Macrobenthic Diversity During Pre and Post Drought Period of a Floodplain Wetland in Vaishali District of Bihar.

ABSTRACT

Qualitative and quantitative estimation of macrobenthic fauna was done during pre and post drought period. A total of 18 species of macrobenthos were recorded during pre drought and 17 in post drought period. Maximum number of species was reported in Mollusca followed by Diptera and Oligochaeta. The average contribution of Mollusca was 94.72%, Dipetra 2.98% and Oligochaeta 2.30% to total benthic species of the Chaur. Bellamya bengalensis, Gabbia orcula, Gyraulus convexiusculus, Lymnaea acuminata and Lymnaea auricularia were the molluccs which were found in all the monthly samples. Number wise Gyraulus convexiusculus was most abundant followed by Gabbia orcula while Lamellidens marginalis and Pila glabosa were the least abundant. In pre drought period average number of macrobenthos was 3176/m2 while in post drought period, it was 2676/m2. Analysis of the various index showed that diversity of benthic fauna was higher in WIN season followed by RMON, PRM and MON season. Winter seems to be a favourable season for benthic organisms. Availability of different species of mollusks indicated the good cultural and unpolluted condition of Chaur.