Alabama’s Phenomenal Biodiversity
Although not a state that immediately comes to mind for most people when considering states with high levels of biodiversity, Alabama is one of the most biologically diverse states in the nation. It is the most biologically diverse state east of the Mississippi, and only Florida can match its diversity in the number of species per square mile. One of the reasons for Alabama’s phenomenal biodiversity is the numerous river systems and diverse geology in the state, which contributes to the incredible diversity of the state’s aquatic fauna. Alabama has more species of freshwater fish, mussels, snails, crayfish, turtles, and caddisflies than any other state. In fact, Alabama and the adjoining states in the Mobile and Tennessee River basins are global hotspots in terms of the diversity of freshwater mussels, snails, turtles, and crayfish.
Examples of nationally outstanding aquatic systems located in Alabama include the Cahaba and Paint Rock rivers. The Cahaba River has more fish species (131) than any river its size in North America, and harbors 13 freshwater snail and fish species endemic to its waters. It supports 69 rare and imperiled species, including 10 fish and mussel species listed under the U.S. Endangered Species Act. The spectacular Cahaba lily grows in shoals in the middle of the river, wedging into the sandstone rock crevices.
Further north in the mountains of Jackson County, the Paint Rock River watershed is part of the Tennessee-Cumberland freshwater region which is ranked number one in the U.S. for at-risk species of fish and mussels. The Paint Rock River is one of the most biologically important regions in the state for both aquatic and plant and animal associations, and supports an extremely diverse array of aquatic life, with some 100 species of fish and, historically, 58 species of mussels documented from the river. Seventeen globally imperiled or rare mussels are found in the Paint Rock and its tributaries, including the only known populations for two mussel species, the Alabama lampmussel (Lampsilis virescens) and pale lilliput (Toxolasma cylindrellus), and one of only two known populations for a globally imperiled fish: the palezone shiner (Notropis albizonatus).
Perhaps as equally diverse as Alabama’s aquatic biota, yet even less understood, is the faunal diversity hidden underground in Alabama’s subterranean habitats. The Cumberlands and Southern Ridge and Valley Ecoregion is considered a global center for cave invertebrate diversity, with the Cumberland Plateau region having one of the largest concentrations of caves and cave species in the United States. At the genus level, most U.S. cave fauna diversity occurs in the large limestone karst areas of Texas, the Southeast, and the Sierra Nevada Mountain foothills of California. Alabama ranks second in the nation for its complete cave faunal diversity and is number one in the nation for the number of terrestrial cave-dwelling species. Two of the four counties with the highest cave densities in the U.S. are located in Alabama. The Paint Rock River watershed alone contains more than 760 documented caves with untold biological diversity.
Unfortunately, Alabama is also among the leaders in the level of threats and imperilment to our biological fauna. With Alabama second only to Hawaii in number of species lost to extinction and only Florida, California, and Hawaii have more species listed as threatened or endangered under the Endangered Species Act, it is obvious that human activities have already begun to negatively impact the state's biologically rich ecosystems. One of the primary causes for Alabama’s high number of species extinctions was the damming of the our rivers in the Mobile Basin, which resulted in the demise of 54 species of mussels and snails. The damming and subsequent inundation of the cobble shoals of the Coosa River alone resulted in the loss of 27 aquatic snail species.