NWT RESEARCH DATABASE

Regions: Dehcho Region

Tags: contaminants, water quality, aquatic ecosystems, biology, mining impacts, hydrology, fish, sediment quality, environmental change, invertebrates

Project Description: The objectives of this research are three-fold: 1) to determine the natural variability of benthic invertebrate and fish communities at sites free of human impact; 2) to determine any changes in these due to mining activity relevant to regional variability; and 3) to establish dose response relationships and critical thresholds for stressors including mine effluent, ammonia, a hydrocarbon indicator, and metals such as strontium. Year 1 of this two-year research project will involve determining the natural, reference condition for water and sediment quality, fish and macro-invertebrate communities in wadeable streams within the South Nahanni River basin using Reference Condition Approach (RCA) methods. Any changes in these indicators in waters receiving mine discharges will also be evaluated. Areas of investigative interest include: 1) three sampling sites in relation to the Tungsten mine site, one located upstream and two downstream of the Flat River; 2) three sampling sites on Prairie Creek, one located upstream and two downstream from the Canadian Zinc Corporation's exploration property; and 3) thirty-one comparable or reference sampling sites in streams in the South Nahanni River basin. Thirty-one comparable reference sites will be sampled in streams in the South Nahanni River basin. A helicopter will be used for transportation between sites, with sampling conducted at both the Tungsten Mine and Prairie Creek base camps. One composite water quality and sediment quality sample will be collected at each site and analyzed for general chemistry and composition. Consistent with RCA methods, one composite benthic invertebrate sample will be collected at each site, sorted, counted and identified to the lowest practical taxonomic level (family level is usually sufficient). Fish communities will be sampled at each site using standard RCA electrofishing techniques. In addition, the population structure for slimy sculpin will be determined using primarily non-lethal methods. In order to quantify reference site variability for standard Environmental Effects Monitoring endpoints, approximately 20 males and 20 females of one sentinel species will be sacrificed at each site for liver size, gonad size, length, weight, age, fecundity, egg size and condition estimates. Tissue body burdens for total metals will be included as an indicator in the RCA methodology by compositing the bodies of 10 of the sacrificed male fish per site into one tissue sample. In Year 1, a standard EEM control-impact sampling program will be conducted at reference, near-field and far-field sites on the Flat River and Prairie Creek. The location of the exfiltration basins will be considered a "point source area" which is consistent with approaches used to assess changes in aquatic health in aquatic biota downstream of sewage treatment exfiltration basins. One water and sediment quality sample will be collected at each area. Five replicate benthic invertebrate samples will be collected from each area. A summary of the research findings will be provided to communities and displayed on the Northern Ecosystem Initiative website. The study will be conducted from August 14 to December 31, 2006 at the following locations: Flat River [upstream site, (N61? 58'06.5, W128? 13'28.7); downstream sites to be determined]; Prairie Creek [upstream site, (N61 33'05.5, W124 47'32.8); downstream sites to be determined]; and 31 sites in streams located in the South Nahanni River Basin (exact locations will be determined based on assistance from Parks Canada and Environment Canada).