Freshwater mussels of the Delta National Forest, Mississippi Final Report
Twenty-three species of freshwater mussels were collected during a survey of aquatic habitats in the Delta National Forest, Mississippi. An additional 6 species not encountered in this survey were reported by an earlier study in the Big Sunflower River near the northern proclamation boundary of the Forest. These species are included here, bringing the total species list for the Forest to 29 species. These species are distributed unequally among aquatic habitats in the Forest. Twenty-four species occurred only in large river habitats represented by the Big and Little Sunflower Rivers. Three other habitat types, bayous and small permanent streams, intermittent streams and ditches, and palustrine wetlands, had mussel faunas that were similar to each other but differed from the large river fauna. Two species occurred only in these habitats and not in large rivers. An additional three species were widely distributed among all habitat types. Most species found in large river habitats showed little or no evidence of recent recruitment; most individuals were greater than 10 years old. Five species unique to large stream sites were found only as relict shells, indicating that these species are now rare or extirpated from these sites. In contrast, all species found in bayous and small permanent streams, intermittent streams and ditches, and palustrine wetlands showed evidence of recent recruitment.The continued existence of the diverse and distinctive large stream mussel fauna in the Forest is contingent on: 1) maintaining the habitat integrity of the Little Sunflower and the Big Sunflower rivers; 2) determining factors that are limiting recruitment and eliminating species; and 3) identifying management alternatives that may mitigate these factors. The current conditions for freshwater mussels in the Little Sunflower and Big Sunflower rivers of the Forest are inexorably influenced by upstream watershed conditions. From that perspective, the continued existence of the diverse mussel fauna of the Delta National Forest is also contingent on the cooperation and coordination of 'state and federal management and regulatory activities in the Big and Little Sunflower rivers.