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Ecotoxicology of Freshwater Mussels in Ontario

On 22 January, Dr. Patty Gillis, from Environment Canada’s Aquatic Contaminants Research Division, gave a very informative presentation on freshwater mussels entitled:

"Ecotoxicology of freshwater mussels in Ontario: the joys of working with a complex canary." Laurentian-SETAC hosted Dr. Gillis at Emma’s Back Porch in Burlington, and the presentation was well attended by scientists from government, industry, and academia alike.

Dr. Gillis focused on muscle toxicity studies conducted in the field and the laboratory. Over 70% of the freshwater mussel species in North America are threatened, endangered, or in decline. The early life stages of the mussel life cycle (the glochidia) are the organisms most sensitive to aquatic contaminants such as ammonia, chloride, and metals. Dr. Gillis used the Grand River as an example of a watershed that in the past has supported a great diversity of mussel populations. However, more than 30% of those have been lost due, in part, to pollution, urbanization, and other unknown causes. A multi-year study conducted on the Grand River demonstrated that mussels located downstream from urbanized regions of the river exhibited elevated metal concentrations in body tissues, increased oxidative stress, decreased condition factor, and reduced age. Moreover, the study found an absence of mussels for kilometers downstream from a major wastewater treatment plant, while a survey directly upstream from the plant found several species, including species at risk. Taken together, the data suggest that chronic exposure to urban-derived contaminants in wastewater effluent and runoff has negatively impacted the mussel population in the Grand River. Currently, recovery strategies under the Canada’s Species at Risk Act recognize that water quality affects mussel populations. However, extrapolating from single species studies to an entire population or populations of mussels is challenging, especially in areas with complex mixtures of urban inputs. Efforts are currently underway to pinpoint the main cause of muscle species decline in the Grand River. Submitted by Oana Birceanu

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