Hayward Erin E, Gillis Patricia L, Bennett C James, Prosser Ryan S, Salerno Joseph, Liang Tanner, Robertson Shelby, Metcalfe Chris D
The School of the Environment, Trent University, 1600 West Bank Drive, Peterborough, Ontario, K9L 0G2, Canada.
Aquatic Contaminants Research Division, Water Science and Technology Directorate, Environment and Climate Change Canada, 867 Lakeshore Road, Burlington, ON, L7S 1A1, Canada.
Chemosphere. 2022 Nov;307(Pt 3):135966. doi: 10.1016/j.chemosphere.2022.135966. Epub 2022 Aug 6.
The Grand River watershed in a densely populated region of Ontario supports one of the richest assemblages of freshwater mussels in Canada. However, water quality in this watershed is influenced by urban development, agriculture, and industry. Mussel populations and water chemistry in the lower Grand River and the Boston Creek tributary were evaluated to determine whether point sources of pollution such as discharges of domestic wastewater and industrial effluent, and non-point sources of pollution are affecting mussel distribution and population structure. Semi-quantitative population surveys conducted at 9 study sites identified 20 mussel species, including 3 Species at Risk. Mussel abundance (34-160 mussels/search hour) and species richness indicated that mussel populations in the lower Grand River watershed are continuing to recover from historical lows reported in the 1970s. However, changes in populations at some sites were consistent with altered water chemistry. Most notable was that the three most abundant mussel species in the Boston Creek tributary downstream of a gypsum plant discharge were significantly smaller in length than those upstream of this site. The water chemistry in this habitat was characterized by elevated conductivity (∼2000 μS/cm) and calcium (∼500 mg/L), as well as concentrations of sulfate (∼1000 mg/L) that can be toxic to freshwater mussels. In the Grand River downstream of the confluence with Boston Creek, there tended to be (p > 0.05) fewer mussels (mean 34 ± 20/search h) compared to upstream (mean 67 ± 15/search h) and this corresponded to altered water chemistry, including elevated sulfate (239 mg/L) downstream of the confluence relative to upstream (58 mg/L). These data indicate that chronic exposures to high levels of major ions is likely driving changes to mussel population structure. In addition, the discharges of wash water from a gypsum plant may be impacting sensitive biota in the main stem Grand River well beyond the immediate tributary receiving environment.
安大略省人口密集地区的格兰德河流域拥有加拿大最丰富的淡水贻贝群落之一。然而，该流域的水质受到城市发展、农业和工业的影响。对格兰德河下游和波士顿溪支流中的贻贝种群及水化学性质进行了评估，以确定生活污水和工业废水排放等点源污染以及非点源污染是否正在影响贻贝的分布和种群结构。在9个研究地点进行的半定量种群调查共识别出20种贻贝，其中包括3种濒危物种。贻贝丰度（每搜索小时34 - 160只贻贝）和物种丰富度表明，格兰德河下游流域的贻贝种群正在从20世纪70年代报告的历史低点持续恢复。然而，一些地点的种群变化与水化学性质的改变相一致。最显著的是，石膏厂排放下游的波士顿溪支流中三种最丰富的贻贝物种的长度明显小于该地点上游的贻贝。该栖息地的水化学性质表现为电导率升高（约2000 μS/cm）、钙含量升高（约500 mg/L）以及对淡水贻贝有毒的硫酸盐浓度（约1000 mg/L）。在与波士顿溪交汇处下游的格兰德河中，与上游相比（平均每搜索小时67 ± 15只），贻贝数量往往较少（平均每搜索小时34 ± 20只）（p > 0.05），这与水化学性质的改变相对应，包括交汇处下游的硫酸盐含量（239 mg/L）相对于上游（58 mg/L）有所升高。这些数据表明，长期暴露于高水平的主要离子可能正在推动贻贝种群结构的变化。此外，石膏厂的冲洗水排放可能正在影响格兰德河干流中的敏感生物群落，其影响范围远远超出直接接纳废水的支流环境。
