Freshwater Mussels

Name: Northern Riffleshell Scientific Name: Epioblasma torulosa rangiana Status: Endangered Provincially, Endangered Nationally Details & Range Map: R.O.M.

Freshwater mussels are bivalve mollusks that are soft-bodied, non-segmented invertebrates with a pair of hinged shells. There are nearly 1,000 species of freshwater mussels, of which 54 of them are found in Canada.

There are 41 species of freshwater mussels in Ontario.

Approximately 66% of these species are of provincial conservation concern.

According to the General Status of Species in Canada (2010), there are no species of freshwater mussels are extirpated or extinct in the province, but 12 species are at risk (e.g. Northern Riffleshell, Rayed Bean and Wavy-rayed Lampmussel) and another 6 species may be at risk. Nine species are considered to be sensitive (species that are not believed to be at risk of immediate extirpation or extinction but may require special attention or protection to prevent them from becoming at risk), and 13 species are secure. *Note: Like native freshwater mussels, Zebra mussels and Quagga Mussels belong to the class Bivalvia, but they belong to a different order (order Veneroida) than native freshwater mussels, and are not ranked in the General Status of Species in Canada.  Zebra mussels and Quagga mussels are native to Europe, and both have been accidentlly introduced into the Great Lakes.

Freshwater mussels are susceptible to habitat destruction, poor water quality, damming, alterations to shoreline areas and wetlands, and agricultural run-off. The larvae of freshwater mussels depend on host species, usually fish, as they must attach to their fins or gills before they can mature into adults. Therefore, negative impacts on host fish species have direct impact on the freshwater mussels. The introduction of the Zebra Mussel has had a dramatic impact on native freshwater mussels, resulting in a decline in the numbers and diversity of native species in infested lakes and rivers, including the Great Lakes and St. Lawrence River.

 

For more information on provincially tracked mussels, see the list of species on the Natural Heritage Information Center (NHIC).

For more information on Species at Risk designations and their current status, see the Species at Risk in Ontario (SARO) List and the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) website.

Photography
Shawn Staton