NWT RESEARCH DATABASE

Tags: aquatic ecosystems, biology, environmental monitoring, mining impacts, hydrology, limnology, ecology, habitat

Objective(s): To study the freshwater ecology, hydrology, and hydraulics of small lakes and streams in the Lac de Gras basin before habitat modification; to monitor the changes in ecosystem productive capacity resulting from habitat modifications designed to increase habitat connectivity and fish passage; and to assess the effectiveness of such habitat modifications through the use of a Before-After-Control-Impact design.

Project Description: The objectives of this project are: 1) to study the freshwater ecology, hydrology, and hydraulics of small lakes and streams in the Lac de Gras basin before habitat modification; 2) to monitor the changes in ecosystem productive capacity resulting from habitat modifications designed to increase habitat connectivity and fish passage; and 3) to assess the effectiveness of such habitat modifications through the use of a BACI (Before-After-Control-Impact) design. This research design allows for the assessment of post-construction impacts through a comparison with pristine reference conditions over the same before-and-after periods. Water: Stream gauges will be installed to monitor stream flows, while water level recorders will record lake and stream levels as they change over summer due to evaporation. Temperature loggers will be installed in each of the study lakes and streams to determine thermal conditions over the summer. Water quality traits will be measured directly (specific conductance, turbidity, pH) or water samples will be collected and brought back to the lab for later analysis (total phosphorus, total nitrogen, chlorophyll, and total suspended solids). Habitat: Ground surveys will be used to assess stream geomorphology and substrate composition. We will document the composition and amount of vegetation cover available for young-of-year (YOY) fish, both in the streams and within 1 m of stream banks, at multiple transects at each stream. Organic matter availability and production will be determined by counting instream woody debris and shrub stems. Organic matter processing rates will be assessed by setting out leaf packs in mesh bags over a 2-3 week period to quantify decomposition rates. Organisms: Various techniques will be used to sample fish and invertebrate populations in the lakes and streams. Adult fish will be sampled with trap and gill nets, and angling, including ice fishing in winter/spring. Fish abundance in streams will be determined by electrofishing in mid-summer. Collected fish will be measured for length and mass and their diet will be quantified. Sweep nets, plankton tows, and Surber samplers will be used to collect invertebrates in lakes and streams. Attached algae will be quantified by rock scrapings. Movements of tagged fish through the newly modified stream channels will be assessed by direct observation and electronically. Stable isotope analysis will assess changes in food webs resulting from the increased ecological connectivity brought about by the habitat modifications. Diavik Diamond Mines Incorporated (DDMI) will hire two Aboriginal wildlife monitors from local communities for the duration of the field season. They will work in an interdisciplinary team and will interact with professionals from academia, industry, and government. This dynamic and diverse work environment, alongside graduate students and mentors, will facilitate social and cultural exchanges of ideas. The monitors 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. Regular communications (email, teleconference, meetings) will be maintained throughout the project between the University of Alberta (U of A) Research Team on the one hand and DDMI, Golder Associates, and Department of Fisheries and Oceans (DFO) on the other. The research team will summarize activities at an annual DFO-sponsored workshop in Yellowknife. The U of A Research Team will also give a presentation at a meeting of EMAB (Environmental Monitoring Advisory Board) associated with DDMI to discuss the status, results, and subsequent steps to be taken in the study. There will be opportunities for attendees to communicate their ideas and thoughts about the project to the aforementioned parties. Copies of graduate student theses, peer-reviewed articles, and presentations given at conferences could be sent to interested groups and/or individuals. The fieldwork for this study will be conducted from May 2, 2012 to October 31, 2012.