 10% suspension feeders, 6% deposit feeders and 22% infaunal feeders, while the historic sites had 56% grazers, 16% suspension feeders, 5% deposit feeders and 23% infaunal feeders. In only one multiple species site-pair did the proportion of functional feeding groups remain the same (N1068/CN1005). The contemporary collections found new fimctional-feeding groups at nine of the 16 sites (N1003, N1091, NllOO, N1102, N1103, N1009, N1107, N0108 and NOl 13), v.hereas functional-feeding groups had been lost at two sites (N1073 and N1103). Discussion Community Comparisons The results of both the similarity indices and the cluster analysis showed very low levels of similarity between the contemporary and historical fireshwater mollusc collections. Low community similarity indices can be indicative of stress, with lower diversity occurring in stressed communities (Norris and Georges 1993). Given the assumed increase in natural resource use in northern BC during the last 25 years (1972 - 1997), the habitat improvement suggested by higher contemporary diversity seems unlikely. Possible alternative interpretations of the data are: 1. Diversity has increased naturally as freshwater molluscs continue to be passively dispersed into northern BC. Most northern BC aquatic habitats have probably been in place for hundreds to thousands of years and it seems unlikely that such a large amount of immigration would have occurred in the 25 year interval examined here. 2. Climate change. Average annual temperatures in the Prince George area of northern BC have typically been above the 50 year mean o f the records since about the mid-1970's (Petticrew et al. 1999). Freshwater molluscs historically restricted from northern climes by life history requirements may 75 have been able to move northwards with the advent of a warming trend in northern BC. Contemporary collections at the 16 sites found 13 taxa not recorded by Clarke from these same sites (Table 3-4). However, Clarke’s collections may have been incompletely processed (see below), and the distribution maps published by Clarke (1981) are reasonably consistent with current known distribution for nine of these taxa (Table 3-4). Of remaining four taxa, Vahata sincera sincera, Musculium securis and Pisidium milium are all recorded from the Northwest Territories (Clarice 1981) so it is unlikely their being newly recorded from northern BC has been due to a warming climate trend. The absence of previous records for the fourth taxa, Ferrissia parallelus, may be due to collection technique (see below) as contemporary collections of this taxa were most often made from the bottoms of lily pads accessed only by entering the water in chest waders. Thus, there are no apparent increases in diversity that can be readily linked to climate change in northern BC. Table 3-4. List of taxa recorded contemporarily but not historically from the sixteen sites compared in northern British Columbia with historical distribution as recorded by Clarke (1981). Taxa Distribution recorded by Clarke (1981) Valvata sincera sincera Not recorded in northern BC Stagnicola catascopium catascopium Mapped consistently with present known distribution Stagnicola caperata Mapped consistently with present known distribution Gyraulus d^ectus Mapped consistently with present known distribution Gyraulus parvus Mapped consistently with present known distribution Menetus opercularis Mapped consistently with present known distribution Planorbula campestris Mrqrped consistently with present known distribution Ferrissia parallelus Not recorded in northern BC Sphaerium striatinum Mapped consistently with present known distribution Musculium securis Not recorded in northern BC Pisidium conventus Mapped consistently with present known distribution Pisidiumferrugineum Mtqrped consistently with present known distribution Pisidium milium Not recorded in northern BC 76 3. Sampling bias. Bias is the magnitude and direction of the tendency to measure something other than was intended (Eisenhart 1968). Estimates of community diversity from samples are always biased (Green 1979) but attempts can be made to minimize bias by: (a) standardizing operator expertise, or ensuring that results are interpreted similarly by experts or novices. Booth and Dussart (1998) found that the number of species found in searches for terrestrial macromolluscs varied significantly with operator experience. Further, rapid bioassessment protocols of aquatic habitats require that field crews with varying degrees of expertise be able to accomplish similar levels of identification in grouping analyses of aquatic macroinvertebrates (Cummins 1993). (b) using standard collection techniques - Dorazio (1999) found that in surveys o f freshwater mussels, the composition and relative abundance of species differed significantly with collection method. If Clarice’s collection techniques differed fix>m that used in the contemporary study (e.g., may have been made only fit>m shore), this could account for the lesser number of species that were generally collected historically. (c) effort expended - the probability of encountering a common species is probably good regardless of effort, whereas the probability of encountering a rare species increases significantly with additional effort (Metcalfe-Smith et al. 1997). Thus, the number of species collected fiom a given site is related to the effort expended. As shown in Table 3-2, more time was often spent making the contemporary collections than was spent historically. The result was that contemporary study expended 1.6 times as much search-effort resulting in 2.4 times as many collections. Collection effort expended is an important component of community comparisons. 4. Incomplete processing and archiving of collections. While Clarke’s field notes (Clarite 1972, 1973a) did not always include species lists, some of the taxa that he noted are not confirmed by voucher specimens at the Canadian Museum 77 of Nature (CMN). Examples of these are listed in Table 3-5. Important collections not confirmed by voucher specimens are Acroloxus coloradensis and Margaritifera falcata, which had previously been recorded fiom single locations in northern BC. In the BC collections at the CMN, there are 75 lots of unidentified collections fiom the Family Lymnaeidae and 72 lots fiom the Family Physidae (Lee and Ackerman 1998a). Thus, Clarke’s collections fiom northern BC may have been incompletely processed and archived. Table 3-5. Species noted by Clarke (1972,1973a) as occurring at sites listed that are not confirmed by voucher specimens at the Canadian Museum of Nature. Site Collections noted in field notes not verified by CNM voucher specimens CNIOI1 - Summit Lake Physa sp.; Helisoma sp.; Ferrissia sp. CN1012-McLeod Lake Valvata sp. CN 1015 - Purden Lake Acroloxus coloradensis; Physa sp. CN1022 - Lakelse River Margaritifera falcata Communitv Similaritv Sorenson’s Community Comparison Index provided little infoimation about the nature of the temporal change in community structure. While the index was generally less than 100%, indicating differing diversity, this was just as easily seen by a count of the total number of species. According to Poole (1974), a count of species is the only truly objective measure of diversity. Examination of species lists is also the only means by which to determine changes in feeding guilds. Pielou (1969) states that fashionable trends such as the use of diversity indices “have led to false analogies that produce no noticeable advance in ecological understanding”. Based on the results of this study, 1 agree with Green’s (1979) statement that “the use of derived indices as indicators of environmental quality in some general sense is not an {q>proach about which I am enthusiastic”. Cluster analysis was an effective technique for pairing sites that were identical or very 78 similar. However, the clustering of sites of lesser similarity were of limited ecological interpretability when only the vertical icicle plot was examined (Figure 3-2). Again, a direct examination of species lists provided more readily interprétable findings. Feeding Guilds There does not appear to be a precedent for the examination of aquatic systems by the proportions of fi^shwater mollusc feeding guilds. The overall proportion of these guilds remained quite similar during the 25 year interval studied (Table 3-3) suggesting no overall change in the types o f food resources available to molluscs. However, when examined individually, 10 of the 16 sites had different guilds present (nine of the contemporary sites had new guilds and two of them lost guilds; Table 3-3). Of the remaining six sites, five had similar proportions in both studies but N1105/CN1000 had changed considerably (Table 3-3). Therefore, based on change in guild structure, 11 of the 16 sites (69%) appear to have undergone habitat change during the 25-year interval. While this may be the case, other problems related to the historic data discussed above preclude the possibility of assessing habitat change by comparisons of these records. Conclusions The comparison of the contemporary and historic collections was expected to have provided some information on the manner in which the increase in human activities in northern BC has affected aquatic ecosystems and their resident molluscs. However, the uncertainty regarding how the historical data was collected and processed precludes the possibility of direct comparisons. The resolution of retrospective answers to ecological questions will always be limited by the accuracy, extent, and spatial and temporal coverage o f historic data (Steedman et al. 1996). Management practices can only be based on existing information so it is important that data be as comprehensive as possible so that assessments are scientifically defensible. In 79 this study, it appears that differences in collection time, perhaps collection technique, and the apparent incomplete processing and archiving of historic collections, has limited the use of these records in assessing possible environmental change. 80 CHAPTER 4 - THE EFFECTS OF FOREST PRACTICES ON FRESHWATER MOLLUSC HABITAT: A CASE STUDY FROM THE TORPY RIVER WATERSHED IN EAST-CENTRAL BRITISH COLUMBIA Introduction Potential conflicts between forest practices and preservation of aquatic habitats are widely recognized. However, these conflicts are difficult to assess or predict as there is insufficient evidence on aquatic conununity responses to habitat alterations (Newbold et a l 1980). Moreover, the most basic relationships pertaining to forest harvest effects on aquatic systems still remain theoretical (Miller et al. 1997). While freshwater molluscs have unique strengths as water quality monitors (Strayer 1999a), little reference has been made to this group as indicators of habitat change such as those that may result from forest practices. Available information often relates only to freshwater mussels and is anecdotal or descriptive rather than based on scientific study. For example, shifts in mussel community composition, declining mussel abundance and local extinction have been attributed to, but not proven to be caused by, changes in habitat caused by deforestation and the destruction o f riparian zones (Neves 1992, Williams et a l 1993, Morris and Corkum 1996, Bogan 1998, Box and Mossa 1999). As the ecology of fireshwater snails and clams is often quite different firom that of fireshwater mussels, it is difficult to generalize information about mussels to other fireshwater molluscs. Evidence firom other fireshwater organisms, mainly aquatic insect larvae, shows that while species diversity may decrease following timber removal, the abundance o f the remaining aquatic insect larvae generally increases (Newbold et a l 1980, Noel et a l 1986, Carlson et a l 1990, Fore et a l 1996, Stone and Wallace 1998). Given the differences in taxonomy and potential responses, the effects of forest practices on fireshwater molluscs remains to be elucidated. Forest practices alter the natural landscape in many ways including the construction of 81 access roads that may result in the creation of wet areas (i.e., lentic or standing water sites). For example, low-lying seepage areas may be culverted or channeled into ditches to avert road flooding. In some cases, equipment scars may become permanent wet areas. When road construction requires a stream to be crossed, a bridge or culvert is installed (Society of American Foresters 1984; British Columbia Ministry of Forests 1995a). Culvert installation in lotie (flowing) sites alters the natural stream hydraulics by channeling the water through a narrow opening, often resulting in the formation of a pool on the upstream side of the culvert. Lotie conditions might also be affected by the loss or reduction of riparian vegetation, although vegetation may be maintained in a riparian reserve zone to mitigate against such impacts (Society of American Foresters 1984; British Columbia Ministry of Forests 1998). Increased sedimentation has been associated with complete timber removal in a watershed close to that of the present study (Brownlee et al. 1988). Consequently, it would be reasonable to examine whether riparian condition affects sediment dwelling moUuscan diversity or abundance. The Torpy River watershed in east-central British Columbia (BC) provides an opportunity to access a wide range of forestry and related impacts because of a long history of forest practices. The ubiquitous freshwater clam Pisidium casertanum (maximum 5-mm shell length) provides a model species by which to examine sediment accumulation resulting from forest practices as it can readily inhabit newly created aquatic habitats with sediment substrates (pers. obs.) where it burrows out canals and feeds upon interstitial bacteria (Meier-Brook 1969, Lopez and Holopainen 1987). An examination o f the local distribution and abundance o f this species, as well as comparisons of mollusc community stmcture, should provide data with which to assess the effects of forest practices on freshwater molluscs. The results of the study would also be o f interest to forest managers, specifically with respect to how road building and riparian conditions can affect the habitat of sediment dwelling stream organisms. 82 Materials and Methods Study Area The Torpy River watershed is located about 90 km east of Prince George, BC, Canada (Figure 4-1). This area is mountainous with an alluvial substrate of clay, sand and gravel. Streams are mainly first order, either spring fed or the result of snow melt and groundwater inputs. The forest cover is primarily coniferous dominated by white spruce {Picea glauca), subalpine fir {Abies iasiocarpa), and hemlock {Tsuga spp ). This watershed has a 40-year history of forestry activity (British Columbia Ministry of Forests 1995b) and forest practices and the requisite landscape alterations of access road construction and timber removal continue. The watershed comprises one large lake (Pass Lake) and three rivers (West, Upper, and Lower Torpy Rivers). There is limited access to the West Torpy River. The Upper Torpy River flows through very steep terrain and initial survey woric for this study found that the fast flowing tributary streams and the surrounding landscqx offered little freshwater mollusc habitat. The Lower Torpy River (LTR) watershed is the focus of this study. The low slope of the landsctq>e Watershed Figure 4-1. The Torpy River Watershed and its location in British Columbia. 83 adjacent to the LTR allows for the fonnation of natural pools in the tributary streams and for the occurrence of other types of water bodies that can host populations of freshwater molluscs. An access road approximately 47 km long runs parallel to the LTR. This road crossed 119 tributary streams and there were 58 adjacent wet areas. Habitat Classification Habitats were classified as either lentic or lotie based on inspections. Lentic habitats, in which the water is not flowing except during rainfall or snowmelt, were categorized as follows: 1. Water accumulations - low-lying areas adjacent to the road fed by seepage or ground flow that have been culverted to prevent excessive water accumulation fix>m flooding the road; 2. Ditches - areas excavated parallel to the road to divert seepage or groundwater flow; 3. Cattails - areas adjacent to the road where road building equipment had created shallow scars that became permanently wet or filled with water, and that had characteristic vegetation of cattails (Typha latifolia)', 4. Pools - water bodies < 100 m^ surface area adjacent to the road resulting from road building equipment creating deeper scars (up to 0.5 m depth) that had become permanently filled with water but did not have populations of cattails; and 5. Ponds - there were three large ponds (> 0.5 m depth, > 1000 m^ surface area) adjacent to the road in the LTR watershed that probably existed prior to forest practices. All o f the lotie habitats were tributary streams flowing into the LTR. In these streams, the installation o f culverts had caused pools to form on the upstream side of the culverts. These streams were categorized according to the type of upstream riparian condition based on forest cover maps produced by British Columbia Ministry of Forests (1995b) and updated fiom observations ofm ore recent activity. The four categories were: (1) Unlogged - where the original forest remained intact; 84 (2) Old Clearcut - where the original forest adjacent to the stream has been removed, but sufficient time had elapsed for some forest regrowth (logged >10 years prior to study); (3) New clearcut - where the original forest adjacent to the stream has been removed and no significant regrowth had occurred (logged <10 years prior to study) and; (4) Riparian Reserve Zone - where a 20 to 50 meter wide area of intact forest immediately adjacent to a stream was left within a clearcut (adjacent clearcut made <10 years prior to study). Sampling Suitable sites for molluscs were considered to be low discharge streams with soft sediment substrates and all lentic habitats adjacent to the LTR road. High discharge sites with rocky substrates were considered non-suitable sites based on preliminary collections within the area. All habitats that appeared to offer suitable freshwater mollusc habitat along the length of the LTR road were assessed for the presence of molluscs. Selected streams, chosen on the basis of downstream clam densities and upstream accessibility, were surveyed to ascertain whether populations of clams {P. casertanum) were present upstream. Pass Lake was also sampled to examine local mollusc biodiversity. The presence of molluscs was assessed with an 18 cm diameter stainless steel mesh net with a nominal pore size of iqiproximately 1.5 mm, attached to a broom handle by hose clamps. This net was used to sweep vegetation for snails and to dig into soft sediments for the collection of clams and sediment grazing snails. All molluscs found were collected, preserved, and identified using criteria presented in Burch (1975a, 1975b, 1989), Claftte (1973b, 1981) and Herrington (1962,1965). If several net samples (4 to 6 minimum) in soft sediments yielded at least one clam, the area was sampled quantitatively with 63.5-mm (2.5-inch) diameter plexiglass coring tubes (area 85 0.0031 m^). These were pushed ^proximately 64 nun into the sediment; a lid was attached to create a vacuum, and the tube was withdrawn with the contents intact. Four replicate cores were collected at each site. The content of each core was transferred into a labeled plastic bag and returned to the laboratory where three o f the cores were washed through 2000 pm and 850 pm sized mesh sieves to expose clams. The clams were removed, counted, and preserved in 70% ethanol. Density o f clams was determined from the mean number of clams found in the three cores. The fourth core was dried and ashed to determine organic content according to methods outlined in Standard Methods for the Examination of Water and Wastewater (American Public Health Association 1995). Homogenized subsamples were dried in preweighed evaporating dishes, weighed and ignited in a muffle furnace at 550°C for one hour. The weight of the remaining ash represented the inorganic content and the lost weight represented the organic content of the sample. At all site where quantitative samples were taken, four environmental variables were measured as follows: (1) water temperature (X ) with an alcohol thermometer, (2) dissolved oxygen (% saturation), and (3) conductivity (microSiemens - pS) with a Coming Checkmate Modular Meter System (Coming Inc., Coming, NY, USA) and; (4) pH with a Canlab (Mississauga, ON, Canada) portable digital pH meter Model 607. Results One hundred and seventy-seven sites in the Lower Torpy River watershed plus Pass Lake were examined for the presence o f freshwater molluscs. Eighty of the LTR sites were deemed unsuitable due to high discharge or rocky substrates, 25 sites appeared suitable but no molluscs were found, and 24 sites had molluscs but an extremely low density of clams, or substrate character (e g., dense plant roots) prohibited quantitative sampling. Approximately 27% of the total number of sites examined (i.e., 20 lotie sites and 28 lentic sites put o f a total of 177 sites) 86 were sampled quantitatively for clams. Estimated densities for Pisidium casertanum at these sites ranged from 105 clams m'^ to 20,329 clams m*^ (Figure 4-2). The density of P. casertanum along the LTR road was not uniform, and six sites of high densities (>10,000 clams m'^) were observed at 8, 21, 24,28,32 and 42 km spread along the length of the survey area (indicated by “•’’ in Figure 4-2). 25000 15000 W Figure 4-2. Density of Pisidium casertanum along the Lower Torpy River Road. “• ’’ indicates area of high density (>10,000 m'^). Lotie Habitats The mean density of clams and environmental conditions measured in the twenty lotie habitats are shown in Table 4-1. In seven streams, it was possible to access natural upstream pools o f a variety of riparian conditions in order to assess variability in clam density within each stream. In three of the streams, two additional pools were found upstream, and a third was found in another stream (Table 4-2). b 64% o f the cases (i.e., 12 of 18 pools examined), the pools at the culverts had densities of P. casertanum that were similar to the upstream pools (Table 4-2). In the two streams where statistically significant differences in clam density were found, AGIO had a rather small culvert pool density and no populations were detected upstream, while at 87 A022, the density was significantly higher at the culvert pool than in upstream sites. While the riparian condition classification of these latter two streams was old clearcut, there were also two old clearcut streams with similar culvert and upstream clam densities. Table 4-1. Average clam density and environmental conditions (mean ± SE [standard error]) in all categories of habitat and riparian condition in the Lower Torpy River watershed. Organic Temp. % °C DO - % Cond. Satvratkw US 27 ±4 11.8 ±0.4 77±2 266 ± 23 7.40 ±0.08 2,686 ±1,547 34±9 10±1 85 ±1 236 ±54 7.26 ±0.28 2,749 ± 701 23 ±6 12.6 ±0.5 72 ±4 279 ±37 7.41 ±0.11 New Clearcut 5 Riparian 1 Reserve Zone Lentic HaUtats 28 (pooled) 2,970 ±1,169 29 ± 3 11.3 ±0.4 77 ±2 268 ±33 7.44 ±0.16 5,846 30 13 80 303 7.75 5,496 ± 922 25 ±3 14±1 62±3 222 ±22 6.71 ±0.11 Water accum 6 5,618 ±1,763 26±7 14±2 55±6 208 ±35 6.65 ±0.14 Ditch 8 5,793 ±2,356 22±5 12±1 52±8 202 ±60 6.40 ±0.13 Cattail 4 8,506 ±1,876 13±4 15±1 73±7 166 ±58 6.30 ±0.41 Pool 7 4,620 ±1,672 33 ±8 15±2 66±4 263 ±30 7.16 ±0.20 Pond 3 2,493 ±1,229 31 ±4 14±2 77±9 273 ±19 7.05 ±0.35 Habitat Type Lotie Habitats (pooled) No. Density sites clams/m' 20 2,947 ± 536 Unlogged 4 Old Clearcut 10 Table 4-2. Culvert and upstream densities of Pisidium casertanum. significantly different than culvert density at P < 0.05. pH indicates density is Density (Mean ± SE) of Pisidium casertanum (Clams m^). Lotie Site Riparian Condition AOlO Old Clearcut 6.6 211± 105 0* A022 Old Clearcut 11.0 6,004 ± 182 3265 ± 421* 1,580 ± 836* A037 Unlogged 19.7 7,163 ± 3,655 8,005 ± 737 4,424 ± 483 A045 Old Clearcut 212 737± 380 A074 New Clearcut 33.5 3,476 ± 1,493 2,844 ± 2,372 A091 New Clearcut 39.8 211± 105 211 ± 105 . A104 Old Clearcut 432 4,951 ± 2281 6,109 ± 1,916 - Distance Cnivert along road n « 3 (km) Upstream Location 1 n »3 1,053 ± 211 Upstream Location 2 n=3 - Upstream Location 3 n *3 • 211±211* • 10,744 ± 3,466 8S Riparian Condition The twenty streams with populations of P. casertanum at the culvert pools were put into four categories according to the upstream riparian condition (Table 4-1). The Riparian Reserve Zone had the highest mean density of clams but the sample size of one precluded meaningful comparisons. Statistical evaluation of these data failed to find significant difference between riparian condition and clam densities or environmental conditions regardless of how the groups were compared (Table 4-3). Post-hoc testing of the 36 possible pair-wise comparisons failed to find significant pair-wise differences (P > O.OS). These results indicate that all types of riparian conditions in the LTR watershed have statistically similar clam densities and environmental conditions at the culvert pools. Table 4-3. Results of ANOVA of density of Pisidium casertanum at culvert pools and various combinations of upstream riparian conditions in the Lower Torpy River watershed. Hypothesis Tested H o “ IkJnlogged ” MoldOeaicut ~ltN ew C laacut~ lUUpinin m ove zone Test Result F(3,16)=0.482 Probability P = 0.699 H o ~ MdUpuiu raove zone ■>'Uniogged) ~ Mold cloicut ~ PNow cleneiit F(2,i7)= 0.085 P = 0.919 H o — M 89 0.05). These results indicate that all lentic habitats in the LTR watershed have statistically similar clam densities and environmental conditions. This data also showed that the conditions in the four habitat types created by forest practices (water accumulations, ditches, cattails and pools) were not significantly different fiom those observed in the naturally-occurring pond habitats (multivariate ANOVA: Ho = Pcnued lemic= Mpomd: Wilks’ Lamba(6^o)= 0.789, Roa’s R{6 .2 0 )= 0.893, P = 0.518). Lotie vs. Lentic Habitats A comparison between the pooled data for lotie and lentic sites revealed a significant difference between these habitat types (multivariate ANOVA: Ho: piode = litntic; Wilks’ Lamb8 (6 ,4 0 ) = 0.472, Roa’s R<6 ,40 ) = 7.458, P < 0.001). Post-hoc testing found significant differences in: (1) density of P. casertanum, with lotie < lentic; (2) water temperature, with lotie < lentic; (3) dissolved oxygen, with lotie > lentic; and (4) pH, with lotie > lentic (Table 4-4). The direction of these differences suggests that movement of the water is the driving force causing the difference in the measurements. Higher densities o f clams were found in lentic habitats with less water movement and higher water temperature, and with lower dissolved oxygen and pH values. Table 4-4. Comparison of lotie and lentic habitats (mean ± SE) in the Lower Torpy River Watershed and probability level of differences in means. Factor Lode (pooled data) Lentic (pooled data) Density (clams m ') 2947 ± 536 (n = 20) 5496 ± 922 (n = 28) F(i.*) = 4.641 Organic Content (%) 27 ± 4 (n = 20) 25± 3(0 = 28) F(1.46)= 0-171 P = 0.682 Temperature (“C) 11.8± 0.4(n=20) I4± I(n = 28) P(i.46)=4.834 P = 0.033 Dissolved O2 (%) 77 ± 62 ± 3(n=27) F(I.4J)= 12.03 P = 0.001 Conductivity (^tS) 266 ± 23(n=20) 222± 22(0 = 27) F(1.45)= 1-921 P = 0.173 pH 7.40 ± 0.08 (n= 20) 6.7110.11 (n = 27) F(i.43)==20.91 P <0.001 2(n = 20) Test Result Probability P = 0.036 90 Community Composition Fifteen taxa of molluscs were found in the Torpy River watershed, comprising eight taxa of snails and seven taxa of clams (Table 4-S). No freshwater mussels were found. Freshwater clams of the genus Pisidium were the most common molluscs with five species, while the snail genus Gyraulus comprised three species, and the clam genus Muscuiium two species. The remaining five genera of snails had one taxa each. Five of the taxa collected occurred only in Table 4-5. List of freshwater molluscs and their habitats in the Torpy River watershed. Freshwater Molluscs Taxon Common Name Habitat ClasUSaittoiHMla UnaMs) Subclass Prosobranchia Family Valvatidae Vaivata iewisi iewisi fringed vaivata pool, pond Subclass Pulmonata Family Lymnaeidae Fossaria parva pygmy fossaria stream, water accum., ditch, cattails Stagpicola catascopium catascopium woodland pondsnail lake Family Physidae Physella sp. n/a lake, cattails, pool, pond Family Planorbidae Gyraulus circumstriatus disc gyro lake Gyraulus d^ectus flexed gyro Gyraulus parvus ash gyro Planorbella subcrenata rou^ rams-hom lake lake, stream, ditch, cattails, pool. pond lake ÇIm i B|viiIyIii Family Sphaeriidae (dams) Muscuiium lacustre lake fingemailclam cattails, pool, pond Muscuiium securis pond fingemailclam lake, cattails, pond Pisidium casertarmm ubiquitous peaclam Pisidium compressum ridgd>eakpeaclam lake, stream, water accumulations, ditches, cattails, ponds, pools lake Pisidiumferrugineum msty peaclam pond Pisidium milium quadrangular peaclam cattails, pond Pisidium ventricosum 1globular peaclam cattails 91 Pass Lake, which, as a large lentic water body was a different type o f habitat from the others examined in this study. While some of the remaining ten species were found in the lake, they were also found in various habitats throughout the LTR watershed (Table 4-5). In lode habitats, in addition to P. casertanum, some collections of Fossaria parva and Gyraulus parvus were made at both culvert and upstream pools. In the lentic habitats, ten taxa of molluscs were found o f which seven taxa were found in both the natural and the created habitats. The clam Pisidium ferrugineum was found only in one pond (natural), the clam P. ventricosum was found only in one cattail area (created), and the snail Fossaria parva was found only in several of the created lentic habitat types. Discussion At lotie sites, the common mollusc Pisidium casertanum was found at similar or greater densities at created culvert pools as compared to natural upstream pool sites. Given this observation, it appears that in the LTR watershed, the installation of culverts for the construction of forest access roads has increased the number of lotie habitats for, and thus the abundance of P. casertanum. The five categories o f lentic habitats identified were visually distinct, but not significantly different in terms of clam density or environmental conditions. Clam density in the four types of habitats created by forest practices was similar to that found in the naturallyoccurring ponds. Given this observation, it tqipears that in the LTR watershed, forest practices have increased the number o f lentic habitats for, and thus the abundance of P. casertanum. There does not appear to be a measurable downstream effect on clam population density with respect to upstream riparian condition (Table 4-1) although the sample size was limited in some cases. It may be that the thick, herbaceous riparian vegetation that grows in the LTR areas continues to provide sufficient buffering capacity to the streams and surrounding soil regardless 92 o f the extent of timber harvest. Another possible explanation is that the density P. casertanum at the culvert pools is not related to the amount of sediment deposited and so this clam is may not be an effective monitor of the quantity of downstream sedimentation. Lotie and lentic habitats differed significantly in the density of P. casertanum and iit several environmental conditions, with clam density significantly higher in the higher temperature lentic habitats. Endothermie animals, such as P. casertanum, often have increased metabolic rates with increased temperature. This was confirmed by Hombach (1985) who found variability in the metabolic rates of freshwater clams related to environmental factors. In specific studies of P. casertanum, Hombach and Cox (1987) found a significant difference in fecundity for P. casertanum in two ponds of differing quality. In the pond with more favourable conditions, P. casertanum had increased reproductive output and young bom early in the season were able to reproduce during the same season. Fecundity was lower in the less favourable conditions. In the present study, it is possible that the LTR lentic habitats were more favourable for growth and reproduction than the lotie ones. Habitats with higher temperature regime would result in an increased metabolic rate of clams, and consequently, an increased reproductive output. Thus, the significantly higher clam density observed in the lentic habitats may be associated with the significantly higher temperature measured there. All of the fifteen species of fieshwater mollusc found in the Torpy River watershed are common in Canada (Clarice 1981), although Muscuiium securis, Pisidium milium and P. ventricosum had not been recorded previously from northem BC. The lotie sites in the LTR watershed hosted three species of molluscs that were found in both the natural and culvert pools. The lentic sites hosted 10 species of molluscs. O f the three lentic molluscs appearing to be distributed differently between created and natural habitats, P. ventricosum was found only in one created cattail habitat and P. ferrugineum was found only in one natural pond. Results obtained throughout northem BC (Chrqpter 2) indicated that P. ventricosum may be able to 93 tolerate conditions of lower conductivity and pH than can P. ferrugineum and so can occupy some habitats unavailable to P. ferrugineum. However, in the LTR watershed, P. ventricosum was collected at conditions within the range of those recorded for P. ferrugineum throughout northem BC so the different distributions cannot be explained by the current information. Fossaria parva was found in lentic habitats only at created sites. Its absence firom the natural ponds may be a collection artifact as very few specimens of this species were collected in the LTR watershed, and it was collected at natural lotie pools. In general, however, the diversity of freshwater snails and clams in the LTR watershed was similar in both natural and created habitats. Thus, this study found no change in the diversity of fireshwater molluscs as a result of forest practices but did find apparent increases in abundance. Unfortunately, there is no way to determine that amount of molluscan habitat that was impacted or lost due to forest practices in the LTR watershed. It is clear however, that landscape alterations associated with forest practices can provide habitat for certain freshwater molluscs. In this study, created culvert pools and lentic habitats were found to provide suitable habitats for the fieshwater clam Pisidium casertanum and other locally occurring freshwater molluscs. In the case of culvert pools, these habitats may support greater clam densities than can natural upstream pools. This impact of forest practices is likely to be confined to those organisms with habitat requirements that include standing water and the accumulation of sediments. Additional research is warranted and should be directed towards particular taxa and fimctional groups. 94 CHAPTER 5 - INTEGRATION AND CONCLUSIONS A goal of the large-scale spatial study in northern BC was to record freshwater mollusc biodiversity. As time was limited, site selection was skewed towards large, vegetated, lentic water bodies which contain a greater diversity of molluscs than do lode or smaller lentic sites (Lassen 1975). Conversely, in the small-scale spatial study in the Lower Torpy River (LTR) watershed, all aquatic habitats adjacent to the access road were assessed for mollusc presence. The results of these different site selection criteria are apparent from histograms of the number of species per site with lentic and lotie sites distinguished (Figure 5-1). For example, in Figure 5-la, the large-scale study, four species were collected at nine sites, four of these were lode sites and the remaining five were lendc whereas in Figure 5-lb, the small-scale study, four species were collected at only two sites, both of which were lendc. Of the 112 large-scale ecological sites (Torpy River area records N1110 and N1111 removed finm original 114 sites) plotted in Figure 5-la, only 12% were lode sites. This is in contrast to the 98 small-scale LTR sites (177 sites minus 80 high discharge/gravel substrate creeks plus Pass Lake as per Chapter 4) plotted in Figure 5-lb where 52% were lode sites. The lode sites in the large-scale study were often slow moving areas o f large rivers, which yielded up to 12 species of molluscs (Lee and Ackerman 1999a), whereas in the small-scale study, the small tributary streams yielded a maximum of three species of molluscs (Chapter 4). Figure 5-la also shows site selecdon bias towards potendal high diversity molluscan habitats in that only 5.3% (6 of 112 sites) of the sites selected in the large-scale study did not contain molluscs. Conversely, Figure 5-lb shows that in the small-scale study, 25.3% (25 of 99 sites) of the did not contain molluscs. Further, in the large-scale study, 12.5% o f the sites had one or two species, whereas in the small-scale study, 63.3% of the sites had one or two species. Thus, both the type and the size of sites examined were factors in the freshwater mollusc diversity found. 