Diversity and Seasonal Variation of Fish Assemblages of Dingapota Haor an Eutrophic Wetland of Northeastern Bangladesh

Abstract

Wetlands are considered as the heart of natural feeding and breeding grounds of many indigenous fishes of Bangladesh. These are also the most diversified habitat in the world. However, the wetlands of Bangladesh are in danger of extinction due to various manmade and natural causes. Therefore, wetlands need special attention to conserve this unique ecosystem of Bangladesh. As a part of the conservation measures needed for wetland ecosystem, the present study was undertaken to describe the abundance and diversity status of fish in Dingapota wetland of Bangladesh and to identify the key environmental factors influencing the fish community assemblage. A total of 52 fish species were recorded from 7 orders during the study period. Cypriniformes comprises the most abundant order (47.91%) followed by Perciformes (20.71%) and Clupeformes (20.22%). Higher number of species was recorded in post-monsoon season. Fish community assemblage was significantly differentiated among the three seasons (ANOSIM, Global R = 0.803, P < 0.05), while the overall average differences in the period of three seasons was estimated as 39.92% and similarity percentage analysis (SIMPER) revealed the greater contribution of Osteobrama cotio, Esomus danricus, Nandus nandus, Gudusia chapra and Chanda nama to ascertain this dissimilarity. Multivariate analysis based on non-metric multidimensional scaling (nMDS) generated three separate groups of each seasonal samplings and cluster analysis to find out natural grouping of samples according to their abundance. Diversity indices (Shannon-Weiner diversity (H), Margalef's richness (D) and Pielou's evenness (e)) were found to vary significantly among the seasons. Canonical correspondence analysis (CCA) revealed the significant roles of temperature, depth, transparency, pH, dissolved oxygen and alkalinity for structuring the community assemblage of fish in Dingapota wetland. Essential baseline information generated by this study will help the respective authority to formulate sustainable conservation measures for Dingapota wetland.