Freshwater Clams Highly Endangered

That breathing is one reason we should think about clams even if they don't think about us. As filter-feeders, they are cleaning agents, says The Star.

In other ways, too, they are among the foundations of freshwater ecosystems, reports The Star. The news agency says that natural beds of them grip and stabilize underwater `ground' not unlike plant roots, preventing erosion and loss of habitat. Also, their shells are a source of calcium needed by other creatures in fresh water, and are raw material for other animals' habitats. And freshwater mollusks, though not as palatable to people as their salt-water cousins, are food for fish, birds, and mammals.

Yet freshwater clams – or mussels – or "unionids" – "are the most endangered animal group in North America," according to the U.S. Geological Survey's Great Lakes Science Centre in Michigan. The centre, whose research programs date back to the 19th century, lists almost three quarters of about 300 native fresh-water mollusks as "recently extinct, endangered, threatened, or of special concern." Environment Canada ranks mussels second, among Canadian animal groups, to reptiles as most at risk, says The Star.

"The loss of mussels from our waterways should not be taken lightly – it is indicative of greater impending problems," says Todd Morris, a biologist at Fisheries and Oceans Canada who studies species at risk. About 55 of the North American species live in Canada, with 11 under federal endangered status and four more in the process of being added.