The Tombigbee drainage system lies in a part of North America that has been relatively free of major changes for a very long period of time. As time passes, the biotic diversity of an area tends to increase. (Futato et. all 1989: 21)
In 1992 the Nature Conservancy listed the Upper Tombigbee as well as the Buttahatchee tributary among a list of 87 rivers in the nation with 10 or more at-risk freshwater fish and mussel species. The Upper Tombigbee ranked 32nd and the Buttahatchee 29th for their high number of imperiled aquatic species. The Buttahatchee has 15 at-risk species with 6 of these listed as federally threatened or endangered. The Upper Tombigbee harbors 14 at-risk species with 7 of these listed as federally threatened or endangered. (TNC-Appendix B)
According to this Report both of these sections as well as the Luxapallila tributary (with 10 at-risk mussel and fish species), the Sipsey River (with 15 species), Middle Tombigbee-Lubub section (with 7 species), and the Lower Tombigbee (with 5 species) are amongst the most critical watersheds in the nation to conserve aquatic biodiversity. Within Alabama the Tombigbee represents 6 of a total of 27 of these critical sections of river. (Appendix C)
In short, the Tombigbee is a vitally important river from the perspective of species diversity.
The Ovate clubshell (Pleurobema perovatum), an endangered species, was once known from all the major rivers of the Mobile Basin. A recent survey (94-96) found only one specimen on the Sucarnoochee River of the Tombigbee system. (GSA)
The Heavy Pigtoe Mussel (Pleurobema taitanum), an endangered species,
One extremely rare species of crayfish Procambarus (Pennides lagniappe) is found in the middle reaches of the Sucarnoochee River (mainly in Mississippi). This represents one of three locality ranges for this species in Alabama, and all are in Sumter County. (GSA)