Freshwater Mollusks of Alabama

Alabama has 180 known freshwater mussel species, the most of any area in North America [1]. Two families occur in the state: Margaritiferidae (2 species) and Unionidae (178). Rivers isolated for millions of years let mussels evolve separately in each drainage, and Alabama avoided the glacial erasure of river systems that affected northern areas. Yet Alabama has also lost more mussel species than any other state. See Biodiversity of Alabama.

Biology

Mussels are bivalves whose shells are made of nacre, mainly calcium carbonate taken from the water. Their larvae, called glochidia, are parasites that attach to fish gills or fins for several weeks to several months while developing, and a single adult fish can carry up to 3,000 without harm. Adults rarely move more than a few feet, so the fish host spreads the offspring. Some species lure fish with prey-like structures or release larvae in conglutinates resembling insects or small fish [1].

Human use

Native Americans ate mussels in large quantities, leaving shell middens along riverbanks, and used the shells for tools and ornaments. Pearl button manufacturing drove harvesting: Alabama shells were used by 1904, and by 1942 the Tennessee River was the leading U.S. source of shell. Plastic buttons replaced pearl buttons starting in the 1940s. Since the 1950s shell has been exported for cultured pearls, with annual revenues as high as $20 million [1]. See Indigenous Peoples of Alabama.

Habitat and threats

Most species need clean, free-flowing water with gravel or sand bottoms, conditions that were common before most Alabama rivers were dammed in the early twentieth century. Reservoir beds are mostly mud, which many species cannot tolerate. Other threats include pollution, sedimentation, dredging and non-native species [1]. See Rivers of Alabama.

Conservation

Of the 180 recorded species, 22 are extirpated from Alabama and 27 are believed extinct, 39 are federally endangered and 6 federally threatened. The Alabama Aquatic Biodiversity Center, established in 2006 near Marion in Perry County, is the largest state nongame aquatic wildlife restoration program in the United States and focuses on captive rearing of mussels and snails. Recovery is limited by a shortage of suitable release sites, so efforts focus on improving habitat [1].

FAQs

How many mussel species are in Alabama? 180.

How are mussel larvae spread? By attaching to fish gills or fins.

Where are mussels raised for release? At the Alabama Aquatic Biodiversity Center near Marion.

Sources

1. Encyclopedia of Alabama: Freshwater Mussels in Alabama

Editorially reviewed by Specialty Digest Editorial TeamLast reviewed November 10, 2026Researched and drafted with AI assistanceReport an issue