NWT RESEARCH DATABASE

Tags: aquatic ecosystems, biology, mining impacts, hydrology, limnology, habitat, environmental impact assessment

Objective(s): To study the freshwater ecology, hydrology, and hydraulics of the Lac de Gras basin before habitat modification; to monitor the changes in fish productivity resulting from the removal of blocks to fish passages; and to assess the effectiveness of such habitat modifications to increase fish productivity through the use of a BACI (Before-After-Control-Impact) design.

Project Description: This licence is being issued for the scientific research application No.1287. The objectives of this project are 1) to study the freshwater ecology, hydrology, and hydraulics of the Lac de Gras basin before habitat modification; 2) to monitor the changes in fish productivity resulting from the removal of blocks to fish passages; and 3) to assess the effectiveness of such habitat modifications to increase fish productivity through the use of a BACI (Before-After-Control-Impact) design. This experimental design allows for the assessment of post-construction impacts through a comparison with pristine reference conditions. Ground surveys, aerial photographs, and topographic maps will be used to assess stream geomorphology and substrate composition. The researchers will document the composition and amount of vegetation cover available for young-of-year (YOY) fish at transects at each stream. Organic matter availability and production will be determined by counting instream woody debris and shrub stems, collecting drift with nets, and estimating vegetation coverage within 1 m of stream banks. In-stream vegetation assessments will be conducted once a summer in 40-m segments along reference and modified streams. Drift will be collected monthly, three times per day. Stream gauges will be installed to monitor hydrologic conditions and data retrieved every 1-2 weeks. Temperature loggers will be installed at each end of the streams to be modified and at reference streams to determine degree-days during the season. Specific conductance, turbidity, and pH will be measure in situ, while water samples will be collected for total phosphorus, total nitrogen, total suspended solids, and dissolved organic carbon analyses. Various techniques will be used to sample fish and invertebrate populations. Fish egg collection will be by kick sampling. Migration and spawning surveys of fish will be recorded on video. YOY use of habitat will also be monitored via videos. Adult fish will be sampled with trap and gill nets and angling. Fish density and biomass in streams will be determined by electrofishing in mid-summer. Collected YOY fish will be measured for length and mass and their diet will be quantified. Sweep nets and Surber samplers will be used to collect invertebrates. DDMI will hire an Aboriginal student from a local community for each of the four field seasons. These students will be trained in field sampling techniques related to fisheries, limnology, hydrology, and hydraulics. They will work in an interdisciplinary team and will interact with professionals from academia, industry, and government. This dynamic and diverse work environment, alongside other students and mentors, will facilitate social and cultural exchanges of ideas. The students will also have opportunities to communicate to their peers and communities about the issues relating to habitat compensation projects and underlying ecological and hydrological principals. At the completion of the project, the Aboriginal assistants will be equipped with the skills and knowledge necessary to conduct arctic field research locally and elsewhere in the Canadian North, thus becoming members of a small group of highly trained professionals. For the duration of this project, an annual workshop will be held in the winter in Yellowknife. At these meetings, the Principal Investigators, Department of Fisheries and Oceans, DDMI, Golder Associates, and EMAB (Environmental Monitoring Advisory Board) will present and discuss the status, results, and subsequent steps to be taken in the study. The community is invited to participate in these workshops. There will be opportunities for attendees to communicate their ideas and thoughts about the project to the aforementioned parties. Theses, peer-reviewed articles, and presentations given at conferences could be sent to interested individuals. The fieldwork for this study will be conducted 5-6 lakes and outlet streams into Lac Gras from May 18 to Sept. 21, 2010.