Mussels Expose Chemical Threats in Ontario's Grand River

In September 2025, a team of scientists in Ontario is studying freshwater mussels in the Grand River to better understand how chemicals are affecting the local environment. Patty Gillis, a research scientist with Environment and Climate Change Canada, is leading the effort, using the mussels as "messengers of the water quality" to track the distribution and effects of contaminants.

The researchers are focusing their work downstream of Brantford's municipal wastewater treatment plant, analyzing the mussels' population, stress levels, and chemical accumulation in their tissues. This is part of a larger initiative called the Integrated Chemical Mixtures Project (ICMP), which is also examining the impacts on other species like snails, birds, and fish at sites in Brantford and Windsor.

The ICMP project aims to gain a comprehensive understanding of the effects of complex chemical mixtures on the environment and human health. Burlington chemist Mark Hewitt, a coordinator on the project, says these mixtures are "something Canadians need to know about," likening them to an iceberg where the full extent of the problem is still largely unknown.

By studying the mussels and other organisms, the researchers hope to identify any harmful effects and work towards solutions. Next year, they plan to place mussels upstream and downstream of the wastewater plant and an industrial area to further investigate how quickly the animals are stressed and how chemicals accumulate in their bodies. This multifaceted approach will provide a broader picture of the environmental health in the region.