Distributional Pattern and Environmental Response of Snail in South-central Bhutan

Abstract

Terrestrial and freshwater snails are adapted to specialised ecological niches with a low mobility. They are highly susceptible to environmental changes, rapid urbanisation and the associated development activities. Snail diversity in different habitats and response of snails to environmental variables were studied in south-central Bhutan. Terrestrial habitat was subdivided into undisturbed and disturbed category (Dekidling and Gelephu gewogs respectively) under Sarpang district. Snails were collected from 88 (44 plots each) random sampling quadrats (20 x 20 m) with subplots of 5 (1 x 1 m) each in the main plots. Sampling in freshwater (nine plots) was carried out in 100 m interval with 20 m stretch. A total of 4,477 individuals comprising of 35 snail species belonging to 11 families were
collected. There was significant difference in species richness in all the habitat types (p < .05). Terrestrial and freshwater snail species richness, diversity, evenness and abundance had no significant correlation with biotic factors except altitude (r = .65)and vegetation cover (r = .65) had significant positive correlation to the indices. The undisturbed terrestrial habitat supports more of small-body snails with higher species richness. However, disturbed terrestrial habitat supports large-body snails with less species richness but with higher species abundances. Melanoides tuberculata and Tarebia lineatawere rarely recorded in freshwater habitat indicating the needs fo further studies in monsoon season.