The Shell Game

The most endangered and at risk species in Canada and the United States are the mussels that live in freshwater; 16 of 55Canadian species, and greater proportions reported by several states. There is a modest variety of freshwater mussel species compared to the many thousands of species of insects; about 300 for all of North America. However, there are more species of freshwater  mussels in North American than anywhere else. Like insects, these mussels are distributed far and wide and can be found in most streams, lakes and ponds. While they are notable for their interesting and explicit names, like the Fatmucket, Giant Floater, Dwarf Wedgemussel, Hickorynut, and the Eastern Elliptio, they are most notable for what they can tell us about the troubled status of aquatic environments.

Ottawa River freshwater clam species

Ottawa River clam species

These creatures do not have the most active escape behaviors (moving 3 or 4 meters in a day is like setting an Olympic record for a freshwater mussel), so when they call a place home they settle in for the long haul. When aquatic habitats change from a build-up of silt, the accumulation of toxins, become invaded by new, exotic species like the Zebra Mussel, or worse dry up, these populations are pushed to their tolerance limits and often perish. An earlier threat was from human consumption when the shells were used for making buttons. A more recent demand is the use of shell fragments to seed marine pearl production.

The most obvious signs that these clams exist are the shells that often litter river banks and shorelines as a result of feeding by muskrats and raccoons.

However, scientists like André Martel at the Canadian Museum of Nature go far beyond shell spotting and have active research programs to provide accurate scientific names, information about distribution and population size, to study the many features of their natural history, and to keep a record in well conserved collections for future reference. Careful long-term study on species that are strong indicators of environmental change provide important results for stewardship actions and management plans.

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