NWT RESEARCH DATABASE

Regions: Inuvialuit Settlement Region

Tags: water quality, benthic sampling, benthic invertebrates, transboundary, biomonitoring, Beavers, CABIN, biomarkers

Objective(s): To answer the research question is: How will beaver activity in the tundra impact aquatic ecosystem health?

Project Description: This licence has been issued for the scientific research application No. 5936. The broad research question is: How will beaver activity in the tundra impact aquatic ecosystem health? This will be answered by addressing the following specific objectives and questions: Generate an understanding of beaver activity impacts on aquatic food webs in tundra streams. Question 1: How does beaver activity influence basal food web processes that support healthy fish populations? Question 2: What are the effects of in-channel beaver impoundments on mercury in downstream food webs in the tundra and how may this impact fish populations? Water quality samples will be taken from all sample locations to measure a suite of quality indicators and contaminants including nutrients, metals, microplastics, and mercury to give an overall picture of stream health at all sampling sites. Focus will be on a total of ~12-16 stream reaches in the Inuvialuit Settlement region (e.g., Trail Valley Creek, Hans Creek, Zed, Ghuny) with known beaver activity. All sites will be located along the Inuvik-Tuktoyaktuk Corridor (ITC). This study design will allow assess to the comparative upstream/downstream contribution of beaver dams to total mercury and methylmercury concentrations in stream food. Reference sites (upstream) will give us relative estimates of total mercury and methylmercury concentrations in food webs that may be contributed by other climate-driven processes (e.g., permafrost thaw, deposition), and may lead to data spurring future research. These sites have been partially chosen through conversations with members of the Imaryuk Monitoring Program, Joint Secretariat, and local HTCs. A scientifically robust approach will be used to compare impact to reference stream reaches and to investigate magnitude and severity of beaver activity, including in- channel impoundments. The focus will be on sites inaccessible from the road (accessed via helicopter) to limit human disturbance. The research program will be enhanced through collaborative fieldwork and shared knowledge from the Imaryuk Monitors from Inuvik and Tuktoyaktuk. All fieldwork will be staged out of Aurora Research Institute in Inuvik. To assess effects of beaver activity on stream biotic communities and food web structure, Canadian Aquatic Biomonitoring Network (CABIN) techniques will be used to collect benthic macroinvertebrates as bioindicators of impact and water quality samples. This approach will be enhanced through developing a multi-trophic understanding of total (THg) and methyl mercury (MeHg) bioaccumulation through collecting leaf litter and other deposited organic material, biofilm on rock surfaces, and primary consumer and predatory invertebrates for mercury analysis. To evaluate the risk of mercury bioaccumulation in fish communities near beaver activity, electrofishing/seining surveys will be used. To measure total mercury and methyl mercury in fish, a minimum number required for study design will be collected, including 2 species from each site, ideally using one small-bodied, such as nine-spine stickleback, and one large- bodied, such as Arctic grayling, northern pike, or a whitefish species depending on fish abundance). If a large-bodied species cannot be sampled, then two small-bodied species that differ in trophic ecology (e.g., slimy sculpin, nine-spine stickleback) will be sampled. Sample size will not exceed 5 fish per site for a species with total and methyl mercury samples being collected from each fish. Therefore, a total of 10 fish would be collected at each study reach. All total and methyl mercury samples will be processed at the Biotron Analytical Service Laboratory at Western University, which is CALA and ISO accredited in THg and MeHg of both solid and liquid samples, at ultra-trace detection limits. Trophic levels and dietary habits across the stream food web will be assessed using stable isotope analyses (specifically, d15N) using a subset of sample material from the biotic specimens collected above. This will provide a means of assessing pathways for mercury biomagnification across trophic levels. Stable Isotope Analyses will be conducted at the University of New Brunswick Stable Isotopes in Nature Laboratory (SIN Lab). Several metrics will be used to understand uptake and transfer of mercury into beaver-impacted food webs including the bioconcentration factor, trophic transfer factor and bioaccumulation factor. A set of candidate models will be constructed for each of the metric associated with methylmercury in stream food webs based on physio-chemical variables and occupancy related metrics to investigate the drivers of potential methylmercury in food webs of beaver impacted streams in the tundra. Archived water samples will be kept for future analysis of microplastics through ECCC and at the University of Guelph. Visual occupancy methods, electrofishing, and eDNA samples will also be used to assess the presence of fish and macroinvertebrates at each of our sites. Electrofishing will be used to collect minimal fish samples required for mercury analysis and will only be used if approved from the Inuvik and Tuktoyaktuk Hunters and Trappers committees. Lastly, each site will have a camera trap deployed to monitor beaver activity throughout the summer (upon approval of GNWT Wildlife Survey Permit). 1) Water quality data will be submitted to the Mackenzie Datastream annually. 2) The results of this project will be presented at the NWT Environmental Research and Monitoring Workshop. 3) Annual meetings to communicate results with the Inuvialuit Game Council, Fisheries Joint Management Committee, and/or Inuvik and Tuktoyaktuk Hunters and Trappers Committees will take place. 4) Aquatic insect, habitat, and water chemistry data will be submitted to the Canadian Aquatic Biomonitoring Network. Training opportunities will be made available so that interested community members can become qualified to access data and continue sampling as part of any future biomonitoring opportunities. 5) Workshop opportunities will be coordinated with other Wilfrid Laurier Researchers, associated with Northern Water Futures and the Aurora Research Institute, for students in college or mid/high school. 6) All publications developed from this research will be made available to community organizations. The fieldwork for this study will be conducted from: June 24 - November 1, 2024