Habitat Variation Among Aquatic Gastropod Assemblages of Indiana, USA~!2008-11-19~!2008-12-24~!2009-01-22~!

Abstract

We collected aquatic gastropods at 137 sites in lakes and streams of Indiana and tested for patterns of assemblages with environmental variables. The survey resulted in 32 species with a mean of 2.8 species at each site, and a mean abundance at each site of 144 individuals. Nonmetric multidimensional scaling (NMS) multivariate analyses resulted in watershed drainage area, water conductivity, substrate category frequency, and dissolved oxygen as significant correlates of gastropod assemblage structure. Gastropod assemblages of lakes were not significantly different than assemblages of streams in the ordination. Prosobranch taxa occurred in higher abundances than pulmonate taxa at sites with lower conductivity in larger watersheds. There were no pairs of gastropod species that tended to co-occur more frequently than random. Our analyses resulted in local environmental variables providing explanation of aquatic gastropod assemblage structure.

Distribution and Environmental Influences on Freshwater Gastropods from Lotic Systems and Springs in Pennsylvania, USA, with Conservation Recommendations

“…Total drainage area is also an important predictor of species richness in other studies of snails in streams and lakes (Dillon and Benfi eld 1982, Jokinen 1987, Prezant and Chapman 2004 and in freshwater mussels (Ortmann 1920, Strayer 1983. We found headwaters dominated by pulmonate species, and larger streams dominated by pleurocerids and vivi parids, as reported in the literature (Brown et al 1998, Minton et al 2008, Pyron et al 2009). Barnese et al (1990) documented resource partitioning between pulmonate and prosobranch snails, while Johnson and Brown (1997) found that current regime and light penetration were important in Elimia semicarinata (Say, 1829).…”

“…Pyron et al (2009) determined that most species were found at sites with pH values ranging from 7.8 to 8. Temperature, a variable we expected to be important in infl uencing species richness, was not signifi cant.…”