Diversity and Distribution of Freshwater Gastropods in the Bayou Bartholomew Drainage, Arkansas, U.S.A.

Abstract

Bayou Bartholomew is a low-gradient river system that drains much of southeastern Arkansas and northeastern Louisiana, U.S.A. As one of the few southeastern streams remaining un-impounded, the Arkansas reach of the bayou harbors a rich freshwater molluscan fauna. Collecting efforts have historically focused on documenting freshwater mussel and fish diversity, and there was no prior survey focusing on freshwater gastropods. This survey of the drainage yielded 13 gastropod species representing three orders and seven genera. Pulmonates were most abundant in low-order reaches of the drainage, while gill-breathing snails dominated higher-order reaches. Co-occurrence analyses indicated that pulmonates occurred significantly more often with other pulmonates than they did with gill- breathers; this trend was also observed in gill-breathers. Both stream order and predominant substrate influenced species richness and abundance. Our findings were consistent with other published studies on freshwater snail distribution but may be confounded by drought conditions experienced during the survey.