Freshwater Mussels

Historically, the Thames River supported one of the richest communities of freshwater mussels in Canada; however, research shows that there has been a decline in freshwater mussel diversity. In 1997-98 surveys, 30% of species previously reported in the Thames River were not found alive.

Three species are believed to be extirpated from the river and two more 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 10 mussel species with federal and provincial SAR status listed for the Thames.

Mussels start off their life as a parasitic larvae attached to specific host species of fish or an amphibian, as in the case of the mudpuppy mussel. 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)