95 (a) Numbar of Spaciea Par SHa at Eeologieal Sitea in northam BC (nsii2) ■ Lentic sites □ Lotie sites ' of s p e c k # 0 |SJ% a .m 2 1 3 OLMIeMni • 5 4 1 9 9 7 14 loUiBMM 1 0 « 1 1 0 4 0 1 4 9 9 9.0% 9 J% 13.4% A 9 0 0 14 10 11 12 13 19 19 19 20 ^ 9 19 t7 7.1% 9.9% 93% 7.1% 19% 2.7% 03% 13% 0.0% 0.0% 0.0% 0.0% 103% 7 7 9 2 0 O i l : 0 0 « 3 ' 1 1 0 0 0 0 1 0 ! 0 0 0 0 0 1 (b) Numbar of Spacias Par Sita In tha Lowar Torpy Rivar Watarahad (nmse) ■Lentic sites □Lotie sites 1--0 “ tH 4 19 6 7 9 10 !1--11 112 j 13 114 19 ; 19 117 119 i 19 120 i 21 1 No.ofspacm 293%493% l193%11%11%113%23%00%10.0%1.0%03%|03%ao%|0.0%10.0%0.0%10.0%j0.0%110%i10%110%110%1 laiMleMn 1 24 12 i 4 2 1 2 0 r r 1 0 1 0^ 0 o l o l o i o i o l o j o l o LL. iOLOICMW124 ~a1 3 11 0 0 0 0 1 0 0 1 0 1 0 ol 0 0 | 0 | o | o | o i o i o ! 0 r Figure S-1. (a) Number of species per site at ecological sites in northem British Columbia (largescale study) wiüi percentage o f sites per species number and number o f lentic and lotie sites per species number, (b) Num bâ of species per site in the Lower Torpy River watershW and Pass Lake (small-scale study)with percentage o f sites per species number and number o f lentic and lotie sites per species number. 96 In the large-scale study, the mean number of species per site (excluding “0” sites, n = 106) was 7.3 with 56% of the sites below, and 44% of the sites above the mean resulting in a relatively normal distribution. In the small-scale study, the mean number of species per site (excluding “0” sites, n = 73) was 1.7 with 38% of the sites below, and 62% above the mean so that the distribution is skewed to the low end of the scale of the number of species. If site selection in the small-scale LTR study had been based on the same criteria as it was in the large-scale northem study, it is likely that only Pass Lake and one o f the natural ponds would have been examined. This would have resulted in nine species collected &om Pass Lake and periiaps 6 species collected firom a pond for an average of 7.5 species per site. This is very close to the average number of species per site for the entire northem study (7.3). Eleven taxa of molluscs would have been recorded firom the LTR watershed (nine species from Pass Lake and two additional species firom a pond), whereas the intensive study yielded 15 species in total. Of the remaining four species, three were collected in nearby sites (on a large scale) and so their patterns of distributions in northem BC were would not have been significantly affected by the absence of their records in the LTR area. However, the one remaining species, Fossaria parva, has only been recorded in northem BC firom the LTR watershed. The intensity of this smallscale study added information not obtained by larger scale, less intense site selection. As discussed in Chq)ter 3, more intensive searches (i.e., longer search times) can result in the collection of greater numbers of species. More intense sampling in northem BC may discover additional species. The results of the large and small-scale studies are examples o f how scale determines study design and thus affects the outcome. According to Levin (1992), scaling issues affect all ecological investigations and the problem of relating phenomena across scales is the central problem in biology and in all of science, hi this study, this problem is exemplified by the different site selection criteria required when the scales were of different magnitudes. The 97 creation of additional suitable habitats for local freshwater molluscs found in the small-scale study cannot be extrapolated to the patterns of distribution found for molluscs in the large-scale study. Thus, the integration of the results of these two studies is problematic. However, the combination of these large and small-scale studies provides important information for the maintenance o f biodiversity and for the conservation of the freshwater molluscs of northem BC. Mollusc community composition changes that may result from habitat change could be tracked from the distributions of molluscs recorded herein. The water conditions that appear to affect the distribution of the molluscs could be used for restoration of habitats and to predict potential impacts of perturbation. The ubiquitous freshwater clam Pisidium casertanum may provide a useful measure to assess the quality of certain types of aquatic habitats created by landscape alteration. 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Burch for his permission to use many of the figures presented in Appendix I. Woric at the Canadian Museum of Nature was undertaken with the assistance of Dr. JeanMarc Gagnon, Chief Manager, Invertebrate Collections and Dr. Andre Martel, Research Scientist. Information from the Royal British Columbia Museum was obtained fix)m Kelly Sendall, Invertebrate Collections Manager. Mtqjping of collections sites was with the instruction and assistance of the Geographic Information Technical staff, Charlene Vantyghem and Kara Woodcock, at the Conservation Data Centre, a unit of the Resource and Inventory Branch of the Ministry of Environment in Victoria, BC. The committee overseeing this project was comprised of my supervisor. Dr. Josef Daniel Ackerman, as well as Dr. Max Blouw, Dr. Ellen Petticrew and Dr. Roger Wheate acting as members, and Dr. Andre Martel as the External Reviewer. Many thanks go to them for their support o f this woric, and to Dr. Ackerman for his thorough reviews of the drafts of this thesis. Funding for this study was provided by funding fiom a Forest Renewal BC grant, the British Columbia Conservation Data Centre, the Committee on the Status of Endangered Wildlife in Canada, and the National Science and Engineering Research Council to Dr. J.D. Ackerman. 106 APPENDIX I Table A-1. Site number, collection date, site description, NAD83 UTM coordinates and environmental variables for locations of freshwater mollusc collection sites in northem British Columbia. Table A-2. Systematic listing of the freshwater mollusc taxa of northem British Columbia including figure number of distribution map in Appendix I, maximum shell size (fix)m Clarke 1981), and occurrences out of 176 sites. Uncommon species were found at ^10 sites, common species were found at 11 to SO sites, and very common species were found at >50 sites. Taxa summaries/Figures A1 - A-63. Distribution maps, location information, and environmental variables (where measured) and discussion of findings for the 63 taxa of freshwater molluscs identified from northem British Columbia. Classification and nomenclature are as listed by Turgeon et al. (1998). The length of the scale bars in the illustrations of the molluscs is 1 mm. Figure A 64 - Ecological sites where molluscs were not collected. Figure A-65 - The ecoprovinces of northem British Columbia. 107 Table A-1. Site number, collection date, site description, NAD83 UTM coordinates and environmental variables for locations o f freshwater mollusc collection sites in northem British Columbia. Legend: ZN = NAD83 UTM zone number, EAST = NAD83 UTM easting coordinate, NORTH = NAD 83 UTM Northing coordinate, TEMP = water temperature in "C, DO = dissolved oxygen, COND = conductivity in microSiemens, C a^ = calcium concentration in mg/1 as derived from Rodhe (1949). SITE NIOOO NIOOI NI002 N1003 NI004 NIOOS N1006 N1007 N1008 N1009 NIOIO N IO ll N10I2 NI013 NI014 N I0I5 N I0I6 NI017 N1018 N1019 N1020 N1021 N1022 NI023 N1024 N102S N1026 N1027 NI028 N1029 N1030 N1031 DATE LOCATION 19970806 W side Hwy 97 ~100 km N o f Prince George; Crooked River/Rediocky Lake 19970806 Kerry Lake. N o f Prince George 19970900 Shane Lake, Prince George 19970806 McLeod Lake. Whiskers Point Prov. Park fsame site as CN10121 19970806 Carp Lake. Carp Lake Provincial Park 19970807 Gatiaga Lake. E o f Hwy 39 to Mackenzie 19970807 Dina #1. Dina Lake Recreation Site 19970807 Dina #10. Dina Lake Recreation Site 19970807 Azouzetta Lake fsame site as CN1013] 19970808 Moberly Lake, at exit into Moberly River 19970808 pond E o f Hwy 29.10.2 km south o f tum off fiom Chetwynd to Tumbler Ridge 19970808 Gwillim Lake. Gwillim Lake Provincial Park 19970808 ix>nd on E side o f road S o f Tumbler Ridge 19970808 Stony Lake. Stony Lake Recreation Site. SE o f Tumbler Ridge 19970808 One Island Lake. One Island Lake Prov Park 19970809 Swan Lake. Swan Lake Prov. Paric 19970809 Tate Creek, at bridge on Hwy 2 S o f Tomslake fsame site as CN1014] 19970809 pond behind beaver pond N o f Kiskatinaw River on Old Alaska Hwy 19970809 artificial pond behind home N o f Kiskatinaw River on Old Alaska Hwy 19970810 Charlie Lake. Charlie Lake Prov. Park 19970810 swampy area at south end o f Charlie Lake. N o f Ft St John 19970810 Cecil Lake. E o f Ft St John 19970810 artificial pond beside Beatton River. E o f Ft St John 19970810 swamp about 2.1 km up Utrper Cache Creek Rd N o ff Hwy 29 19970811 beaver pond about 8 km E on 151 Rd o ff Hwy 97 N o f Ft St John 19970811 culverted creek about 2.3 km E on 151 Rd o ff Hwy 97 N o f Ft St John 19970811 Inga Lake. Inga Lake Recreation Site 19970811 pond at Wonowon, Hwy 97 19970811 roadside pond on Hwy 97 between Wonowon and Pink Mountain 19970811 Duhu Lake. Duhu Lake Recreation Site 19970812 wetland opposite entrance to Prophet River Rec. Area 19970812 dugout pond on side o f Hwy 97 about 25 km N o f Prophet River Rec Area ZN EAST NORTH TEMP DO COND Ca*^ 10 519239 6052108 19.6 66 203.0 28.9 10 514012 6058090 23.8 83 178.6 25.3 10 510701 5971211 19.5 57 284 41.0 10 503776 6084272 26.2 79 155.5 21.8 10 477617 6075301 24.5 73 76.9 10.1 10 495834 6120646 20.5 68 146.8 20.6 10 480649 6154034 19.8 87 172.7 24.4 10 480649 6154034 15.0 8 255.0 36.7 10 523868 6138721 16.3 96 160.4 22.6 10 584531 6187321 13.4 84 206.0 29.4 10 589820 6162718 18.5 87 321.0 46.5 10 604301 6136156 17.0 81 193.0 27.4 10 639226 6093084 181.0 25.7 17.5 85 10 655990 6079252 18.0 64 218.0 31.2 10 672672 6131990 16.0 63 193.0 27.4 19.8 75 182.0 25.8 10 687631 6157373 16.9 64 227.0 32.5 10 684351 6160609 10 650522 6205196 25.0 7 1568.0 232.5 10 650522 6205196 22.0 73 247.0 35.5 21.0 130 180.5 25.6 10 624588 6241947 10 626599 6238996 19.2 81 690.0 101.5 19.6 135 326.0 47.3 10 649432 6243636 26.8 83 638.0 93.8 10 641394 6239593 10 597168 6234767 24.0 19 394.0 57.4 18.8 65 540.0 79.2 10 611165 6275669 17.8 41 67.6 10 611171 6275683 8.7 23.1 71 107.3 14.7 10 583707 6275598 23.2 73 10 571613 6288801 76.5 10.1 10 551904 6315995 22.4 86 987.0 145.8 19.2 74 1.6 10 511887 6336160 19.7 18.1 56 313.0 45.3 10 513070 6424982 23.8 87 278.0 40.1 10 520061 6458867 pH 7.25 7.85 7.1 7.50 6.95 7.75 7.85 6.50 7.65 7.45 8.00 8.15 8.55 7.95 8.30 8.00 6.95 7.25 7.80 9.25 7.20 8.50 9.00 7.75 6.35 5.15 7.05 8.00 7.50 5.75 7.05 8.50 108 Table A -1 (cont.). Site number, collection date, site description, NAD83 UTM coordinates and environmental variables for locations of A ^hw ater mollusc collection sites in northem British Columbia. Legend: ZN = NAD83 UTM zone number, EAST = NAD83 UTM easting coordinate, NORTH = NAD 83 UTM Northing coordinate, TEMP = water temperature in "C, DO = dissolved oxygen, COND = conductivity in microSiemens, C a ^ = calcium concentration in mg/1 as derived from Rodhe (1949). SITE NI032 NI033 NI034 N103S NI036 N1037 N1038 N1039 NI040 NI041 NI042 N1043 NI044 NI04S N1046 NI047 NI048 NI049 NIOSO NIOSi NI0S2 NI0S3 N10S4 N1055 NI0S6 NI057 N10S8 NI0S9 NI060 N I06I NI062 N1063 DATE LOCATION 19970812 culverted stream flowing under Hwy 97 S o f Ft Nelson 19970812 Andy Bailey Lake. Andy Bailey Rec. Area 19970812 Parker Lake, W o f Ft Nelson 19970813 swamp about 148 km up road to Helmut 19970813 pond about 132.8 km up road to Helmut 19970813 woody swamp with beaver lodge about 119.4 km up road to Helmut 19970813 swamp/t*ond on both sides o f road about 103.4 km up road to Helmut 19970813 cattail area about 87.8 km up road to Helmut 19970813 swamp on both sides o f road about 68.1 km up road to Helmut 19970813 swamp about 47.5 km up road to Helmut 19970813 swamp about 28.8 km up road to Helmut 19970814 Beaver Pond Rec. Site, about 10 km N on Fort Liard Hwy 19970814 Summit Lake. Stone Mt. Prov. Park, at campground [same site as MNI0131 19970814 lake just W o f Summit Lake. Stone Mountain Provincial Park 19970814 swamp/beaver pond at Toad River 19970815 Muncho Lake. Muncbo Lake Provincial Park 19970815 lake 10.4 km NW o f bridge over Smith Rvr. between Hwy 97 and Liard Rvr 19970815 small pond 2.3 km NW o f bridge over Smith Rvr on opposite side to Liard Rvr 19970816 small pond on side o f Hwy 97 past Fireside 19970816 swamp/pond on side o f Hwy 97 11 km past (NW of) site N1050 19970816 lake on N side o f Hwy 97 (no name in BC gazetteer) 19970816 lake 13.6 km NE o f Hyland River (in Yukon) 19970816 Wye Lake, in Watson Lake (comm.). Yukon 19970816 Second Wye Lake, in Watson Lake (comm.). Yukon 19970817 High Lake, just into BC from Yukon on Hwy 37 19970817 Cormier Creek. 5 km S o f High Lake 19970817 Blue Lake, on W side o f Hwy 37 19970817 Blue Lake, on E side o f Hwy 37 19970817 Twenty-eight Mile Creek 19970817 swamp on E side Hwy 37 S o f Baking Powder Ck. just N o f Beaver Dam Ck 19970817 Boya Lake. Boya Lake Provirrcial Park 19970817 Good Hope Lake ZN EAST NORTH TEMP DO COND C a" pH 10 516933 6476264 18.5 71 175.9 24.9 6.95 10 528755 6490008 26.2 66 183.8 26.1 7.15 10 505655 6520700 27.2 67 277.0 40.0 7.05 10 614042 6543542 20.4 23 253.0 36.4 5.90 10 600082 6538387 20.4 47 529.0 77.5 7.30 10 591074 6531437 21.5 80 254.0 36.5 7.05 10 595678 6517268 22.2 25 481.0 70.4 6.85 10 588492 6507910 24.0 64 434.0 63.4 7.50 10 571575 6511956 21.8 41 140.0 19.5 6.55 10 553679 6512159 22.7 31 359.0 52.2 7.30 10 536777 6513751 23.7 53 123.3 17.0 6.65 10 490168 6537402 17.7 87 247.0 35.5 7.80 10 404140 6502364 7.30 13.7 93 231.0 33.1 10 400806 6501719 12.7 86 168.4 23.8 7.25 10 371232 6525136 16.1 99 735.0 108.3 7.25 10 340614 6537463 14.3 91 315.0 45.6 7.75 9 633480 6609108 7.25 22.2 80 475.0 69.5 7.20 9 640729 6605826 13.5 84 453.0 66.2 9 593907 6621683 13.8 54 928.0 137.0 7.40 9 586707 6628783 14.5 45 550.0 80.7 7.95 8.90 9 580218 6649892 20.3 98 269.0 38.8 9 560065 6652099 22.5 67 289.0 41.8 8.05 196.0 27.9 7.50 9 516505 6658786 22.4 58 21.6 59 277.0 40.0 7.50 9 517693 6657991 16.9 72 161.1 22.7 8.40 9 496506 6649663 7.35 15.2 43 353.0 51.3 9 494973 6645924 16.6 80 336.0 48.8 9 492692 6632286 8.15 8.00 16.1 65 329.0 47.7 9 492680 6632436 7.85 9 490200 6613881 15.7 46 434.0 63.4 8.05 16.1 60 426.0 62.2 9 488581 6589361 8.45 9 493933 6580986 16.3 65 336.0 48.8 18.7 90 384.0 55.9 8.55 9 483014 6572501 109 Table A l (cont.). Site number, collection date, site description, NAD83 UTM coordinates and environmental variables for locations of freshwater mollusc collection sites in northem British Columbia. Legend: ZN = NAD83 UTM zone number, EAST = NAD83 UTM easting coordinate, NORTH = NAD 83 UTM Northing coordinate, TEMP = water temperature in “C, DO = dissolved oxygen, COND = conductivity in microSiemens, C a^ = calcium concentration in mg/1 as derived from Rodhe (1949). SITE N1064 NI06S N1066 NI067 N1068 NI069 N1070 N107I NI072 N1073 NI074 NI075 N1076 N1077 NI078 N1079 NI080 NIOSI N1082 NI083 NI084 NI08S NI086 NI087 NI088 NI089 NI090 N I09I N1092 NI 093 NI094 NI09S DATE LOCATION ZN EAST NORTH TEMP DO COND Ca*+ pH 13.8 70 19970818 pond on E side o f Hwy 37 S o f Lana Lake 9 457582 6563947 93.6 12.6 6.85 9 457229 6561813 10.4 79 19970818 Twin Lakes, SE end 98.7 13.4 6.20 9 457319 6561748 15.2 72 8.6 19970818 lake 16.5 km S o f Twin Lakes (site N1065) 66.4 7.25 9 442196 6531603 8.7 64 193.0 27.4 8.35 19970818 creek on W side o f Hwy 37 just N o f Elbow Lake 13.8 84 245.0 35.2 9 437039 6506710 19970818 Dease Lk. about mid-way on opp. side to Hwy 37 fsame lake as CNI005/MN101I] 7.70 9 370860 6421142 20.9 85 292.0 42.2 8.50 19970819 Sawmill Lake. NW o f Telearaph Creek 20.8 37 812.0 119.7 7.40 9 389992 6436248 19970819 swamp on S side o f lioad to Telearaph Creek 15.6 89 9 401817 6454636 182.0 25.8 7.40 19970819 Cariboo Camp Creek, an road to Telearaph Creek 9 422966 6470362 18.8 85 435.0 63.5 7.25 19970819 arassy swamp about 24 km W o f Dease Lake on road to Telearaph Creek 14.0 55 180.0 25.5 9 442184 6402721 8.25 19970820 Eddonteiujon Lake, SW shore fsame lake as CN1004] 15.3 50 187.8 26.7 6.55 9 426008 6368382 19970820 swampy area o f stream under Hwy 37 just N o f Willow Creek 73.6 9.6 9 423404 6327310 20.2 48 7.05 19970820 lake on side o f Hwy 37 (no ruune in BC aazetteer) 9 446584 6288863 22.6 64 89.3 12.0 7.05 19970820 lake on W side o f Hwy 37 26.5 29 47.4 5.95 9 478282 6233065 5.7 19970820 pond on W side o f Hwy 37 S o f Bell Irvina River bridae 19.5 66 147.0 20.6 7.65 9 443878 6211893 19970821 Clements Lake (locally known as Bear Lake) near Stewait 9 461357 6217849 9.0 34 178.0 25.2 6.90 19970821 beaver pond on Hwy 37A to Stewait 20.6 91 9 480859 6215735 119.1 16.4 8.25 19970821 Meziadin Lake, Meziadin Lake Prov. Park 161.9 22.8 8.05 9 514749 6171840 22.9 83 19970821 Sideslip Lake II9.6 16.5 8.55 9 556875 6137187 22.2 78 1997082! Kitwancool Lake 67.8 16.9 80 8.8 6.45 9 514387 6032595 19970822 Lakelse River fsame site as CN1022] 163.4 23.0 9 530339 6027050 17.1 44 6.15 19970822 Lakelse Lake fsame site as MN1014] 2.6 9 506744 6029334 21.2 67 26.7 N/A 19970822 swamp on Terrace/Prince Rupert Hwy 18.2 18 81.5 10.8 3.95 9 443924 6010276 19970822 swamp on Terrace/Prince Rupert Hwy 155.2 21.8 4.75 9 430164 6009430 20.4 64 19970822 Rainbow Lake 18.5 77 20.1 9 426463 6010897 1.7 5.25 19970822 Prudhomme Lake 19.6 52 110.0 15.1 6.00 9 547764 6068303 19970823 swamp on E side Hwy 37 just N o f Legate Creek 148.0 20.7 20.2 50 6.55 9 570414 6105741 19970823 swamp on S side o f Hwy 16 just E o f Hwy 37 junction 22.1 69 141.3 19.7 7.15 9 583455 6117455 19970823 Seeley Lake, Seeley Lake Prov. Park fsame site as CN1021] 116.5 16.0 6.90 21.1 91 9 615074 6076443 19970823 Lake Kathlyn, in Smithers 6059269 17.4 275.0 633278 91 8.75 9 39.7 Round Lake. SE o f Smithers 19970824 16.3 55 211.0 30.1 6.40 9 653221 6031120 19970824 Bulkley River, at E side o f Houston 17.9 71 7.25 86.7 11.6 9 681284 6077748 19970824 Fulton River, near Topley Landing at Fulton River Salmon Proiect (live) no Table A-1 (cont.)- Site number, collection date, site description, NAD83 UTM coordinates and environmental variables for locations of freshwater mollusc collection sites in northem British Columbia. Legend: ZN = NAD83 UTM zone number, EAST = NAD83 UTM easting coordinate, NORTH = NAD 83 UTM Northing coordinate, TEMP = water temperature in “C, DO = dissolved oxygen, COND = conductivity in microSiemens, C a^ = calcium concentration in mg/1 as derived from Rodhe (1949). SITE N1096 NI097 NI098 N I099 NI 100 NI 101 NI 102 NI 103 NI 104 NI 105 NI 106 NI 107 NI 108 N II0 9 N IIIO N llll NI 112 N III3 NOlOO NOlOI N0I02 N0I03 NO 104 N0I05 N 0I06 N0I07 NO 108 NO 109 NOIIO NOIII N 0II2 N 0II3 ZN LOCATION EAST NORTH TEMP DO COND Ca + pH DATE 9 680737 6081999 17.0 79 19970824 Babine Lake. Red Bluffs Provincial Park, in lake 95.9 13.0 6.25 9 680886 6081965 17.1 44 5.60 19970824 Babine Lake. Red Bluffs Provincial Park, in pond behind grassy area in lake 90.3 12.1 9 673846 6043587 17.7 67 203.0 28,9 6.80 19970824 pond at rest area just W o f junction o f Hwy 16 and Topley Landing Road 16.0 81 10 313384 5993777 90.9 12.2 7.70 19970825 Francois Lake 10 316295 6018157 16.7 89 114.9 15.8 7.40 19970825 Decker Lake fsame site as CNI0201 10 359914 5995723 12.2 23 1199.0 177.4 6.85 19970825 lake on N side o f Hwy 16 W o f Endako 10 375665 5990440 19.3 93 94.6 12.8 7.90 19970825 Stellako R. at bridge just E o f native settlement on Hwy I6[same site as CNI0I91 10 399956 5990489 20.0 15 419.0 61.1 6.55 19970825 slough o f Nechako River just E o f Ft Fraser fsame site as CNI0I81 19.8 93 10 408870 6058932 19970825 TezzeionLake 119.7 16.5 8.15 10 406159 6031181 16.2 90 II 1.8 15,3 7.55 19970826 Stuart Lk. btwn Sowchea Bay R A and Paarens Beach P.P. fsame lake as CNIOOOl 10 432564 5985486 18.9 32 185.0 26.2 7.25 19970826 swamp/creek on Hwy 16 at W entrance to Vaadahoof 10 571899 5975210 14.0 90 120.1 16.6 6.35 19970600 Purden Lake, including Purden Lake Prov. Park fsame site as CNI0I51 36.5 67 1155.0 170.9 7.80 9 664306 6591082 I997I00I Alpha Stream. Liard River Hotsprings Prov. Park fsame site as CNI0231 9 664506 6590982 1.5 81 946.0 139,7 8.10 I997I00I Warm Swamp. Liard River Hotsprings P. Park fsame site as M NI0I2/CNI023] 24.5 98 10 604300 5994812 204 29.1 8.4 19970700 Pass Lake, in Torpy River watershed 10 600901 5982411 12.1 68.6 240.5 34.5 7 19970700 Lower Torpy Road, follows SW o f Lower Torpy River 200 28.5 10 543058 5994185 26.5 77 8.5 19970700 Eaglet Lake. NE o f Prince George 9.6 70 213 30.4 8 10 566500 5972560 19980700 Bowron River, at Sgiruce Credc (UTM is for Hwy 16 crossing) 10 571989 5995256 n/a n/a n/a n/a n/a 19970700 pond E o f Upper Fraser n/a n/a n/a 10 500600 5958710 n/a n/a 19980700 Chilako (Mud) River (live) n/a n/a n/a 10 488800 5986811 n/a n/a 19970600 Circle Lake. Eskers Prov. Park n/a n/a n/a n/a n/a 10 489500 5986811 19970600 Erickson Lake. Eskers Prov. Park n/a n/a n/a n/a n/a 10 489400 5988211 19970700 Pine Marsh. Eskers Prov. Park n/a n/a n/a n/a n/a 10 489300 5989011 19970700 Ridgeview Lake. Eskers Prov. Park n/a n/a n/a 10 459900 5954711 n/a n/a 19970700 Eulatazella (Graveyard) Lake. SE o f Vanderfaoof n/a n/a n/a n/a n/a 10 455700 5958711 19970700 pond at km 39 on road to Eulatazella (Graveyard) Lake. SE o f Vandethoof n/a n/a n/a n/a n/a 10 461400 5973610 19970700 Clucluz Creek at Hwy 16 rest-stop fsame site as C74I0I71 n/a n/a 10 460300 5971910 n/a n/a n/a 19970700 Cluculz Lake at Sunset Bay n/a n/a n/a 10 311499 5974709 n/a n/a 19970700 Takysie Lake n/a n/a n/a n/a 10 473300 5969511 n/a 19970700 Bednesti Lake n/a 10 516900 5972211 n/a n/a n/a n/a 19970700 Hudson Bay Slough. Prince George fsame site as MNI004] n/a n/a n/a 10 521901 6018911 n/a n/a 19970618 Summit Lake, on Hwy 97 N o f Prince George fsame site as CNIOl If I ll Table A-1 (cont.). Site number, collection date, site description, NAD83 UTM coordinates and environmental variables for locations o f freshwater mollusc collection sites in northem British Columbia. Legend; ZN = NAD83 UTM zone number, EAST = NAD83 UTM easting coordinate, NORTH = NAD 83 UTM Northing coordinate, TEMP = water temperature in "C, DO = dissolved oxygen, COND = conductivity in microSiemens, Ca** = calcium concentration in mg/I as derived from Rodhe (1949). SITE N 0 II4 NOUS N01I6 N 0II7 N 0II8 NQII9 N0I20 N 0I2I N0I22 N0I23 N0I24 N0I2S N0I26 N0I27 N0128 NO! 29 NO! 30 N013I N0I32 N0133 N0I34 N0I35 N0136 N0137 N0I38 N0139 NO 140 CNIOOO CNIOOl CN1002 CN1003 CN1004 LOCATION DATE 19970600 Nadsilnich (West) Lake. West Lake Prov. Park 19970600 Beaverley Creek, at culvert under Blackwater Road. SW o f Prince George 19970600 Shesta Lake. SW o f Prince George I9970S00 beaver ixmd E down Edric Road o ff Hwy 97 about 45 km N o f Prince George 19970600 Bear Lake. Crooked River Prov. Park 19970700 ditches E o f Prince George on Hwy 16 at Foreman Road 19970806 wet area 1.5 km down road to Kerry Lake off Hwy 97.1.0 km before lake 19970700 Seymour Lake, near Smithers 19970700 ixmd 22 km W o f Fraser Lake (may be Loch Garry) 19970700 Salmon River near Teardrop Lake. N o f Prince George (shell only) 19970700 Sakeniche River, tributary to Takla Lake (shell only) 19970S00 Nelson Lake, about 42 km N o f Prince George, near Sununit Lake 19970612 roadside marsh near One Island Lake Prov. Park 19970615 flooded area ofFRedwillow River about 96 km S o f Pouce Coupe 19970617 marsh along road about 0.5 km o ff Hwy 29 into Moose Lake Rec Area 19970618 large fen/bog/ttuush W o f Chetwynd 19970619 sedge pond N o f Chetwynd 19970625 dugout (?) about 60 km S o f Ft Nelson 19970625 big bog/fen near Andy Bailey Rec. Area. S o f Ft Nelson 19970626 Carex marsh about 85 km E o f Ft Nelson 19970726 Lost Creek. N o f Clayhurst 19970726 Gunn Lake. NE BC 19970727 Thunder Creek. N o f Redwillow 19970730 km 125.6 on Desan High Road (road to Helmut) 19970730 Sphagnum wetland at km 136 on Kotcho Lake Road, iust SW o f lake 19970814 Boundary Creek. S end 19980800 Fraser R. at railway bridge E on Hwy 16. Cottonwood Island Park (shells only) 19720817 Stuart Lake. N side in cove fsame lake as N 11051 19720817 Takla Lake. E side and N o f Takla Landing 19720817 Bear Lake, at S facing point near middle 19720817 Thutade Lake. W end near small. N-flowing river mouth 19720817 Eddontenajon Lake, N end [same lake as N10731 ZN EAST NORTH TEMP DO COND C a^ pH 10 509800 5953810 n/a n/a n/a n/a n/a 10 509201 5959710 n/a n/a n/a n/a n/a 10 500201 5941610 n/a n/a n/a n/a n/a 10 525900 6006211 n/a n/a n/a n/a n/a 10 521301 6036711 n/a n/a n/a n/a n/a 10 523100 5974777 n/a n/a n/a n/a n/a 10 514151 6057910 n/a n/a n/a n/a n/a 9 618284 6068200 n/a n/a n/a n/a n/a 10 360299 5995710 n/a n/a n/a n/a n/a 10 471701 6030711 n/a n/a n/a n/a n/a 10 322498 6113911 n/a n/a n/a n/a n/a 10 522901 6018711 n/a n/a n/a n/a n/a 10 668200 6135700 n/a n/a n/a n/a n/a 10 676590 6092380 n/a n/a n/a n/a n/a n/a n/a 10 609296 6122615 n/a n/a n/a 10 597200 6192800 n/a n/a n/a n/a n/a 10 602100 6207100 n/a n/a n/a n/a n/a 10 516710 6479510 n/a n/a n/a n/a n/a 10 527000 6491730 n/a n/a n/a n/a n/a n/a n/a n/a n/a 10 579070 6511410 n/a n/a 10 681010 6243833 n/a n/a n/a n/a n/a n/a n/a n/a 10 690400 6097300 n/a n/a n/a n/a n/a n/a 10 677400 6095290 n/a n/a n/a 10 592290 6535390 n/a n/a 10 598860 6538150 n/a n/a n/a n/a n/a n/a n/a n/a 10 678604 6246704 n/a n/a 10 518101 5973911 n/a n/a n/a n/a n/a 10 380399 6060011 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a 9 684993 6162274 n/a n/a n/a n/a n/a 9 636495 6219614 n/a n/a n/a n/a n/a 9 607080 6294995 n/a n/a n/a n/a n/a 9 441885 6409192 112 Table A~1 (cont.). Site number, collection date, site description, NAD83 UTM coordinates and environmental variables for locations of freshwater mollusc collection sites in northern British Columbia. Legend: ZN = NAD83 UTM zone number, EAST - NAD83 UTM easting coordinate, NORTH = NAD 83 UTM Northing coordinate, TEMP = water temperature in ”C, DO = dissolved oxygen, COND = conductivity in microSiemens, C a^ = calcium concentration in mg/1 as derived from Rodhe (1949). SITE CNIOOS CNI006 CNI007 CNIOOS CN1009 CNIOlO CNIOII CN10I2 CNI013 CNI014 CNIOIS CN1016 C N I0I7 CNIOIS CNIOlO CN1020 C NI02I CNI022 CNI023 CNI024 MNIOOO MNIOOl M NI002 MNI003 MNI004 MNI005 M NI006 MNI007 MNIOOS MNIOOO MNIOlO M N IO ll ZN EAST NORTH TEMP DO COND Ca^^ pH DATE LOCATION 9 Deaw Lake, nr village o f Deaae Lake [same siieas MNIOl i/same lake as NI068] 439397 6480388 n/a n/a n/a n/a n/a I0720SI7 9 488601 6507685 I0720S1S Cry Lake. N aide. W end near two creek outlets laame site as MNI0031 n/a n/a n/a n/a n/a 9 568704 6517884 n/a n/a n/a n/a I0720SIS Tumagain River, about 2 miles N o f mouth o f Dali River n/a 9 578804 6497385 10720SI0 Dali Lake. E side o f N end n/a n/a n/a n/a n/a 9 585354 6484885 n/a n/a n/a I0720SI0 Denetiah Lake. W end near inlet n/a n/a 10 336561 6402940 n/a n/a n/a n/a n/a I0720SI0 Weissener Lake 10 521901 6018911 n/a n/a n/a n/a n/a I0720S20 Summit Lake. 30 miles N o f Prince George fsame site as NOI131 10 503776 6084272 n/a n/a n/a n/a n/a I0720S20 McLeod Lake, 5.2 miles S o f village o f McLeod Lake [same site as N 10031 10 523868 6138721 n/a n/a n/a n/a n/a I0720S20 Azouzetta Lake. Fine Pass fsame site as NI0081 10 684351 6160609 n/a n/a n/a n/a 10720S20 Tate Creek. apfUDx 1 miles S o f Tonulake.S o f Dawson Ck fsame site as NI 0161 n/a 10 571899 5975210 n/a n/a n/a n/a n/a I0730S0S Purden Lake. 40 miles E o f Prince George fsame site as N I 1071 10 474150 5969961 n/a n/a n/a n/a n/a I0730S00 Pond 31 miles W o f Prince George 10 461400 5973610 n/a n/a n/a n/a n/a I0730S00 Cluculz Creek. 20 miles SE ofVarxlerboof fsame site as N01081 10 399956 5990489 n/a n/a n/a n/a n/a I0730S00 Small inlet o f Nechako River. 1 mile east o f Fort Fraser fsame site as N11031 10 375665 5990440 n/a n/a n/a n/a n/a I0730SO0 Stellako R...5 miles W o f mouth at Fraser Lake fsame site as NI 1021 10 316295 6018157 n/a n/a n/a n/a n/a I0730S00 Decker Lk. 1 mile E o f village o f Decker Lake fsame site as N 11001 9 583455 6117455 n/a n/a n/a n/a n/a I0730SI0 Seeley Lake. 3 miles SW o f Hazelton fsame site as N10911 9 514387 6032595 n/a n/a n/a n/a n/a I0730SI0 Lakclsc River. 9 miles SW o f Terrace fsame site as N10831 n/a n/a 9 664506 6590982 n/a n/a n/a I0730SI0 Liard Hot Springs fsame site as N1108/Nl 109/NI109/MNI0121 n/a n/a n/a n/a n/a 9 442700 6479485 I0720SI7 Hotel Creek, at mouth, near village o f Dease Lake 8 573097 6604573 n/a n/a n/a n/a n/a 10250808 Atlinarea 10 601896 6175514 n/a n/a n/a n/a n/a 10630703 9.8 miles E on Hwy 97 from Chetwynd = Little Prairie n/a n/a 9 485899 6490185 n/a n/a n/a 10620830 Eaglehead Lake n/a n/a n/a n/a n/a 9 488601 6507685 10620810 Cry Lake, from stomach contents o f lake trout fsame site as CN10061 n/a n/a 10 516900 5972211 n/a n/a n/a 18750000 Fort George, in creek fsame site as NOI 121 n/a n/a 10 384399 5994710 n/a n/a n/a 10660825 Fraser Lake. 25 miles W o f Vanderhoof n/a n/a n/a n/a n/a 10 377401 6172959 10660712 Gemumsen Lake n/a n/a n/a n/a n/a 9 441196 6477038 10050000 Lake House, marsh n/a n/a 10 425200 5975861 n/a n/a n/a 10660820 Nulki Lake. 11 miles from Vanderhoof n/a 10 6518809 n/a n/a 345506 n/a n/a 10500711 12 miles S o f Muncho Lake. Alaska Hwy n/a 9 595057 6621933 n/a n/a n/a n/a 10620531 Alaska Hwy. mile 550 n/a n/a n/a 9 439397 6480388 n/a n/a 10620831 Dease Lake fsame site as CN1005/same lake as N10681 113 Table A-1 (cont.). Site number, collection date, site description, NAD83 UTM coordinates and environmental variables for locations of freshwater mollusc collection sites in northern British Columbia. Legend: ZN = NAD83 UTM zone number, EAST = NA083 UTM easting coordinate, NORTH = NAD 83 UTM Northing coordinate, TEMP = water temperature in “C, DO = dissolved oxygen, COND = conductivity in microSiemens, C a ^ = calcium concentration in mg/1 as derived fiom Rodhe (1949). SITE M N I0I2 MNI013 MN1014 DATE LOCATION 19590000 Liant Hot Springs fsame site as N i 109/CN10231 19590802 Summit Lake, mile 392 Alaska Hwy fsame site as NI044] 19740714 Lakelse Lake. Bean Station Road near Tenace fsame site as N 10841 ZN EAST NORTH TEMP DO COND Ca*^ pH n/a n/a n/a 9 664506 6590982 n/a n/a n/a 10 404140 6502364 n/a n/a n/a n/a n/a n/a n/a n/a n/a 9 530339 6027050 114 Table A-2. Systematic listing of the freshwater mollusc taxa of northern British Columbia including figure number of distribution map in Appendix I, maximum shell size (from Clarice 1981), and occurrences out o f 176 sites. Uncommon species were found at <10 sites, common species were found at 11 to SO sites, and very common species were found at >50 sites. Class Gastropoda Subclass Prosobranchia Family Valvatidae Valvata lewisi lewisi Valvata sincera sincera Valvata sp. Figure Shell Size (max) Occurrence A-1 A-2 A-3 5 nun wide 42 - common 7 mm wide 40 - common n/a n/a Subclass Pulmonata Family Acroloxidae Acroioxus coioradensis A-4 4.6 mm long Family Lymnaeidae Fossaria galbana Fossaria modicelia Fossaria parva Lymnaea atkaensis Lymnaea stagnaiis oppressa Lymnaea sp. Stagnicola arctica Stagnicola caperata Stagnicola catascopium catascopium Stagnicola elodes Stagnicola sp. - juveniles A-5 A-6 A-7 A-8 A-9 A-10 A-11 A-12 A-13 A-14 A-15 11 mm high 4 - uncommon 9.5 mm high 9 -uncommon 8 mm high 1 - uncommon 42 mm high 5 - uncommon 56 mm high 33 - common n/a n/a 22 mm high 26-com m on 16 mm high 4 -uncommon 33 mm high 7 - uncommon 32 mm high 6 2 -v e ry common <10 mm high 5 -uncommon Family Physidae Aplexa elongata Physa Jennessi Physa skinneri Pkysella sp. Physella lordi Pkysella propinqva Pkysella virginea Physella wrighti A-16 A-17 A-18 A-19 A-20 A-21 A-22 A-23 18 mm high 6 -uncommon 9 mm high 1 - uncommon 12 mm high 7 -uncommon 26 mm high 69 -v e ry common 26 mm high 2 -uncommon 19 mm high 2 -uncommon 1 - uncommon 1 7m m h i^ 9.1 mm high 1 - uncommon Family Planorbidae Gyraulus circumstriatus Gyrauhis crista Gyraulus deflectus Gyraulus parvus Gyraulus vermicularis Menetus opercularis Promenetus exacuous exacuous A-24 A-25 A-26 A-27 A-28 A-29 A-30 5 mm wide 3 mm wide 8 mm wide 5 mm wide 7 mm wide 8 mm wide 7 mm wide 7 - uncommon 70-v e ry common 4 -uncommon 3 3 -com m on 2 8 -com m on 10-uncom mon 10-uncommon 37-com m on 115 Table A-2 (cont.)- Systematic listing of the freshwater mollusc taxa of northern British Columbia including figure number of distribution map in Appendix I, maximum shell size (from Clarice 1981), and number of occurrences at the 176 sites. Uncommon species were found at ^10 sites, common species were found at 11 - SO sites, and very common species were found at >50 sites. Family Planorbidae (cont) Planorbula armigera Planorbula campestris Helisoma anceps anceps Helisoma sp. Planorbella binneyi Planorbella subcrenata Figure A-31 A-32 A-33 A-34 A-35 A-36 Shell Size (max) Occurrence 8 mm wide 2 - uncommon 12 mm wide 5 - uncommon 20 mm wide 9 - uncommon n/a n/a 32 mm wide 3 - uncommon 32 mm wide 5 9 - very common Family Ancylidae Ferrissia fragilis Ferrissia parallelus Ferrissia sp. A-37 A-38 A-39 5.5 mm long 1 - uncommon 7.6 mm long 31 - common n/a 1 - uncommon Class Bivalvia Family ManEaritiferidae Margaritifera falcata A-40 125 mm long Family Unionidae Anodonta kennerlyi A-41 120 nun long 22 - common Family Sphaerildae Sphaerium nitidum Sphaeriwn rhomboideum Sphaeriwn simile Sphaerium striatinum Muscuiium lacustre Musculium securis Muscuiium transversum Pisidium casertanum Pisidium compressum Pisidium conventus Pisidium fallax Pisidium femigineum Pisidium idahoense Pisidium insigne Pisidium lilljeborgi Pisidium milium Pisidium nitidum Pisidium punctatum Pisidium rotundatum Pisidium variabile Pisidium ventricosum Pisidium sp. A-42 A-43 A-44 A-45 A-46 A-47 A-48 A-49 A-50 A-51 A-52 A-53 A-54 A-55 A-56 A-57 A-58 A-59 A-60 A-61 A-62 A-63 6 mm long 18-common 14 mm long 3 - uncommon 25 mm long 13-com mon 14 mm long 1 - uncommon 14 mm long 40 - common 6 mm long 46 - common 15 mm long 1 - uncommon 5 mm long 81 - very common 5.5 mm long 29-com mon 3 mm long 6 -uncommon 3.5 mm long 4 - uncommon 3 mm long 23-common 12 mm long 17-com mon 2 mm long 1 - uncommon 4 mm long 15-com m on 3 mm long 20-com m on 3 mm long 13-common 1.7 mm long 1 - uncommon 3.3 m long 1 - uncommon 5 mm long 4 8 -com mon 3 mm long 25-common n/a 1 - uncommon 8 - uncommon 116 Family Valvatidae Valvata leviisi lewisi Valvata lewisi lewisi* C u rrie r, 1868 Fringed Valvata SITES (42): Nl000,N1002/CN10l9Jil004, I NlOl I.N1014,N1015,N1026,N1033,N1034,N1037, NL043J^1046,N1048;41051,N1057,N1059J^I060, N1063J41065J41068,N1072JJ1073J41074^1075, N1080,N1097,N1098,N1102J41103,N l 105,Nl 107, N11II J40103,N0104,N0110,N0115,N0121,N0132, N0134,N0137,CN1016 DRAINAGE/WATERSHED PACIFIC; Fraser: Fraser (2),Nechako (7),Stuart (3); Nass: Meziadin (1); Sireena: Babine (I), Bulkley (2) Stiidnc: Stddne (4) ARCTIC: Liard: Dease(5)ft Nelson(6),Liard(3), Toad (I) Peace: Kiskatinaw (l)feac e (5)fine (1) ECOPROVINCE/ECOREGION Boreal Plains: Central Alberta Uplands (l)feace Figure A-1 - Collection sites for Valvata lewisi lewisi. BIOGEOCLIMATIC (BGC) ZONE Boréal White and Black Spruce (23) Engelmann Spruce - Suba^ine Fir (1) Interior Cedar -Hemlock (2) Sub-Boreal Spruce (16) River Basin (1),Southern Alberta Uplands (2) Central Interior: Fraser Plateau (6) Coast & Mountains: Nass Basin (1) Northern Boreal Mountains: Northern Canadian Rocky Mountains (1), Liard Basin (S), Boreal Mountains and Platemis (6) Sui^Boreal Interior: Fraser Basin (10),Central Canadian Rocky Mountains(2),Skeena Mts. (1) Taiga Plains: Hay River Lowland (4), Northern Alberta Uplands (2) Environmental Information: Meuuremcnt Std. Error Minimum Maximum Count Mean 0.69 10.40 27.20 Temperature C^) 18.13 32 15.00 99.00 Dissolved 0%(% Saturation) 69.18 3.36 32 735.00 Conductivity (pSiemens) 252.48 27.40 73.60 32 9.64 4.09 108.25 Calcium (mg/litre) 32 36.31 7.34 0.12 5.60 8.55 32 pH Previously recorded distribution in northern BC: Throu^out northern EC (Clarice 1981). Discussion: Valvata lewisi lewisi was a common mollusc in northern BC being found at 42 of 176 sites. It was found in both the Pacific and Arctic drainages and in all of the ecoprovinces within the study area. The four BGC zones in which it was found have mean average temperatures of -3.0 to 8.7°C with up to 7 months below 0 ^ and up to 5 months above 10^ and annual precipitation ranging fiom 330 to 2200 mm. The range and the means of the aivironmental variables for V. lewisi lewisi are shown in Figure 2-9. 