Metal levels in large-bodied fishes near communities along the Mackenzie River compared to impacted lakes near Yellowknife, NWT

The primary objective of this project is to enhance the baseline information collected within various regions across the Northwest Territories (NWT). The overarching goal of this project is to investigate additional aspects of aquatic health that address community-driven questions and concerns and to conduct trend assessment for trace metals, and both total and methyl mercury using fish tissue as biological indicators. The proposed project will provide additional indicators of the environmental condition of rivers and lakes in the NWT and contribute to capacity building efforts at the community level to address their ecosystem health concerns. In the NWT, metals generally enter the aquatic environment through long-range atmospheric deposition, erosion of the geological matrix, or as the result of anthropogenic activities (e.g., land use change, industrial effluents, domestic sewage and waste, and mining wastes). Climate change is also affecting contaminant transfer pathways in NWT aquatic ecosystems. Vast community concern regarding the health of the aquatic ecosystem continues to exist; related in particular to the quality of water and fish for human consumption in areas surrounding NWT communities. In stream food webs, biofilm are intensively grazed by protozoa, macrobenthic invertebrates and some fish. Variability in the composition and concentration of metals in biofilms and fish tissue is based on the site specific physicochemical characteristics of the surrounding environment (e.g., water chemistry, sediments, organic material). As such, these media can be used for the early detection of environmental change from stressors, making them an excellent tool for assessment of aquatic ecosystem health.

本项目的首要目标是完善加拿大西北地区（Northwest Territories, NWT）各区域的现有基线监测数据。本项目的总体目标在于针对社区提出的水生健康相关问题与关切，开展多维度水生健康状况调研，并以鱼类组织作为生物指示剂，对痕量金属、总汞及甲基汞的含量变化趋势进行评估。本拟建项目将为加拿大西北地区河湖的环境健康状况提供额外的评估指标，同时助力社区层面的能力建设工作，以回应当地民众对生态系统健康的关切。在加拿大西北地区，金属污染物通常通过长距离大气沉降、地质基质侵蚀，或是人为活动（如土地利用变更、工业废水、生活污水与废弃物以及采矿废弃物）等途径进入水生环境。气候变化亦对加拿大西北地区水生生态系统中的污染物迁移路径造成影响。当地社区对水生生态系统健康的广泛关切始终存在，尤其聚焦于加拿大西北地区各社区周边区域的饮用水与食用鱼类的质量安全。在溪流食物网中，生物膜（biofilm）会被原生动物、大型底栖无脊椎动物以及部分鱼类大量牧食。生物膜与鱼类组织中金属的组成与浓度差异，取决于周边环境的特定理化特征（如水体化学性质、沉积物与有机质含量）。因此，这些介质可用于早期检测环境胁迫因子引发的生态变化，成为评估水生生态系统健康状况的高效工具。