Assemblage patterns and community structure of macro-zoobenthos and temporal dynamics of eco-physiological indices of two wetlands, in lower gangetic plains under varying ecological regimes: A tool for wetland management

Abstract Wetlands are rich biological resources and support livelihood and nutritional security to a huge populace globally. In the present study, two ecologically distinct floodplain wetlands viz ., Khalsi and Akaipur located in the sub-basin of Jamuna river in lower Gangetic basin, were studied for abundance, species richness and diversity indices of macro-zoobenthic communities across four seasons. The selected wetlands vary in terms of ecological regimes such as, water volume, depth, link channel, agricultural runoffs, macrophyte coverage etc. Khalsi, a seasonally open beel (wetland) that occasionally exchange water with river Jamuna during high flood, while Akaipur is a closed beel with no exchange of water. The studies indicated higher community richness in macrophyte dominated seasonally open Khalsi wetland (22species) as compared to closed Akaipur wetlands (20 species). The community abundance was higher in Khalsi (8496 nos/m 2 ) as compared to Akaipur. Average Dominance, Simpson and Shannon diversity indices for Khalsi and Akaipur were calculated as 0.3, 0.7 & 1.5 and 0.2, 0.8 & 1.7, respectively. The community structure of wetlands revealed dominance of a single group, gastropoda (99%), followed by bivalvia (0.64%), diptera (0.27%) and oligochaeta (0.09%) in Khalsi, whereas, Akaipur depicted community structure with dominance of gastropoda (46.18%) followed by oligochaeta (41.36%), diptera (11.22%) and bivalvia (1.24%). The trophic state index (TSI) based on chlorophyll a (Chla), Secchi disc transparency and total phosphorus showed significant (p