Microcrustacea (Crustacea: Branchiopoda) of Deepor Beel, Assam, India: richness, abundance and ecology

Abstract

Plankton samples collected from two sampling stations of Deepor Beel, an important floodplain lake of Assam and a Ramsar site of India, revealed 51 species of Microcrustacea and showed qualitative dominance of Cladocera (45 species). Microcrustacea comprised a significant quantitative component (45.6 � plus or minus 5.8 and 50.8 � plus or minus 4.5 %) of zooplankton and exhibited bimodal and trimodal annual patterns with peaks during winter. Cladocera > Copepoda are important quantitative groups. ANOVA registered significant variation in species richness and abundance of Microcrustacea over time and between stations. Richness and abundance were inversely correlated with water temperature and rainfall, and positively correlated with specific conductivity and dissolved oxygen. Multiple regression registered significantly higher cumulative effects of ten abiotic factors on these two parameters. Our results are characterized by higher species diversity, higher evenness and lower dominance of Microcrustacea and show lack of distinct quantitative importance of individual species.