Mussels are critical to the health of our environment, our waterways, and our drinking water. You can think of a single mussel as a self-contained water treatment facility—one adult mussel is capable of cleaning up to 20 gallons of water per day! Mussels help stabilize healthy river habitats from the ground up—capturing nutrients, transforming them into less polluting forms, storing them, and releasing smaller amounts as fertilizer. But freshwater mussels are one of the most imperiled animals in North America. Cleaner river water depends on their existence in our rivers and streams.
The decline in freshwater mussel populations has many causes. Deforestation along waterways, subsequent erosion, water pollution, and dams that prevent fish from swimming up and downstream all play a role. Other contributing factors include the historic pearl button industry, the current cultured pearl industry, and the outdated use of mussels as fishing bait. All have had a hand in freshwater mussel decline.
A pearl is formed when a small particle, such as sand, gets trapped inside a bivalve and becomes encased in nacre (mother-of-pearl) over time. The American clothing industry used freshwater mussel shells to make pearl buttons from the 1880s to the 1920s. Today, pearl buttons have been mostly replaced by plastic, but mussel populations have not yet recovered from this destructive and once widespread practice. Though freshwater mussels were often harvested for their natural pearls, their shells are more valuable to the cultured pearl industry after being pulverized into small particles. These shell particles are placed inside of a pearl oyster, which creates a pearl around it. This method of placing a small particle inside a pearl oyster is widely used to make cultured pearls for jewelry. The next pearl you see might have part of a freshwater mussel shell at its center!