117 Fifflfly Valvaiidie Valvata lewisi lewisi Temperature: Figure 2-9a shows that V. lewisi lewisi was found at temperatures >2S°C suggesting temperature may not be a limiting factor in the distribution of this species in northern BC. Dissolved Oxygen: Figure 2-9b shows that V. lewisi lewisi was found in habitats of relatively low dissolved oxygen (>15% saturation). While prosobranchs are generally described as less hypoxia tolerant than pulmonates (Boycott 1936), this may not be the case for V. lewisi lewisi and it may be oxygenindependent. Thus, the dissolved oxygen saturation of a habitat may not be a limiting factor in the distribution of this species in northern BC. Conductivity and Calcium Concentration: Figure 2-9c shows that V. lewisi lewisi was found at a minimum calcium concentration of 9.6 mg/1. Given the relatively large sample size for this species (n=32), this may indicate that there is a minimum calcium concentration required by this species in order to occupy a habitat. The conductivity/calcium concentration of a habitat may be a limiting factor in the distribution of this species in northern BC. OiL The mean pH for V. lewisi lewisi is significantly lower that for V. sincera sincera (Table 2-7). Figure 2-9d shows that while both Valvata taxa species display relatively wide ranges of tolerance to pH, V. lewisi lewisi was found at sites where the pH was lower than the minimum measured for V. sincera sincera. It appears that V. lewisi lewisi may be better able to tolerate low pH levels than can V. sincera sincera and this may allow V. lewisi lewisi to occupy a wider range of habitats in northern BC than can V. sincera sincera. Three families were included in the Canonical Correspondence Analysis (CCA) analysis that includes the Valvata species (Group 1; Figure 2-15). The results of this CCA are that the species are responding significantly to the environmental variables (p = 0.040) with 13.2% of the species presence accounted for). The plot shows V. lewisi lewisi to correspond to lower than average temperature and dissolved oxygen, neither of which appeared to be particularly important in its ecology as extrapolated from the range plots. Clarke (1981) records V. lewisi lewisi as occurring throughout northern BC, which concurs with the findings of this study. This widespread distribution gives no indication that any barriers to its dispersal were encountered. According to Clarke (1981), V. lewisi lewisi occurs principally in lakes, often at considerable depth, and usually on mud among submersed aquatic vegetation, and it is also occasionally found in slowmoving rivers and in muskeg pools. Clarice (1979a) lists V. lewisi lewisi as an indicator species of oligotrophic lakes but Clarice (1973b) states that it also occurs in small water bodies in the northern part of its range, hr this study, V. lewisi lewisi was found in lakes and in slow moving rivers and creeks but it was also found in small water bodies throughout the study area. As this species is known in the northern 118 Family Valvatidae Valvata lewisi lewisi United States from New York west to Minnesota (Burch 1989) and throughout BC into the Yukon (Clarke 1981), findings of the current study would be consistent with Clarke’s (1973b) statement of this taxa being found in smaller water bodies in the northern part of its range. It may also be that in the northern part of its range, it is no longer so indicative of oligotrophy as, in this study, it was often collected from small, thickly vegetated ponds. *Note; This species is referred to as Valvata sincera sincera by Clarice (1973b, 1979a, 1981) but more recent authorities use V. lewisi lewisi (Burch 1989). The distinctive shell sculpturing of raised coUabral striae is reflected in its common name, the fiinged valvata (Turgeon et al. 1998). 119 Family Valvatidae Valvata sincera sincera Valvata sincera sincera* S ay, 1824 Mossy Valvata SITES (40): Valvata alncm ahKera N1001.N1002,N1003,N1007,N1009.N1015,N1052, N1053J^1054,N1055,N1056^1059J^l062Jil067, N1068J41069,N1074^1081,N1082,N1091,N1092, N1093J41100,N I101,N l 102,N1104J41105J41106, N l 112,N0109,N0110,N0113,N0114,N0115,N0116, N0122,N0125,MN1000,MN1003,MN1011 DRAINAGE/WATERSHED PACIFIC: Fraser: Fraser (1), Nechako (10), Stuart (3); Nass: Nass (1); Skccna: Bulkley (2), Skeena (2); Stikine: Stildne (2); Yukon: Atlin (1) ARCTIC; Liard: Dease (6),Liard (5); Peace: Peace (7) ECOPROVINCE/ECOREGION Boreal Plains: Peace River Basin (l),Southem Alberta Uplands (1) Central Interior: Fraser Plateau (8) Coast & Mts.: Nass Ranges (l),Nass Basin (2) Northern Boreal Mountains: Boreal Figure A-2 - Collection sites for Valvata sincere sincera. Mountains and Plateaus (7)JJaid Basin (7) Sub-Boreal Interior: Onuneca Mountains (1), BIOGEOCLIMATIC (BGC) ZONE Fraser Basin (12) Boreal White & Black Spruce (IS) Interior Cedar-Hemlock (3) Spruce-Willow-Birch (1) Sub-Boreal Spruce (21) Enviromneiital Infomuition: Measurement Count Mean Std. Error Minimum Maximum Temperature (°C) 29 18.89 0.77 8.70 26.50 Dissolved 0%(% Saturation) 29 98.00 71.10 4.01 8.00 Conductivity (pSiemens) 29 1199.00 237.08 36.70 94.60 177.44 Calcium (mg/litre) 29 34.01 5.47 12.77 8.90 29 7.77 0.12 6.50 pH ............. Previously recorded distribution in northern BC: Clarke (1981) does not include BC within the range of this species, but Clarke (1973b) reports a collection firomDease Lake, BC. Discussion: Valvata sincera sincera was a common mollusc in northern BC being found at 40 of 176 sites. It was found in both the Pacific and Arctic drainages and was absent only fixrm the Taiga Plains ecoprovince. The four BGCs in which this species was found have mean average terrqreratures ranging fipom -2.9 to 8.7°C with tqr to 7 months below OT and tq> to 5 months above 1(PC and with annual precipitation ranging finm 330 to 1200 mm. The range and the means of the environmental variables for V. sincera sincera are shown in Figure 2-9. 120 Family Vmivmüdme Fa/vaca tineera smetra Temperature: Figure 2 9a shows that V. sincera sincera was found at temperatures >2S°C suggesting tenqierature may not be a limiting factor in the distribution of this species in northern BC Dissolved Oxygen: Figure 2-9b shows that V. sincera sincera was found in habitats of relatively low dissolved oxygen saturation (>8%). While prosobranchs are generally described as less hypoxia tolerant than pulmonates (Boycott 1936), this may not be the case for V. sincera sincera and it may be oxygenindependent. Thus, the dissolved oxygen saturation of a habitat may not be a limiting factor in the distribution of this species in northern BC. Conductivity and Calcium Concentration: Figure 2-9c shows that V. sincera sincera was found at a minimum calcium concentration of 11.3 mg/1. Given the relatively large sample size for this species (n 29), this may indicate the minimum calcium concentration required by this species in order to occupy a habitat. The conductivity/calcium concentration of a habitat may be a limiting factor in the distribution of this species in northern BC. pH: The mean pH for V. sincera sincera is significantly hi^er that for V. lewisi lewisi (Table 2-7). Figure 2-9d shows that while both Valvata taxa display relatively wide ranges of tolerance to pH, V. lewisi lewisi was found at sites where the pH was lower than the minimum measured for V. sincera sincera. It appears that V. sincera sincera may be less able to tolerate low pH levels than V. lewisi lewisi, and that this may restrict the number of habitats available to this taxa in northern BC as compared to those available to V. lewisi lewisi. Three families were included in the Canonical Correspondence Analysis (CCA) analysis that includes the Valvata species (Group 1; Figure 2-15). The results of this CCA are that the species are responding significantly to the environmental variables (p = 0.040) with 13.2% of the species presence accounted for. The plot shows V. sincera sincera to correspond to hi^er than average pH. Figure 2-9d and the results of the significance testing do indicate that pH may be an important ecological factor for this taxa in northern BC. Valvata sincera sincera has not been previously recorded in BC and was previously known in Canada only firom east of the Rocly Mountains (Clarke 1981). While it was found east of the Rocky Mountains in this study, near Fort St. John, it was most commonly found in the west of the study area. V. sincera sincera was not collected firom the northeast of the study area but is recorded as occurring in northern Alberta and the Northwest Territories (Clari» 1981) so it is expected that this area is within its range. This widespread distribution gives no indication that any barriers to its dispersal were encountered. According to Clarke (1981), V. sincera sincera is principally an arctic and sub-arctic species, however, Butch (1989) reports V. sincera sincera from as far south as Indiana, and Wu (1989) 121 Family Valvatidae Valvata smcera sincera reports V. sincera from Colorado so the distribution of this species is not as limited to northern climes as believed by Clarke. Clarke (1981) states that V. sincera sincera occurs in lakes, poiids, slow>moving rivers and streams, and in muskeg pools. This concurs with the types of habitats in which V. sincera sincera was found during this study. *Note: This species is referred to as Valvata sincera helicoidea by Clarke (1973b, 1981) but more recent authorities use V. sincera sincera (Burch 1989) or V. sincera (Wu, 1989). 122 Kd/voiasp. Valvata sp. SITES (6): CN I003,CN1008,CN1009,CN1012.CN1017.CN1018 DRAINAGE/WATERSHED PACIFIC; Fraser: Nechako (2) ARCTIC: Liard: Kechika (2); Peace: Finlay (1), Peace (I) ECOPROVINCE/ECOREGION Central Interior: Fraser Plateau (1) Northern Boreal Mountains: Boreal Mountains and Plateaus (3) Sub-Boreal Interior: Fraser Basin (2) BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (1) Spruce - Willow • Birch (2) Sub-Boreal Spruce (3) Figure A-3 - Collection sites for Valvata sp. Discussion: These unidentified specimens were all collected by Clarice and assistants during the 1972 and 1973 surveys and are included here to give a complete record of freshwater mollusc collections from northern BC. All the sites for these unidentified specimens are within the known range of both of the two Valvata taxa recognized from northern BC and were found in the same drainages, ecosections and biogeoclimatic zones. Thus, no information as to what taxon any of these collections may be is gained from comparisons to the distribution maps the two identified taxa. Site CN1012 is the same site as N1003 where Valvata sincera sincera was collected and site CNIOIS is the same site as Nl 103 where V. lewisi lewisi was collected. However, this cannot be used to imply that that the current collections may be the same taxa as historic collections as both taxa of Valvata were often collected from the same sites during this study. 123 Family Acroloxidae Aerobma coioradensis Acroioxus coioradensis (H en d erso n , 1930) Rocky Mountain capshell AenlOKusGolondensis SITES (7): N1002, N1004, N1005, N1097, N1098, Nl 100, N1107/CN1015 DRAINAGE/WATERSHED PACIFIC; Fnser: Fraser (1), Nechako (2); Skccna: Babine (1), Bulkley (1) ARCTIC: Peace: Peace (2) ECOPROVINCE/ECOREGION Central Interior: Fraser Plateau (2) Sub-Boreal Interior: Fraser Basin (5) BIOGEOCLIMATIC (BGC) ZONE Sub-Boreal Spruce (7) Figure A-4 - Collection sites for Acroioxus coioradensis. Environmental Information: Maximum Measurement Count Mean Std. Error Minimum 14.00 7 18.57 1.26 24.50 Temperature (°C) 7 69.71 6.22 44.00 90.00 Dissolved 0%(% Saturation) 7 76.90 284.00 Conductivity (pSiemens) 148.00 27.51 7 3.70 8.92 36.76 Calcium (m ^tre) 18.48 5.60 7 6.84 0.27 7.75 pH Previously recorded distribution in northern BC: Known only from 1 site (Clarice 1981). Discussion: Acroioxus coioradensis was an uncommon mollusc in northern BC being found at only seven of 176 sites. It was found in both the Pacific and Arctic drainages and only in the interior-type ecoprovinces. It was found the Sub-Boreal Spruce BGC zone, which has a mean annual temperature of 1.7 to S.O^ with 4 to 5 months below (PC, and 2 to 5 months above 1(PC and with annual precipitation ranging firom440 - 990 mm. The range and the means of the environmental variables for A. coioradensis are shown in Figure 2-9. Temperature: The habitats in which A. coioradensis was found did not include those with water temperature >24.5° (Figure 2-9a). Other factors suggest that A. coioradensis may be restricted to stable, perennial habitats (see below) and lower temperatures may be characteristic of these types of habitats. A. coioradensis has been previously described as a cold water stenotherm (Bryce 1970) but the variety of 124 Family Acntoxidae Acroioxus coioradensis habitats and tenqieratures at which it was found in this study suggests that this may not be a valid descriptor of this taxa. Dissolved Oxygen: A. coioradensis was only collected from habitats of relatively high dissolved oxygen saturation (>40%; Figure 2>9b). Eurasian species of Acroioxus are oxygen-dependent (Russell-Hunter 1978) and A. coioradensis may also be limited to well-oxygenated habitats. This may restrict the its distribution to perennial habitats with relatively stable conditions. Conductivity and Calcium Concentration: A. coioradensis was collected at a minimum calcium concentration of -10.1 mg/1 calcium (Figure 2-9c). However, sites with lower measures occurred only outside of the physical distribution range for A. coioradensis. Thus, it cannot be discerned if this calcium level is a minimum requirement for A. coioradensis, if it is a result of a range restricted by other factors, or if it is an artifact of small sample size (n=7). pH: A. coioradensis is one of the few molluscs in this study found in habitats with an acidic mean pH, although it was found in alkaline conditions (Figure 2-9d). It may be that perennial, stable habitats within the range of A. coioradensis tend to be acidic and that a preference for acidic water is not a distinctive characteristic of the species. Three families were included in the Canonical Correspondence Analysis (CCA) analysis that includes A. coioradensis (Group 1; Figure 2-15). The results of this CCA are that the species are responding significantly to the environmental variables (p = 0.040) with 13.2% of the species presence accounted for. A. coioradensis occurs on the plot most closely associated with lower than average pH, which is consistent with the observations from the range plot of pH (Figure 2-9d). Prior to this study, A. coioradensis was known only from only one location in BC (Clarice 1981), that of Purden Lake, about 60 km east of Prince George. As there were very few locations for this species in Canada, it is a candidate for federal endangered species listing with the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Based on the findings of this study in which A. coioradensis was found at many new locations, many of which are protected, and in a greater range of habitat types than it was previously believed to be capable of inhabiting, a recommendation for COSEWIC to list A. coioradensis as “Not at Risl^’ has been submitted (Lee and Ackerman 1999c), in which a report on the current status of this species is available. A. coioradensis appears to be restricted to the southeast of the study area where it was found only in the Sub-Boreal Spruce biogeoclimatic (BGC) zone. This zone has a mean annual tenqserature above 0°C and more months above 10°C than do the more northeriy BGC zones (Table 2-5). However, if A. coioradensis was restricted to the south of the study area by climatic requirements, it would be expected to also occur further south in the province but this has not been verified to date. Fossil evidence indicates 125 Family Acnloxidae Aerokaaa coioradensis that A. coioradensis was once more widespread in North America (Bryce 1970). As it is currently most commonly known in western North America from disjunct locations in the Rocky Mountains (i.e. northern BC, Montana and Colorado; Lee and Ackerman 1999c), it may have survived glaciation in lakes in nunataks. Its current limited distribution may reflect a limited capacity for post-glacial dispersal away fiem these small réfugia although the possible location of these réfugia has not been examined. Clarice (1981) states that A. coioradensis is characteristic of rocky, exposed portions of oligotrophic and mesotiophic lakes, where it occurs in shallow water on the undersides of rocks. In this study, A. coioradensis was collected from rocks, submerged wood, aquatic vegetation and submerged deciduous leaves, and these collections were sometimes made in small, eutrophic ponds. These findings indicate that A. coioradensis can inhabit a far greater range of habitats than was believed prior to this study. 126 Family Lymnaeidae Fossaria galbana Fossaria galbana* (S ay, 1825) Boreal fossaria SITES (4): N1001,N1014,N1047,N1055 DRAINAGE/WATERSHED ARCTIC; Liird: Liard (2); Peace: Kiskatinaw (1), Peace (1) ECOPROVINCE/ECOREGION Boreal Plains: Southern Alberta Uplands (1) Northern Boreal Mountains: Liard Basin (1), Northern Canadian Rocky Mountains (1) Sub-Boreal Interior : Fraser Basin (1) BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (2) Spruce - Willow - Birch (I) Sub-Boreal Spruce (1) Figure A 5 - Collection sites for Fossaria gaibana. Environmental Information: Measurement C oiut Mean Std. Error Minimum Maximum Temperature CC) 4 18.93 2.25 14.30 23.80 Dissolved 0%(% Saturation) 4 74.00 7.72 59.00 91.00 Conductivity (pSiemens) 4 240.90 32.87 178.60 315.00 Calcium (m^itre) 4 25.29 34.58 4.90 45.63 4 7.85 0.17 7.50 8.30 pH Previously recorded distribution in northern BC: Far east of northern BC only (Clarice 1981). Discussion: Fossaria galbana was an uncommon mollusc in northern BC being found at five of 176 site. It was found only in the Arctic drainage in three of the six ecoprovinces. The three BGC zones in which it was found have mean annual temperatures ranging fimm-3.0 to SSfC with iq>to seven months below OT and tq>to five months above 10°C and with annual precipitation ranging from 330 to 990 mm The range and means of the environmental variables measured for F. gaibana are shown in Figure 2-10. Temperature: Figure 2-lOa shows that F. galbana was found in relatively h i^ terrqierature habitats (i.e., iq> to 23.8T). F. galbana is described as a cold water species (Clarke 1981), so it may be that it inhabits cooler microhabitats within the lakes where it was found, as often only shells were collected. 127 Family Lymnaektae Fossaria galbana Dissolved Oxygen: Figure 2-lOb shows that F. galbana was only collected in habitats of relatively high dissolved oxygen. However, as lynmaeids are often reliant on atmospheric air for respiration, F. galbana may be confined to these habitats by other 6ctors and that high dissolved oxygen is an intrinsic feature of the large water bodies where it was found. Conductivity and Calcium Concentration: Figure 2-lOc shows that F. galbana was collected fiom habitats with a minimum level of calcium concentration of 25.3 mg/1, a higher minimum calcium concentration than for most of the other lymnaeids. It may be that F. galbana is a calciphilic gastropod, restricted to habitats with high levels of calcium (i.e. > 20 mg/l)as per Russell-Hunter (1978) although the small sample size (n=4) may not have allowed for true representation of its range of tolerance. pH: Figure 2-lOd shows that F. galbana was found only in habitats with alkaline pH. As high pH is associated with high calcium, the restriction of F. galbana to alkaline habitats may be due to its putative high minimum requirement for calcium. The results of the CCA are that the lymnaeid species are responding significantly to the environmental variables (p = 0.010) with 6.3% of the species presence accounted for (Figure 2-16). The plot shows F. galbana to be most closely correlated with higher than average pH. The sample size for F. galbana is small (n=4) which may prevent development of a strong unimodal response, however, the above discussion suggests F. galbana may differ ecologically fiom most other lymnaeids in that it was only collected at sites of alkaline pH. There are no known previous records of the occurrence of F. galbana in BC (Lee and Ackerman 1998a, c). Clarke (1981) includes the far northeastern area of BC within the range of this species probably because it has been collected fiom the Mackenzie River system in Alberta and the North West Territories (Clarice 1973b). While this study extends the range of F. galbana further east into BC, this range is still within the Mackenzie River drainage and is east of the Rocky Mountains. This distribution suggests that F. galbana migrated post-glacially out of the Mississippi refuge and was halted fiom further dispersal by the geographic barrier of the Rocly Mountains. F. galbana is described as being a cold-water species occurring only in lakes and rivers (Clarke 1981). Clarke (1979a) states that F. gqlbana is an indicator species of oligotrophic and mesotrophic lakes. The collections of F. gfdbana in this study were made fiom large lakes, which concurs with Clarice’s observations. *Note: Referred to as Fossaria decampi by Clarke (1979a, 1981), Lymnaea decampi by Clarice (1973b), Lymnaea obrussa decampi by Mozley (1938) and Galba obrussa decampi by Baker (1911). 128 Fimily Lymnaeidie Fossaria modicelia Fossaria modicelia* {Svy, 1825) Rock fossaria SITES (9): Fo$Mtrtamodlc»ttê N1017.N1033, N1034,N1060,N1062,N1071,N108 l ^ I 109.N0119 DRAINAGEmATERSHED PACIFIC; Fraser: Fraser(l);Stildne: Slildne(l) ARCTIC: Liard: Dease (2), Fort Nelson (2), Liard (1); Nass: Nass (1); Peace: Kiskatinaw (1) ECOPROVINCE/ECOREGION Boreal Plains: Peace River Basin (1) Coast & Mountains: Nass Basin (1) Northern Boreal Mountains: Boreal Mountains and Plateaus (1), Hyland Highland (1), Liard Basin (2) Sub-Boreal Interior: Fraser Basin (1) Taiga Plains: Hay River Lowland (2) Figure A-6 - Collection sites for Fossaria modicelia. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (7) Interior Cedar - Hemlock U) Sub-Boreal Spruce (I) Enviroomental loformatioii: Measurement Count Mean Std. Error Minimum Maximum Temperature CC) 8 18.80 3.01 1.50 27.20 8 Dissolved O2 (% Saturation) 63.00 7.00 83.00 9.31 Conductivity (tiSiemens) 8 511.09 176.02 161.90 1568.00 Calcium (mg/litre) 8 74.87 26.24 22.80 232.45 8 7.66 0.18 7.05 pH 8.45 Previously recorded distribution in mordtem BC: Throughout northern BC (Clarke 1981). Discussion: Fossaria modicelia was an uncommon mollusc in northern BC being found at nine of 176 sites. It was found in both the Pacific and Arctic drainages and in all ecoprovinces except the Central hiterior. F. modicelia has been collected in the Central Interior outside of the study area (Lee and Ackerman 1998b). The three BGC zones in which it was found have mean annual temperatures ranging fiom -2.9 to 8.7°C with up to 7 months below 0°C and up to S months above KPC and with annual precipitation ranging from 330 to 1200 mm. The range and means of the environmental variables measured for F. modicelia are shown in Figure 2-10. Temperature: Figure 2-lOa shows that F. modicelia was found at tençeratures >25"C suggesting that high water tengterature may not be a limiting Actor in the distribution of this species in northern BC. 129 Family Lymnaektae Fossaria modicelia Dissolved Oxygen: Figure 2-lOb shows that F. modicelia was found in habitats of relatively low dissolved oxygen ( 20 mg/1) as per Russell-Hunter (1978). pH: Figure 2-lOd shows that F. modicelia was found only in habitats with alkaline pH. As high pH is associated with high calcium, the restriction of F. modicelia to alkaline habitats may be due to its putative high minimum requirement for calcium The results of the CCA are that the lymnaeid species are responding significantly to the environmental variables (p = 0.010) with 6.3% of the species presence accounted for (Figure 2-16). The plot shows F. modicelia to be most closely correlated with higher than average conductivity. The above discussion suggests F. modicelia may differ ecologically from most other lymnaeids in this study in that it was only collected at sites of relatively high conductivity. Clarice (1981) indicates that the distribution o ff. modicelia includes all of northern BC, which is consistent with the findings of this study, f. modicelia was not collected often (n=9), but was found throu^out the study area. This widespread distribution gives no indication of any barriers imposed during post-glacial dispersion. Clarice (1981) states that f . modicelia occurs in perennial lakes, ponds, streams, and in vernal pools and ditches, which concurs with the findings of this study. *Note: Referred to as Lymnaea modicelia by Clarice (1973b) and Mozley (1938) and Galba kumilis modicelia by Baker (1911). 130 Family Lymnaeidae Fossariaparva Fossaria parva* (I. L ea, 1841) Pygmy fossaria SITES (1): Nl 111 (14 subsites within) DRAINAGE/WATERSHED PACIFIC; Fraser: Fraser ECOPROVINCE/ECOREGION Sub-Borcal Interior: Central Canadian Rocky Mountains BIOGEOCLIMATIC (BGC) ZONE Engelmann Spruce - Subalpine Fir Figure A-7 - Collection site tor Fossaria parva. Environmental Infomution: Maximum Std. Error Minimum Meuurement Count Mean 0.94 17.00 14 12.10 7.75 Tenmerature (°C) 91.00 14 67.50 4.10 36.00 Dissolved 0%(% Saturation) 27.49 44.00 Conductivity (^Siemens) 14 273.30 83.10 39.41 64.27 Calcium (mg/litre) 14 39.30 11.05 7.17 0.15 6.10 8.15 14 pH , . . Previously recorded distribution in northern BC: Far east only (Clarke 1981). Discussion: Fossaria parva was an uncommon mollusc in northern BC being found at one of 176 sites. However, this one site represents a compilation of 14 records collected during an intensive study of one watershed (Lower Torpy River; see Ciuqiter 3). While there is a range of environmental variables available, they are considered to have been collected only at one site (Nl 111). This one site is in the Pacific drainage, the sub-Boreal Interior ecoprovince and the Engelmann Spruce - Subalpine Fir BGC zone. This BGC zone has a mean annual temperature of -2.0 to 2.0°C with 5 to 7 months below 0°C and 0 to 2 months above KPC and with annual precipitation ranging fiom 400 to 2200 mm. The range and mean of the environmental variables measured at the 14 locations within this one site are shown in Figure 2-10. F. parva was found most commonly associated with small streams that had been impacted by the construction of access roads for timber harvest. These lotie locations are unlike any of those sampled during the course of the study presented in Chuter 2. The collections of F. parva were also made eariier in the season than were the collections for the Chapter 2 study. The difference in 131 rwniijF Fossaria parva these lotie, early season locations is reflected primarily in the temperature, of which the mean is significantly lower than for most of the other lymnaeids in this study (Table 2-7). Temperature: As discussed above, the collections of F. parva were made earlier in the season than most other collections in this study. This seems to be reflected in the water temperatures recorded for this species as Figure 2-10a shows the temperature range for F. parva to have a much lower maximum than those ranges for the other lymnaeids in this study. Dissolved Oxvgen: Figure 2-lOb shows that F. parva was collected in habitats of relatively high dissolved oxygen. F. parva is an amphibious species (Clarke 1981) and, as a lymnaeid, would generally be reliant on atmospheric air for respiration. The high measures probably reflect the higher levels of oxygen expected to be found in the cooler water temperature locations rather than an ecological requirement for F. parva. Conductivitv and Calcium Concentration: Figure 2-lOc shows that F. parva was found at calcium concentrations with a minimum of 11.0 mg/1. Few sites within the area in which F. parva was collected have lower conductivity/calcium values than this, therefore, this may not represent a physiological requirement for F. parva but rather the minimum conditions within the only area in which it was found. pH: Figure 2-lOd shows that, unlike the other Fossaria species collected in this study, F. parva was found in habitats of both acidic and alkaline conditions so that its mean pH is significantly lower than for F. galbana and F. modicelia (Table 2-7). This tolerance for acidic pH may be in keeping with the putative lower calcium requirement for F. parva than for F. galbana and F. modicelia. The results of the CCA are that the lymnaeids responded significantly to the environmental variables (p = 0.010) with 6.3% of the species presence accounted for (Figure 2-16). The plot shows F. parva to correspond most closely to lower than average temperature. As above, the mean temperature at which F. parva was collected was significantly lower than that for most other lymnaeids in this study. There are no previous records of F. parva in BC (Lee and Ackerman 1998a, c). Clarke (1981) probably includes northeastern BC within its range based on collections fix)mthe Mackenzie River system in Alberta and the NWT. hi this study, it was found in the Pacific drainage fiom the Fraser River watershed extending the range of F. parva into BC and into an area west of the Rocky Mountains. Clarice (1981) states that F. parva is anqihibious and lives on wet mud flats, lake shores and river banks near the water’s edge, and in marshes. The locations where F. parva was collected in this study are consistent with this previously recorded ecology. *Note: Referred to as Lymnaea parva by Clarice (1973b), Lymnaea parva sterldi by Mozely (1938) and Galba parva by Baker (1911). 132 Family Lymnaddae Lymnaea atkaensis Lymnaea atkaensis* D ali, 1884 Frigid lymnaea Lyrtwmtê atkatntis SITES (5): N1048,N1068,CN1005/MN1011,CNIOlO, MN1002 DRAINAGEAVATERSHED ARCTIC: Liard: Dease (3), Liard (1); Peace: Finlay (1) ECOPROVINCE/ECOREGION Northern Boreal Mountains: Liard Basin (1), Northern Canadian Rocky Mountains (1), Borràl Mountains and Plateaus (3) BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (3) Spruce - Willow - Birch (2) i*mm( Figure A-8 - Collection sites for Lymnaea atkaensis. Environmental Information: Measurement Count Mean Std. Error Minimum Maximum Temperature (°C) 4.20 13.80 2 18.00 22.20 Dissolved 0%(% Saturation) 2.00 80.00 2 82.00 84.00 Conductivity (pSiemens) 115.00 245.00 2 360.00 475.00 Calcium (mg/litre) 17.14 35.19 2 52.34 69.49 0.23 7.25 2 7.48 7.70 pH Previously recorded distribution in norAem BC: Northwest only (Clarice 1981). Discussion: Lymnaea atkaensis was an uncommon mollusc in northern BC being found at five of 176 sites. It was found only in the Arctic drainage and only in the Noithem Boreal Mountains ecoprovince. The two BGC zones in which it was found have mean annual tenqieratures of -3.0 to 2.0"C with up to 7 months below o r and tq>to 4 months above lOT and with annual precipitation ranging from 330 to 700 mm. L. atkaensis was collected from two ecological sites. The range and means of the environmental variables measured at these two sites are shown in Figure 2-10. Temperature: Figure 2-lOa shows that I. atkaensis was collected at low temperatures relative to other lymnaeids in this study. L. atkaensis is restricted to the far northwest of the study area where it has only been collected from lakes. Low temperature may be indicative of these habitats rather then of a physiological requirement of this species. 133 Family LymnaeidM Lymnaea atkaensis Dissolved Oxvyen: Figure 2-IOb shows that L. atkaensis was found in habitats of high dissolved oxygen. However, as lymnaeids generally maintain a dependence on atmospheric air, it is not expected that their distributions may be limited by the amount of dissolved oxygen in a habitat. Conductivitv and Calcium Concentration: Figure 2-lOc shows that L atkaensis was collected firom habitats with high levels of dissolved calcium (35.2 mg/1 minimtim). It may be that I. atkaensis is a calciphilic gastropod, restricted to habitats of high calcium concentration (i.e., > 20 mg/1) as defined by Russell-Hunter (1978). pH: Figure 2-lOd shows that L. atkaensis was collected only at sites of alkaline pH. As alkaline pH and high calcium levels are related, this may be in keeping with its putative high calcium requirement. The results of the CCA are that the lymnaeid species are responding significantly to the environmental variables (p = 0.010) with 6.3% of the species presence accounted for (Figure 2-16). The plot shows L atkaensis to be associated with hi^er than average dissolved oxygen. The small sample size (n = 2) does not allow development of a unimodal response to any particular variable and the level of dissolved oxygen is probably of limited ecological consequence to this species. L atkaensis is known only firom Alaska and northwest Canada (Burch 1989). Previous to Clarke’s northern BC surveys, L atkaensis appears to have been known only fiom the Aleutian Islands (Mozely 1938, Baker 1911). I. atkaensis was found only at two sites during this study, once fiom the same lake fiom where there were previous records (Dease Lake) and also in a new location in a lake in the same major watershed (Liard). According to Clarice (1981), I. atkaensis is a Bermgian relic species and the results of this study are in accordance with that assessment. L atkaensis displays a very restricted distribution that concurs with hypothesized dispersal routes for fieshwater fish fiom the Bering Refuge (McPhail and Lindsey 1970). Clarice (1979) states that I. atkaensis is known only fiom oligotrophic lakes but in this study was collected in one lake with abundant vegetation. Clarice (1981) describes L atkaensis as occurring on rocks and among sparse submersed vegetation. At the two ecological sites at which it was collected in this study, it was observed actively crawling through soft substrates adding additional information to the previously recorded ecology. *Note: Referred to as Galba atkaensis by Baker (1911). 134 Family Lynuteidie Lymnaea sagnalis appressa Lymnaea stagnaiis appressa* S ay, 1821 Swamp lymnaea 7 9 SITES (33): NIOOI,N1010,N10I5^1020,N1033, N1037J<1038JJ1042,N1043;41048,N1052,N1053, N1055,N1056,N1058^1059J41060,N1062,N1069, N1072,N1091,N1096,N1097J^1105.Nl 107,NO135, N0137,MN1000,MN1001,MN1004,MN1010, CN1012.CN1016 DRAINAGEAVATERSHED PACIFIC: Fraser: Fraser (2), Nechako (1), Stuart (1); Skeena: Babine(2), Skeena(l); Stikine: Stikine (2); Yukon: Atlin (1) ARCTIC: Liard: Dease (4), Fort Nelson (5), Liard (6); Mackenzie: Hay (1); Peace: Beatton (1), Peace (3), Pine (2), Smoky (1) ECOPROVINCE/ECOREGION Boreal Plains: Central Alberta Uplands (1), Southern Alberta Uplands (4) Coast & Mountains: Nass Ranges (1) Northern Boreal Mountains: Liard Basin (10), Figure A-9 - Collection sites for Lymnaea stagnedis Boreal Mountains and Plateaus (3) BIOGEOCLIMATIC (BGC) ZONE Sub-Boreal Interior: Fraser Basin (8) Boréal White and Black Spruce (24) Taiga Plains: Hay River Lowland (1), Northern Interior Cedar - Hemlock (1) Alberta Uplands (2), Hay River Lowland (3) Sub-Boreal Spruce (8) Environmental Information: Measurement Count Mean Maximum Std. Error Minimum 14.00 Temperature CC) 19.48 26.20 25 0.62 72.44 25.00 Dissolved 0%(% Saturation) 3.40 98.00 25 90.30 Conductivity (pSiemens) 25 274.13 29.35 690.00 Calcium (mg/litre) 39.54 12.13 101.54 25 4.38 5.60 25 0.16 8.90 7.51 pH Previous^ recorded dbtributioii in northern BC: Throughout noithem BC (Clarice 1981). Discussion: Lymnaea stagnaiis appressa is a common mollusc of northern BC being found at 33 of 176 sites. It was found in both the Pacific and Arctic drainages and in all ecoprovinces except the Central hiterior. This species has been collected in the Central hiterior outside of the study area (Lee and Ackerman 1998b). The three BGC zones in which it was found have mean annual tenqieratures ranging fiom-2.9 to 8.7°C with up to 7 months below (fC and up to S months above 10°C and with annual precipitation ranging firom 330 to 1200 mm. The range and means of the environmental variables measured for L stagnaiis appressa are shown in Figure 2-10. 135 Funily LymnMMbe Lymiuea sugiulis oppressa Temperature: Figure 2-10a shows that L stagnaiis appressa was found at temperatures >25°C suggesting that temperatures may not be a limiting factor in the distribution of this species. Dissolved Oxygen: Figure 2-lOb shows that L stagnaiis appressa was found over a wide range of dissolved oxygen. As lymnaeids generally maintain a dependence on atmospheric air, it is not expected that their distributions may be limited by the amount of dissolved oxygen in a habitat. Conductivitv and Calcium Concentration: Figure 2-lOc shows that the minimum calcium concentration at which L stagnaiis appressa was collected was 12.1 mg/1. As there were lentic habitats with lower conductivity/calcium levels, this may represents a minimum calcium requirement of a habitat for L. stagnaiis appressa. pH: Figure 2-lOd shows that L. stagnaiis (^pressa was collected over a very wide range of pH in both acidic and alkaline conditions. This suggests that pH may not be a limiting factor in the distribution of this species in northern BC. The results of the CCA are that the lymnaeid species are responding significantly to the environmental variables (p = 0.010) with 6.3% of the species presence accounted for (Figure 2-16). On the plot, L stagnaiis appressa occurs between higher than average temperature and higher than average pH, althou^ it is located close to the origin. The above discussion does not indicate that either of these variables is of particular ecological importance to L stagnaiis appressa. Clarke (1981) indicates that the distribution of L stagnaiis appressa includes all of noithem BC. This concurs with the findings of this study where L stagnaiis appressa was found throuÿiout the study area. This widespread distribution gives no indication of any barriers encountered during post-glacial dispersion. Clarice (1981) states that L. stagnaiis appressa occurs in all perennial-water vegetated habitats and that it is an indicator species of eutrophic water bodies (Clarke 1979a). In this study, it was always collected fiom vegetated areas in lakes, ponds, swamps or slow streams, which concurs with Clarice’s statement. *Note: Referred to by Clarke (1981) and Mozley (1938) as Lymnaea stagnaiisjugularis. 