200 Years. 200 Stories. Story 195: “Impressive Underdogs ”

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freshwater mussels collected from the Delaware River
Freshwater mussels from the Delaware River.

Impressive Underdogs

Nearly 75 percent of North America’s 300 freshwater mussel species are in decline or heading toward extinction. A study by the Academy’s Patrick Center for Environmental Research and the Partnership for the Delaware Estuary has yielded some promising results. Dr. Danielle Kreeger, an affiliated Academy scientist and science director at the Partnership for the Delaware Estuary, and Roger Thomas, Patrick Center staff scientist, led the survey of the Delaware River between Chester, PA, and Trenton, NJ, that revealed beds of seven or more different species of native freshwater mussels. Two of the species were thought to have died out in Pennsylvania. These findings are exciting because freshwater mussels are very sensitive to pollution, dams, and water flow.

Mussels can live to be 50 to 100 years old and are important indicators of water quality and ecosystem health. They used to be abundant in the region but have declined since the rise of mill dams, which prevent fish from traveling upstream into areas where mussels are found. Today, many dams are being removed, allowing more fish to travel upstream to historic mussel beds. This may lead to increased mussel recruitment and distribution.

Mussels may be doing better in the Delaware River than in smaller streams because the Delaware is relatively free flowing. Natural beds of healthy mussels like those in the Delaware River help maintain water quality. Preliminary studies look promising, as two mussel species, the Eastern Floater and Eastern Elliptio, were reintroduced to two streams last May and were still thriving despite record flooding from Hurricane Irene and Tropical Storm Lee!

Learn more about the latest Partnership and Academy research projects helping to protect the future of the region’s freshwater mussels.

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