Mussels at Risk
The Thames River supports one of the richest communities of freshwater mussels in Canada. In fact, for these species, the Thames is one of a few remaining strongholds in the country.
Historically, the Thames River was home to 32 species of native freshwater mussels. Research shows that there has been a continuous decline in freshwater mussel diversity over time. Kidneyshell mussels are believed to be functionally extirpated from the Thames and other species may persist as non-reproducing populations.
The mussel species that have disappeared were characteristic of a healthy aquatic environment, so their loss is an indication that conditions in the river may be deteriorating. Currently, there are nine mussel species with federal or provincial Species at Risk (SAR) status listed for the Upper Thames River.
Mussels start off their life as a parasitic larvae attached to specific host species of fish or, in the case of the Mudpuppy Mussel, an amphibian. The habitats of both the mussels and their larval host must be present to maintain a species over the long term.
Threats to mussel populations include:
- pollution
- siltation
- impoundments (dams, weirs)
- muskrat and raccoon predation
- invasive species (e.g., zebra mussels)
- channelization
- loss of larval host species (e.g., fish, mudpuppy)
| Common Name | Species Name | Current Status under the federal Species at Risk Act | Current Status under the provincial Endangered Species Act |
|---|---|---|---|
| Fawnsfoot | Truncilla donaciformis | Endangered | Endangered |
| Kidneyshell | Ptychobranchus fasciolaris | Endangered | Endangered |
| Mapleleaf | Quadrula quadrula | Special Concern | Special Concern |
| Purple Wartyback | Cyclonaias tuberculate | Not Listed (Not on Schedule 1) | Threatened |
| Rainbow | Cambarunio iris | Special Concern | Special Concern |
| Rayed Bean | Paetulunio fabalis | Endangered | Endangered |
| Round Pigtoe | Pleurobema sintoxia | Endangered | Endangered |
| Salamander Mussle | Simpsonaias ambigua | Endangered | Endangered |
| Wavy-rayed lampmussel | Lampsilis fasciola | Special Concern | Threatened |
For the most up-to-date information on Aquatic species at risk listed under the Species at Risk Act (SARA), please contact Fisheries and Oceans Canada (DFO). You can find an overview of distributions at-risk species on the DFO website:
https://www.dfo-mpo.gc.ca/species-especes/sara-lep/map-carte/index-eng.html
For more information on how the Endangered Species Act applies to at-risk aquatic fish and mussels, please contact the Ministry of Environment Conservation and Parks (MECP). More information is available on the MECP website:
https://www.ontario.ca/page/how-species-risk-are-protected