Abstract

Throughout the United States, freshwater mussel faunae are rapidly declining. Evaluations of disease threats to such species are an important component of conservation efforts. Of North Carolina's five endangered mussel species, the Carolina Heelsplitter (Lasmigona decorata) is found in only two localities, the Goose and Waxhaw Creeks in the southern piedmont province of the state, with population numbers too unstable to allow for invasive diagnostic sampling. In this study, a sympatric freshwater mussel, Elliptio complanata, was used as a surrogate for evaluation of health risks to the Carolina Heelsplitter.

Bacteriological sampling of the gastrointestinal tracts and histological evaluations of internal organs were conducted on ten E. complanata from each of the two aforementioned sites. Of the nineteen bacterial species isolated from the digestive tracts, Aeromonas hydrophila (55.0%), Enterobacter spp. (40.0%), and Bacillus spp. (30.0%) were predominant. Histological lesions of internal organs included mild to moderate digestive gland atrophy, inflammation in one mussel, and variable deep tissue parasitism in multiple individuals. Distinct differences in parasite prevalence were evident between mussels from the two creeks. This study provides baseline health data of E. complanata in south-central North Carolina and presents a method of evaluating potential disease threats to an endangered freshwater mussel population by use of a surrogate species.