Healthy populations of freshwater mussels can greatly improve water quality in tidal and non-tidal rivers. Each adult mussel can filter 10 gallons of water per day, removing bacteria and suspended solids, and improving water clarity. In a recent survey, small numbers of eight native mussel species were identified in the Anacostia and Potomac Rivers in Washington, DC. The District of Columbia Department of Energy & Environment (DOEE), U.S. Fish and Wildlife Service (Service), and the Anacostia Watershed Society (AWS) have teamed up to enhance populations of these native species. One of these locations is at the base of the 11th Street Bridges. If successful, we’ll incorporate mussel habitat as part of the future Bridge Park.
In June 2018, the team started their first controlled experiment to see if mussels will survive and thrive in the Anacostia watershed. The eastern lampmussel (Lampsilis radiata), one of the eight native species, was chosen because it tolerates a wide range of water quality conditions. The mussels for this experiment were raised by the Harrison Lake National Fish Hatchery from reproducing adults collected the previous fall in the Potomac River at Piscataway National Park. To start the experiment, batches of juvenile, 1-centimeter-long, mussels were placed in floating baskets and submerged silos at 10 locations. Seven locations span the tidal Anacostia from Buzzard Point to Bladensburg, two are in Beaverdam Creek (Greenbelt, MD), and one is at Piscataway National Park. Each week, the team monitors the mussels and water quality. After 10 weeks they will document mussel survival and growth at all locations to see which ones are promising as potential nursery areas. Water quality measurements include evaluating the quantity and quality of seston (minute particles floating in the water) used as food by mussels.
In fall 2018, AWS will build on the knowledge gained from the summer study to conduct year-long exposures of hatchery-raised juvenile eastern pond mussel (Ligumia nasuta) and alewife floater (Anodonta implicata) in floating baskets. Both are listed as Species of Greatest Conservation Need in the District of Columbia’s Wildlife Action Plan. In addition, AWS will start a hands-on “Mussels in the Classroom” project in which DC elementary school students will raise and monitor the growth of these two species of mussels in aquariums.
Building on the results of these experiments, mussel restoration in the Anacostia will be modeled after efforts in Maryland’s Patapsco River and the Delaware River watershed. The goal is to develop beds that are home to millions of naturally-reproducing wild mussels. The water quality benefits of such beds are huge. For example, one mussel bed in Southeast Pennsylvania removed 26 metric tons of solids from the water in a single summer season.
Mussels are keystone organisms that provide many ecological services. Mussel beds are “hotspots” of biological activity where many species of bottom-dwelling organisms thrive. These beds serve as habitat for fish that consume algae, insect larvae, and mussels. Thus, mussels are a key part of the food chain, eating algae and bacteria, and in turn being eaten by fish, turtles, mammals, and birds.
The Year of the Anacostia is an opportunity for scientists and citizens to transform the River and watershed into vibrant and healthy communities. Mussel power can help.