MOLLUSKS

As filter-feeders, freshwater mussels provide a vital service to Maine’s lakes, ponds, rivers and streams by removing suspended particles such as algae, bacteria, and detritus from the water column. Because they constantly filter large volumes of water, reside in the benthic substrate, can’t leave their surroundings, and live a long time (more than 100 years for some species!), freshwater mussels are sensitive to contaminants and changes in their environment. Consequently, they are a valuable indicator of water quality and aquatic ecosystem health, but they also are one of the most imperiled groups of animals in the country. Of the nearly 300 species of freshwater mussels found in the United States, more than a third have already vanished or are in danger of extinction and over 75% are listed as Endangered, Threatened, or Special Concern on a state level. These dramatic declines have been caused largely by the degradation and loss of mussel habitat from pollution, dams, and the channelization and sedimentation of once clean, free-flowing rivers and streams. In some parts of the country, the accidental introduction of a prolific foreign competitor, the zebra mussel, is also jeopardizing many populations.  Read more...