Freshwater mussels, vital organisms for natural water purification, are declining in the U.S. and significantly impacting ecosystems.
Freshwater rivers and lakes in the U.S. are losing an important ally: freshwater mussels. An essential part of the natural cleaning “team,” their absence can negatively affect countless water bodies across the U.S. and beyond, as reported by IFL Science on November 8.
Cloudy water tank without mussels (left) and tank containing 15 mussels (right) after 90 minutes, showing clear water. Photo: D. Kreeger/Partnership for the Delaware Estuary
To emphasize the importance of these shelled organisms, the U.S. Fish and Wildlife Service (FWS) shared a photo from the Partnership for the Delaware Estuary, showcasing their impressive filtering ability. The image depicts two tanks filled with murky lake water containing mud and algae, but one tank has 15 mussels. Within just 90 minutes, the tank with mussels became clear, while the tank without remained cloudy. “Never underestimate the power of freshwater mussels,” FWS stated.
It is estimated that a single freshwater mussel can pump and filter 30 to 57 liters of water each day. Acting like mini vacuum cleaners, they help improve water quality by filtering out bacteria, algae, and pollutants. If a freshwater body suddenly loses its mussels, water quality will decline sharply, leading to significant ecological changes.
Many species of freshwater mussels can live for over a century. Despite their resilience, they are facing serious troubles in many parts of the U.S. In recent years, several populations of freshwater mussels have experienced mass die-offs across Michigan, Minnesota, North Carolina, Ohio, Oregon, Virginia, Washington, and Wisconsin.
Due to their filtering capabilities and bottom-feeding behavior, pollution and environmental contaminants are often blamed for mussel mortality. However, no specific factors have been identified in recent die-off cases.
Another possibility is the emergence of a new virus. A 2020 study found a previously unseen virus from the Densovirinae subfamily that was more common in sick mussels compared to healthy ones. Thus, the virus may be a contributing factor to mass mortality events.
While this new discovery is a breakthrough, there are likely many other ongoing threats, including various pollutants and pathogens. “If we lose mussels, rivers and lakes, along with everything that depends on them, will never be the same. They are foundational organisms for freshwater ecosystems,” stated Tony Goldberg, a professor of Pathobiological Sciences at the University of Wisconsin-Madison.
