Drivers of the diversity and spatial heterogeneity of aquatic snails in estuarine habitats: evidence from West Bengal in India

An appraisal of the snail (Mollusca: Gastropoda) assemblage of the Sundarbans mangrove region, West Bengal, India, was made through consistent monitoring of three selected sites. In a span of 3 years, 18 species of snails under 11 families, and 9 orders were collected in 304 samples with the Shanon-Weiner diversity index (H’) ranging between 0.8445 and 1.6909. In terms of numerical abundance, Stenothyra deltae (34.07 ± 5.71SE) and Cerithidia cingulata (26.01 ± 1.33SE) were dominant, while Nassarius stolatus (0.01 ± 0.01 SE) qualified as a rare species in the three sites. Significant differences (p < 0.05) in abundance in the sites were observed for Cerithidia cingulata, C. alata, Gangetica miliacea, and Stenothyra deltae. A canonical correspondence analysis reflected that the abundance of G. miliacea is shaped by the conductivity, C. cingulata is linked with temperature and the phosphate concentration is a better predictor of the abundance of S. deltae. The pattern of the diversity of the snails may probably reflect the variations in the environmental quality including the food resources. Thus, the snail assemblage pattern may be used as a basis for the biological monitoring of the Sundarbans mangroves and other similar sites.