The Chun T’Oh Wudujut is a provincial park located in the Interior Cedar-Hemlock biogeoclimatic zone. My objective was to assess the use of carabid beetles as bioindicators of change in this unique interior temperate rain forest ecosystem. Using a combination of morphotyping and DNA barcoding, I examined the diversity of carabid beetles in three different habitat types: clear-cuts, undisturbed old growth, and disturbed old growth subject to frequent human traffic. Nineteen species of carabid were observed, with the highest diversity occurring in clear-cut sites. Carabid diversity in both old growth habitats was similar, but differed from that in the clear-cuts. Temperature and relative humidity proved more variable in clear-cut sites; this may impact carabid biodiversity, and should be measured in future bioindicative studies. Several species of carabid beetles (alone and in combination) were identified as possible bioindicators, including Scaphinotus marginatus, Trechus chalybeus, Pterostichus herculaneus, and Pterostichus riparius.
Innovative technologies to combat environmental pollution are a significant part of sustainability research due to their increasing economic and environmental impact. The present biological process-based research study described herein was conducted in three phases. It investigated the effects of rhamnolipid-enhanced soil washing (phase 1), bioremediation treatment using indigenous microorganisms (phase 2), and the effect of four specific environmental and nutritional conditions (phase 3) on the biodegradation of petroleum hydrocarbons (PHC) in drill cuttings and petroleum-contaminated soil obtained from sites in northeastern British Columbia. For phase 1, maximum PHC reduction recorded for total petroleum hydrocarbon (TPH) and the petroleum hydrocarbon fractions- F2, F3 and F4 fractions was 58.5%, 48.4%, 63.5% and 59.8% respectively for petroleum-contaminated soil, and 76.8%, 85.4%, 71.3% and 76.9% respectively for drill cuttings. In phase 2, maximum PHC reduction of TPH, F2 and F3 fractions was 94.9%, 98.8% and 94.0% respectively for petroleum-contaminated soil and 82.6%, 94.9% and 59.5% respectively for drill cuttings following 50 days of rhamnolipid-mediated biodegradation treatment. Results from experiments conducted in phase 3 confirmed the importance of oxygen availability in biodegradation and indicated the inhibitory effects of excessive addition of biosurfactants and nutrients to hydrocarbon biodegradation treatments. Promising TPH degradation results were observed in conditions that normally slow down biodegradation. TPH degradation of 59.0%, 59.8% and 56.7% were observed in experiments conducted at an average temperature of ‒7.46 °C, and in waterlogged and air-tight conditions respectively. These results provide important insight on rhamnolipid-mediated biodegradation and indicate the high potential of rhamnolipid washing and bioremediation treatments as a combined approach to reduce PHC to levels within regulatory standards.
Food webs are challenging to describe, particularly for generalist predators whose diet consists largely of taxonomically diverse invertebrates. To better understand predator-prey relationships for fish belonging to Salmonidae and Cottidae, I compared traditional morphological identification of prey with sequencing of individual items and next generation sequencing of fish stomach homogenates. I also used next generation sequencing to assess invertebrate biodiversity from environmental DNA samples – stream water, ethanol preservative from Surber samples and fish stomach homogenates. Morphological identification was often limited to the Order level but allowed for quantitative data. Genetic analysis provided substantially greater taxonomic resolution, with sequencing of stomach homogenates revealing a much more diverse diet in fish. Water samples detected terrestrial and aquatic invertebrate species and Surber ethanol revealed a similar invertebrate diversity as fish stomach homogenates. Fish, however, appeared to be generalist feeders and collectively accounted for the greatest number of unique taxa.
Smolting is an important time in the life of anadromous salmon when juveniles undergo changes that prepare them for life in the ocean. Widely distributed salmon populations have evolved based on the selective pressures of their local environments. I examined population differences in the development, duration (smolt window) and loss of seawater tolerance, how temperature influenced development among populations, and temperature preference throughout smolting in coho salmon (Oncorhynchus kisutch). For my first objective, I compared smolt development among three populations in British Columbia, Canada that each had different migration distances to the ocean. In year one, fish appeared to undergo an incomplete smoltification based on the biochemical marker Na+/K+-ATPase (NKA). Additionally, molecular markers (mRNA expression of gill NKA α1a, NKA α1b, as well as growth hormone (GHR), prolactin (PrlR) and glucocorticoid (GR1) receptors) suggest that fish also did fully develop physiological changes associated with smolting. In year two, the smolt window (approximately 300 accumulated thermal units – ATU) did not differ by population as evident by elevated NKA activity. Molecular markers (gill NKA α1a, NKA α1b, GHR, and PrlR) for smolting also did not show a population difference – indicating that distinct populations do not differ in their development, duration, or loss of seawater tolerance. For my second objective, I examined temperature preference in short- and long-distance migrating populations of coho salmon juveniles. Mean temperature preference did not differ between the two populations (15.9 °C and 16.1 °C) and did not change throughout smolting. Based on the observed temperature preferences, smolts do not prefer temperatures that are advantageous for prolonging the smolt window. Additionally, the disparity between temperature preference and what is likely available in the environment at the time of smolting demonstrates that temperature is not a selective pressure for juveniles to behaviourally regulate the development of seawater tolerance.
Life histories of Pacific salmon are remarkable in that they return to specific freshwater sites to spawn after multiple years of ocean residence. In Chapter 1, I investigated site fidelity at a reach scale for Interior Fraser Coho Salmon (Oncorhynchus kisutch) (IFC). Coho Salmon eggs were incubated at known spawning locations in the Coldwater River, British Columbia, to obtain reference data for comparison to otolith signatures of returning adult salmon. The majority of adults (67%) returned to their natal spawning locations at the reach scale, while 33% strayed to other spawning sites within the Coldwater River, illustrating straying at small scales. Straying to novel incubation sites at the reach scale demonstrated plasticity in homing within a watershed. In Chapter 2, I investigated the characteristics of the hyporheic redd zone over two years where Coho Salmon were observed to spawn. Within a reach, physical variables were homogenous, but heterogeneity was found among reaches where Coho Salmon were observed to spawn – particularly for intragravel temperature and dissolved oxygen. The difference in temperature and dissolved oxygen among sites had a pronounced effect on survival, rate of development, and emergence time for Coho Salmon fry. Heterogeneity among spawning locations demonstrate trade-offs that exist between rate of development and survival. Chapter 3 investigated the effect of low and variable dissolved oxygen on developing salmon embryos. A family effect was found as smaller eggs produced smaller alevin, but the effect of low dissolved oxygen on growth was also greater for the families with small eggs. Treatment affected rate of development and initially had an effect on length and mass, but by button-up there was no longer an effect of low dissolved oxygen on size. My work demonstrates plasticity in Coho Salmon at different life stages. Plasticity is important for utilizing new habitats or adapting to existing habitats as they change.