136 Family Lynuueidae Avmimea sp. Lymnaea sp. SITES (1): MNIOOO DRAINAGE/WATERSHED PACinC; Yukon; Atlin ECOPROVINCE/ECOREGION Northern Boreal Mountains: Boreal Mountains and Plateaus BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce Figure A-10 - Collection sites for Lymnaea sp. Discussion: This collection, identified only as Lymnaea sp., has been included as it is one of the few records for freshwater molluscs for the Yukon watershed in BC (Taylor 1993). Althouÿ it is identified as Lymnaea sp., it is not possible to determine to what genus this collection may belong as Dr. Dwight Taylor, who examined these specimens, identifies most members of the Faniily Lymnaeidae as belonging to the genus Lymnaea (e g. Taylor 1993), whereas other authors subdivide this genus into many genera (e.g., Fossaria. Stagnicola. Lymnaea), which is the nomenclature used in this study. 137 Family Lymnuidae Stagnicola arctica* (I. L ea , 1864) Arctic pondsnail I Stoffucola arctica SITES (26): N1012.N1020J41029^1033, N103S, Nl036J^1041J^l062.Ni067,Nl068J25°C suggesting that temperatures may not be a limiting factor in the distribution of this species in northern BC. Dissolved Oxygen: Figure 2-10b shows that S. arctica was found over a wide range of dissolved oxygen. As lymnaeids generally maintain a dependence on atmospheric air, it is not expected that their distributions may be limited by the amount of dissolved oxygen in a habitat. Conductivity and Calcium Concentration: Figure 2-lOc shows that S. arctica was found at the minimum conductivity/calcium concentration measured in this study. This suggests that the conductivity/calcium of a habitat may not be a limiting factor in the distribution of this species. pH: Figure 2-lOd shows that S. arctica was found over a wide range of pH in both acidic and alkaline conditions. This suggests that pH may not be a limiting factor in the distribution of this species. The results of the CCA are that the lymnaeid species are responding significantly to the environmental variables (p = 0.010) with 6.3% of the species presence accounted for (Figure 2-16). On the plot, S. arctica corresponds most closely with lower than average dissolved oxygen. As lymnaeids are generally reliant on atmospheric air, this placement on the plot may be of limited ecological importance. Clarke (1981) describes 5. arctica as an arctic and sub-arctic species occurring only in the far north of BC. This study found S. arctica to be distributed rather consistently throughout the study area, so that the limits of its distribution are much further south than those indicated by Clarke (1981). S. arctica was not collected near the coast of northern BC (i.e., in the Coast and Mountains ecoprovince) where the climate is milder, so it may indeed be the cold-adapted arctic to sub-arctic species described by Clarice but with a noore southerly distribution than previously recorded. According to Clarice (1981), species with a subarctic distribution are not necessarily considered to have dispersed from glacial réfugia but rather from adjacent regions to the south and cold adapted species may have moved south and then north with advancing and retreating ice sheets. S. arctica q>pears to be such a species although its currently known distribution does not indicated if it has repopulated northern BC from only the Mississippi Refuge or from the Pacific as well. Clarke (1981) states that S. arctica occurs in lakes, ponds, rivers, streams, ditches and muskeg pools which is consistent with the habitat types in which it was found in this study. *Note: Referred to as Lymnaea arctica by Clarke (1973b) and as Galba vaUii arctica by Baker (1911). 139 Family Lymnaeidae StaffttcoiacaptTata Stagnicola caperata* (S ay, 1829) Wrinkled marshsnail SITES (4): N 1016,N 1017,N 1032,N 0127 DRAINAGEAVATERSHED ARCTIC: Liard: Fort Nelson (1); Peace: Kisicatinaw (1), Peace (1), Smoky (1) ECOPROVINCE/ECOREGION Boreal Plains : Peace River Basin (1), Southern Alberta Uplands (2) Taiga Plains: Hay River Lowland (1) BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (4) I« M l Figure A-12 - Collection sites for Stagnicola caperata. Environmental Information: Measurement Count Mean Maximum Std. Error Minimum Temperature C*C) 2.48 25.00 3 20.13 16.90 Dissolved Oz (% Saturation) 20.27 71.00 3 47.33 7.00 Conductivity (uSiemens) 656.97 455.76 1568.00 3 175.90 232.45 Calcium (mi^tre) 3 96.62 67.95 24.89 0.10 7.25 pH 3 7.05 6.95 Previously recorded distribution in northern BC: Not previously recorded (Clarice 1981). Discussion: Stagpicola caperata was an uncommon mollusc in noithem BC being found at four of 176 sites. It was found only in the Arctic drainage in the Boreal Plains and Taiga Plains ecoprovinces, east of the Roclqr Mountains. The BGC in which it was found has a mean annual temperature of -2.9 to 2.0T with 5 to 7 months below (fC and 2 to 4 months above KPC and with annual precipitation ringing from 330 to 570 mm. The range and means of the environmental variables measured at the sites where S. caperata was collected are shown in Figure 2-10. Temperature: Figure 2-lOa shows that & c c^a ta was found at temperatures up to 2S’C suggesting that high water tenqierature may not be a limiting factor in the distribution of this species in northern BC. 140 Family Lymnaeidae SugHieola captraia Dissolved Oxygen: Figure 2-lOb shows that S. caperata was found over a wide range of dissolved oxygen. As lymnaeids generally maintain a dependence on atmospheric air, it is not expected that their distributions may be limited by the amount of dissolved oxygen in a habitat. Conductivity and Calcium Concentration: Figure 2*10c shows that S. caperata was collected only in habitats where the concentration of dissolved oxygen was greater than the 20 mgl used by Russell*Hunter (1978) to classify freshwater molluscs as calciphiles. However, the sample size for S. caperata is small (n = 3) and the range measured may not be truly representative of the minimum calcium requirement for this species. pH: Figure 2-lOd shows that S. caperata was only collected from habitats of almost neutral (6.95) to alkaline pH. Alkaline pH is related to h i^ calcium concentration and, as discussed above, it may be that the small sample size for S. caperata does not give true representation of its range of tolerance to pH. The results of the CCA are that the lymnaeid species are responding significantly to the environmental variables (p = 0.010) with 6.3% of the species presence accounted for (Figure 2-16). On the plot, 5. caperata corresponds with higher than average conductivity. The sample size for this species is small (n = 3), which does not allow the formation of any strong unimodal response. However, as discussed above, conductivity/calcium concentration may be an important ecological factor for S. caperata in northern BC. Clarke (1981) indicates that the western limit of S. caperata in Canada is west central Alberta. The distribution of 5. caperata found in this study differs somewhat from that indicated by Clarke. The presence of S. caperata on the Boreal Plains in BC is just a s li ^ extension west of its know distribution in Alberta and this is where most of the collections were made. However, an additional collection was made in the Taiga Plains near Fort Nelson, which extends the range of this species to the north. However, S. caperata is still only known in Canada from east of the Rocky Mountains. With the distribution as illustrated by Clarice (1981) and this new information, it would appear that the post-glacial dispersal of S. caperata was from the Mississippi Refuge and its continued dispersal may have been irrqieded by the geognqrhic barrier of the Roclgr Mountains. *Note: Referred to as Lymnaea caperata by Taylor (1981), Clarke (1973b) and Mozley (1938) and as Galba caperata by Baker (1911). 141 Family Lymnaeidae Stagnicola eatascopium catascopium Stagnicola catascopium catascopium* (Say, 1817) Woodland pondsnail Stagntola catascopium catascopium SITES (7): NI 107, NI 110, N1113, N0106, N0109, N0I14,MN1006 DRAINAGE/WATERSHED PACIFIC; Fniier: Fraser (3), Nechako (3) ARCTIC: Peace: Omineca (1) ECOPROVINCE/ECOREGION Sub-Boreal loterior: Central Canadian Rocky Mountains (1), Omineca Mountains (1), Fraser Basin (S) BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (2) Sub-Boreal Spruce (S) Figure A-13 - Collection sites for Stagnicola catascopium Environmental Information: Maximum Std. Error Minimum Measurement Count Mean 24.50 9.60 4.42 Temperature (°C) 3 16.03 98.00 70.00 8.33 3 86.00 Dissolved 0%(% Saturation) 213.00 120.10 3 179.03 29.58 Conductivity (pSiemens) 30.42 4.41 16.57 3 25.36 Calcium (m ^tre) 8.35 6.35 7.57 0.62 3 ........................... . pH Previously recorded distribution in northern BC: Absent fifomthe northeast (Clarke 1981). Discussion: Stagnicola catascopium catascopium was an uncommon mollusc in northern BC being found at seven of 176 sites. It was found in both the Pacific and Arctic drainages and only in the Sub-Boreal Interior ecoprovince. The two BGC zones in which it was found have mean annual tenqperatures o f-3.0 to 2XPC with up to seven months below 0°C and up to 4 months above 10°C and with annual precipitation ranging firom 330 to 700 mm. The range and means of the environmental variables measured for S. catascopium catascopium are shown in Figure 2-10. Température: Figure 2-lOa shows that S. arctica was found at tenqieratures up to 24.S*C suggesting that temperatures may not be limiting factor in the distribution of this species in northern BC. 142 Fiinüy Lynmaddie Supueola eauseopium catascopium Dissolved Oxygen: Figure 2-lOb shows that S. catascopium catascopium was only found in habitats of h i^ dissolved oxygen. As lymnaeids generally maintain a dependence on atmospheric air, it is not expected that their distributions may be limited by the amount of dissolved oxygen in a habitat. Conductivity: Figure 2-lOc shows S. catascopium catascopium was collected over a very limited range of conductivity/calcium concentration with a minimum of 16.6 mg/1 of calcium. However, the sample size for S. catascopium catascopium was small (n=3), and range measured may not give a true representation of the minimum calcium requirement for this species. pH: Figure 2-lOd shows that S. catascopium catascopium was collected from a range of pH that includes both acidic and alkaline conditions. This suggests that pH may not be a limiting factor in the distribution of this species in northern BC. The results of the CCA are that the lymnaeid species are responding significantly to the environmental variables (p = 0.010) with 6.3% of the species presence accounted for (Figure 2-16). On the plot, S. catascopium catascopium corresponds most closely to lower than average conductivity. However, the sample size for this species is small, which prohibits formation of the requisite unimodal response required for ecological interpretations to be made from the plot. This study found S. catascopium catascopium to have a much more limited distribution than that indicated by Clarice (1981). Clarice records S. catascopium catascopium as occurring throughout northern BC except for that area in the northwest inhabited by Lymnaea atkaensis. A search of museum records (Lee and Ackerman 1998a, c) found only one record for S. catascopium catascopium firom northern BC, at site MN1006 (Germanson Lake) which is the most northerly point on the map included here. Clarice’s extended distribution beyond these locations may be speculative based on this species presence elsewhere in watersheds which extend into BC but this is not supported by the findings of this study. The distribution of S. catascopium catascopium based on this study and as given by Clarke (1981) indicate that S. catascopium catascopium probably moved into northern BC from a southern refuge such as the Mississippi. Clarice (1981) states that the most firequent habitat of S. catascopium catascopium is on rocks exposed to waves or currents, although Clarke (1973b) describes a more varied ecology for this species with rocks being a prominent feature in only 10 of 27 collection sites. Clarke (1979a) states that S. catascopium catascopium is indicative of oligotrophic and mesotrophic lakes, hi this study, while 5. catascopium catascopitm was collected firomrocks in a river, it was generally collected from the shallow edges of oligotrophic to mesotrophic lakes which concurs with Clarice’s listing of S. catascopium catascopium as an indicator species of these trophic levels. 143 Family Lymnaeidae Stagnicola catascopium cafoscopnim *Note: Referred to as Lymnaea catascopium catascopium by Clarice (1973b, 1981). Other works on the Family Lymnaeidae refer only to Stagnicola catascopium (Turgeon et al. 1998, Burch 1989). Clarice (1973b, 1981) identified several subspecies and this nomenclature has been used in this study as the subspecies found in BC appears to be quite distinct fiom the others described by Clarice. Other worics refer to Lymnaea catascopium (Baker 1938) and Galba catascopium (Baker 1911). 144 Stagnicola ebxks Stagnicola elodes* (S ay, 1821) Marsh pondsnail SITES (62): N1003/CN1012,N1004,N1005^1008/CN1013, N1009J^l010^10ll,N1015J^l020jn021,Nl022, N1026J^1030,N1033J^1034^1035,N1036,N1037, Nl039Jil040^l044/MN10l3JJl046,N1047, N1055,N1057J^1058,N1059,N1060,N1061,N1062, N1063,N1065,N1068J^1070,N1071,N1073,NI082, N1092^1093,N1096,N1097,N1099,N110l.Nl 102, N1105.N1106,N0126,N0127,N0131,N0132,N0133. N0136,N0138,N0139,CN1000,CN1007,CN1010, CN1018.MN1004.MN1005.MN1011.MN1012 DRAINAGE/WATERSHED PACIFIC: Fraser: Fraser (1),Nechako (S),Stuart (3); Skeena: Babine (2), Bulkley (2), Skeena (1) Stildne: Stikme (3) ARCTIC: Liard: Dease (9), Fort Nelson (11). Kechika(l).Liard (4),Toad (1); Mackenzie: Hay (2) Peace: Finlay (1). Kiskatinaw (1). Parsnip (1). Peace (7). Pine (2). Smoky (2). Beatton (3) Figure A-14 - Collection sites for Stagnicola elodes. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (41) Interior Cedar - Hemlock 0 ) Spruce - Willow - Birch (3) Sub*Boreal Spruce (17) ECOPROVINCE/ECOREGION Boreal Plains: Central Alberta Uplands (2). Peace River Basin (4). Southern Alberta Upland (S) Central Interior: Fraser Plateau (7) Coast & Mountains: Nass Basin (1) Northern Boreal Mountains: Hyland Highland (1). Northern Canadian Rocky Mountains (4), Liard Basra (7), Boreal Mountains and Plateaus (8) Sub-Boreal Interior: Fraser Basin (9),Central Rocky Mountains (2) Taiga Plains: Hay River Lowland (3). Northern Alberta Uplands (3), Hay River Lowbmd (6) Environmental Information: Maximum Std. Error Minimum Measurement Count Mean 0.59 10.40 18.63 27.20 Temperature CC) 46 3.26 23.00 71.61 135.00 Dissolved 0%(% Saturation) 46 76.90 296.50 32.88 1199.00 Conductivity (pSiemens) 46 38.44 4.42 8.92 159.73 Calcium (m ^tre) 46 7.50 0.11 5.60 9.00 46 pH ........................................... Previously recorded tUstribution in noithem BC: T hrou^ut noithem BC (Clarke 1981). Discussion: Stagnicola elodes is one of the very common molluscs in northern BC being found at 62 of 176 sites. It was found in both the Pacific and Arctic drainages and in all of the northem ecoprovinces. The four BGC zones in which it was found have mean average temperatures ranging fiom -3.0 to 8.7"C with up to 7 months below 0 ^ and tq>to S months above lOT and with annual precipitation ranging fiom 330 to 1200 mm. 145 Family LymnMMtae Stttffücola elodes The range and means of the environmental variables measured at the sites where S. elodes was collected are shown in Figure 2-10. Temperature: Figure 2-lOa shows that S. elodes was found at temperatures >2S°C suggesting that tenq>eratures may not be a limiting factor in the distribution of this species. Dissolved Oxvnen: Figure 2-lOb shows that 5. elodes was not collected in habitats of extremely low dissolved oxygen saturation. However, as lymnaeids generally maintain a dependence on atmospheric air, it is not expected that their distributions may be limited by the amount of dissolved oxygen in a habitat. Conductivitv and Calcium Concentration: Figure 2-10c shows that shows that the minimum calcium concentration at which S. elodes was collected was 10.1 mg/1. As there is a relatively large sample size for this species (n=46), this minimum amount recorded may represent the minimum requirement of a habitat for S. elodes. pH: Figure 2-lOd shows that 5. elodes was found over a wide range of pH in both acidic and alkaline conditions. This suggests that pH may not be a limiting factor in the distribution of this species. The results of the CCA are that the lymnaeid species are responding significantly to the environmental variables (p = 0.010) with 6.3% of the species presence accounted for (Figure 2-16). The plot shows S. elodes to occur near the origin of all the environmental variables and correspond to no particular variable. Clarke (1981) indicates that the distribution of S. elodes includes all of northem BC and that it is found in all kinds of aquatic habitats. This distribution and ecology is in accordance with the findings of this study. This widespread distribution gives no evidence of any barriers inqposed during post-glacial dispersion. *Note: Referred to as Lymnaea elodes by Clarice (1973b), Lymnaea palustrus by Mozely (1938) and Galba elodes by Baker (1911). 146 Family Lymnaeidae Stagnicola sp. - juveniles Stagnicola sp . - ju v en iles stagnicola sp. •juvonHas P SITES (5): N1052, N1072, N1074, N1080, NOl 10 DRAINAGE/WATERSHED PACIFIC! Fraicr: Nechako (1): Nass: Meziadin (1); Stildne: Sdkine (2) ARCTIC: Llard:Liard(n ECOPROVINCE/ECOREGION Central Interior : Fraser Plateau (1) Coast & Mountains: Nass Basin (1) Northern Boreal Mountains: Liard Basin (I), Boreal Mountains and Plateaus (2) BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (3) Interior Cedar - Hemlock (1) Sub-Boreal Spruce (1) Figure A-15 - Collection sites for Stagnicola sp. Environmental Information: M easurement Count Mean Std. E rror Minimum Maximum Temperature C^> 4 18.75 15.30 20.60 1.22 Dissolved 0%(% Saturation) 4 81.00 50.00 10.67 98.00 Conductivity (pSiemens) 4 68.04 119.10 252.73 435.00 4 Calcium (m^litre) 14.60 32.56 57.05 9.15 4 7.74 pH 0.52 6.55 8.90 Discussion: Specimens of the Family Lymnaeidae that are less than 10 mm in h ei^t and have less than four whorls are juveniles of the genus Stagnicola (Clarke 1973b). When juveniles were collected with adult specimens in this study, the two were combined. The five records included here are for sites where only juveniles S/agiuco/o were collected. The range and means of the environmental variables measured at the sites where Stagnicola sp. juveniles were collected are shown in Figure 2-10. This table shows that the ranges and means for these juveniles are different fiom those of any of the other Stagnicola species so they cannot be tentatively identified by their afBnity with the ranges of the environmental variables for other species. As they cannot be identified to species, the measurements of environmental variables will not be further discussed. The CCA plot shows Stagnicola sp. juveniles to correspond most closely to hi^er than average pH. This does not seem to be a particularly inqwrtant ecological factor for this taxon. 147 Family Physidae A p la a eloH gim Aplexa elongata* (S ay, 1821) Lance aplexa SITES (6): N104l,N1096,N1097, N0127,N0133,N0136 DRAINAGE/WATERSHED PACIFIC; Skeena: Babine (2) ARCTIC: Liard:Ft Nelson(2); Peace:Smoky(2) ECOPROVINCE/ECOREGION Boreal Plains: Southern Alberta Uplands (2) Snb>Boreal Interior: Fraser Basin (2) Taiga Plains: Hay River Lowland (2) BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (4) Sub-Boreal Spruce (2) N aonow n Figure A-16 - Collection sites for Aplexa eiongata. Environmeiitnl Information: Measurement Count Mean Std. Error Minimum Maximum Temperature CC) 17.00 22.70 3 18.93 1.88 Dissolved 0%(% Saturation) 31.00 79.00 3 51.33 14.33 Conductivity (uSiemens) 90.30 359.00 3 181.73 88.65 (Calcium (mglitre) 3 25.76 12.13 52.19 13.22 3 6.38 0.50 5.60 7.30 pH Previously recorded distribution in northern BC: Throughout northon BC (Clarke 1981). Discussion: Aplexa elongata is an uncommon mollusc in northern BC being found at six of 176 sites. It was found in both the Pacific and Arctic drainages and in three of the six ecoprovinces. The two BGC zones in which it was found have mean annual tenqieratures ranging fiom -2.9 to 5.0T with up to 7 months below (PC and iq) to S months above KPC and with annual precipitation ranging fiom 330 to 990 mm. The range and means of the environmental variables measured at the sites where A. elongata was collected are shown in Figure 2-11. Temperature: Figure 2-1 la shows that A. elongata was found only at temperatures up to 22.TC. However, the small sample size of this taxa (i^3) may not give an adequate representation of its true range of tolerance to h i^ water temperature. 148 Family PhysidM Aplexa eloHgau Dissolved Oxygen: Figure 2-1 lb shows that A. elongata was not found in habitats where the dissolved oxygen was very low. However, as physids generally maintain a dependence on atmospheric air, it is not expected that their distributions may be limited by the amount of dissolved oxygen in a habitat. Conductivitv and Calcium Concentration: Members of the Physidae were not collected in the habitats of the lowest conductivity/calcium concentration measured in this study (Figure 2-1 Ic). The minimum level at which X. elongata was collected was 12.1 mg/1, However, the small sample size (n = 3) may not give an adequate representation the minimum calcium requirement of this species. pH: Figure 2-1 Id shows that A. elongata is one of the few gastropods in this study with a mean pH less than neutral (7.0). This mean is significantly lower than that for Physa skinneri (p=0.01S) and the ranges of the two species do not overlap. This suggests that these two species may be separated ecologically by the pH of a habitat. However, the sample sizes for both of these species is small (n = 3 and n = 4) and these values may not give an adequate representation of the true ranges of tolerance for pH of these taxa. The results of the CCA are that the Physidae taxa are responding significantly to the environmental variables (p = 0.005) with 23.6% of the species presence accounted for (Figure 2-17). The plot shows A. elongata to be correlated to below average dissolved oxygen and pH. However, the small sample size (n = 3) would have prohibited development of a strong unimodal response to a particular variable so this correspondence may not be relevant to the ecology of this taxa. Clarice (1981) gives the distribution ofW. elongata as throu^out northem BC. This study did not find such a widespread distribution but Burch (1989) describes the distribution to include Alaska and Washington states which implies the distribution may include much of the study area. This potentially widespread distribution gives no indication of any barriers encountered during post-glacial dispersion. Clarice (1981) describes ofX. elongata as occurring principally in vernal habitats. The ecological sites in study were surveyed primarily during August when many vernal habitats may not have been conspicuous and, during this time, A. elongata was collected only firom perennial-type habitats (lakes and ponds). The collections made at the non-ecological sites were made earlier in the season and were made fimm vernal habitats (marshes and flooded areas). *Note: Referred to as Aplexa hypnorum by Clarke (1973b, 1981). A. hypnorum is now recognized as being a distinct Eurasian species ^urch 1989). 149 WMM/ • — ■ Physajauiessi PhysaJennessi* D ali, 1919 Obtuse physa Physajennessi SU ES (1): CNI005 DRAINAGE/WATERSHED ARCTIC; Liard: Dease 3 ECOPROVINCE/ECOREGION Northern Boreal Mountains: Boreal Moumains and Plateaus BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce Figure A-17 - Collection sites for Physajennessi. Previously recorded distribution in northern BC: Not previously recorded (Clarice 1981). Discussion: Physa Jennessi from northem BC is represented by one collection held at the Canadian Museum of Nature. Clarice (1981) reports the distribution of P. jennessi jennesi (see *Note below) as the Arctic region of Canada although he made this collection at Dease Lake in 1972. Burch (1989) gives the distribution of P. jennessi as Alaska, Northwest Territories and BC. Further survey woric is required to further define the actual distribution of this species in BC. *Note: Referred to as Physa jennessi jennessi by Clarice (1973b, 1981) and as Physa jennessi by Burch (1989) and by Turgeon et ai. (1998). 150 Family Physidae Physa dàm eri Physa skinneri* T a y lo r, 1954 Glass physa Pfiysa «Mnnarf SITES (7): NIOIO, N1014, N1051, N1068 N0127, MNlOOO.MNlOll DRAINAGE/WATERSHED PACmC; Yukon: Atlin (1) ARCTIC: Liard: Dease (2), Liard (1); Peace: Kiskatinaw (1), Pine (1), Smoky (1) ECOPROVINCE/ECOREGION Boreal Plains: Southern Alberta Uplands (3) Northern Boreal Mountains: Liard Basin (1), Boreal Mountains and Plateaus (3) BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (7) Figure A-18 - Collection sites for Physa skinneri. Environmental Information: Measurement Count Mean Maximum Std. Error Minimum Temperature (T ) 4 1.04 13.80 15.70 18.50 4 45.00 Dissolved 0%(% Saturation) 69.75 9.83 87.00 4 Conductivity (pSiemens) 78.76 193.00 327.25 550.00 4 11.74 Calcium (mg/litre) 47.46 27.44 80.67 pH 4 7.99 0.12 7.70 8.30 Previously recorded distribution in northern BC: Recorded from far eastern area (Clarke 1981). Discussion: PiQfsa skinneri is an uncommon mollusc in northem BC being found at seven of 176 sites. It was found in both the Pacific and Atlantic drainages and in the boreal-type ecoprovinces. The BGC zone in which it was found has a mean annual temperature of-2.9 to 2.0^ with up to 7 months below 0°C and up to 4 months above 10°C with annual precipitation ranging from 330 to 570 mm. The range and means of the environmental variables for the sites where P. skinneri was collected are shown in Figure 2-11. Temperature: Figure 2-1 la shows that Physa skinneri was collected only in habitats of relatively low temperature. However, Taylor (1988) indicates that P. skinneri occurs frequently throu^out western North America, as 6 r south as Colorado, and so it seems unlikely that temperature would be a limiting factor in the distribution of this species. 151 Family Physidae Physa sUnneri Dissolved Oxvyen: Figure 2-1 Ib shows that P. skinneri was not found in habitats where the dissolved oxygen was as low as it was for most other physids in this study. However, as physids generally maintain a dependence on atmospheric air, it is not expected that their distributions may be limited by the amount of dissolved oxygen in a habitat. Conductivitv and Calcium Concentration: Figure 2-1 Ic shows that P. skinneri was only found in habitats of relatively high conductivity/calcium concentration with a minimum of about 27.4 mg calcium/1 recorded. Although the sample size is small (n=4) and may not allow representation its full range of tolerance, it may be that P. skinneri is a calciphilic gastropod, restricted to habitats with high levels of calcium as defined by Russell-Hunter (1978). p H: Figure 2-1 Id shows that P. skinneri is one of the few gastropods in this study to be collected only in alkaline conditions. The mean pH of P. skinneri is significantly higher than that for A. elongata (p=0.015) and the ranges of the two species do not overlap. This suggests that these two species may be separated ecologically by the pH of a habitat. However, the sample sizes for both of these species is small (n = 3 and n = 4) and these values may not accurately represent their true ranges of tolerance to pH. The results of the CCA are that the Physidae taxa are responding significantly to the environmental variables (p = 0.005) with 23.6% of the species presence accounted for (Figure 2-17). The CCA plot of the environmental variables shows P. skinneri not to be correlated with any paiticular environmental variable, which may be due to its small sample size. Clarice (1981) indicates that P. skinneri occurs in northern BC only in the far eastern area. This study found a more widespread distribution, with P. skinneri also being collected firom the northwest of the study area. Taylor (1988) describes the distribution of P. skinneri as Alaska southeast to Ontario and Michigan; south in the western United States to eastern Washington, Nevada, southern Colorado, and northem Nebraska, and Burch (1989) describes the distribution as Canada firom (Quebec to BC; south to Washington, Montana, Wyoming, Nebraska, Iowa, Ohio, Pennsylvania and New England. Thus, the distribution of P. skinneri seems to be much broader than that recognized by Clarice (1981), which concurs with the findings of this study. As P. skinneri is also known firom the USSR (Taylor 1988), it may be that P. skinneri moved into BC from both the Mississippi and Bering réfugia. In this study, and in those cited above, P. skinneri does not appear to be associated with the Pacific coast. Clarice (1981) describes the habitat of P. skinneri as lakes, ponds, marshes, and slow-moving streams, and Taylor (1988) as ponds and marshes or small streams near such situations. While P. skinneri was never found in a stream during this study, it was found in lakes, ponds and marshes. *Note: Referred to as Physajennessi skinneri by Clarice (1973b, 1981) and as Physa skinneri by Taylor (1988), Burch (1989) and Turgeon et ai. (1998). 152 Family Physidae Physella spp. Physella sp p . SITES (69): N1000,N1001^1002,N1003J^1004, N1005,N1011,N1014,N1015,N1016,N1017,N1019, Nl020,Nl02l,Ni026,N1030,Nl033,N1036,N1037, N1040,N1043,N1046,N1048J41049JJ1052,N1054, N1055J^1057,N1058a^l059^1060J41070,N108l, N1G84,N1091,N1092J^1093JJ1097,N1098,NIIOO, N1101,Ni 102.N1103.N1104.N1105.N1106.N1107, NI 110.N1111,N1112,N0100,N0105,N0107,N0110, NOl 12.N0113.N0114JJ0115.N0116,N0120,N0125, N0132,N0133,CNI01 l,CN1015,MN1004JdN1005, MN1008.MN1010 DRAINAGE/WATERSHED PACIFIC: Fraser: Fraser (8),Necfaako (12),Stuart (4); Nasi: Nass (1); Skeena: Babine(l), Bulkley(3), Lakelse(l),Skeeiia(l); Stildne: Stildne (1) ARCTIC: Liard: Dease (3)Jo rt Nelson (8),Liard (7), Toad(l); Peace: Beanon(3)JCiskatinaw(2),Peace(l2), Pined) ECOPROVINCE/ECOREGION Boreal Plains: Peace River Basin (2), Central Figure A-19 - Collection sites for Physella spp. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (30) Coastal Western Hemlock (1) Engelmann Spruce - Subalpine Fir (1) Interior Cedar - Hemlock (2) Sub-Boreal Spruce (35) Alberta Uplands (3), Southern Alberta Uplands (3) Central Interior: Fraser Plateau (11) Coast & Mountains: Coastal Gap(l),Nass Basin(l), Nass Ranges (1) Northem Boreal Mountains: Boreal Mountains & Plateaus (1), Northem Canadian Rocky Mountains (1), Liard Basin (10) Snb-Boreal Interior: Fraser Basin (24), Central Canadian Rocky Mountains (3) Taiga Plains: Hay River Lowland (2), Northern Alberta Uplands (2), Hay River Lowland (4) Environmental Information: Measurement Count Mean Maximum Std. Error Minimum 19.47 Temperature (”C) 50 0.50 12.10 26.50 Dissolved Oj (% Saturation) 7.00 50 70.33 3.58 135.00 Conductivity (pSiemens) 50 304.15 76.90 1568.00 39.36 Calcium (mgriitre) 50 44.01 5.87 10.13 323.45 7.47 50 0.10 5.60 9.25 pH Previously recorded distribution in northern BC: Throu^out northern BC (Clarice 1981) Discussion: The Pkyseiia spp. group has not been identified to species in this study as the anatomical expertise necessary to do so was not available. These physids are very common molluscs of northem BC being found at 69 of 176 sites. They were found in both the Pacific and Arctic drainages in all of the northem ecoprovinces. They were found in all but the Spmce-Willow-Birch BGC zone, which was one of the least represented BGC zones in this study. The range and means of the environmental variables measured at the sites where Physella spp. were collected are shown in Figure 2-11. 153 Family Physidae Physella spp. Temperature: Figure 2-1 la shows that the Physella spp. group was found at temperatures >2S°C suggesting that high temperature may not be a limiting factor in the distribution of this taxa. Dissolved Oxygen: Figure 2-1 lb shows that Physella spp. were found over a wide range of dissolved oxygen. However, as physids generally maintain a dependence on atmospheric air, it is not expected that their distributions may be limited by the amount of dissolved oxygen in a habitat. Conductivitv and Calcium Concentration: Although Physella spp. were common throughout the study area. Figure 2-1 Ic shows that they were not collected 6om the habitats of lowest conductivity measured in this study. This suggests that these physids may have a minimum calcium requirement that may restrict them to certain habitats within their range. pH: Figure 2-1 Id shows that Physella spp. were collected over a wide range of pH, in both acidic and alkaline conditions. This suggests that pH may not be a limiting factor for this taxon, however, the tolerances of the species that may be contained within this group is presently unknown. The results of the CCA are that the Physidae taxa are responding significantly to the environmental variables (p = 0.005) with 23.6% of the species presence accounted for (Figure 2-17). The CCA plot of the environmental variables shows Physella spp. to occur at the mean of all the measures and not to correlate to any particular variable. The Canadian Museum of Nature has approximately 79 lots of unidentified physids from BC in the accessed collections and approximately 45 lots in the backlog of non-accessed collections. At least five of these lots are known to be fiom northem BC. Meanwhile, while Clarke (1981) indicates that Physella gyrina should be a common species throughout northem BC, there are no voucher specimens to substantiate this statement. This study found Physella spp. throu ^u t northem BC but further identification is necessary to delimit the distributions of the species within this group. Physella species are known fiom almost all perennial and temporary habitats (Clarke 1981, Burch 1989), which concurs with the wide habitat range found for the Physella spp. group in this study. 154 Family Physidae Physella lordi Physella lordi (B a ird , 1863) Twisted physa Phyaemlordl SITES (2): CN1012,MN100l DRAINAGEAVATERSHED ARCTIC: Peace: Peace (I), Pine (1) ECOPROVINCE/ECOREGION Boreal Plaint: Southern Alberta Uplands (1) Sub-Boreal Interior: Fraser Basin (1) BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (1) Sub-Boreal Spruce (1) Figure A-20 - Collection sites for Physella iordi. Previously recorded distribution in northem BC: Peace River system (Clarke 1981). Discussion: Physella lordi from northem BC is represented by two collections held at the Canadian Museum of Nature. The Physella species collected during this study have not been identified to species and this group of collections may include additional records for Physella lordi. Clarice (1981) states that P. lordi is found fiom northem BC (Peace River system) south to the westem United States. 155 Family Physidae Physella propinqm Physella propinqua (T ry o n , 1865) Rocky Mountain physa PhystM pmpinqua SITES (2): CN1017.CNI021 DRAINAGEAVATERSHED PACIFIC; Fraser: Nechako (1); Skeena: Skeena (1) ECOPROVINCE/ECOREGION Coast & Mountains: Nass Ranges (1) Sub>Boreal Interior: Fraser Basin (1) BIOGEOCLIMATIC (BGC) ZONE Interior Coastal Hemlock (1) Sub-Boreal Spruce (1) l e i a w r wÉiawiiHBi waoaioaam Figure A-21 - Collection sites for Physella propinqua. Previously recorded distribution in northem BC: Central BC (Clarke 1981). Discussion: Physella propinqua from northem BC is represented by two collections held at the Canadian Museum of Nature. The Physella species collected during this study have not been identified to species and this group of collections may include additional records for Physella propinqua. Clarke (1981) states that P. propinqua occurs on Vancouver Island and throughout central and southern BC south to California. 156 Family Physidie PhyseUa virginea Physella virginea* (G o u ld , 1847) Sunset physa SITES (1): N1109/CN1023/MN1012 DRAINAGEAVATERSHED ARCTIC: Litrd: Liard ECOPROVINCE/ECOREGION Northern Boreal Mountains: Hyland Highland BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce Figure A-22 - Collection site for Physella virginea. Previously recorded distribution in northem BC: Not previously recorded. Discussion: Clarice (1981) states that Physella virginea is tentatively considered a synonym of P. lordi, and Taylor (1981) includes P. virginea in a list of synonyms of P. gyrina. However, Burch (1989) and Turgeon et al. (1998) recognize P. virpnea as a distinct species. Physella virginea fipom northern BC is represented by one collection held at the Canadian Museum of Nature. The Physella species collected during this study have not been identified to species and this group of collections may include additional records for Physella virginea. Burch (1989) list the distribution of this species as BC south to California. *Note: Specimens at the CMN are labded “type specimens” but it seems unlikely that the specimens described by Gould in 1847 were collected fiom this location. 