Jones, Nick

Brook trout (Salvelinus fontinalis) are declining across Ontario in both numbers and distribution, prompting concern for their future. Here, conventional, emerging, and predictive tools were combined to document brook trout occupation across seasons using streams in Haliburton County, ON as model systems. By using the Ontario Ministry of Natural Resources and Forestry's (OMNRFs) Aquatic Ecosystem Classification (AEC) system variables with environmental DNA (eDNA) sampling and backpack electrofishing, my research supports the development of species occupancy models (SOMs) and eDNA as tools to document brook trout occurrence. To do this, eDNA sampling was validated in Canadian Shield stream environments by comparison with single-pass backpack electrofishing before seasonally sampling two river systems across their main channel and tributaries to assess occupancy. Streams were classified as potential high, moderate, and low-quality brook trout habitats using indicator variables within the AEC and sampled seasonally with eDNA to quantify occupancy and relate it to habitat potential at the county scale. Results showed eDNA to be an effective tool for monitoring fish across Canadian Shield landscapes and that brook trout occupancy varied seasonally within and across watersheds, suggesting that habitat and fish management strategies need to consider seasonal movement and spatial connectivity. Using these tools will enable biologists to efficiently predict and document brook trout occurrences and habitat use across the landscape.

Author Keywords: Aquatic Ecosystem Classification, brook trout, Canadian Shield, connectivity, environmental DNA, seasonal occupation

Changes in climate and land-use practices are leading to higher peak flows and increased transport capacity of channel substrate. Semi-alluvial streams underlain by bedrock or clay were examined to understand the potential impacts of alluvium loss on the biological community and overall productive capacity of semi-alluvial rivers. More specifically, this research investigates the productivity of gravels, bedrock, and consolidated clay, through the biomass and density of periphyton, coarse particulate organic matter, benthic invertebrates, and fish. The ecological approach undertaken demonstrates the relationships among each trophic level and linkages to productive capacity between different substrate types. Significant results were detected at the stream type level and substrate level. Bedrock-based streams were overall more productive in terms of CPOM, biomass and density of benthos in comparison to clay-based streams. Stream reaches with small to large areas of exposed bedrock or clay at the site level did not differ to areas with 100% gravel coverage in the comparison of any variable, including stream fishes. At the substrate level, gravels demonstrated the highest productive capacity in comparison to bedrock and clay substrates. CPOM biomass in gravels compared to bedrock and clay at a ratio of 30:14:1, respectively. Biomass of benthic invertebrates also demonstrated a higher productivity on gravels with a ratio of 59:19:1 in comparison to bedrock and clay, respectively. Positive relationships between CPOM and benthic invertebrate biomass were detected in both stream types.

Relationships were also detected between fish biomass and benthic invertebrate biomass. Examination of benthic fishes also demonstrated positive relationships with benthic invertebrate biomass and density. Clay substrate on all accounts supported little biota. Results indicate alluvium loss in clay bed streams could reduce productive capacity. Understanding and integration of the potential impacts of alluvium loss would aid management and No Net Loss compensation plans to protect fisheries resources in semi-alluvial streams.