NWT RESEARCH DATABASE

Tags: physical sciences, mercury, sediment

Objective(s): To investigate mercury levels in Great Bear Lake trout and cisco to assess mercury trends.

Project Description: The objectives of this research project are to collect sediment cores from up to six sites in Great Bear Lake to investigate the temporal record of diatom and lake productivity and the deposition of mercury and other metals; to investigate spatial gradients in lake productivity as influenced by station depth, distance from shore, and river influences; and to continue to investigate mercury levels in Great Bear Lake trout (March 2018 and fall/winter 2018) and cisco (fall/winter 2018) to assess mercury trends. Sediment cores will be collected over March 5-12, 2018 at up to six locations in Great Bear Lake and/or potentially Lac Ste. Therese and Kelly Lake. Water samples may be collected for nutrient and chlorophyll analyses. Cores subsequently will be dated and analyzed for diatom remains, chlorophyll, mercury and other metals. 20 lake trout will be collected from Great Bear Lake by local fishermen in March 2018 and again in fall/winter 2018. 20 cisco may be collected in fall/winter 2018. This project is a component of a current Cumulative Impacts Monitoring Program (CIMP) study “Combining biological, limnological and palaeolimnological data to study past, present and future impacts of climate change on the Great Bear Lake ecosystem”. This project is investigating different aspects of Great Bear Lake fish communities and has had much community involvement including project planning and implementation during the extensive summer field campaigns. The research team contribution to CIMP’s project consists of specialized sediment core studies over a 3-day period. Community involvement to date has included discussions of the study and site selection considerations including the fact that sediment cores can only be successfully collected in certain regions of a lake. Benefits of the coring study will occur through information exchange on how such studies are conducted and sharing of results by various means including community presentations, posters, and email and telephone communications. Overall, the research team will be able to inform the community as to how the changing climate has impacted Great Bear Lake with respect to its productivity and on deposition trends for mercury and other metals. The Principal Investigator (PI) has been emailing and talking with Deline and more recently the Renewable Resource Committee at Kelly Lake; these communications will continue. Furthermore, the PI hopes to visit Deline around March 5 before the coring starts to go over this study and potentially communicate some of CIMP’s findings. Additional communications will include posters and short reports including Kim's annually reporting to CIMP. The fieldwork for this study will be conducted from March 3, 2018 to December 31, 2018.