157 Family Physidae Physella wrighti Physella wrighü T e a n d C la rk e , 1985 Hotwater physa Ptiysma wrigm SITES (1): N1108/CN1023 DRAINAGE/WATERSHED ARCTIC! Ltord; Liard ECOPROVINCE/ECOREGION Northern Boreal Mountains: Hyland Highland BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce Figure A-23 - Collection site for Physella wrighti. Environmental Information: Measurement Count Observed 36.50 Temperature CO 1 1 67.00 Dissolved O2 (% Saturation) Conductivity (pSiemens) 1 1155.00 170.90 Calcium (mg/litre) 1 pH 7.80 1 Previously recorded distribution in northern BC: Liard River Hotsprings Provincial Park (Te and Clarke 1985). Discussion: Physella wrighti was found at one site during this study. This is its type locality, a 34-m reach of Alpha Stream, which emerges from Alpha Pool in Liard River Hotsprings Provincial Paric. The climatic and environmental conditions are very different at this site than elsewhere in northern BC. Knvimnmental Variables: The environmental variables for the one site for P. wrighti are presented in Figure 2-11. This unique habitat has the hipest tenqperature recorded in this study (36.5°C) and the third highest conductivity (1155 pS). The temperature and conductivity for P. wrighti were found to be significantly higher than for any of the other physids in this study for which these measurements are available (Table 2-7). This reflects the very different habitat of P. wrighti as compared to other physids in this study. The dissolved oxygen and pH at which P. wrighti was found were within the range of most of the other physids species. 158 Family Physidae Physella wrighti The results of the CCA are that the Physidae taxa are responding significantly to the environmental variables (p = O.OOS) with 23.6% of the species presence accounted for (Figure 2-17). While there is an insufficient sample size of P. wrighti for the CCA analysis of the environmental variables to show a unimodal response, this species does appear on the plot associated with very high measures of temperature and conductivity which is in accordance with its ecology. P. wrighti is believed to be a relict species, having survived glaciation at its type locality. Prest (1976) states that stratigraphie evidence indicates that the Cordilleran and Keewatin ice sheets made contact in only a few places in the Liard Plateau and adjacent plains leaving the interval unglaciated. It is within this unglaciated area that Liard River Hotsprings is located. Te and Clarke (1985) believe that P. wrighti may have survived at its present locality for at least 100,000 years. A full review of the known habitat parameter and biology of P. wrighti is presented in Lee and Ackerman (1999b). Based on this report, this species has now been listed as “Endangered” by the Committee on the Status of Endangered Wildlife in Canada (1998). 159 Family Planoibidae Gyraubis cireumsfriaius Gyraulus circumstriatus (Tryon, 1866) Disc gyro m Qyrauhmekamstrietus ### Figure A-24 - Collection sites for Gyraulus circumstriatus. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (43) Coastal Westem Hemlock (2) Engelmann Spruce - Subalpine Fir (1) Interior Cedar - Hemlock (6) Sub-Boreal Spruce (18) SITES (70): N1000,N100l,N1002J41003, N1004,N1006J41007J^1008,N1009J^1010J^1012, N1014^1023,N1026,N1027JJ1030J41031,N1033, N1035,N1036Jil037,NI039,N1040^1041JJ1043, NI046,NI048J41050,NI051^1052J4i053,N1054, N1055;41056^1057,N1058,N1059,N1060^1061, N1062J41063,N1068^1069J41070,N1072J41073, N1074,N1077,N1078JJ1081,N1082,N1084,NI089, N1090.N1091,N1092,N1093,N1098,N110l,Nl 102, N1103,N1104 105J41109/CN1023J41110, NOl 13,N012I,N0126,CN1014,MN1000 DRAINAGE/WATERSHED FRASER: Coastal: North Coast (1); Fraser: Fraser (1), Nechako (4), Stuart (2); Nass: Meziadin (1), Nass (l);Skeena: Bulkley (4), Lakelse (1), Skeena (4); Stildne: Stildne (5) Yukon: Atlin(l) ARCTIC: Liard: Dease(7), FtNelson(8), Liaid(10),Toad(l): Maclùnzie: Hay (2) Peace: Halfway (1), Kiskatinaw (2), Parsnip (l)fe a c e (ll),P in e (2 ) ECOPROVINCE/ECOREGION Boreal Plains: Central Alberta Uplands (2), Peace River Basin(2), Southern Alberta Uplands (S) Central interior: Fraser Plateau (7) Coast & Mountains: Northem Coastal Mts.(l), Coasttl Gap (1), Nass Basin (3), Nass Ranges (3) Northern Boreal Mountains: Northern Canadian Rocky Mountains (1), Liard Basin (14), Hyland Highland (1), Boreal Mts. and Plateaus (8) Sub-Boreal Interior: Central Canadian Rocky Mts. (2), Omineca Mountains (2), Fraser Basin (8) Taiga Plains: Hay River Lowland (7), Northem Alberta Uplands (3) Environmental Information: Maximum Std. Error Minimum Measurement Count Mean 1.50 26.50 0.51 Temperature (T ) 65 19.16 8.00 99.00 2.80 65 66.20 Dissolved 0%(% Saturation) 47.40 1199.00 27.27 65 297.12 Conductivity (iiSiemens) 5.73 177.44 4.07 42.97 Calcium (m ^tre) 65 5.90 8.90 7.54 0.09 65 p H ................................ . Previously recorded distribution in northem BC: Absent firom far northwest (Clarice 1981). Discussion: Gyraulus circumstriatus was a very common mollusc in northem BC being found at 70 of 176 sites. It was found in both the Pacific and Arctic drainages, in all of the major watersheds, and in all of the ecoprovinces. Within the five BGC zones in which G. circumstriatus was collected, mean annual 160 Family Planoibidae Gyraulus circumstriaius temperatures range from -2.9°C to 10.5°C with up to 7 months below 0°C and up to 6 months above 10°C and with annual precipitation ranging from 330 to 4400 mm. The ranges and means for the environmental variables measured at the sites where G. circumstriatus was collected are shown in Figure 2-12. Temperature: Figure 2-12a shows that G. circumstriatus was found at tenqieratures >25°C suggesting that high temperature may not be a limiting factor in the distribution of this taxa. Dissolved Oxvgen: Figure 2-12b shows that G. circumstriatus was collected from habitats of very low oxygen saturation. This suggests that G. circumstriatus may be an oxygen-independent species and that the dissolved oxygen saturation of a habitat may not be a limiting factor in its distribution in northem BC. Conductivitv and Calcium Concentration: Figure 2-12c shows that G. circumstriatus, while collected from habitats of relatively low conductivity/calcium, was not collected at the sites of lowest conductivity in this study. Given the large sample size for this species, it may be that G. circumstriatus requires a minimum of -5.0 mg/1 calcium to successfully colonize a habitat. pH: Figure 2-l2d shows that while G. circumstriatus displays a wide range of tolerance to pH, and was found in both acidic and alkaline conditions, it was not found at as low pH as were some other planorbids in this study. As G. circumstriatus was a very common species at ecological sites (i^ 5 ), the findings here may be a good indication of its tolerance and it may not be able to tolerate pH levels lower than the minimum of 5.9 at which it was found. This may be linked to its putative minimum requirement for calcium as discussed above. The results of the CCA are that the Flanorbidae are responding significantly to the environmental variables (p = 0.005) with 8.8% of the species presence accounted for (Figure 2-18). The plot shows G. circumstriatus to correspond most closely with slightly h i^er than average conductivity. Given the wide range of conductivity/calcium over which G. circumstriatus was found, it does have a somewhat hiÿier mean for this variable than do many other planorbids. However, conductivity/calcium does not appear to be a particularly inqmrtant ecological factor for G. circumstriatus and its placement on the plot is close to the origin may be of limited ecological interpretability. Clarice (1981) indicates that G. circumstriatus is found in all but the &r northwest of northem BC. This study collected G. circumstriatus from thro u^u t the study area and found a record for this species in the &r northwest (MNKXX)) indicating that the range of G. circumstriatus is throughout all of northem BC. Clarice (1981) states that G. circumstriatus is characteristic of small vernal habitats, hi this study it was found in all types of habitats, both small and large, and both perennial and vernal. Clarice (1981) 161 Family Planoibidae Gyraubis circumsirianis includes another Gyraulus species, G. vermicularis, as occurring in northem BC in perennial habitats. His description of this species was not succinct enough to distinguish it from other Gyraulus species and G. vermicularis is not recognized by Burch (1989) or by Turgeon et al. (1998). Therefore, the more diverse habitat type found for G. circumstriatus in this study may be the result of G. vermicularis being included with G. circumstriatus when specimens from this study were identified. 162 Family Planoibidae Cyraulus crisla Gyraulus crista* (Linnaeus^ 1758) Star gyro SITES (4): N1023, N1054,N1101,N1104 DRAINAGEAVATERSHED PACIFIC; Fraser: Nechako (1), Stuart (1) ARCTIC: Liard: Liard (1), Peace: Peace (1) ECOPROVINCE/ECOREGION Boreal Plains: Peace River Basin (1) Central Interior: Fraser Plateau (1) Northern Boreal Mountains: Liard Basin (1) Sub-Boreal Interior: Fraser Basin (1) BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (2) Sub-Boreal Spruce (2) Figure A-2S - Collection sites for Gyraulus crista. Enviromncntal Information: Measurement Maximum Count Mean Std. Error Minimum Temperature CC) 4 24.00 2.61 12.20 19.60 Dissolved O2 (% Saturation) 4 17.30 19.00 93.00 48.25 Conductivity (pSiemens) 4 119.70 1199.00 477.18 247.45 Calcium (mg/litre) 4 177.44 69.81 36.90 16.51 4 0.27 7.56 6.85 8.15 pH Previously recorded distribution in northern BC: Not previously recorded (Clarice 1981). Discussion: Gyraulus crista was an uncommon mollusc in northern BC being found at four of 176 sites. It was found in both the Pacific and Arctic drainages and in four of the six northern ecoprovinces. The two BGC zones in which is was found have mean annual tenqperatures ranging from -2.9 to S.(PC with up to 7 months below (PC and up to 5 months above 10°C and with annua! precipitation ranging from 330 to 990 mm. The ranges and means for the environmental variables measured at the sites where G. crista was collected are shown in Figure 2-12. Temperature: Figure 2-12a shows that G. crista was found at relatively h i^ tenqieratures suggesting that tenqierature may not be a limiting frctor for the distribution of this species in northern BC. 163 rw u u y rw iM u n iw Gynuba crista Dissolved Oxygen: Figure 2-12b shows that G. crista was collected from habitats of low oxygen saturation. This suggests that G. crista may be an oxygen-independent species and that the dissolved oxygen saturation of a habitat may not be a limiting factor in its distribution in northern BC. Conductivity and Calcium Concentration: Figure 2-l2c shows that G. crista was not found in habitats of as low conductivity/calcium as were many other planorbids in this study (minimum 16.5 mg/1). However, the small sample size (n=4) for this species may not give true representation of the minimum calcium requirement for this species. pH: Figure 2-12d shows that G. crista was found at a relatively restricted range of pH as compared to other species of planorbids and was usually collected from alkaline conditions. The pH, being related to the calcium concentration of a habitat, may be a factor restricting the distribution of G. crista. However, the small sample size (n=4) many not give an accurate representation of the entire range tolerable by this species. The results of the CCA are that the Planorbidae are responding significantly to the environmental variables (p = 0.005) with 8.8% of the species presence accounted for (Figure 2-18). The plot shows G. crista to correspond most closely with higher than average conductivity. Figure 2-12c shows that G. crista has the hipest mean conductivity of any taxa in this family but it is probably the minimum calcium requirement that is important to most taxa and the small sample size for G. crista (n=4) limits the interpretabUity of placement on the plot. Clarite (1981) does not include northern BC within the range of this species althou^ his inclusion of a site in the NV/T indicates that the range is probably more widespread than was known at that time, hi this study, G. crista was collected from sites scattered throughout the study area including sites east of the Rocky Mountains in BC and in the Pacific drainage, greatly increasing the recorded distribution for this species. Clarice (1981) states that this species lives among dense vegetation in eutrophic ponds and slow moving streams, hi this study, G. crista^ which is very small, was only found in careful examination of the bottom of rocks or submerged wood and was never collected from sweepings of vegetation. Thus, the habitat range rqipears to be more diverse than that indicated by Clarice. *Note: Referred to by Clarice (1973b, 1981) as Anniger crista. 164 ranuiy rianwuwmc Gyraubts d^ectus Gyraulus deflectus (Say, 1824) Flexed gyro Qymulua ddhetua SITES (33): N1001,N1004J^1005J41006J41014J<1015,N1026, N1032J41033,N1034,N1037,N1038,N1042,N1056, N1092J41093,N1096J41097,N1098,N1100,N l 101, N1104,N1106,N1107,N1110,N1112, N0104,N0114, NOl 15J40116,N0122 MN1008,MN1011 DRAINAGE/WATERSHED PACIFIC; Fraser: Fraser (3), Nechako (7), Stuart (3); Skecna: Sabine (2), Bulkley (3) ARCTIC: Liard: Dease (1), Fort Nelson (5), Liard (1); Mackenzie: Hay (1); Peace: Kiskatinaw(l), Peace (6) ECOPROVINCE/ECOREGION Boreal Plains: Central Alberta Uplands (1), Figure A-26 - Collection sites for Gyraulus deflectus. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (12) Sub-Boreal Spruce (21) Southern Alberta Uplands (2) Central Interior: Fraser Plateau (8) Northern Boreal Monntains: Boreal Mountains and Plateaus (1), Liard Basin (1) Suh^Boreal Interior: Central Canadian Rocky Mountains (1), Omineca Mountains (1) Sub-Boreal Interior : Fraser Basin (12) Taiga Plains: Northern Alberta Uplands (1), Hay River Lowland (S) Environmental Information: Std. Error Minimum Maximum Meaiuremcnt Count Mean 0.77 12.20 27.20 20.25 Temperature CC) 26 4.00 23.00 98.00 70.31 Dissolved 0%(% Saturation) 26 42.44 216.80 76.90 1199.00 Conductivity (pSiemens) 26 5.70 8.92 159.73 Calcium (mg/litre) 27.73 26 7.34 0.15 5.60 8.75 26 pH Previously recorded distribution in northern BC: Throughout northern BC (Clarice 1981). Discussion: Gyraulus deflectus was a common mollusc in northern BC being found at 33 of 176 sites. It was found in both the Pacific and Arctic drainages and in all of the northern ecoprovinces. It occurred in only two BGC zones, these zones being those containing most of the sites in this study. These two BGC zones have mean annual temperatures ranging fiom -2.9 to S.lfC with up to 7 months below O^C and up to 5 months above 10°C and with annual precipitation ranging fiom 330 to 990 mm. The range and mean for the environmental variables measured at the sites where G. deflectus was collected are shown in Figure 2-12. 165 rinuiy riu o n n o K Gyraulus deflectus Temperature: Figure 2-12a shows that G. deflectus was collected at temperatures >2S°C suggesting that temperature may not be a limiting factor for the distribution of this species in northern BC. Dissolved Oxveen: Figure 2-12b shows that G. deflectus was collected from habitats of relatively low levels of oxygen saturation. This suggests that G. deflectus may be an oxygen independent species that the dissolved oxygen saniration of a habitat may not be a limiting Actor in its distribution in northern BC. Conductivity and Calcium: Figure 2-12c shows that G. deflectus, while collected from habitats of relatively low conductivity/calcium, was not collected at the sites of lowest conductivity in this study. Given the relatively large sample size for this species, it may be that G. deflectus requires a minimum of ~10.0 mg/1 calcium to successfully colonize a habitat. pH: Figure 2-12d shows that G. d^ectus displays a wide range of tolerance to pH being found in both acid and alkaline conditions. This suggests that pH may not be a limiting factor in the distribution of this species within northern BC. The results of the CCA are that the Planorbidae are responding significantly to the environmental variables (p = 0.005) with 8.8% of the species presence accounted for (Figure 2-18). The plot shows G. deflectus to correspond to slightly lower than average values of pH. Figure 2-12d does not indicate that pH is a significant variable for this species and its placement on the plot, so near the origin yet sUghtly offset to pH, may be of limited ecological consequence. Clarke (1981) indicates the distribution range of G. d^ectus to include all of northern BC. This concurs with the findings of this study wherein G. deflectus was found to have a widespread distribution. This widespread distribution gives no evidence of any barriers inqwsed during post-glacial dispersioiL Clarke (1981) states that G. deflectus occurs in all kinds of permanent-water, eutrophic habitats, ha this study, G. deflectus was collected from those types of habitats being found in the vegetated portions of lakes, ponds, swançs and the slow moving areas of streams. 166 Family Planoibidae Gyrauluspanus Gyraulus parvus (Spy, 1817) Ash gyro Qyrmjim p K w s # SITES (28): N l008,N1009,Nl0l0,Nl0ll^l0l2,N 1034j;i044, N1049,N1051.N1053,N1059,N1061,N1062J^1069, N1074^l076,N1097J^l 110,N1111,N1112.N0102, N0103^0105,N0106J40l 11 I8>IN1000 DRAINAGEAVATERSHED PACIFIC; Fraser: Fraser (3), Nechako (2), Stuart (3); Nass: Bell Irving (1); Skeena: Sabine (1); StUdae: Stildne (2); Yukon: Atlin (I) ARCTIC: Liard: Dease (3), Fort Nelson (2), Liard (3); Peace: Parsnip (1), Peace (3), Pine (3) ECOPROVINCE/ECOREGION Boreal Plains: Peace River Basin (1), Southern Alberta Uplands (2) Northern Boreal Mountains: Northern Canadian Figure A-27 - Collection sites for Gyraulus parvus. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (14) Engebnann Spruce - Subalpine Fir (2) Interior Cedar >Hemlock (1) Spruce - Willow - Birch (1) Sub-Boreal Spruce (10) Rocky Mouiuains (1), Boreal Mountains and Plateaus (3), Liard Basin (6) Sob-Boreal Interior: Skeena Mountains (I), Central Canadian Rocky Mountains (4), Fraser Basin (9) Taiga Plains: Hay River Lowland (1) Environmental Information: Measurement Maximum Count Menu Std. Error Minimum Temperature CC) 20 12.10 2720 18.08 1.00 Dissolved O2 (% Saturation) 20 98.00 7328 44.00 3.62 Conductivity (uSiemens) 20 550.00 262.82 89.30 26.15 Calcium (m^itre) 80.67 20 37.85 11.98 3.90 7.67 8.55 20 0.17 5.60 pH Previously recorded distribution in northern BC: Throughout northern BC (Clarke 1981). Discussion: Gyraulus parvus was a common mollusc in northern BC being found at 28 of 176 sites. It was found in both the Pacific and Arctic drainages and in four of the six ecoprovinces. The four BGC zones in which it was collected have mean annual tençeratures ranging fiom -3.0 to 8.7°C with up to 7 months below OPCand up to 5 month above lO^C and with armual precipitation ranging fiom 330 to 2200 mm. The range and mean for the environmental variables measured at the sites where G. parvus was collected are shown in Figure 2-12. 167 Family Flinonndae GyrauUiSparvus Temperature: Figure 2-12a shows that G. parvus was found at tenq>eratures >2S°C suggesting that high temperature may not be a limiting factor in the distribution of this taxa. Dissolved Oxygen: Figure 2-12b shows that the minimum oxygen saturation at which G. parvus was collected is higher than for many of the other planorbids in this study, and higher than for any other Gyraulus species. This may indicate that G. parvus, unlike the other Gyraulus species, is oxygen* dependent. This hypoxia intolerance may be a limiting factor in the distribution of G. parvus in northern BC. Conductivity and Calcium: Figure 2*12c shows that G. parvus was collected down to a minimum of 12.0 mg/1 calcium concentration. It may be that G. parvus requires this minimum level in order to successfully occupy a habitat and that this may limit its distribution in northern BC. pH: Figure 2-12d shows that G. parvus displays a wide range of tolerance to pH being found in both acid and alkaline conditions. This suggests that pH may not be limiting factor in distribution of this species within northern BC. The results of the CCA are that the Planorbidae are responding significantly to the environmental variables (p = 0.005) with 8.8% of the species presence accounted for (Figure 2-18). The plot shows G. parvus to correspond to lower than average tenqrerature and higher than average pH. The above information extrapolated from the range plots does not indicate that either of these factors is of particular ecological inqrortance to this species. Clarke (1981) indicates that G. parvus is found throughout northern BC. This is in accordance with the findings of this study where G. parvus was found throughout the study area. This widespread distribution gives no evidence of any barriers irrqwsed during post-glacial dispersion. Clarice (1981) states that G. parvus lives in all kinds of permanent or temporary water-filled habitats that support vegetation. This is consistent with the findings of this study where G. parvus was found in many different types of vegetated habitats. 168 Family Planoibkbe Gyraulus vermieularis Gyraulus vermieularis (Gould, 1847) Pacific coast gyraulus* Gynuus vemiieularia )sP ^ SITES (10): CN1000,CN1001,CN1004,CN1005,CN1008,CN1 009,CN1010,CN1024>IN1005>fNl007 DRAINAGE/WATERSHED PACIFIC: Fraser: Nechako (1), Stuart (2); Stildne: Iskut(l) ARCTIC; Liard: Kechika (2), Dease (3); Peace: Finlay (I) ECOPROVINCE/ECOREGION Central Interior: Fraser Plateau (I) Northern Boreal Mountains: Northern Canadian Rocky Mountains (1), Boreal Mts. and Plateaus (6) Sub-Boreal Interior: Fraser Basin (1), Omineca Mountains (1) Figure A-28 - Collection sites for Gyraulus vermieularis. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (S) Spruce - Willow - Birch (2) Sub-Boreal Spruce (3) Previously recorded distribution in northern BC: hi Pacific drainage (Clarke 1981). Discussion: Gyraulus vermieularis was not recognized as being a distinct species for this study. Clarke’s (1981) description of this species was not succinct enough to distinguish it from other Gyraulus species and G. vermieularis is not recognized by Burch (1989) or by Turgeon et al. (1998). Clarke describes G. vermieularis as occurring in perennial habitats and G. cireumstriatus as occurring in small vernal habitats. The species identified as G. cireumstriatus in this study was found in all types of habitats, both small and large, and both perennial and vernal. Therefore, the more diverse habitat type found for G. cireumstriatus in this study may be the result of the species identified by Clarice as G. vermieularis, being included with G. cireumstriatus. Clarice (1981) also characterized G. vermieularis as being found only in the Pacific drainage but the results of his own collections show that he collected G. vermieularis from both the Pacific and Arctic drainages. This further puts in to question the validity of G. vermieularis as a distinct species restricted to the Pacific Coast. *Note: The common name comes from Clarke (1981). 169 ramiiy rianoretate Menetus opercufaris Menetus opercularis* (Gould, 1847) Button sprite Marwftiscywrcudtrfs SITES (10): N1080,N1081,N1084J«I1085,N1088,N1092,N1096, N1100J^1102,N1104 DRAINAGEAVATERSHED PACIFIC: Coastal: North Coast (I); Fraser: Nechako (2), Stuart (1); Nass: Meziadin (I), Nass(l) Skecna: Babine(l)3ulkley(l),Lakelse(l),Skeena(l) ECOPROVINCE/ECOREGION Central Interior: Fraser Plateau (3) Coast & Mountains: Nass Ranges (I), Coastal Gap (2), Nass Basin (2) Sub-Boreal Interior: Fraser Basin (2) BIOGEOCLIMATIC (BGC) ZONE Coastal Western Hemlock (3) Interior Cedar - Hemlock (2) Sub-Boreal Spruce (5) Figure A-29 - Collection sites for Menetus opercularis. Environmental Information: Measurement Count Mean Std. Error Minimum Maximum Temperature (T ) 10 19.42 0.66 16.70 22.90 Dissolved 0%(% Saturation) 10 4.88 44.00 93.00 80.70 Conductivity (pSiemens) 10 103.28 15.20 20.10 163.40 Calcium (m ^tre) 10 14.06 in 1.66 23.03 9 7.14 0.36 5.25 8.25 pH Previously recorded distribution in northern BC: Known only firomPacific coast (Clarke 1981). Discussion: Menetus opercularis was an uncommon mollusc in noithem BC being found at 10 of 176 sites. It was found only in the Pacific drainage in the three southwestern ecoprovinces. The three BGC zones in which it was found have mean annual temperatures ranging from 1.7 to 10.S°C with tq> to 5 months below (fC and up to 6 months above 10^ and with mean «imiMl precipitation ranging from 440 to 4400 mm. The range and means of the environmental variables at the sites where M. opercularis was collected are shown in Figure 2-12. Temperature: Figure 2-12a shows that M. opercularis was not collected at temperatures as hiÿi as were other members of this &mily. hi this study, M. opercularis was only collected from large, permanent water-habitats where the tenqierature are often more stable than in smaller habitats. These data are not sufficient evidence to suppose that M. opercularis is restricted to these habitats due to intolerance of high temperature. Other fiætors, such as h i^ oxygen requirement, may restrict it to stable habitats. 170 r«iiu>7 riAuuiuMMw Menetus opercularis Dissolved Oxygen: Figure 2>I2b shows that M. opercularis was not collected in habitats where the dissolved oxygen was as low as for other species in this family. This suggests that M opercularis may be oxygen-dependent. This hypoxia intolerance may be a factor that limits the distribution of M opercularis in northern BC. Conductivity and Calcium: Figure 2-12c shows that M. opercularis was found at the lowest conductivity levels measured in this study. This suggests that the level of calcium concentration in a habitat may not be a 6ctor limiting the distribution of M. opercularis in northern BC. The limited range of conductivity/calcium over which it was found may be inherent to the perennial water habitats that may be required to supply necessary oxygen. pH: Figure 2-12d shows that M. opercularis was collected over a wide range of pH and in both acidic and basic conditions, down to the lowest pH measured in this study. This suggests that pH may not be a limiting factor in the distribution of this species in northern BC. The results of the CCA are that the Planorbidae are responding significantly to the environmental variables (p = 0.005) with 8.8% of the species presence accounted for (Figure 2-18). The plot shows M. opercularis to correlate to higher than average dissolved oxygen and lower than average conductivity. This is in accordance with the information derived fiom the range plots in Figure 2-12, as discussed above, and acts to verify that these environmental variables may be important factors in the ecology of this species. Clarice (1981) indicates that M opercularis is found in northern BC in areas very near the coast. In this study M opercularis was found farther east than previously recorded but was still found only in the Pacific drainage. Clarice (1981) also records this species fiom two locations in Alberta and includes photographs of an Alaskan specimen, and Burch (1989) records the distribution of M. opercularis as Alaska south to Alberta and southern California. However, evidence fiom this study combined with Clarke’s (1981) information, suggests that M. opercularis is probably a migrant fiom the Pacific refuge. Clarke (1981) states Af. opercularis is found among submersed vegetation in perennial-water lakes, ponds and slow-moving portions of rivers and streams, hi this study, M. opercularis was found in similar habitats. *Note: Referred to by Clarice (1981) as Menetus cooperi. 171 Family Planoibidae Promenems exaaïaus eiacuous Promenetus exacuous exacuous* (Say, 1821) Sharp sprite # r i# SITES (37): N1002JJ1004^1005^1006,N1007, N1009,N1015,N1021^1033J41034J^1043.N1046, Nl053J^1055,^1060,Nl082,Nl09i;41092.N1093, N1096.N1097.N1100,N1102,N1103,Nl 104,N1105, Nl i07,N 1112,N0103,N0104,N0113,N0115,N0116, N0121,N0130,CN1000,CN1001 DRAINAGEAVATERSHED PACIFIC: Fraser: Fraser (2), Nechako (6), Stuart (6);Skeciia: Babine (2), Bulkley (3), Skeena (2) ARCTIC: Limrd: Dease(l), Fort Nelson(3),Liard(2), To#d(l); Peace: Beatton (1), Peace (7), Fine (1) ECOPROVINCE/ECOREGION Boreal Plaint: Southern Alberta Uplands (1), Peace River Basin (3) . . _ Central Interior; Fraser Plateau (7) Figure A-30 - Collecüon sites for Promenetus exacuous & Mountains: Nass Basin(l),Nass Ranges(l) Northern Boreal Mountains: Northern Canadian BIOGEOCLIMATIC (BGC) ZONE Rocky Mountains (1), Liard Basin (3) Boreal White and Black Spruce (11) Sab>Boreal Interior: Fraser Basin (14), Omineca Interior C edar-H em lock (2) Sub-Boreal Spruce (24) Mountains (3) Taiga Plains: Hay River Lowland (3) Environmental Information: Count Mean Measurement Std. Error Minimum Maximum 28 Temperature (T ) 19.59 0.69 13.40 27.20 28 Dissolved 0%(% Saturation) 74.18 4.76 8.00 135.00 Conductivity (pSiemens) 28 218.25 76.90 26.51 735.00 Calcium (m^itre) 28 31.21 3.95 10.13 108.25 28 0.14 7.44 5.60 8.75 pH Previously recorded distribution in northern BC: Only in eastern area (Clarke 1981). Discussion: Promenetus exacuous exacuous was a common mollusc in northern BC being found at 37 of 176 sites. It was found in both the Pacific and Arctic drainages in all of the ecoprovinces. The three BGC zones in which it was found have mean annual temperatures ranging from -2.0 to 8.7°C with up to 7 months below 0°C and up to S months above 10°C and with annual precipitation ranging from 330 to 1200 mm. The range and means of the environmental variables measured at the sites where P. exacuous exacuous was measured are shown in Figure 2-12. 172 Family Planoibidae Promenetus exacuous exacuous Température: Figure 2-12a shows that P. exacuous exacuous was found at temperatures >2S°C suggesting that high temperature may not be a limiting factor in the distribution of this taxa. Dissolved Oxygen: Figure 2-12b shows that P. exacuous exacuous was found at the widest range of dissolved oxygen, and at the lowest levels measured for members of this family. This suggests P. exacuous exacuous may be oxygen-independent and that dissolved oxygen saturation of a habitat may not a limiting factor in its distribution. Conductivity: Figure 2-12c shows that P. exacuous exacuous was found at a minimum level of calcium of 10.1 mg/l. This may indicate the minimum required level for P. exacuous exacuous to occupy a habitat which may limit its distribution in northern BC. pH: Figure 2-12d shows that P. exacuous exacuous was collected with habitats with a broad range of pH, spanning both acidic and alkaline conditions. This suggests that the pH of a habitat may not be a limiting factor in the distribution of this species in northern BC. The results of the CCA are that the Planorbidae are responding significantly to the environmental variables (p - 0.005) with 8.8% of the species presence accounted for (Figure 2-18). The plot shows that P. exacuous exacuous occurs near the origin of all of the environmental variables and so it is not responding strongly to any single variable. Claike (1981) indicates that the distribution of P. exacuous exacuous includes the far east and northeast of northern BC. Burch (1989) states that this species occurs in the US only east of the Rocky Mountains. This study found P. exacuous exacuous widely distributed throu^out much of the study area, and to be common west of the Rocky Mountain. This greatly expands the previously recorded distribution for this species. Clarice (1981) states that P. exacuous exacuous is a common species found in all types of habitats. In this study, P. exacuous exacuous was collected fiom rivers, streams, lakes, ponds and vernal habitats which concurs with Clarice's findings. *Note: Clarke (1973b, 1981) uses the subspecies P. exacuous exacuous and P. exacuous megas to differentiate different groups found in Canada. These subspecies are not recognized by Burch (1989) or Turgeon et al. (1W8), which refer only to P. exacuous. 173 Family Planoibidae Planorbula armigera Planorbula armigera (S ay, 1821) Thicklip rams’hora Ptanortuâaamigam SITES (2): N1033.N0132 DRAINAGEAVATERSHED ARCTIC; Liard: Fort Nelson (2) ECOPROVINCE/ECOREGION Taïga Plains: Hay River Lowland (2) BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (2) s. Figure A 31 - Collection sites for Planorbula armigera. Environmental Information: Measurement Count Observed Temperature (°C) 1 26.20 1 Dissolved 0%(% Saturation) 66.00 Conductivity (pSiemens) 1 183.80 Calcium (mg/litre) 1 26.10 1 7.15 pH Previously recorded distribution in northern BC: Only recorded from northeast (Clarke 1981). Discussion: Planorbula armigera was an uncommon nuUusc in northern BC being collected from two of 176 sites. These sites were very close together in the northeast of the study area. It was found only in the Arctic drainage in the Taiga Plains ecoprovince. The BGC in which it was found has a mean annual temperature of -2.9 to 2.0°C with iq* to 7 months below (PC and up to 4 months above 10°C and with annual precipitation ranging fiom 330 to 570 mm. P. armigera was collected fiom only one ecological site. The measurements recorded at this site are shown on Figure 2-12 with a dot. Environmental Variables: Figure 2-12a shows that the tenqierature measured at the one ecological site for P. armigera is quite h i^ (26.2°C) suggesting that it may not be h i^ temperature that limits the distribution of P. armigera in northern BC. Figure 2-12b,c,d shows that the dissolved oxygen, conductivity/calcium concentration and pH measures at this one site were all within the range those of 174 rim iiy riuoiD iaw Planorbula anrn^jera most other planoihids found in this study. This single observation does not supply sufficient information to hypothesize as to the environmental factors that may affect the distribution of P. armigera in northern BC. The results of the CCA are that the Planorbidae are responding significantly to the environmental variables (p - 0.005) with 8.8% of the species presence accounted for (Figure 2-18). The measurements fiom the single site for P. armigera does not allow development of a unimodal response to any variable and P. armigera appears on the plot associated with higher than average temperature. This is in accordance with the findings fiom Figure 2-12 that shows that the most distinctive measurement for this species taken at the single site was that of the high temperature. Clarke (1981) indicates that the distribution of P. armigera includes the far northeast of the study area. This concurs with the findings of this study where P. armigera was collected only fiom sites in the northeast. This distribution, along with the further distribution shown by Clarke (1981), indicates that P. armigera may have had its migration fiom the Mississippi refuge halted by the geographic barrier of the Rocky Mountains. Clarke (1981) states that P. armigera lives among vegetation in perennial-water habitats especially stagnant, heavily-vegetated water bodies, and Clarke (1979a) states that it is indicative of eutrophic lakes. In this study, P. armigera was collected fiom vegetation ini a large lake where the water was not necessarily stagnant and fiom a Carex marsh in the same area where water conditions are unknown. 175 Family Planoibidae Planorbula eampestris Planorbula eampestris (Dawson^ 1875) Meadow rams-hom Planortuila eampestris SITES (5): N1023, N1096, N1097, Nl 105, N0133 DRAINAGE/WATERSHED PACIFIC; Fraser: Stuart(l); Skeena: Babine<2) ARCTIC: Liard: FtNelson(l); Peace: Peace (1) ECOPROVINCE/ECOREGION Boreal Plains : Peace River Basin (1) Sub-Boreal Interior: Fraser Basin (3) Taiga Plains: Hay River Lowland (1) / ’* BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (2) Sub-Boreal Spruce (3) Figure A-32 - Collection sites for Planorbula eampestris. Environmental information: Measunmcnt Count Mean Std. Error Minimum Maximum Temperature (T ) 4 18.58 24.00 1.82 16.20 Dissolved Oj (% Saturation) 4 58.00 90.00 16.28 19.00 Conductivity (pSiemens) 4 173.00 73.81 90.30 394.00 Calcium (mg/litre) 4 24.46 11.00 57.41 12.13 4 6.79 pH 0.52 5.60 7.75 Previously recorded distribution in northern BC: Only from extreme east of BC (Clarice 1981). Discussion: Planorbula canqtestris was an uncommon mollusc in northern BC being collected from five of 176 sites. It was found in both the Pacific and Arctic drainages and in three of the six ecoprovinces. The two BGC zones in which it was found have mean annual temperatures ranging from -2.9 to 5.0”C with up to 7 months below (XC and up to 5 months above lOT and with annual precipitation ranging from 330 to 990 mm. The range and means of the environmental variables measured at the sites where P. eampestris was collected are shown in Figure 2-12. Temperature: Figure 2-12a shows that P. armigera was found at temperatures >25°C suggesting that high temperature may not be a limiting factor in the distribution of this taxa. 176 Family PUnofbidae Planorbula eampestris Dissolved Oxygen: Figure 2-12b shows that P. eampestris was collected from habitats with a wide range of dissolved oxygen, down to levels of <20% saturation. This suggests that this species may be oxygenindependent and may be able to occupy a wide range of habitats in northern BC. Conductivity and Calcium Concentration: Figure 2-12c shows that P. eampestris was collected from habitats with a minimum calcium concentration of 12.1 mg/l. While this may reflect a minimum requirement for this species, the sample size (n=4) may be insufficient to ensure that this range truly reflects the minimum calcium requirement for P. eampestris. pH: Figure 2-12d shows that P. eampestris is one of the few gastropods in this study with an acidic mean pH although it was found in both acidic and alkaline conditions. This mean is significantly different from that obtained for P. binneyi (Table 2-7) and the ranges for the two species do not overlap (Figure 2-12d). However, the sample sizes being compared (n = 4 and n=2) are too small to ascertain whether this represents an ecological difference between the species or if the ranges accurately represent to tolerances for either species. The results of the CCA are that the Planorbidae are responding significantly to the environmental variables (p = 0.005) with 8.8% of the species presence accounted for (Figure 2-18). The plot shows P. eampestris to correspond to lower than average conductivity. The range plot (Figure 2-12c) does not indicate that conductivity/calcium concentration is a particularly important Actor in the ecology of this species. Its placement here on the CCA plot may be due to its small sample size not enabling a strong unimodal response to any particular variable. Clarke (1981) indicates that the distribution of P. eampestris includes only the far eastern section of the northern BC. In this study, P. eampestris was collected from two locations in the far east as well as from two locations in the south central part of the study area thus extending the range further west than was previously recorded. As this qiecies is also known from Vancouver Island, the Yukon, and across central Canada (Clarke 1981), there is no clear indication that P. eampestris migrated out of any particular glacial refuge. Clarice (1981) states that P. eampestris is characteristic of vernal ponds, swamps, and springtime flooded portions of permanent water bodies, frt this study, P. eanqiestris was collected from vernal ponds but also from permanent ponds and lakes indicating its habitat may not be as restricted as previously recorded. 177 Family Planoibidae Helisoma anceps anceps Helisoma anceps anceps* (Menke, 1830) Two-ridge rams-hom SUES (9): N1001,NI003/CNIOI2,N1005,N1033^I084, N1107J41112JI0106,N0113 DRAINAGE/WATERSHED PACIFIC; Fraser: Ftaser (2), Nechako (I); Skecna: Lakelse (1) ARCTIC: Liard: FtNelson(I); Peace: Peace(4) ECOPROVINCE/ECOREGION Coast & Mountains: Coastal Gap (1) Sui>>Boreal Interior: Fraser Basin (7) Taiga Plains: Hay River Lowland (1) BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (1) Coastal Western Hemlock (1) Sub-Boreal Spruce (7) Figure A-33 - Collection sites for Helisoma anceps anceps. Environmental Information: Maximum Count Mean Std. Error Minimum Measurement 14.00 26.50 7 22.04 1.88 Temperature (°C) 90.00 44.00 7 5.68 Dissolved Oj (% Saturation) 72.43 200.00 120.10 7 10.00 Conductivity (pSiemens) 164.03 16.57 28.48 1.49 7 Calcium (m ^tre) 23.12 6.15 8.45 7 7.31 0.31 pH Previously recorded distribution in northern BC: Recorded only from far east (Clarice 1981). Discussion: Helisoma anceps anceps was an uncommon mollusc in northern BC being found at 9 of 176 sites. It was found in both the Pacific and Arctic drainages in three of the six northern ecoprovinces. The three BGC zones in which it was found have mean annual temperatures ranging from -2.9 to 10.S*C with up to 7 months below 0°C and up to 6 months above lOT and with annual precipitation ranging from 330 to 4400 mm. The range and means of the environmental variables measured at the sites where H. anceps anceps was collected are shown in Figure 2-12. Temperature: Figure 2-12a shows that H anceps anceps was found at tenqieratures >2S°Csuggesting that temperature may not limiting factor in the distribution of this qiecies in northern BC. 178 Family Planoibidae Helisoma anceps anceps Dissolved Oxveen: Figure 2-12b shows that H. anceps anceps was not collected in habitats where the dissolved oxygen was as low as for some other members of this family. This suggests that H. anceps anceps may be oxygen-dependent. This hypoxia intolerance may be a factor that limits the distribution of H. anceps anceps in northern BC. Conductivitv and Calcium Concentration: Figure 2-l2c shows that H. anceps anceps was collected at a minimum level of conductivity/calcium of 16.6 mg/l. It may be that H. anceps anceps is limited to habitats within noithem BC that can supply it with this minimum level of calcium. pH: Figure 2-12d shows that H. anceps anceps displays a relatively wide range of tolerance to pH being found in both acid and alkaline conditions. This suggests that pH may not be a limiting factor in the distribution of this species in northern BC. The results of the CCA are that the Planorbidae are responding significantly to the environmental variables (p = 0.005) with 8.8% of the species presence accounted for (Figure 2-18). The plot shows H. anceps anceps to correspond most closely to higher than average temperature and lower than average pH. These environmental variables, as discussed above, do not appear to be particular importance to the ecology of H. anceps anceps. Clarice (1981) indicates H. anceps anceps occurs only in the east and southeast of northern BC. While this is consistent with most of the collections made in this study, an additional collection was made in the southwest of the study area extending the distribution much further west than previously recorded. This type of distribution pattern gives no evidence of any barriers imposed during post-glacial distribution. Clarice (1981) states that H. anceps anceps lives in lakes, ponds, rivers and streams. In this study, it was found only in lakes. *Note: Clarice (1973b, 1981) and Burch (1989) both use the H. anceps anceps to separate this subspecies fiom other subspecies. Turgeon et al. (1998) does not list subspecies. 179 Family Plinoibidae Helisoma sp. Helisoma sp . Hatsomaap. SITES (1): CNlOll DRAINAGE/WATERSHED Peace: Peace ECOPROVINCE/ECOREGION Sub-Boreal Interior: Fraser Basin BIOGEOCLIMATIC (BGC) ZONE Sub-Boreal Spruce Figure A-34 - Collection site for Helisoma sp. Discussion: This record has been included here only to provide a comprehensive record of the species collected by Clarke during 1972 and 1973. While there is cunently only one species in the genus Helisoma recognized from northern BC, at the time of Clarice’s collections, both the species currently recognized as Planorbella binneyi and Planorbella subcrenatum were included in the genus Helisoma. Thus, this record only indicates that one of the larger planorbids was collected at this site, but does not give any information as to the species. 180 Family Planoibidae Planorbella binneyi Planorbella binneyi* (Tryon, 1867) Coarse rams-hom Pmnnmmw hinrmvt SITES (3); N1082,N1104,CN1017 DRAINAGE/WATERSHED PACIFIC: Fraser; Nechako (1), Stuart (1) Skeena: Skeena (i) ECOPROVINCE/ECOREGION Coast & Mountains: Nass Basin (1) Sub-Boreal Interior: Fraser Basin (2) BIOGEOCLIMATIC (BGC) ZONE Interior Cedar *Hemlock (1) Sub-Boreal Spruce (2) Figure A-3S - Collection sites for Planorbella binneyi Environmental Information: Maximum Measurement Std. Error Minimum Count Mean 19.80 22.20 Temperature (°C) 2 21.00 1.20 93.00 7.50 78.00 Dissolved 0%(% Saturation) 2 85.50 0.05 119.60 119.70 Conductivity (pSiemens) 2 119.65 0.01 16.50 16.51 Calcium (mg/litre) 2 16.50 0.20 8.55 2 8.35 8.15 PH Previously recorded distribution in northern BC: Far southeast only (Clarke 1981). Discussion: Planorbella binneyi was an uncommon mollusc in noithem BC being found at three of 176 sites. It was found only in the Pacific drainage in two of the six ecoprovinces. The two BGC zones in which it was found have mean annual temperatures ranging fiom 2.0 to i.TC with up to S months below 0 ^ and up to S months above lO T and with annual precipitation ranging fiom 440 to 1200 mm The range and means of the environmental variables measured at the two ecological sites where P. binneyi was collected are shown in Figure 2-12. Temperature: Figure 2-12a shows that P. binneyi was collected at a lower maximum tenqierature than were most species within this fiunily. However, the small sample size for this species may not give accurate representation of its range of tolerance. Dissolved Oxveen: Figure 2-12b shows that P. binneyi was collected only at sites where the dissolved oxygen was quite h i ^ This may correlate with the relatively low temperatures at which P. binneyi was 181 Family Planoibidae Planorbella binneyi found. The sample size (n=2) is too small to suggest whether this species may be oxygen-dependent or independent. Conductivitv and Calcium: Figure 2-12c shows that the two collection sites for P. binneyi had almost identical conductivities/calcium concentrations. However, the samples size is too small (n = 2) to presume that this may indicate the minimum calcium level required by this species. Figure 2-12d shows that the pH at the two ecological sites for P. binneyi were both alkaline and were both > pH 8. High pH is associated with high calcium but the sample size for P. binneyi is insufficient to make any hypotheses about the distribution of this species in relation to pH. The results of the CCA are that the Planorbidae are responding significantly to the environmental variables (p = O.OOS) with 8.8% of the species presence accounted for (Figure 2-18). The shows P. binneyi to correspond to no particular variables. The small sample size does not allow the development of any measurable unimodal response to these factors. Clarice (1981) indicates that the distribution of P. binneyi includes only the far southwest of the study area. This study found P. binneyi at sites farther west than indicated by Clarice but still appears to be confined to the Pacific drainage suggesting post-glacial migration firomthe Pacific refuge. Clarice (1981) states that P. binneyi occurs in eutrophic, well-vegetated lakes. Clarice's collection site for northern BC (CN1017) was such a site but, in this study, P. binneyi was collected fiom large, oligotrophic lakes with little vegetation at the collection areas. *Note: Clarice (1973b, 1981) refers to this species as/fe/iroma/rivo/vfihmR^'. 182 Family Planoibidae Planorbella sybcrenata Planorbella subcrenata* (Carpenter, 1857) Rough rams-hom PlnnmMln «ihmanaM SITES (59): N1001,N1002,N1003/CN1012, Nl004J<1005,N10lO,N1015,N1020a^l026,Nl033, N1034J^1037^1038JI1039^1042,N1043J41048, N1052,N1054,NI055Jil059,Nl061J«ll075,N1081, N1085J41090,N1091,N1093J^1097,N1098,N1101, N l 106J41107,Nl 110,N1112,N0102,N0103,N0104, N0106,N0108,N0109,N0113,NOl 14,N0115,N0116, N0122,N012S,N0133,N0134,N0137,N0139, CN1016,CN1018,CN1020,MN1001,MN1004, MN100S>1N1008MN1010 DRAINAGE/WATERSHED PACIFIC; Fraser: Fraser (4), Nechako (14), Stuart (4); Nass: Nass (1); Skeena: Babine (1), Bulkley (2), Skeena (3); Stildne: Stildne (1) ARCTIC: Liard: Dease (2), Fort Nelson (7), Liard (5); Mackenzie: Hay (2); Peace: Beatton (1), Peace (11). Pine (2) Figure A-36 - Collection sites for Planorbella subcrenata. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (24) Coastal Western Hemlock (1) Interior Cedar - Hemlock (4) Sub-Boreal Spruce (31 ) ECOPROVINCE/ECOREGION Boreal Plains: Central Alberta Uplands (2), Peace River Basin (2),Soutbem Alberta Uplands (3) Central Interior: Fraser Plateau (9) Coast & Mountains: Nass Basin (1), Nass Ranges (3), Liard Basin (7) Snb*Boreal Interior: Skeena Mts. (1), Central Canadian Rocky Mountains (1), Fraser Basin (22) Taiga Plains: Hay River Lowland (7), Northern Alberta Uplands (2) Environmeiital Information: Maximum Std. Error Minimum Measurement Count Mean 0.60 12.20 27.20 20.89 Temperature (°C) 35 23.00 98.00 3.15 67.86 35 Dissolved O2 (% Saturation) 26.70 1199.00 35.98 Conductivity (pSiemens) 261.20 35 177.44 5.37 2.65 37.61 Calcium (mglitre) 35 8.90 0.12 5.60 34 7.41 pH ............................... Previously recorded distribution in northern BC: Throu^out noithem BC (Clarke 1981). Discussion: Planorbella subcrenata was a very common mollusc in northern BC being found at 59 of 176 sites. It was found in both the Pacific and Arctic drainages and five of the six northern ecoprovinces. The four BGC zones in which it was found have mean average temperatures ranging fiom -2.9 to 10.5°C with up to 7 months below OT and up to 6 months above l(yc. Altitude within these BGC zones ranges fiom 0 to 13000 feet with mean annual precipitation ranging fiom 330 to 4400 mm. 183 Family Planoibidae Planorbella subcrenata The range and means of the environmental variables measured at the sites where P. subcrenata was collected are shown in Figure 2-12. Temperature: Figure 2-12a shows that P. subcrenata was found at temperatures >2S°C suggesting that high temperature may not be a limiting factor in the distribution of this taxa. Dissolved Oxvgen: Figure 2-12b shows that P. subcrenata was collected from habitats of relatively low oxygen saturation (23%). This suggests that P. subcrenata may be an oxygen-independent species and can tolerate hypoxic conditions so that the level of dissolved oxygen of a habitat may not be a limiting factor in the distribution of this species in northern BC. Conductivitv and Calcium Concentration: Figure 2-12c shows that P. subcrenata was collected in habitats of very low conductivity/calcium concentration (< 3 mg/l). This suggests that the level of dissolved calcium in a habitat may not be a limiting factor in the distribution of P. subcrenata in northern BC. CHl Figure 2-12d shows that P. subcrenata was found over a wide range of pH in both acidic and alkaline conditions. This suggests that pH may not be an environmental variable that greatly limits the distribution of this species in northern BC. The results of the CCA are that the Planorbidae are responding significantly to the environmental variables (p - O.OOS) with 8.8% of the species presence accounted for (Figure 2-18). The plot shows P. subcrenata to correspond most closely with hiÿier than average water temperature. Figure 2-12a did not suggest that temperature m i^t be a particularly important environmental variable in the ecology of P. subcrenata. Its placement on the plot, rather close to the origin but skewed towards temperature may be of limited ecological consequence. Clarice (1981) indicates that P. subcrenata occurs throuÿtout northern BC which concurs with the findings of this study. This widespread distribution gives no evidence of any barriers imposed during post-glacial distribution. Clarke (1981) states that P. subcrenata occurs in nearly all perennial-water habitats that support significant rooted vegetation. P. subcrenata. was found to occur in these types of habitats in this current study. *Note: Referred to as Helisoma trivobns subcrenatum by Clarke (1973b, 1981). 184 Family Ancylidae FerrissiafraffUs Ferrissia fragilis (T ry o n , 1863) Fragile ancylid FêfrisaJa fragilis SITES (1): CN1021 DRAINAGE/WATERSHED PACIFIC; Skeena: Skeena ECOPROVINCE/ECOREGION Coast & Mountains: Nass Ranges BIOGEOCLIMATIC (BGC) ZONE Interior Coastal Hemlock Figure A-37 - Collection site for Ferrissiafragilis. Previously recorded distribution in northern BC: Not previously recorded (Clarke 1981) Discussion: Ferrissia fraplis and F. parallelus are both found in lentic habitats and are most easily distinguished on the basis of size (Burch 1989). F. fragilis rarely exceeds 3.5 mm in length whereas F. parallelus may be up to 9 mm long. All the Ferrissia species found in this study in northern BC were found in standing water and all sites generally had specimens exceeding 3.5 mm in length. The site where Clarite records collecting F. fragilis (CN1021 - Seeley Lake) is the same site where F. parallelus was recorded during this study (N1091). Therefore, there may be some question as to the identity of Clarice’s collection. This may be why Clarice (1981) chose not to include northern BC within the range of any of the Ferrissia species known in Canada. Clarke’s collection should be re-examined to confirm the species identification and to verify whether or not the range of F. fragjilis extends into northern BC from it present recorded Canadian distribution of southern Vancouver Island and the Lower Mainland (Clarice 1981). 185 Family Ancylidae Ferrissia parallelus Ferrissia parallelus* (H ald em an , 1841) Oblong ancylid Ferrissia panUekis SITES (31): N1001J41002^1003,N1005,N1006^1014J41015, N1026^1033,N1062,N1080,N1081J41084,N1088, N1090.N1091^1092,N1093.N1098J41100J41101, Nl 107J41112,N 0104^0106^0107,N0108^0113, N0ll4,N0121,N0122 DRAINAGEAVATERSHED PACIFIC; Coûtai: North Coast (1); Fraser: Fraser(2), Nechako (8), Stuart (1); Nass: Meziadin(l), Nass (1) Skecna: Bulkley (4), Lakelse (1), Skeena (2) ARCTIC: Liard: Dease (1), Fort Nelson (1); Peace: Kiskatmaw (1), Peace (7) ECOPROVINCE/ECOREGION Boreal Plains: Central Alberta Uplands (1), Southern Alberta Uplands (2) Central Interior: Fraser Plateau (7) Coast & Monnttdu: Coastal Gap(2),Nass Basin(2), Figure A*38 - Collection sites for Ferrissia parallelus. BIOGEOCLIMATIC ZONE (BGC) Boreal White & Black Spruce (5) Coastal Western Hemlock (2) Interior Cedar • Hemlock (4) Sub-Boreal Spruce (20) Nass Ranges (2) Northern Boreal Mountains: Liard Basin (1) SnIvBoreal Interior: Omineca Mountains (1), Fraser Basin (12) Taiga Plains: Hay River Lowland (1) Envlronmentel Infomuition; Meuurement Maximum Count Mean Std. Error Minimum 19.92 0.79 12.20 26.50 Temperature CC) 23 Dissolved 0%(% Saturation) 72.00 3.55 23.00 91.00 23 Conductivity (pSiemens) 214.00 46.80 20.10 1199.00 23 Calcium (mg/litre) 6.29 1.29 159.73 23 27.35 23 7.39 0.18 5.25 8.75 pH Previously recorded distribution in northern BC: Not previously recorded (Garice 1981). Discussion: Ferrissia parallelus was a common mollusc in northern BC being found at 31 of 176 sites. It was found in both the Pacific and Arctic drainages and in all of the ecoprovinces within the study area. The four BGC zones in which it was found have mean annual temperatures tanging fiom -2.9 to 8.7*C with up to 7 months below 0°C and up to 6 months above 10°C and with annual precipitation ranging fiom 330 to 4400 mm. The range and the means of the environmental variables at the sites where F. parallelus was collected are shown in Figure 2-9. 186 Funily Ancylidae Ferrissia parallelus Temperature: Figure 2-9a shows that F. parallelus was found at temperatures >25°C suggesting that temperature may not be a limiting factor in the distribution of this species in northern BC. Dissolved Oxvgen: F. parallelus is a truly aquatic pulmonate, not dependent on atmospheric air. Figure 2-9b shows that F. parallelus was collected over a wide range of dissolved oxygen. However, at the one site for this species where low dissolved oxygen was recorded (23%; next lowest measurement 44%), F. parallelus was collected 6om the undersides of lily pads where it would have had access to higher levels of oxygetL It may be that the F. parallelus is an oxygen-dependent species and that in habitats with lower overall dissolved oxygen, it selects appropriate microhabitats within the water body where sufBcient oxygen is available. Conductivitv and Calcium Concentration: Figure 2-9c shows that F. parallelus was collected over a wide range of conductivity/calcium concentration down to almost the lowest level measured in this study. This suggests that the calcium concentration of a habitat may not be a limiting factor in the distribution of this species in northern BC. Ciii Figure 2-9d shows that F. parallelus was collected over a wide range of pH being found in both acidic and basic conditions. This suggests that pH may not be a limiting factor in the distribution of this species in northern BC. In other studies, F. parallelus has been found at pH ranging from 6.0 to 8.3 (Pennak 1989). Three families were included in the Canonical Correspondence Analysis (CCA) analysis that includes F. parallelus (Group 1; Figure 2-15). The results of this CCA are that the species are responding significantly to the environmental variables (p = 0.040) with 13.2% of the species presence accounted for. The plot shows F. parallelus to correspond most closely with lower than average conductivity. The wide range of conductivity/calcium concentration displayed by this species does not indicate that conductivity is a paiticulariy important ecological Actor for F. parallelus. Clarke (1981) does not record F. parallelus west of Manitoba, which is also the distribution given by Burch (1989). The only Ferrissia species Clarke includes in BC is F. fragilis fiom southern Vancouver Island and the Lower Mainland. Clarke, however, did collect F. fragilis fiom Seeley Lake (CNIOI1) and a Ferrissia sp. fiom Summit Lake (CN1021) (Lee and Ackerman 1999a). F. parallelus was common in this study, most often in the south of the study area but with a few collections in the north. It is possible that this linqret is still migrating northwards, periiaps fiom both the Pacific and Mississippi réfugia, and has to date only successfully colonized large lakes in the north of the study area. This widespread distribution of F. parallelus gives no indication of any barriers it encountered during dispersal. 187 Family Ancylidae Ferristia parallelus In eastern Canada, Clarke (1981) found F. parallelus to live in lakes, swamps, and slow-flowing rivers among thick or moderately thick vegetation and that it was often found on the stems of cattails {Typha) and sedges (Scirpus) or on the undersides of lily pads. In this study, F. parallelus was found in similar habitats, most often on the undersides of lily pads, but also often on the undersides of rocks and on submerged wood. *Note: This species is referred to as Ferrissia parallela by Clarke (1973b, 1981). 188 Family Ancylidae Ferrissia tp. Ferrissia sp . SITES (1): CNlOll DRAINAGE/WATERSHED ARCTIC; Peace: Peace ECOPROVINCE/ECOREGION Sub>Boreal Interior: Fraser Basin BIOGEOCLIMATIC (BGC) ZONE Sub-Boreal Spruce Figure A-39 - Collection sites for Ferrissia parallelus. Previously recorded distribution in northern BC: Not previously recorded (Clarke 1981). Discussion: Clarke (1981) does not include northern BC within the range of any of the Ferrissia species known fiom Canada although this record (collected in 1972) indicates that Clarice was aware of the occurrence of Ferrissia in northern BC prior to publication of the results of his study. 189 rw niiy m v ^ n u ic n u o c Mar^ritiferafalcata Margaritifera falcata (G o u ld , 1850) Western pearlshell SITES (8): N1083/CNI022J^1094,N1095,Nl 113*, N0101,N0123*,N0124*,N0140* *shelb only found at these sites DRAINAGE/WATERSHED PACIFIC; Fraser: Fraser (3), Ncchako (I), Stuart (1); Skecne: BtAine (1), Bulkley (1), Lakelse(l) ECOPROVINCE/ECOREGION Central InterionFraser Plateau (1) Coast & Mountains: Nass Ranges (1) Sub-Boreal Interior: Fraser Basin (6) BIOGEOCLIMATIC (BGC) ZONE Coastal Western Hemlock (1) Sub-Boreal Spruce (7) Figure A-40 - Collection sites for Margaritiferafalcata. Environmental Information: Maximum Count Mean Std. Error Minimum Measurement 17.90 1.89 9.60 4 15.18 Temperature CC) 55.00 80.00 4 69.00 5.18 Dissolved 0%(% Saturation) 67.80 213.00 4 144.63 39.09 Conductivity (pSiemens) 8.77 30.42 4 20.23 5.83 Calcium (mg/litre) 8.00 6.40 4 7.03 0.38 pH Previously recortled distribution in northern BC: Known only from Lakelse River (Clarke 1973a). Discussion: Margaritifera falcata was an uncommon mollusc in northern BC being found at e i^ t of 176 sites. It was found only in the Pacific drainage and in the three southernmost ecoprovinces in the study area. The two BGC zones in which it was found have mean annual temperatures ranging from 1.7 to 10.5*C with up to 5 months below (XC and up to 6 months above 10"C with annual precipitation ranging from 440 to 4400 mm. The range and means of the environmental variables at the sites where M. falcata was collected are shown in Figure 2-13. Temperature: Figure 2-13a shows that M. falcata was collected firom sites where the tenqierature was generally lower than that for most of the other bivalves in this group. The mean temperature for M. falcata was significantly lower than for the other freshwater mussel in northern BC, À. kemeriyi (Table 27). This is in accordance with the different habitats of these two species. M. falcata is a lotie species 190 Family Maiguitifcndae Margariiifarafalcata found in running streams wider than four meters (Clarice 1981), whereas A. kemeriyi is a lentic species found in lakes in this study. The temperature in flowing water would generally he lower than that found in standing water. Dissolved Oxygen: Figure 2-13b shows that M. falcata was only collected from habitats of relatively high dissolved oxygen. M. falcata may be restricted to lotie habitats by its need for oxygen (i.e., oxygendependent), or it may be restricted by other factors, and high oxygen is an intrinsic factor of these habitats. Conductivity and Calcium Concentration: Figure 2-13c shows that M.falcata was collected from habitats with a minimum calcium concentration of 8.8 mg/1 and that it was collected over a very limited range. This limited range may be characteristic of Pacific drainage systems and/or it may be that M. falcata is restricted to streams providing this minimum level. pH: Figure 2-13d shows that M. falcata was found in both acid and alkaline conditions. This suggests that the pH of a habitat may not be a limiting factor in the distribution of this species in northern BC. The results of the CCA are that the large bivalves are not responding significantly to the environmental variables (p - 0.480) with 5.1% of the species presence accounted for (Figure 2-19). However, the placement of M falcata on the plot corresponds to lower than average temperature, which is in keeping with the ecology of this species. M. falcata is known only from the Pacific drainage in western North America (Burch 1975b), which suggests that M. falcata dispersed from the Pacific Refuge, and Clarke (1981) lists it as a species characteristic of this type of dispersal. Prior to this study, M. falcata was known in northern BC from only one site, the Lakelse River near Terrace (Clarke 1973a, 1981). This study, while not extending the range much farther north, extends the range much farther east within the Pacific drainage. M. falcata would appear to reach its northern limit within the &r south of the study area yet Burch (1975b) states that it is also found in southern Alaska. As the distribution of freshwater mussels is linked to the distribution of their host fishes, it may be conditions suitable for the host fish that limit the distribution of M. falcata in northern BC. 191 Family Unionidae Anodona kemeriyi Anodonta kemeriyi L ea, 1860 Western floater Anodonta ktnnertyl SITES (22): N1000,N1001J^1003/CN1012, N1005,N1082J41084/MN1014,N1088^1096, Nl 100/CNI020J^ 1104.N1105.NI 112.N0102. N0l06.N0ll0.N0l 13/CNlOl I.N0114.CN1002. CN1017.CN1018.MN1005.MN1008 DRAINAGE/WATERSHED PACIFIC; Coastai:Noith Coast (1); Fraser: Fraser (1). Ncchako (8). Stuart (3); Skeena: B abine(l)4^1se (l).Skeena (l).Sustut (I) ARCTIC; Peace; Peace (5) ECOPROVINCE/ECOREGION Central Interior ; Fraser Plateau (5) Coast & Mountains:Nass Basin(l).Coastal Gap(2) Sub-Boreal Interior ; Gmineca Mountains (1). Fraser Basin (13) Figure A-41 - Collection sites for Anodonta kennerlyi. BIOGEOCLIMATIC (BGC) ZONE Coastal Western Hemlock (2) bterior Cedar - Hemlock (1) Sub-Boreal Spruce (19) Environmeiital Information: Mensurament Count Mean Std. Error Minimum Maximum 20.34 Temperature (°C) 12 1.04 16.20 26.50 Dissolved 0%(% Saturation) 12 76.92 3.80 44.00 93.00 Conductivity (pSiemens) 12 135.78 14.63 20.10 203.00 Calcium (mg/litre) 12 18.91 2.18 1.66 28.93 7.34 12 0.29 5.25 8.55 pH Previously recorded distribution in northern BC: From far south of study area (Clarke 1981). Discussion: Anodonta kennerlyi was a common mollusc of northern BC being found at 22 of 176 sites. It was found in both the Pacific and Arctic drainages in the southernmost ecoprovinces of the study area. The three BGC zones in which it was found have mean annual tenqieratures ranging fiom 1.7 to 10.ST with up to 5 months below 0 ^ and iq) to 6 months above lOT with annual precipitation ranging fiom 440 to 4400 mm. The range and means of the environmental variables at the sites where A. kennerlyi was collected are shown in Figure 2-13. Temperature: Figure 2-13a shows that A. kennerlyi was collected fiom sites where the tenqierature was relatively high. The mean tenqierature for A. kennerlyi was fotmd to be significantly higher than for M falcata (Table 2-7). This is in accordance with the different habitats of these two species. A. kennerlyi is 192 ram iiy unioim iie Anodonta kemeriyi a lentic species found in lakes within the study area whereas M falcata is a lotie species found in running streams wider than four meters (Clarke 1981). The tenqieratiire in standing water m i^t generally be higher than that found in flowing water leading to the significant difference of the means. The high temperature at which A. kennerlyi was collected suggests that tenqierature may not be a factor that limits its distribution in northern BC Dissolved Oxygen: Figure 2-13b shows that A. kennerlyi was only collected fiom habitats of relatively high levels of dissolved oxygen, which suggest it may be an oxygen-dependent species. However, Lewis (1984) found that another Anodonta species, A. grandis, was oxygen-independent, being able to maintain nearly constant oxygen consumption down to very low levels. It may be that A. kennerlyi also has this ability but this was not reflected in the oxygen content of the habitats in which it was found in northern BC. Conductivity and Calcium: Figure 2-13c shows that A. kennerlyi was collected fiom habitats with a minimum calcium concentration of 1.7 mgfl, which is close to the minimum recorded in this study. This suggests that the conductivity/calcium concentration of a habitat may not be a factor that limits the distribution of A. kennerlyi in northern BC. dH: Figure 2-13d shows that A. kennerlyi was collected firom habitats with a wide range of pH including both acidic and alkaline conditions. This suggests that pH may not be a factor that greatly limits the distribution of A. kennerlyi in northern BC. The results of the CCA are that the large bivalves are not responding significantly to the environmental variables (p = 0.480) with S.1% of the species presence accounted for (Figure 2-19). However, the placement of A. kennerlyi on the plot corresponds with hi^er than average dissolved oxygen, which is in keeping with other data fiom this study. A. kennerlyi is known in Canada firom across southern BC and into west central Alberta and extends southward in the Pacific drainage to Oregon (Clarice 1981). This distribution pattern suggests dispersal fiom the Pacific Refuge. However, unlike M. falcata, which is believed to have a similar origin, A. kennerlyi also occurs in the Arctic drainage in BC and Alberta. The distribution of freshwater mussels is linked to that of their fish hosts (Watters 1992) and it is believed that the entry of Pacific species of fish into the upper Peace is due to a relatively recent minor headwater transfer, as few species have dispersed much farther down the Peace than to the Alberta/BC border (McPhail and Lindsey 1970). It may be that and the headwater transfer may have included A. kennerlyi or fish carrying their glochidia as this is the distribution pattern recorded by Clarke (1981), which concurs with the findings of this study. 193 FiinilySphacriidae ^p/iaerium niiidum Sphaerium nitidum Westerlund, 1876 Arctic fingemailclam Sphaenjm nudum V SITES (18): N1004,N1011,N1015J41027J>I1029J>I1033,N1046, N1048,N1054J^1059,N1075^1084,N10882^1101, N0126,CN1004,CN1008>IN1003 DRAINAGE/WATERSHED PACIFIC: Coastal: North Coast (1); Fraser: Ncchako (I); Skeena: Lakelse (1); StUdne: Iskut (l),Stikm e(l) ARCTIC: Liard: Kechika (l)J)case (2)fort Nelson (l)^iard (2), Toad (1); Peace: Beatton (I), Halfway (I), Kiskatinaw (l)fe a c e (2), Pine (1) ECOPROVINCE/ECOREGION Boreal Plains: Central Alberta Uplands (1), Figure A-42 - Collection sites for Sphaerium nitidum. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (12) Coastal Western Hemlock (2) Interior Cedar • Hemlock (1) Spruce - Willow - Birch (1) Sub-Boreal Spruce (2) Muskwa Plateau (1), Southern Alberta Uplands (2) Central Interior: Fraser Plateau (1) Coast & Mountains: Coastal Gap (2) Northern Boreal Mountains: Northern Canadian Rocky Mountains (1), Boreal Mountains and Plateaus (3), Liard Basin (3) Sub*Boreal Interior : Skeena Mountains (1), Central Canadian Rocky Mts. (1), Fraser Basin (1) Taiga Plains: Hay River Lowland (1) Environmental Information: Maiimnm Std. Error Minimum Meuurement Count Mean 26.20 14 1.02 12.20 Temperature C*C) 19.62 99.00 14 66.86 5.02 23.00 Dissolved 0%(% Saturation) 1199.00 19.70 14 280.21 87.70 Conductivity (pSiemens) 177.44 1.60 14 40.44 13.08 Calcium (m ^tre) 7.09 8.15 14 0.23 5.25 pH Previously recorded distribution in northern BC: Throughout northern BC (Clarke 1981). Discussion: Sphaerium nitidum was a common mollusc in northern BC being found at 18 of 176 sites. It was found in both the Pacific and Arctic drainages in all of the ecoprovinces. It lacks representation only in the ESSF BGC zone, which is the least represented in this study. The five BGC zones in which it does occur have mean annual temperatures ranging fiom -3.0 to 10.S°C with up to 7 months below 0°C and up to 6 months above 10°C with aimual precipitation ranging fiom 330 to 4400 mm. The ranges and means for the environmental variables measured at the sites where S. nitidum was collected are shown in Figure 2-13. 194 Family Sphaeriidae ^)ham um nitidum Temperature: Figure 2-13a shows that S. nitidum was collected at temperatures >2S°C suggesting that temperature may not be a limiting factor in the distribution of this species in nonhem BC. Dissolved Oxygen: Figure 2-13b shows that S. nitidum was collected in habitats with dissolved oxygen saturation down to the lowest measured for other bivalves in this group (23%). According to Burky (1983), Sphaerium species are oxygen-dependent but can estivate under hypoxic conditions. Only one site with relatively low dissolved oxygen (23%) was measured for this species, with the next lowest site having 44% oxygen saturation. As Burky has examined the oxygen physiology of Sphaerium species, it may be assumed that the one low measure recorded in this study may not be indicative of the usual conditions under which this species is found, or that the specimens collected were estivating. Conductivity and Calcium: Figure 2-13c shows that S. nitidum was collected in habitats where the conductivity/calcium concentration was the lowest measured in this study. This suggests that the distribution of 5. nitidum in northern BC may not be restricted by the level of conductivity/calcium of a habitat. pH: Figure 2-13d shows that 5. nitidum was collected over a wide range of pH, in both acidic and alkaline conditions, and at the lowest value measured for this genus. This suggests that pH may not be a factor that greatly limits the distribution of this species in northern BC. The results of the CCA are that the large bivalves are not responding significantly to the environmental variables (p = 0.480) with S.1% of the species presence accounted for (Figure 2-19). The placement of S. nitidum on the plot corresponds to lower than average pH, which may be of limited ecological importance to this species. Clarke (1981) indicates that the range of 5. nitidum includes all of northern BC, which is consistent with the findings of this study. Clarke (1979a, 1981) states that 5. nitidum is a cold-water species that occurs in lakes and rivers and that it is an indicator species of oligotrophic lakes, hi this study, S. nitidum was often collected finm large oligotrophic lakes, but was also collected fiom mcsotrophic lakes and fiom pomls. 195 Family SphMiüdae Sphaerium rhomboideum Sphaerium rhomboideum (Say^ 1822) Rhomboid fingemailclam Spnatrim momooldeum SITES (3): N1093.N0104.N0115 DRAINAGE/WATERSHED PACIFIC: Fraser: Nechako (1), Stuart (l) Skecna: Bulkley (1) ECOPROVINCE/ECOREGION Central Interior : Fraser Plateau (1) Sub-Boreai Interior: Fraser Basin (2) BIOGEOCLIMATIC (BGC) ZONE Sub-Boreal Spruce (3) Figure A-43 - Collection sites (or Sphaerium rhomboideum. Environmental Information: Count Observed Measurement Temperature C^) 1 17.40 1 91.00 Dissolved 0%(% Saturation) Conductivity (pSiemens) 1 275.00 1 39.70 Calcium (mg/litre) 1 8.75 pH .. Previously recorded distribution in northern BC: Not previously recorded (Clarice 1981). Discussion: Sphaerium rhomboideum was an uncommon mollusc in northern BC being collected at only three of 176 sites. It was found only in the Pacific drainage in the interior ecoprovinces. The BGC zone in which it was found has mean annual temperature ranging fiom 1.7 to 5.0 "C with iq> to 5 months below o r and up to 5 months above lOT and with annual precipitation of440 to 990 mm. S. rhomboideum was only collected fiom one ecological site. The values of the environmental variables measured at this site are indicated on Figure 2-13 with a dot. Environmental Variables: Figure 2-I3a shows that the tenqierature at which 5. rhomboiekum was collected is within the range of the tenqxratures recorded for most other bivalves in this grotqi. Figure 213b.c,d shows that the site at which 5. rhomboideum was collected had relatively hiÿr measures of dissolved oxygen, conductivity/calcium concentration and pH. These single values gives no indication of 196 Family Sphaeriidae Sphaerium rhomboideum what the range of tolerance to these variables may be for this species, and so does not allow the formation of any ecological hypotheses. The results of the CCA are that the bivalves in this group are not responding significantly to the environmental variables (p = 0.480) with S.1% of the species presence accounted for (Figure 2-19). The placement of S. rhomboideum on the plot corresponds to higher than average dissolved oxygen but is of limited ecological interpretability due to the small sample size. Clarke (1981) does not include northern BC within the range of S. rhomboideum. S. rhomboideum has been found in other provinces only as far north as it was in this study. Thus, the distribution of 5. rhomboideum in northern BC may be limited by climatic restrictions. Clarice (1981) describes the habitat of S. rhomboideum as lakes, ponds and streams. In this study, the three sites for S. rhomboideum were a lake, a pond and a stream. 197 Family Sphacfüdae Splutaium simile Sphaerium simile (Say, 1817) Grooved fingemailclam SITES (13): NlOOO,N100l,N1003J2S”C suggesting that temperature may not be a limiting factor in the distribution of this species in northern BC. 198 Family Sphaeriidae Sphaerium simUe Dissolved Oxvgen: Sphaerium species are described as being oxygen-dependent (Burky 1983). Figure 213b shows that S. simile was collected at a minimum dissolved oxygen saturation of 32%, which may be consistent with requirements for relatively high levels of dissolved oxygen. Conductivitv: Figure 2-13c shows that S. simile was found down to a minimum of 16.6 mg/1 calcium. This suggests that the distribution of S. simile may be limited by the level of conductivity/calcium of a habitat, and that this may affect its distribution in northern BC. pH: Figure 2-13d shows that S. simile was found in both acidic and alkaline conditions but within a relatively limited range. It may be that S. simile is unable to tolerate extreme pH habitats, which may restrict its distribution in northern BC. The results of the CCA are that bivalves in this group are not responding significantly to the environmental variables (p = 0.480) with S.1% of the species presence accounted for (Figure 2-19). The plot shows S. simile to correlate most closely to higher than average temperature. As per the above discussion, temperature does not seem to be a particularly inqmrtant ecological for S. simile and its placement here on the plot may be of limited ecological importance. Clarke (1981) does not include northern BC within the distribution of S. simile. Most of the collections of S. simile made during this study were made in the southeast of the study area, extending the range indicated by Clarice only slightly northward. However, there was also a collection made in the northeast and another in the southwest of the study area, which changes Clarke’s recorded distribution considerably. Clarke (1979a, 1981) describes 5. simile as occurring in all kinds of perennial water habitats and that it is an indicator species of eutrophic lakes, h this study it was often found in large oligotrophic to mesotrophic lakes and in the slow moving area of streams, as well as in some eutrophic water bodies thus, it has a much broader habitat range than has been previously indicated. 199 Family Sphaeriidae Sphaerium siriaiinum Sphaerium striatinum (Lamarck, 1818) Striated fingemailclam Sphaerium smamum SITES (1): N1107 DRAINAGE/WATERSHED PACIFIC; Fraser: Fraser ECOPROVINCE/ECOREGION Sub>Borcal Interior: Fraser Basin BIOGEOCLIMATIC (BGC) ZONE Sub-Boreal Spruce Figure A-4S - Collection sites for Sphaerium striatinum. Environmental Information: Meuurement Count Observed 14.00 Temperature CC) 1 Dissolved 0%(% Saturation) 1 90.00 Conductivity (pSiemens) 1 120.10 Calcium (mg/litre) 1 16.60 pH 1 6.35 Previously recorded distribution in northern BC: Eastern area (Clarite 1981). Discussion: Sphaerium simile was an uncommon mollusc in northern BC being found at one of 176 sites. It was found only in the Pacific drainage in the Sub-Boreal hiterior ecoprovince. The BGC zone in which it was found has a mean annual tenqierature ranging fiom 1.7 to S.(PC with up to S months below 0°C and up to S months above IO°C and with annual precipitation ranging fiom 440 to 990 mm. 5. striatinum was only collected fiom one ecological site. The values of the environmental variables measured at this site are indicated on Figure 2-13 with a dot. Environmental Variables: Figure 2-l3a shows that the one measurement available for 5. striatinum is relatively low. However, if hiÿt temperature were a limiting factor for S. striatinum, it would be expected to be more common in the north of BC than in the south. As this is not the case, intolerance to hiÿt water tenqierature may not be a limitmg factor in the distribution of this species in northern BC. Figure 2-l3b shows that the one measurement of dissolved oi^gen for S. striatinum is relatively high, and 200 Family Sphaeriidae Sphatrium siriaiitmm Figures 2-13c,d show that the measures for both conductivity/calcium concentration and pH are within the range of most other Sphaerium species in this study. These single values gives no indication of what the range of tolerance to these variables may be for this species, and so does not allow the formation of any ecological hypotheses. The results of the CCA are that the bivalves in this group are not responding significantly to the environmental variables (p = 0.480) with S.1% of the species presence accounted for (Figure 2-19). The placement of S. striatinum on the plot corresponds to lower than average temperature, but this is of limited interpretability due to the small sangle size. Clarke (1981) includes the eastern area of northern BC in the distribution range for S. striatinum but no records could be found to support this. However, the collection made during this study in the southeast of the study area concurs with the distribution indicated by Clarice. This one record for northern BC gives no indication of possible post-glacial dispersion routes. Clarke (1979a, 1981) describes 5. striatinum as living principally in rivers and streams but also occurring in large lakes and rarely, in small lakes and that it is indicative of mesotrophic lakes. In this study, S. striatinum was collected fiom a large lake where it was found in the roots of aquatic plants near the shore. 201 Family Sphaeriidae MuscuUum lacustre MuscuUum lacustre* (Müller, 1774) Lake fingemailclam SITES (40): N1010,N1012,N1015^1020,N1027,N1028,N1033, N1034J«I1036,N1037J^1038;^1039,N1040J<1041, N1042^1043,N1054J41055JJ1059^1072,N1084, N1085,N1088,N1090J41091J41092,N1093,N1096, N1097J41102,N1105,NI 106,N l 111,N0100,N0104, N0107,N0108,N0131.CN1014,CN1018 DRAINAGE/WATERSHED PACIFIC: Coastal: North Coast (1); Fraser: Fraser (2), Nechako (4), Stuart (3); Skeena: Babine(2), Bulkley(2),Lakelse (l),Skeena (3) StUdne: Stikme(l) ARCTIC: Liard: Dease (1), Fort Nelson (9), Liard (2); Mackenzie: Hay (2) Peace: Beatton(2), Halfway(l), Peace(2)Pme(2) ECOPROVINCE/ECOREGION Boreal Plains: Central Alberta Uplands (3), Southern Alberta Uplands (4) Figure A-46 - Collection sites for MuscuUum lacustre. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (21) Coastal Western Hemlock (3) Engelmann Spruce - Subalpine Fir (2) Interior Cedar • Hemlock (2) Sub-Boreal Spruce (12) Central Interior: Fraser Plateau (4) Coast & Mts.: Coastal Gap (2),Nass Ranges (3) Northern Boreal Mountidns: Boreal Mountains and Plateaus (1), Liard Basin (3) Sub-Boreal Interior : Central Canadian Rocky Mountains (1), Fraser Basin (8) Taiga Plains: Hay River Lowland (9), Northern Alberta Uplands (2) Environmental Information: Measurement Count Mean Std. Error Minimum Maximum Temperature CO 20.15 0.54 33 12.10 27.20 66.99 Dissolved 0%(% Saturation) 33 3.36 25.00 93.00 Conductivity (pSiemens) 33 254.90 34.85 20.10 987.00 Calcium (mg/litre) 36.67 33 5.20 1.66 145.83 32 7.22 0.13 5.25 8.75 pH Previously recorded distribution in northern BC: Far east only (Clarke 1981). Discussion: MuscuUum lacustre was a common mollusc in northern BC being found at 40 of 176 sites. It was found in both the Pacific and Arctic drainages in all of the ecoprovinces. It was found in all but the Spruce-WUow-Birch BGC zone. The five BGC zones in which it was found have mean annual temperatures ranging fiom -2.9 to 10.S”C with up to 7 months below 0°C and up to 6 months above KPC and with annual precipitation ranging fiom 330 to 4400 mm. The range and mean of the environmental variables measured at the sites where M. lacustre was collected are shown in Figure 2-13. 202 Family Sphaeriidae MuscuUum lacustre Temperature: Figure 2-13a shows that M. lacustre was collected at temperatures >25^C suggesting that high temperature may not be a limiting factor in the distribution of this species in northern BC. Dissolved Oxygen: Figure 2-13b shows that M lacustre was collected over a broad range of dissolved oxygen but was never found in habitats of very low dissolved oxygen (i.e., <23%). MuscuUum species have been described as oxygen-dependent (Burky 1983), which may be consistent with the findings of this study Conductivitv: Figure 2-l3c shows that M. lacustre was collected at sites with the lowest conductivity recorded in this study. This suggests that conductivity may not be limiting factor in the distribution of this species in northern BC. pH: Figure 2-13d shows that M lacustre was collected over a broad range of pH, in both acidic and alkaline conditions. This suggests that pH may not be a factor that greatly limits the distribution of this species in northern BC. The results of the CCA are that the bivalves in this group are not responding significantly to the environmental variables (p = 0.480) with S.1% of the species presence accounted for (Figure 2-19). The plot shows M. lacustre to correspond most closely with higher than average conductivity. The above discussion does not indicate that this may be of any particular iirqportance in the ecology of M. lacustre in that it was found in very low conductivity habitats. Clarice (1981) indicates that M. lacustre occurs in northern BC only in the eastern area. In this study, M. lacustre was found most commonly in the east, but was found th ro u ^u t the study area thus expanding the range much further north and east in BC than that range indicated by Clarke. This widespread distribution gives no indication of any barriers imposed during post-glacial dispersion. Clarice (1981) describes the habitat of M. lacustre as perennial water lakes, ponds, rivers and streams which concurs with the types of habitats in which M. lacustre was found in this study. *Note: This genus is referred to as Sphaerium by Clarice (1973b, 1981) and Herrington (1962) but other authors use MuscuUum (Butch 1975a, Turgeon et al. 1998). 203 Family Sphaeriidae Musculium securis MuscuUum securis* (Prime, 1852) Swamp fingemailclam SUES (46): NlOOl J^1002J41005,N1012, N1020J<1026,N1027J41031J41033J41039,N1048, N1052^1053J41058;^1059,N1062,N1066JJ1069, N1075,N1077,N1084,N1085,N1088Jil090J41091, N1092J^10931096;M1097J^1098.N1100^1101, N l 104,N1107,Nl 110,N1111,N0102,N0103,N0104, N0108,N0109,N0113,N0115,N0120,N0127JJ0129 DRAINAGE/WATERSHED PACIFIC: Coastal: North Coast (1); Fraser: Fraser (3), Nechako (6), Stuart (4); Nass: Meziadin (1); SlwcDa: Sabine (2), Bulkley (3), Lakelse (1), Skeetu (3); Stiidne : Stddne (2) ARCTIC: Liard: Dease (4), Fort Nelson (2), Liard (3); Mackenzie: Hay (1), Peace: Beatton (1), Halfway (l)feace (S),Pine (2),Smoky (1) ECOPROVINCE/ECOREGION Boreal Plains: Peace River Basin (1), Southern Alberta Uplands (2), Central Alberta Uplands (3) Figure A<47 - Collection sites for Musculium securis. Central Interior: Fraser Plateau (5) BIOGEOCLIMATIC (BGC) ZONE Coast & Moiutains: Nass Basin (1), Coastal Gap (2), Nass Ranges (3) Boreal White and Black Spruce (17) Northern Boreal Mountains: Boreal Coastal Western Hemlock (3) Mountains and Plateaus (2), Liard Basin (6) Engelmann Spruce - Subalpine Fir (2) Sub-Boreal Interior: Skeena Mountains (1), Interior Cedar • Hemlock (4) Fraser Basin (15),Central Canadian Rocky Mts. (2) Sub*Boreal Spruce (20) Taiga Plains: Hay River Lowland (3) Environmental Information: Maximum Std. Error Minimum Meisurement Count Mean 26.50 12.10 0.60 19.62 Temperature (T ) 36 98.00 23.00 71.24 3.02 Dissolved 0%(% Saturation) 36 1199.00 20.10 35.98 231.99 Conductivity (uSiemens) 36 1.66 145.83 36.67 5.20 36 Calcium (m^itre) 8.90 5.25 0.16 7.36 35 pH ..................... Previously recorded distribution in northern BC: Not previously recorded (Clarice 1981). Discussion: Musculium securis was a common mollusc in northern BC being found at 46 of 176 sites. It was found in both the Pacific and Arctic drainages in all of the ecoprovinces. It was found in all but the Spruce-Willow-Birch BGC zone. The five BGC zones in which it was found have mean annual temperatures ranging fiom -2.9 to 10 with up to 7 months below OC and tq> to 6 months above IOC and with «muMl precipitation ranging fiom 330 to 4400 nm. The range and mean of the environmental variables measured at the sites where M securis was collected are shown in Figure 2-13. 204 Family Sphaeriidae Musculium securis Temperature: Figure 2-13a shows that M securis was collected at temperatures >2S°C suggesting that high tenqierature may not be a limiting factor in the distribution of this species in northern BC. Dissolved Oxygen: Figure 2-13b shows that M securis was collected over a broad range of dissolved oxygen but was never found in habitats of very low dissolved oxygen (i.e., <23%). Musculium species have been described as oxygen-dependent (Buricy 1983), which may be consistent with the findings of this study Conductivitv: Figure 2-13c shows that M. securis was collected at sites with the lowest conductivity recorded in this study. This suggests that conductivity may not be a limiting factor in the distribution of this species in northern BC. pH: Figure 2-13d shows that M. securis was collected over a broad range of pH, in both acidic and alkaline environments. This suggests that pH may not be a factor that greatly limits the distribution of this species in northern BC. The results of the CCA are that the bivalves in this group are not responding significantly to the environmental variables (p = 0.480) with S.1% of the species presence accounted for (Figure 2-19). The plot shows M. securis to correspond to no particular environmental variable as it occurs on the plot very near the origin of all the variables. Clarke (1981) does not include northern BC in the range of M securis althouÿi its range includes most of northern Alberta into the North West Territories. This study found that M. securis was common th ro u ^u t northern BC, which extends the range for this species considerably north and west in BC. This widespread distribution gives no indication of any barriers imposed during post-glacial dispersion. Clarke (1981) describes the habitat of M securis as both vernal and perennial water habitats such as lakes, ponds, rivers and streams, fit this study M. securis was found primarily in lakes and ponds with only two records finm the slow moving areas of streams. *Note: This genus is referred to as Sphaerium by Clarice (1973b, 1981) and Herrington (1962) but other authors use Musculium (Burch 1975a, Turgeon et al. 1998). 205 FamflySphaeiiidae Musculium transvmum Musculium transversum* (Say, 1829) Long fingemailclam ,o SITES (1): CNIOOO DRAINAGEAVATERSHED Fraser: Stuart ECOPROV1NCEÆCOREGION Sub*Boreal Interior: Fraser Basin BIOGEOCLIMATIC (BGC) ZONE Sub-Boreal Spruce Figure A-48 - Collection site ton Musculium transversum. Previously recorded distribution in northern BC: Eastern area (Clarice 1981). Discussion: Clarke collected this species in northern BC during surveys in 1972. This species was not collected during the course of this study. It is included here to give a synoptic record of all of the freshwater molluscs known from northern BC. *Note: Referred to by Herrington (1962) and Clarice (1973b, 1981) as Sphaerium transversum. 206 Family Sphaeriidae Pisidium easeruuium Pisidium casertanum (Poli, 1791) Ubiquitous peaclam PltkHum ctsôrtênuni Figure A-49 - Collection sites for Pisidium casertanum. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (41) Coastal Western Hemlock (4) Engelmann Spruce • Subalpine Fir (2) Interior Cedar - Hemlock (6) Spruce - Willow - Birch (S) Sub-Boreal Spruce (23) SITES (81): N1002,N1006,N1007,N1009;^1010, Nl0I2,N1026^1O27,N1028J^1031^l032,N1033, N1035,N1037,N1038J41040JN1041JII042,N1044, N1048,N1049,N1053,N1054,N1056J41057,N1059, N1060,N1061,N1062,N1063,N1065,N1066,N1068, N1069,N1071J^1072^1073.N1074J^1075,N1076, N1077,N1078J41082,N1084,N1085^1088,N1089, N1090,N1092J^1093,N1096,N1097JJ1102,Nl 103, Nl 104,N1 lOSJ^l 107,NI 109,Nl 110,N1111,NI 112, N0102,N0104,N0105,N0108,N0113,N0116,N0119, N0120,N0125,N0129J40136,CN1003,CN1004, CN1005/MN1011,CN1006/MN1003,CN1009, MN1000>fN100S>fN1007,MN1009 DRAINAGE/WATERSHED PACIFIC: Coastal: North Coast (2); Fraser: Fraser (5), Nechako (6), Stuart (5); Nass: Bell-Irving (1), Meziadin (1); Skeena: Babine(2)3ulkley(2), Lakelse(l).Skeena(4); Stiidne: Iskut (4), Stddne (3); Ynkon: Atlin(l) ARCTIC: Liard: Dease(l l)fo rt Nelson (8), Kechika (l),Liard (7),Toad (1); Mackenzie: Hay(2) Peace: Beatton (1>, Finlay(l),Halfway (l)feace (7), Pine(3),Smoky(l) ECOPROVINCE/ECOREGION Boreal Plains : Peace River Basin (2), Central Alberta Uplands (3), Southern Alberta Uplands (3) Central Interior: Fraser Plateau (6) Coast & Monntains: Northern Coastal Mts. (1), Coastal Gq> (2)J4ass Basin (2)J4ass Ranges (3) Northern Boreal Monntains: H^and Highland (1), Liard Basin (10),Boreal Mountains and Plateaus (16), Northern Canadian Rocky Mountains (2) Snb-Boreal Interior : Skeena Mountains (2), Fraser Basin (15),Central Canadian Rocky Mountains (2), Omineca Mountains (2) Taiga Plains: Northern Alberta Uplands (2), Hay River Lowland (3), Hay River Lowland (4) Environmeiital Information: Maximum Measurement Std. Error Minimum Count Mean 1.50 26.50 Temperature CC) 61 18.70 0.55 98.00 2.77 8.00 Dissolved 0%(% Saturation) 61 67.58 987.00 238.87 23.11 20.10 Conductivity (pSiemens) 61 1.66 145.83 3.45 Calcium (m ^tre) 61 34.28 8.75 5.25 60 7.33 0.11 pH Previously recorded distribution in northern BC: Throughout northern BC (Clarke 1981). Discussion; Pisidium casertanum was a very common mollusc in northern BC being found at 81 of 176 sites. It was found in both the Pacific and Arctic drainages, in all the major watersheds, ecoprovinces and 207 Family Sphaeriidae Pisidium casertanum biogeoclimatic zones. The range and means of the environmental variables for the sites at which P. casertanum was collected are shown in Figure 2-14. Temperature: Figure 2-14a shows P. casertanum was collected at temperatures >2S°C suggesting that temperature may not be a limiting factor in the distribution of this species in northern BC. Dissolved Oxvaen: Figure 2-14b shows that P. casertanum was collected in habitats of very low dissolved oxygen (e.g., 8% saturation). This suggests that f . casertanum may be oxygen-independent and can tolerate low oxygen environments so that the oxygen saturation of a habitat may not be a limiting factor in the distribution of this species in northern BC. Conductivitv and Calcium Concentration: Figure 2-14c shows that P. casertanum was found at the lowest levels of conductivity/calcium concentration measured in this study. This suggests that the level of conductivity/calcium concentration may not be a limiting factor in the distribution of P. casertanum in northern BC. pH: Figure 2-14d shows that P. casertanum was found to occur over a broad range of pH including both acidic and alkaline conditions, down to a low level of pH = 5.25. Most of the other Pisidium species in this study appear to prefer for alkaline conditions. This lower tolerance by P. casertanum may allow it to live in habitats not accessible to many other Pisidium species and may not be a Actor greatly restricting its distribution in northern BC. The CCA results are that the Pisidium species are not responding significantly to the environmental variables measured in this study (p=0.225) with 3.7% of the species presence accounted for (Figure 2-20). The plot shows P. casertanum to occur near the origin of the variables but it is sliÿitly ofiset to lower than average dissolved oxygen and pH. This suggests that P. casertanum may be able to live in habitats of low dissolved oxygen and low pH, which may separate it ecologically firom many other members of this genus in this study. Clarke (1981) indicates that the range for P. casertanum is throu^out northern BC, which concurs with the findings of this study. This distribution gives no evidence of any barriers encountered during post-glacial dispersion. Clarke (1981) and Herrington (1962) state that P. casertanum is the most common species of Pisidium and that it is found in all types of permanent and temporary water habitats, which concurs with the findings of this study. 208 Family Sphaeriidae Pisidium compressum Pisidium compressum Prime, 1852 Ridgebeak peaclam Pisidkjm comprtssum SUES (29): N1000J^1001^1003/CN1013,N1006,N1008^1009, Nl011,N1015,N1016,N1060,N1062,N1082^109l, N1093J^l 102^1104^1106^1107^1110^1112, N0102^0108,N0109^0111.N0114J40134.CN1000, CN1004A1N1006 DRAINAGEAVATERSHED PACIFIC: Fraser: Fraser(3), Necfaako(S), Stuart(4); Skeena: Bulkley (1), Skeena (2); Stiidne: Iskut (1) ARCTIC: Liard: Dease (2); Peace: Omineca (1), Parsnip (2), Peace (8), Pine (1) ECOPROVINCE/ECOREGION Boreal Plains : Peace River Basin (2), Southern Figure A-SO - Collection sites for Pisidium compressum. Alberta Uplands (2) Central Interior : Fraser Plateau (2) Coast S t Mountains: Nass Basin(l), Nass Ranges(l) Northern Boreal Mountains: Boreal Mountains and Plateaus (1), Liard Basin (2) Sub-Boreal Interior: Fraser Basin (13), Omineca Mountains (2), Central Canadian Rocky Mountains (4) BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (10) Interior Cedar - Hemlock (2) Sub-Boreal Spruce ( 18) Enviromnental Information: Maximum Measurement Count Mean Std. Error Minimum Temperature (°C) 20 19.48 13.40 0.85 26.50 Dissolved 0%(% Saturation) 20 77.35 3.76 32.00 98.00 Conductivity (pSiemens) 20 195.38 17.65 94.60 434.00 Calcium (m ^tre) 20 27.80 12.77 2.63 63.37 20 7.79 0.14 6.35 8.75 pH Previously recorded distribution In northern BC: Throuÿiout northern BC (Clarke 1981). Discussion: Pisidium compressum was a common mollusc in northern BC being found at 29 of 176 sites. It was fotmd in both the Pacific and Arctic drainages and in all hut the Taiga Plains ecoprovince. It was absent from the northeast of the study area. The three BGC zones in which it was found have mean annual temperatures ranging from-2.9 to 8.7°C with iq> to 7 months below 0°C and tq>to 5 months above lOT. Altitude within these BGC zones ranges from 230 to 1500 m with mean annual precipitation ranging from 330 to 1200 mm. The range and means of the environmental variables measured at the sites at which P. compressum was collected are shown in Figure 2-14. 209 Family Sphseriidee Pisidmm compressum Temperature: Figure 2-14a shows that P. compressum was collected in habitats where the temperature was >25°C suggesting that high temperature may not be a limiting factor in the distribution of this species in northern BC. Dissolved Oxygen: Figure 2-14b shows that P. con^ressum was not collected in habitats of extremely low dissolved oxygen. This suggests that P. compressum may be an oxygen-dependent species, which may limits its distribution in northern BC. Conductivitv and Calcium: Figure 2-14c shows that P. compressum was not collected from the habitat of the lowest conductivity/calcium measured in this study. It may be that the minimum level at which P. compressum was found (12.8 mg/1), represents the minimum tolerable level for this species. pH: Figure 2-14d shows that unlike many other Pisidium species in this study, P. compressum was collected from habitats of both acidic and alkaline conditions, althouÿi more often in alkaline conditions. It was not found in the habitats of lowest pH measured in this study indicated that it may be somewhat intolerant of acidic conditions. This suggests that P. compressum may be somewhat limited in its distribution in northern BC by the pH level to the habitat. The CCA results are that the Pisidium species are not responding significantly to the environmental variables measured in this study (p=0.225) with 3.7% of the species presence accounted for (Figure 2-20). The plot of environmental variables shows P. con^ressum to occur near the origin of the variables but is slightly offret to hi^er than average dissolved oxygen and pH, which does not appear to be in accordance with the ecology of this species as discussed above. Clarice (1981) indicates that the range of P. con^ressum includes all of northern BC. While P. con^ressum was absent from the northeast of the study area, it was found east of the Rocky Mountains near Fort St. John. This range and Clarice’s (1981) observation that P. compressum occurs throughout northern Alberta and the NWT are consistent with this study. This widespread distribution gives no indication of any barriers encountered during post-glacial dispersion. Herrington (1962) and Clarke (1981) describe the habitat of P. compressum as permanent water bodies, such as lakes, and in the slow moving parts of creeks and rivers. These are the types of habitats in which f . compressum was collected during this study. 210 Family Sphaeriidae Pisidium convtntus Pisidium conventus Clessin, 1877 Alpine peaclam PmMumconvmaus 79 SITES (6): N1031,N1051,N1058,N1081,N1102,NI104 DRAINAGEAVATERSHED PACIFIC: Fraser: Nechako (I), Stuart (1); Nass: Nass (I) ARCTIC: Liard: Dease (I), Fort Nelson (I), Liard(1) ECOPROVINCE/ECOREGION Central Interior: Fraser Plateau (I) Coast & Mountains: Nass Basin (1) Northern Boreal Mountains: Liard Basin (2) Snb-Boreal Interior: Fraser Basin (I) Taiga Plains: Hay River Lowland (1) Figure A-S1 - Collection sites for Pisidium conventus. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (3) Interior Cedar - Hemlock 0 ) Sub-Boreal Spruce (2) Environmental Information: Maximum Std. Error Minimum Count Mean Measurement 14.50 1.46 23.80 Temperature C^) 6 19.48 45.00 80.17 7.35 93.00 6 Dissolved O2 (% Saturation) 94.60 256.70 69.95 550.00 Conductivity OiSiemens) 6 12.77 80.67 36.94 10.43 Calcium (mg/litre) 6 0.09 7.90 8.50 6 8.12 pH Previously recorded distribution in northern BC: T brou^ut northern BC (Clarke 1981). Discussion: Pisidium conventus was an uncommon mollusc of northern BC being found at six of 176 sites. It was found in both the Pacific and Arctic drainages in five of the six northern ecoprovinces. The three BGC zones in which it was found have mean annual temperatures ranging fiom -2.9 to 8.7T with up to 7 months below (PC and up to 5 months above KPC. Altitude within these BGC zones ranges fiom 230 to 1300m with mean annual precipitation ranging fiom 330 to 1200 mm. The range and means of the environmental variables for the sites at which P. conventus was collected are shown in Figure 2-14. Temperature: P. conventus is known as a cold-water species usually occurring in deep water (Clarice 1981). hi this study, it was often only shells that were collected thus, the relatively h i^ tençeratures at which this species was collected miÿit not be representative of the actual conditions at which this species would be found (Figure 2-14a). 211 Famfly Spliaeriidae Pisidium convenais Dissolved Oxvyen: Figure 2-14b shows that P. conventus was collected only firom habitats of relatively h i^ dissolved oxygen. This suggests that P. conventus may be an oxygen-dependent species. However, as discussed above, as often only shells were collected, the environmental variables measured at the sites where P. conventus was collected may not be representative of the actual conditions at which this species would be found. It may be expected that deep-water species would often encounter hypoxic situations and thus, may be oxygen-independent. Conductivitv and Calcium Concentration: Figure 2-14c shows that P. conventus was not collected fi-om the habitat of the lowest conductivity/calcium concentration measured in this study. It may be that the minimum level at which P. conventus was found (12.8 mg/1) represents the minimum tolerable level for this species. pH: Figure 2-14d shows that P. conventus displays a very narrow range of pH tolerance, being collected only in quite alkaline conditions. This may be a factor that affects the distribution of P. conventus in northern BC and that may separate it ecologically firom many other Pisidium species. The CCA results are that the Pisidium species are not responding significantly to the environmental variables measured in this study (p=0.22S) with 3.7% of the species presence accounted for (Figure 2-20). The plot shows P. conventus to correspond with hi^er than average pH. This seems to be an important environmental variable that may separate P. conventus firom other species of this genus. P. conventus is known firom much of Canada and its range includes all of northern BC (Clarice 1981). As almost all collections in this study were made from shallow areas near shore during the summer, it may be that P. conventus is much more common than indicated by the findings of this study but was in deeper, colder water. This widespread distribution gives no indication of any barriers imposed during post-glacial dispersion. (Clarke 1981) states that P. conventus is unusual, in that it is a cold-water species that lives primarily at considerable depths in large lakes within the temperate parts of its range, and at all depths within subarctic and arctic regions. Clarice (1979b) lists P. conventus as indicative of oligotrophic lakes, fit this study P. conventus was collected fiom lakes and ponds, which concurs with its known ecology of being found at shallower depth in the subarctic parts of its range. These habitats were not all oligotrophic and it may be that the designation of P. conventus as an indicator of oligotrophy may also only qrply in the southern part of its range, hi this study, one specimen was also collected from the slow moving area of a river. Identification of this one specimen was problematic and confirmation of this identification should be made before expanding the habitat types of this species. 212 Family spnaenioae Pisidium fallax Pisidium fallax Sterki, 1896 River peaclam SITES (4): NIOOO, NIOIO, N0102, N0103 DRAINAGE/WATERSHED PACIFIC; Fraser: Stuart (2) ARCTIC: Peace: Peace (1), Pine (1) ECOPROVINCE/ECOREGION Boreal Plains : Southern Alberta Uplands (1) Sub-Boreal Interior: Fraser Basin (3) BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (I) Sub-Boreal Spruce (3) V. Figure A-52 - Collection sites for Pisidiumfallax. Environmental Information: Maximum Std. Error Minimum Measurement Count Mean 19.60 18.50 0.55 19.05 2 Temperature C^) 87.00 10.50 66.00 76.50 Dissolved 0%(% Saturation) 2 321.00 59.00 203.00 Conductivity (pSiemens) 262.00 2 46.53 8.80 28.93 37.73 Calcium (mg/litre) 2 8.00 0.38 7.25 7.63 2 pH .. Previously recorded distribution in northern BC: Not previously recorded (Clarke 1981) Discussion: Pisidium fallax was an uncommon mollusc in northern BC being found at four of 176 sites. It was found in both the Pacific and Arctic drainages in only the two southeastern ecoprovinces. The two BGC zones in which it was found have mean annual temperatures ranging fiom -2.9 to 5.0 **Cwith up to 7 months below ifC and tq>to 5 month above 10°C. Altitudes within these BGC zones range fiom 230 to 1300 m and mean annual precipitation ranges fiom 330 to 990 mm. The range and means of the environmental variables for the sites at which P. falltu was collected are shown in Figure 2-14. Temperature: Figure 2-14a shows that P. fallax was collected only at relatively low temperatures. However, the small sanq>le size (n=2) does not allow any ecological hypothesis to be drawn fiom this data. 213 Family Spbacnidae Pisidiumfallax Dissolved Oxygen: Figure 2-I4b shows that P. fallax was collected only at relatively high levels of dissolved oxygen. However, the small sanqile size (n=2) does not allow any ecological hypothesis to be drawn from this data. Conductivity and Calcium Concentration: Figure 2-14c shows that P. fallax was collected only at relatively high levels of conductivity/calcium concentration. However, the small sample size (n=2) does not allow any ecological hypothesis to be drawn firomthis data. pH: Figure 2>14d shows that P. fallax was collected only at alkaline pH. This is very similar to the findings for many other species of Pisidium. However, the small sample size (n=2) does not allow any ecological hypothesis to be drawn fiom this data. The CCA results are that the Pisidium species are not responding significantly to the environmental variables measured in this study (p=0.225) with 3.7% of the species presence accounted for (Figure 2-20). The plot shows f .yü//ox to be associated with higher than average conductivity. While this concurs with the plots in Figure 2-14c, the small sample size does not allow formation of a unimodal response to any variable and its occurrence here is of limited ecological interpretability. The distribution of P. fallax has not been previously recorded to include northern BC (Clarice 1981). This species was not found often in this study and was only found in the southeast of the study area, which extends its range further west than previously described, and also into the Pacific drainage. Identification of the specimens collected in this study was problematic in that while the A2 anterior lateral tooth was very heavy, it did not display the twisting that characterizes this species. However, the specimens were identified as P. fallax as all other characteristics were closest to those described by Herrington (1962) as being distinctive to that species. Clarice (1981) states that P. fallax is uncommon and lives in rivers, streams, and exposed habitats in lakes. Herrington (1962) describes P. fallax as appearing to like moving water and having a substrate preference of sand or gravel. In this study, the specimens identified as P. fallax were collected from lakes and ponds having muddy bottoms. Confirmation of the identification of the specimens collected in this study this should be made before expanding the habitat types of this species. 214 FamflySphaeriidae Pisidium fetTUgineum Pisidium ferrugineum Prime, 1852 Rusty peaclam SUES (23): PlêkHmlémigineum N1007Jil0I4^l0l8J>{1033^1039^1046,Nl048, N1049JJ1052.N1054^1056J41059,N1064^1069, N 1075,N 1078,N 1098lO O ^l 111, N0107.N0115, N0120,CN1006 DRAINAGE/WATERSHED PACIFIC: Coastal: North Coast (1); Fraser: Fraser (1), Nechako (3);Skecna : Bulkley (1) StUdne: Stikine(2) ARCTIC: Liard: Dease(3), FortNelson(l),Liard (5),Toad (1); Mackenzie: Hay (1); Peace: Kiskatinaw (2), Peace (2) ECOPROVINCE/ECOREGION Boreal Plains: Peace River Basin (1), Southern Alberta Uplands (1) lanfenapatoi Nwaiaaan Figure A-S3 - Collection sites for Pisidiumferrugineum. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (14) Coastal Western Hemlock (I) Engelmann Spruce • Subalpine Fir (1) Interior Cedar • Hemlock (1) Sub-Boreal Spruce (6) Central Interior: Fraser Plateau (2) Coast & Mountains: Northern Coastal Mis. (1) Northern Boreal Mountains: Northern Canadian Rocky Mountains (1), Boreal Mountains and Plateaus (3), Liard Basin (6) Sub-Boreal Interior: Skeena Mountains (1), Central Canadian Rocky Mountains (1), Omineca Mountains (1), Fraser Basin (3) Taiga Plahis: Hay River Lowland (2) Environmental Information: Maximum Mcuurement Count Mean Std. Error Minimum 26.20 0.89 12.10 Temperature CC) 19 18.51 99.00 4.57 8.00 Dissolved 0%(% Saturation) 19 69.66 735.00 37.00 73.60 268.18 Conductivity (tiSiemens) 19 9.64 108.25 5.52 Calcium (mg/litre) 19 38.65 8.90 6.50 0.15 19 7.53 ....................... pH Previoiuly recorded distribution in northern BC: Throu^out mrthem BC (Clarke 1981). Discussion: Pisidium ferrugineum was a common mollusc in northern BC being found at 23 of 176 sites. It was found in both the Pacific and Arctic drainages in all of the six ecoprovinces. It was not collected within the Spruce-Willow-Birch BGC zone. The five BGC zones in which it was collected have mean annual temperatures ranging fiom -2.9 to 10.yC with up to 7 months below (fC and up to 6 months above KTC. Altitudes within these BGC zones ranges fiom 0 to 1700 m with mean annual precipitation ranging fiom 330 to 4400 mm. The range and means of the environmental variables for the sites at which P. ferrugineum was collected are shown in Figure 2-14. 215 F inily SphMiiidae PisidiumfemigiiKum Temperature: Figure 2-14a shows that P. ferrugineum was found at temperatures >2S°Csuggesting that temperature may not be a limiting factor in the distribution of this species in northern BC. Dissolved Oxygen: Figure 2-14b shows that P. ferrugineum was collected in habitats of very low dissolved oxygen (8% saturation). This suggests that P. ferrugineum may be oxygen-independent, able to tolerate low oxygen environments. Thus, the level of dissolved oxygen of a habitat may not be a limiting factor in the distribution of P. ferrugineum in northern BC. Conductivity and Calcium Concentration: Figure 2-14c shows that P.ferrupneum was not collected from the habitat of the lowest conductivity/calcium concentration measured in this study. It may be that the minimum level at which P. ferrugineum was found (9.6 mg/1) represents the minimum tolerable level for this species. pH: Figure 2-l4d shows that unlike many other Pisidium species, P. ferrugineum was collected firom habitats of both acidic and alkaline conditions, although more often in alkaline conditions. It was not found in the habitats of lowest pH measured in this study suggesting that it may be somewhat intolerant of acidic conditions. This suggests that P.ferrugineum may be somewhat limited in its distribution by the pH level of the habitat. The CCA results are that the Pisidium species are not responding significantly to the environmental variables measured in this study 0>=0-225) with 3.7% of the species presence accotmted for (Figure 2-20). The plot shows that P. ferrupneum corresponds to no particular variable and occurs very near the origin. Clarke (1981) indicates that the distribution of P. ferrugineum includes all of northern BC, which concurs with the findings of this study. This widespread distribution gives no indication of any barriers encountered during post-glacial dispersal. Clarke (1981) states that P. ferrugineum is found in lakes, ponds, rivers and streams which are the habitat types in which P. ferrugineum was found in this study. 216 Family SphMiiidae Pisidium idahoense Pisidium idahoense E.W. Roper, 1890 Giant northern peaclam PfêUkimUêhotia» SITES (17): NI009J<101i;^l056,NI062J^1067,N1068,N1073, N1080,N1082,N1092,N1102.N1 i04,CN1004 CN1008.CN1010J4N1004J4N1006 DRAINAGE/WATERSHED PACIFIC: Fraser: Fraser (l)J«Iecfaako (1),Stuart (I); Nasi: Meziadin (1); Skeena: Bulkley (1), Skeena (1); Stüdne: Iskut (1), Stddne (1) ARCTIC: Liard: Kechika(l)J)ease(3)JJard (1); Peace: Finlay (l),Om ineca(l)feace (l)fin e (1) ECOPROVINCE/ECOREGION Boreal Plains: Peace River Basin (1) Central Interior: Fraser Plateau (2) Coast & Mountains: Nass Basin (2) Northern Boreal Mountains: Northern Figure A-S4 - Collection sites for Pisidium idahoense. BIOGEOCLIMATIC ZONE Boréal White and Black Spruce (10) Interior Cedar • Hemlock (2) Spruce - Willow - Birch (1) Sub-Boreal Spruce (4) Canadian Rocky Mountains (1), Liard Basin (2), Boreal Mountains aixl Plateaus (S) Snb-Boreal Interior : Central Canadian Rocky Mts. (1), Omineca Mts. (1), Fraser Basin (2) Environmental Information: Measurement Std. Error Minimum Count Mean Maximum 1.14 22.20 Temperature CC) 12 16.93 8.70 Dissolved 0%(% Saturation) 1925 3.67 93.00 12 55.00 Conductivity (pSiemens) 336.00 12 173.63 19.80 94.60 Calcium (mg/litre) 12 24.55 2.95 12.77 48.76 8.04 0.14 12 6.90 8.55 pH .... _ Previously recorded distribution in northern BC: Throu^out noithem BC (Clarice 1981) Discussion: Pisidium idahoense was a common mollusc in noithem BC being found at 17 of 176 sites. It was found in both the Pacific and Arctic drainages in aU but the Taiga Plains ecopiovince and so was absent fiom the northeast of the study area. The four BCjC zones in which it was found have mean annual tenqteratures ranging fiom -3.0 to 8.7C with up to 7 months below (PC and up to S months above lOT. Altitudes within these BGC zones ranges fiom 230 to 1500 m with mean annual precipitation ranging fiom 330 to 1200 mm. The range and means of the environmental variables for the sites at which P. idahoense was collected are shown in Figure 2-14. 217 Family Sphaeriidae Pisidium idahoense Temperature: Figure 2-14a shows that P. idahoense was only collected in habitats of relatively low tenqierature. P. idahoense is known as a cooUwater species (Herrington 1962), most frequently found in cold arctic and mountain lakes (Clarice 1981). This suggests that the distribution of P. idahoense in northern BC may be somewhat limited in its distribution by intolerance for high water temperature. Dissolved Oxvyen: Figure 2-14b shows that P. idahoense was not collected in habitats of extremely low dissolved oxygen. This suggests that P. idahoense may be an oxygen-dependent species. This hypoxia intolerance may be a factor that limits the distribution of P. idahoense in northern BC. Conductivitv and Calcium: Figure 2-14c shows that P. idahoense was not collected from the habitat of the lowest conductivity/calcium measured in this study. It may be that the minimum level at which P. idahoense was found (12.8 mg/1) represents the minimum tolerable level for this species. pH: Figure 2-14d shows that P. idahoense was collected only from habitats of neutral to alkaline pH suggesting that it may be intolerant of acidic conditions. This may be a factor that limits the distribution of this species in northern BC. The CCA results are that the Pisidium species are not responding significantly to the environmental variables measured in this study (p=0.22S) with 3.7% of the species presence accounted for (Figure 2-20). The plot shows P. idahoense to appear in an area where it is not associated with a single variable. Clarice (1981) indicates that the distribution of P. idahoense includes all of northern BC. While P. idahoense was absent from collections made in the far northeast of the study area, the distribution mapped by Clarice includes northern Alberta and the North West Territories. Thus the distribution found in this study probably concurs with that of Clarke. This widespread distribution gives no evidence of any barriers imposed during post-glacial dispersion. Clarice (1981) describes P. idahoense as most frequerrtly being found in lakes, and that it is indicative of mesotrophic lakes (Clarice 1979b). In this study, it was most commonly found in lakes, but often these lakes tended to be oligotrophic. P. idahoense was also collected from the slow moving areas of rivers and streams. 218 Family Spbacnidae Pisidium insigne Pisidium insigne Gabb, 1868 Tiny peaclam Pfskuum maigne SUES (1): N1076 79 DRAINAGE/WATERSHED PACIFIC: N«ss: Bell Irving ECOPROVINCE/ECOREGION Sub>Boreal Interior: Skeena Mountains BIOGEOCLIMATIC (BGC) ZONE Interior Cedar - Hemlock Figure A-S5 - Collection sites for Pisidium insigne. Environmental Information: Measurement Coimt Observed Temperature (X) 1 22.60 Dissolved 0%(% Saturation) 1 64.00 Conductivity (pSiemens) 1 89.30 Calcium (m ^tre) 1 11.98 1 7.05 pH Previously recorded distribution fai northern BC: Not previously recorded (Clarke 1981). Discussion: Pisidium insigne was an uncommon mollusc in northern BC being found at one of 176 sites. It was found only in the Pacific drainage in the Sub-Boreal hrterior ecoprovince. The BGC zone in which it was found has a mean annual temperature of 2.0 to 8.TC with up to 5 months below (PC and up to S months above lOT. The altitude ranges form 100 to 1000 m with annual precipitation ranging fiom 500 to 1200 mm. P. insigne was collected fiom only one ecological site. The measure of the environmental variables at the site where P. insigne was collected are shown on Figure 2-14 as a dot. Environmental Variables: Figure 2-14 shows that the temperature, dissolved oxygen, conductivity/calcium concentration, and pH measured at the one site for P. insigne are within the range of measurements made for most other species within this genus. The measurements made with this single collection do not allow the formation of any hypotheses as to the ecology of this species. 219 Family Sphaeriidae Pisidium insigne The CCA results are that the Pisidium species are not responding significantly to the environmental variables measured in this study (p=0.22S) with 3.7% of the species presence accounted for (Figure 2-20). The plot shows P. insigne is not associated with a single variable. Clarice (1981) indicates that P. insigne is known in Canada only fiom four sites, none of which are in northern BC. This study increases the range for this uncommon species. This one site gives no evidence of any pattern of post-glacial dispersion. This species is very small with the adults less than 2 mm long and almost nothing is known about its biology (Clarke 1981). Clarice (1981) and Herrington (1962) state that P. insigne is found principally in slow moving creeks and spring creeks. In this study, P. insigne was found in a lake. 220 Family SphieriidM Pisidium Iilljeborgi Pisidium iilljeborgi Clessin, 1886 Lilljeborg peaclam SITES (15); NlOOl J41002,N1004JJ1005;^1006, Plaktum Hÿeborgi 7^ N1008,N1011,N1026,N1034,N1052J41054,N1060, N1063,CN1004>IN1003 DRAINAGE/WATERSHED PACIFIC: Fraser: Ncchako (I);StUdne: Iskut (1) ARCTIC: Liard: Dease (3), Fort Nelson (1), Liard (2); Peace: Parsnip (1), Peace (S), Pine (I) ECOPROVINCE/ECOREGION Boreal Plains : Central Alberta Uplands ( 1) Northern Boreal Mountains: Boreal Mountains and Plateaus (3), Liard Basin (3) Sub-Boreal Interior: Omineca Mountains (1), Central Canadian Rocky Mts. (2), Fraser Basin (4) Taiga Plains: Hay River Lowland (1) Figure A-S6 - Collection sites for Pisidium lilljeborp. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (8) Spruce - Willow - Birch (1) Sub-Boreal Spruce (6) Enviromncntal Infomiation: Maximum Measurement Count Mean Std. Error Minimum 27.20 Temperature (°C) 15.70 13 20.68 0.95 98.00 46.00 Dissolved 0%(% Saturation) 13 75.00 4.40 434.00 76.90 Conductivity (uSiemens) 28.84 13 221.52 63.37 10.13 31.69 Calcium (mg/litre) 13 4.30 8.90 6.95 7.70 0.17 pH 13 Previonsiy recorded distribution in northern BC: T hrou^ut northern BC (Clarke 1981). Discussion: Pisidium Iilljeborgi was a common mollusc of northern BC being found at 15 of 176 sites. It was found in both the Pacific and Arctic drainages in four of the six ecoprovinces not being collected fiom the southwest of the study area. The three BGC zones in which it was found have mean annual temperatures ranging fiom -3.0 to 5.0°C with up to 7 months below OC and up to 5 months above 10^ and with mean annual precipitation ranging fiom 330 to 990 mm. The range and means of the environmental variables for the sites at which P. lilljeborp was collected are shown in Figure 2-14. Temperature: Figure 2-14a shows P. Iilljeborgi was collected at temperatures >2ST suggesting that terrqrerature may not be a limiting factor in the distribution o f P. Iilljeborgi in northern BC. 221 Family Spkacriidw PIsldUuH lUljeborgi Dissolved Oxygen: Figure 2-14b shows that P. lUljeborgi was not collected in habitats of extremely low dissolved oxygen. This suggests that P. Iilljeborgi may be an oxygen-dependent species. This hypoxia intolerance may be a factor that limits the distribution o ff. lilljeborg in northern BC. Conductivitv and Calcium Concentration: Figure 2-14c shows that P. lUljeborgi was not collected from the habitat of the lowest conductivity/calcium concentration measured in this study. It may be that the minimum level at which P. Iilljeborgi was found (10.1 mg/1) represents the minimum tolerable level for this species. pH: Figure 2-14d shows that P. lUljeborgi was collected only from habitats of neutral to alkaline pH. It appears that P. lUljeborgi may be intolerant of acidic conditions and that this may be a factor that limits the distribution of this species in northern BC. The CCA results are that the Pisidium species are not responding significantly to the environmental variables measured in this study (p=0.22S) with 3.7% of the species presence accounted for (Figure 2-20). The plot shows P. lUljeborgi correlated to no particular environmental variable. Clarke (I98I) indicates that P. lUljeborgj is found throu^out northern BC which generally concurs with the findings of this study. Although P. lUljeborgi was not collected in the southwest of the study area, it has been collected fix>mcoastal locations elsewhere in BC (Lee and Ackerman 1998b). This widespread distribution gives no evidence of any barriers imposed during post-glacial distribution. Clarice (1981) and Herrington (1962) describe P. lUljeborgi as in all permanent water habitats with a preference for lakes, fit this study it was also found primarily in lakes with one collection from the slow moving area of a creek. 222 Family SphMiiidae Pisidium milium Pisidium milium H eld, 1836 Quadrangular pillclam Pam m m m m SITES (20): N1007J^1011,N1018,N1026,N1034J^I043,N1048, N1049,N1052,N1059,NI066,N1068,N1069J41072, N1074J41098J41 ! 11,N0104^0109,N0113 DRAINAGE/WATERSHED PACIFIC: Fraser: Fraser (1), Nechako (l), Smart (1); Skeena: Bulkley (1); Stüdne: Stildne (3) ARCTIC: Liard: Dease (3), Fort Nelson (2), Liard (3); Peace: Kiskatinaw (1), Peace (3), Pine (1) ECOPROVINCE/ECOREGION Boreal Plains :Central Alberta Uplands (1), Peace River Basin (1) Central Interior: Fraser Plateau (1) Northern Boreal Mountains: Liard Basin (4), Sab>Boreal Interior: Omineca Mountains (1), Central Canadian Rocky Mts. (2), Fraser Basin (3) Taiga Plains: Hay River Lowland (2) Figure A-S7 - Collection sites for Pisidium milium. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (14) Engelmann Spruce - Subalpine Fir (1) Sub-Boreal Spruce (5) Environmental Information: Maximum Std. Error Minimum Measurement Count Mean 27.20 0.98 12.10 17 Temperature (°C) 18.11 98.00 72.09 4.84 8.00 17 Dissolved 0%(% Saturation) 475.00 26.73 66.40 Conductivity (^Siemens) 17 266.00 69.49 3.99 8.S6 17 38.33 Calcium (mg/litre) 8.90 0.16 6.50 17 7.46 pH Previously recorded distribution in northern BC: Not previously recorded (Clarke 1981). Discussion: Pisidium milium was a common mollusc in northern BC found at 20 of 176 sites. It was found in both the Pacific and Arctic drainages and was absent from the Coast and Mountains ecoprovince in the southwest of the study area. The three BGC zones in which it was found have mean annual temperatures ranging from -2.9°C to 5.0^ with up to 7 mnnths below 0 ^ and up to S month above 10^. Annual precipitation in these zones range from 330 to 2200 mm. The range and means of the environmental variables for the sites at which P. milium was collected are shown in Figure 2-14. Temperature: Figure 2-14a shows that P. milium was collected in habitats where the temperature was >25°C suggesting that h i^ tenq>erature may not be a limiting factor in the distribution of this species in northern BC. 223 Family Sptaaeriidae Pisidhim milium Dissolved Oxvyen: Figure 2-14b shows that P. milium was collected in habitats of very low dissolved oxygen (e g., 8% saturation). This suggests that P. milium may be oxygen-independent and can tolerate hypoxic conditions. Thus, the level of dissolved oxygen of a habitat may not be a factor that limits the distribution of P. milium in northern BC. Conductivitv and Calcium Concentration: Figure 2-14c shows that P. milium was not collected from the habitat of the lowest conductivity/calcium measured in this study. It may be that the minimum level at which P. milium was found (7.5 mg/1) represents the minimum tolerable level for this species. pH: Figure 2-14d shows that unlike many other Pisidium species, P. milium was collected from habitats of both acidic and alkaline conditions, although more often in alkaline conditions. It was not found in the habitats of lowest pH measured in this smdy, indicated that it may be somewhat intolerant of acidic conditions. This suggests that the pH level to the habitat may limit the distribution of P. milium in northern BC. The CCA results are that the Pisidium species are not responding significantly to the environmental variables measured in this study (p=0.225) with 3.7% of the species presence accounted for (Figure 2-20). The plot shows that P. milium does not correspond to a single variable, as it appears on the plot near the origin. Clarke (1981) indicates that the distribution of P. milium does not include northern BC. P. milium was found throu^out northern BC in this study increasing its range much further west in general, and much fiirther north in BC. This widespread distribution gives no indication of any barriers encountered during post-glacial dispersion. Clarke (1981) describes P. milium as uncommon and living in lakes, ponds, and slow-moving streams, hi this study, P. milium was not uncommon, but was found living in the type of habitats as described by Clarke. 224 Family Sphaeriidae Pisidium ititidum Pisidium nitidum Jenyns, 1832 Shiny peaclam SITES (13): PfaUkantMdum N1003,N1005J<1011,NIOI4,N1018J>J1034J41055, N1058,N1059.N0110,N0120,CN1000,CN1014 DRAINAGE/WATERSHED PACIFIC: Fraser: Ncchako (1), Stuart (I) ARCTIC: Liard: Dease (2), Fort Nelson (1), Liard (l);Peace: Kiskatinaw(2), Peace (4), Pine (1) ECOPROVINCE/ECOREGION Boreal Plains: Peace River Basin (1), Southern Alberta Uplands (2) Central Interior : Fraser Plateau (1) Northern Boreal Mountains: Liard Basin (3) Sub-Boreal Interior: Central Canadian Rocky Mountains (1), Fraser Basin (4) Taiga Plains: Hay River Lowland (1) Figure A-S8 - Collection sites for Pisidium nitidum. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (8) Sub-Boreal Spruce (S) Environmental Information: Measurement Count Mean Std. Error Minimum Maximum Temperature C*C) 9 16.00 20.36 1.43 27.20 Dissolved 0%(% Saturation) 9 70.56 59.00 2.68 81.00 Conductivity (pSiemens) 9 239.37 146.80 23.62 336.00 Calcium (mg/litre) 9 34.35 20.55 3.52 48.76 9 7.80 0.13 7.05 pH 8.30 Previously recorded distribution in northern BC: Eastern area only (Clarke 1981). Discussion: Pisidium nitidum was a common mollusc in northern BC being found at 13 of 176 sites. It was found in both the Pacific and Arctic drainages in all but the Coast and Mountains ecoprovince in the southwest of the study area. The two BGC zones in which it was found have mean annual temperatures ranging from -2.9 to S.O °C with up to 7 months below (PC and up to 5 months above KXC and with annual precipitation ranging from 330 to 990 mm. The range and means of the environmental variables for the sites at which P. nitidum was collected are shown in Figure 2-14. Temperature: Figure 2-I4a shows that P. nitidum was collected at tenqieratures >25"C suggesting that h i^ temperature may not be a limiting factor in the distribution of this species in northern BC. 225 Funiiy Sphaeriidae Pisidium nitidum Dissolved Oxygen: Figure 2-14b shows that P. nitidum was collected in habitats of relatively high dissolved oxygen. This suggests that P. nitidum may be an oxygen-dependent species. This hypoxia intolerance may be a factor that limits the distribution of P. nitidum in northern BC. Conductivitv and Calcium Concentration: Figure 2-14c shows that P. nitidum was not collected from the habitat of the lowest conductivity/calcium concentration measured in this study. It may be that the minimum level at which P. nitidum was found (18.3 mg/1) represents the minimum tolerable level for this species. qH: Figure 2-14d shows that P. nitidum was collected only from habitats of neutral to alkaline pH. This suggests that P. nitidum may be intolerant of acidic conditions and that this may be a factor that limits the distribution of this species in northern BC. The CCA results are that the Pisidium species are not responding significantly to the environmental variables measured in this study (p=0.225) with 3.7% of the species presence accounted for (Figure 2-20). The plot shows P. nitidum to correspond to no particular variable. Clarke (1981) indicates that the range of P. nitidum includes the eastern area of northern BC. Most of the collections made of P. nitidum in this study concur with this area, however, there were two collections made in the central northern region of the study area which extends the range further west than that indicated by Clarke. Clarke (1981) states that states that P. nitidum lives in all kinds of perennial water habitats, hr this study it was collected fiom lakes, ponds and streams. 226 FimilySphacnidae Pisidiimpunetatum Pisidium punctatum* Sterki, 1895 Perforated peaclam PiMiumpunctatum SITES (1): N1030 DRAINAGEAVATERSHED ARCTIC; Liard: Fort Nelson ECOPROVINCE/ECOREGION Taiga Plains: Hay River Lowland BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce Figure A-S9 - Collection sites for Pisidium punctatum. Environmental Information: Meuuremcnt Count Mean Std. Error • Temperature (°C) 1 18.10 Dissolved 0%(% Saturation) 1 56.00 • Conductivity (pSiemens) 1 313.00 Calcium (m ^tre) 1 45.33 1 7.05 pH Minimum Maximum 18.10 18.10 56.00 56.00 313.00 313.00 45.33 45.33 7.05 7.05 Previously recorded distribution in northern BC: Not previously recorded (Clarice 1981). Discussion: Pisidium punctatum was an uncommon mollusc in northern BC being found at one of 176 sites. It was found only in the Arctic drainage in the Taiga Plains ecoprovince. The BGC zone in which it was found has mean annual tenqierature of -2.9 to 2.(FC with up to 7 months below 0 ^ and up to 4 month above KXC with annual precipitation of330 to 570 nun P. punctatum was collected only at one ecological site. The environmental variables at the one site where P. punctatum was collected are shown in Figure 2-14 by a dot. Environmental Variables: The temperature, dissolved oxygen and conductiyity, and pH measured at this one site were within the range of measurements made for most other species within this genus. The single collection does not allow the formation of any hypotheses as to the ecology of this species in regards to these four variables. 227 Fanily Sphaeriidae Pisidium puncurum The CCA results are that the Pisidium species are not responding significantly to the environmental variables measured in this study (p=0.225) with 3.7% of the species presence accounted for (Figure 2-20). The plot shows P. punctatum to correspond to no particular variable. Clarke (1981) indicates the distribution of P. punctatum does not include northern BC and that it occurs only in scattered localities in southern Canada. The identification of this species was problematic as there were only two very small delicate specimens but the features seemed to indicate that P. punctatum was the closest fit for identification. The range distribution for this species should not be changed until this identification is confirmed. Clarke (1981) describes that habitat of P. punctatum as lakes and slow-moving portions of river and streams. In this study, the specimens identified as P. punctatum were collected firom a flooded wetland. The habitat types described for this species should not be changed until the identification of the specimens collected in this study are confirmed. *Note: Herrington (1962) refers to this species as P. punctiferum but later corrects this identification (Herrington 1965). 228 Finiily Sphaeriidae Pisidium roeadatum ■ H i* Pisidium rotundatum* Prime, 1852 Fat peaclam PftJdiumrotundatum SITES (1): CN1008 DRAINAGE/WATERSHED ARCTIC: Liard: Kechika r- ECOPROVINCE/ECOREGION Northern Boreal Mountains: Boreal Mountains and Plateaus BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce Figure A-60 - Collection sites for Pisidium rotundatum. Previously recorded distribution in northern BC: Not previously recorded (Clarke 1981). Discussion: Clarke (1981) does not include northern BC in the distribution of Pisidium rotundatum even thouÿi he made this collection in Dali Lake in 1972. As he chose not to include this in his information, and as P. rotundatum was not collected elsewhere in northern BC during this study, there may be some question as to the identification of this collection. It is included here only to provide a synoptic record of all collections fin>mnorthern BC. *Note: Herrington (1962) refers to this species as P. obtusale; Herrington (1965) revises this to P. ventricosum, form rotundatum; Clarke (1973b) and Burch (1975a) also uses P. ventricosum, form rotundatum; Clarke (1981) and Turgeon et al. (1998) used P. rotundatum which is the nomenclature followed in this study. 229 Family Sphaeriidae Pisidium variabile Pisidium variabile Prime, 1852 Triangular peaclam SITES (48): N1002,N1006,N1008/CN1013, N1009,N1014,N1015^1025.N1029JJ103I,N1032, N1033,N1043,N1048,N1049,N1051JJ1052,N1053, NI054,N1055,N1056J<1057J»I1059^1065^1067, N1068.N1069,N1072,N1073,N1075J^1076,N1080, N1081,N1084^1088,N1093,N1112JI0104,N0115, NOl 16.N0117.N0119,N0130Ji0136,N0137, CN1000,CN1005,CN1008,MN1008 DRAINAGE/WATERSHED PACIFIC: Coastal: North Coast (1); Fraser: Fraser (3), Nechako (4), Stuart (2);Nass: Bell-Irving (l»feziadin (1), Nass (l);Skecna: Bulkley (1), Lakelse (1); Stildne: Stddne (4) ARCTIC: Liard: Kechika(I)43ease (S )ft Nelson (S),Liard (9); Peace: Beatton (2), Kiskatinaw (1), Parsnip (1), Peace (3), Pine (1), Smoky (1) ECOPROVINCE/ECOREGION Boreal Plains : Central Alberta Uplands (1), Muskwa Figure A-61 - Collection sites for Pisidium variabile. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (30) Coastal Western Hemlock (2) Interior Cedar • Hemlock (4) Sub-Boreal Spruce (12) Plateau (1), Peace River Basin (2), Southern Alberta Uplands (3) Central Interior: Fraser Plateau (3) Coast & Mountains: Coastal Gap(2),Nass Basin (2) Northern Boreal Mountains: Liard Basin (10), Boreal Mountains and Plateaus (8) Snb-Boreal Interior : Skeena Mountains (2), Omineca Mountains (1), Central Canadian Rocky Mountains (1), Fraser Basin (7) Taiga Plains: Hay River Lowland (4), Northern Alberta Uplands (1) Enviromncntal Information: Measurement Std. Error Minimum Count Mean Maximum Temperature CC) 18.49 0.67 26.50 36 8.70 Dissolved 0%(% Saturation) 2.64 41.00 98.00 36 71.83 550.00 Conductivity (uSiemens) 224.12 19.70 36 20.36 80.67 Calcium (mg/litre) 32.08 3.04 1.60 36 7.53 8.90 36 0.15 5.15 pH Previously recorded distribution in northern BC: Throughout northern BC (Clarice 1981). Discussion: Pisidium variabile was a common mollusc in northern BC being found at 48 of 176 sites. It was found both the Pacific and Arctic drainages and in all of the ecoprovinces. The four BGC zones in which it was found have mean aimual temperatures ranging from -2.9 to lO.S'C with up to 7 months below (PC and up to 6 months above lOT and with amtual precipitation ranging from 330 to 4400 mm. The range and means of the environmental variables for the sites at which P. variabile was collected are shown in Figure 2-14. 230 Family Sphaeriidae Pisidium variabile Temperature: Figure 2-14a shows P. variabile was collected at temperatures >2S°C suggesting that high temperature may not be a limiting factor in the distribution of P. variabile in northern BC. Dissolved Oxygen: Figure 2-14b shows that P. variabile was not collected in habitats of extremely low dissolved oxygen. This suggests that P. variabile may be an oxygen-dependent species. This hypoxia intolerance may be a factor that limits the distribution of P. variabile in northern BC. Conductivitv and Calcium: Figure 2-14c shows that P. variabile was found at the lowest levels of conductivity/calcium measured in this study. This suggests that the level of conductivity/calcium may not be a limiting factor in the distribution of P. variabile in noithem BC. pH: Figure 2-14d shows that P. variabile was found to occur over a broad range of pH including both acidic and alkaline conditions and was collected at the lowest pH measured for this family. This suggests that pH may not be a factor that greatly limits the distribution of P. variabile in northem BC. The CCA results are that the Pisidium species are not responding significantly to the environmental variables measured in this study (p=0.22S) with 3.7% of the species presence accounted for (Figure 2-20). The plot shows P. variabile to occur very near the origin and so is correlated to no particular variable. Clarice (1981) indicates that the range of P. variabile is th ro u ^u t northem BC, which concurs with the findings of this study. This widespread distribution gives no indication of any barriers encountered during post-glacial dispersion. Clarice (1981) describes P. variabile as occurring in all natural perennial water habitats. This concurs with the findings of this study where P. variabile was collected fiom lakes, ponds and slowmoving areas in creeks, but it was also collected once fiom a highway ditch that had a few pockets of water. 231 Funiiy Sphaeriidae Pisidium veiuricosum Pisidium ventricosum (Prime, 1851) Globular peaclam Pisidium wntncosum SITES (25): N1002J^l0l0,N1014.NI023,N1026Jil027,Nl029, N103IJ41033JI1034^1040J41041J^1048,N1054, N1056^1065,N1069a41072,N1075J41088J4l096, N1097.NI 111, N0I04 DRAINAGE/WATERSHED PACIFIC: Coastal: North Coast (1); Fraser: Fraser (1), Nechako (1), Stuart (l);Skeena: Sabine (2) Stildne: Stildne (3); Yukon: Atlin (1) ARCTIC; Liard: Dease (1), Fort Nelson (S), Liard (3); Peace: Beatton (1), Halfway (1), Kiskatinaw (1), Peace (2), Pine (1) ECOPROVINCE/ECOREGION Boreal Plains: Muskwa Plateau (1), Peace River Figure A*62 - Collection sites for Pisidium ventricosum. BIOGEOCLIMATIC (BGC) ZONE Boreal White and Black Spruce (18) Coastal Western Hemlock (1) Engelmann Spruce - Subalpine Fir (1) Interior Cedar • Hemlock (1) Sub-Boreal Spruce (4) Basin (1), Central Alberta Uplands (2), Southern Alberta Uplands (2) Coast & Mountains: Coastal Gap (1) Northern Boreal Mountaiu: Liard Basin (3), Boreal Mountains and Plateaus (4) Sub-Boreal Interior : Skeena Mountains (1), Central Canadian Rocky Mts. (1), Fraser Basin (4) Taiga Plains: Hay River Lowland (S) Envirooinental Infomutioa: Measurement Std. Error Minimum Maiimum Count Mean TenqieratureCC) 20.07 10.40 2120 23 0.85 3.84 87.00 Dissolved O2 (% Saturation) 19.00 23 65.72 Conductivity (uSiemens) 27.36 19.70 475.00 209.20 23 Calcium (mg/litre) 69.49 4.08 1.60 23 29.86 8.50 0.19 5.25 7.16 23 pH Previously recorded distributioB in northern BC: Not pieviously lecoided (Clarke 1981). Discussion: Pisidium ventricosum was a common mollusc in northern BC being found at 25 of 176 sites. It was found in both the Pacific and Arctic drainages in all but the Central bterior ecoprovince. The five BGC zones in which it was found have mean annual tenqieratures ranging fiom -2.9 to 10.5"C with up to 7 months below (PC and tq> to 6 months above 10°C and with annual precipitation ranging fiom 330 to 4400 mm. The range and means of the environmeniai variables for the sites at which P. ventricosum was collected are shown in Figure 2-14. 232 Family SphMtüdae Pisidium vetioicosum Temperature: Figure 2-14a shows P. variabile was collected at temperatures >2S°C suggesting that high tenqierature may not be a limiting factor in the distribution of P. variabile in noithem BC. Dissolved Oxygen: Figure 2-14b shows that P. ventricosum was collected in habitats of low dissolved oxygen (19% saturation). This suggests that P. ventricosum may be oxygen-independent and so may tolerate low oxygen environments. Thus, the level of dissolved oxygen of a habitat may not be a limiting factor in the distribution of P. ventricosum in northem BC. Conductivitv and Calcium Concentration: Figure 2-14c shows that P. ventricosum was found at the lowest levels of conductivity/calcium concentration measured in this study. This suggests that the level of conductivity/calcium may not be a limiting factor in the distribution of P. ventricosum in northem BC. pH: Figure 2-14d shows that P. ventricosum was found to occur over a broad range of pH including both acidic and alkaline conditions, and was collected at close to the lowest pH measured for collections for this family. This suggests that pH may not be a limiting factor in the distribution of P. variabile in northem BC. The CCA results are that the Pisidium species are not responding significantly to the environmental variables measured in this study (p=0.225) with 3.7% of the species presence accounted for (Figure 2-20). The plot shows P. ventricosum to occur very near the origin and so it is not associated with a single variable. Clarice (1981) indicates that the range of P. ventricosum does not include northem BC. This is a very different distribution than that found in this study, where P. ventricosum was found throughout the study area. This widespread distribution gives no indication of any barriers encountered during post­ glacial dispersal. Clarice (1981) states that P. ventricosum lives in perennial water lakes, ponds, rivers and streams of all sizes. In this study P. ventricosum was found in lakes and ponds, but never in flowing water. 233 Family Sphaeriidae Pisidium sp. Pisidium sp. PIMiumap. SITES (1): N1064 DRAINAGE/WATERSHED ARCTIC; Liard: Dease ECOPROVINCE/ECOREGION Northem Boréal Mountains: Boreal Mountains and Plateaus BIOGEOCLIMATIC ZONE Boreal White and Black Spruce Figure A-63 - Collection sites for Pisidium sp. Environmental Information: Meuuremcnt Count Observed Temperature (T ) 13.80 1 Dissolved O2 (% Saturation) 70.00 I Conductivity (uSiemens) 93.60 1 Calcium (moitié) 1 12.62 6.85 1 .................. pH Discussion: This collection was different than other Pisidium species collected in this study but could not be identified to species. It seemed to best fit the description of Pisidium ultramontanum but as this species has been suggested for endangered species listing in the United States (Frest and Johannes 199S), it did not seem appnqmate to attach this speats name to this collection until the identification can be confinned. However, this unidentified species may be an important component of the freshwater mollusc fauna of noithem BC and its ecological assessment is included here. This collection was made firom a pond. This unknown Pisidium sp. was an uncommon mollusc of noithem BC being collected at one of 176 sites. It was found only in the Arctic drainage in the Northem Boreal Mountains ecoprovince. The BGC zone in which it was found has a mean annual temperature ranging firom -2.9 to 2.(FC with up to 7 months below 0 ^ and up to 4 months above lOT and with annual precipitation ranging fiom 330 to 570 mm. 234 Family SpliaeriidM Pisidium sp. Environmental Variables: The measures of the environmental variables for the site for Pisidium sp. are shown in Figure 2-14 as dots. Figure 2-14 shows that Pisidium sp. was collected at a relatively low tenqierature, average dissolved oxygen, low conductivity, and average pH. The single collection does not allow the formation of any hypotheses as to the ecology of this species with regard to these factors. The CCA results are that the Pisidium species are not responding significantly to the environmental variables measured in this study (p=0.225) with 3.7% of the species presence accounted for (Figure 2-20). The plot shows Pisidium sp. to be associated with low pH and conductivity. The small sample size for this species does not allow this placement on the plot to be interpreted ecologically. If expert identification of this species does result in this collection being identified as P. ultramontanum, this will be the first record for this species in BC. 235 Nil sites Sites w h e re fre s h w a te r m olluscs w e re n o t collected SITES (6): N1013, NI024, NI045, NI079, N1086, NI087 NUsitM DRAINAGEAVATERSHED PACIFIC! Coastal: North Coast; Nats: Meziadin; Skeena: Skeena ARCTIC: Peace: Smoky, Beatton; Liard: Fort Nelson ECOPROVINCE/ECOREGION Coast & Mountains: Coastal Gap (2), Northem Coastal Mountains Boreal Plains: Central Alberta Uplands, Southern Albeita Uplands Northem Boreal Mountains: Northem Canadian Rocky Mountains %. Figure A-64 - Ecological sites where molluscs were not collected. BIOGEOCLIMATIC ZONE Boreal Black and White Spruce (2) Coastal Westem Hemlock (2) Engelmann Spruce - Subalpine Fir (1) Spruce - Willow - Birch (1) Environmental Information: Mean SE N1079 N0186 N1087 Memsurement NI013 N1024 NI04S 16.18 1.79 18.20 20.40 18.00 12.70 9.00 Temperature 18.80 55.17 10.05 18.00 64.00 64.00 86.00 Dissolved Oxygen 65.00 34.00 223.52 65.86 81.50 155.20 218.00 540.00 168.40 178.00 Conductivity 9.54 28.63 8.85 19.45 27.89 71.17 21.22 Calcium 22.51 6.19 0.63 3.95 4.75 7.95 7.25 6.90 6.35 pH . . .... Mean and SE of sites Mean and SE of nil sites(n>^ with moUuscs (n*l08) 16.181 1.79 Temperature 18.96 ± 0.44 55.17110.05 Dissolved Oxygen 68.61 ± 2.19 223.52165.86 Conductivity 284.03 1 25.03 28.631 8.85 Calcium 41.0513.73 6.191 0.63 7.421 0.08 p H ..................... ... Measurement p = value df p = 0.148 p =0.163 p = 0.575 p = 0.440 p = 0.001 112 112 112 112 111 Site Descriptions: N1013: Large oligotrophic lake, substrate of small rocks; searched area near boat launch only. N1024: Recently abandoned beaver pond. Pond is now full of grass with a creek running throuÿr it. There were a few pools of standing water that appeared to offer suitable mollusc habitat but none were found. N1045: Swept lots of vegetation and scooped bottom but no success. According to BC Paries staff, this 236 NU sites lake fieezes completely in the winter. N1079: Habitat, especially mud bottom, appears suitable but water is very cold and is probably coming from nearby glacier. N1086: Appears to be suitable habitat; water brown and has very low pH. N1087: Water very brown with low pH. While the above t-tests show that the sites where no molluscs were found differed significantly fiom the rest of the ecological sites in pH, there may be other reasons why there were not molluscs found at these sites. Site N1013 may have had molluscs elsewhere in the lake but they were not found at the rocky, boat launch area. SiteN0124 had been recently undergone dramatic changes fiom a large beaver pond to scattered wet areas and there may not have been sufGcient time for these areas to become populated by molluscs. Site N1045 fieezes entirely in the winter leaving no refuge area for molluscs. Site N1079 was being fed by glacial melt and so the water source may be seasonal. Sites N1086 and 1087 were close to each other and had very low pH, probably too low to provide suitable circumstances for shell deposition in molluscs. 237 Ecoprovinces AlbM Equal A im Conic Piqjadion NAD 83 Datum Figure A*6S. The ecoprovinces of northern British Columbia. indicates a collection site. 238