Macrobenthic assemblage in the rupsha-pasur river system of the sundarbans ecosystem (Bangladesh) for the sustainable management of coastal wetlands

Abstract

Information on benthic fauna in the coastal region of Bangladesh is scarce. Owing to its geographical location, land characteristics, and multiplicity of rivers, the south western region of Bangladesh contains the world’s largest mangrove forest, the Sundarbans, containing rich floral and faunal biodiversity. Non-forestry product of the Sundarbans e.g. aquatic biotic community becomes more plentiful with presence of benthic invertebrates in the system since macrobenthos perform various ecological roles in mangrove functioning. To obtain insight into macrobenthos assemblage patterns along the Rupsha-Pasur river system, along the Sundarbans, Mongla and Koromjal were the sites of investigation. The macrobenthos assemblage patterns with environmental parameter from 10 m depth during low tide were observed from those sites. Among the major groups found in both sites, Annelida (including echiura, oligochaeta and polychaeta) represented highest diversity with 22 species, followed by 21 species of arthropoda (Crustacea-decapoda), 20 species of Mollusk (gastropoda), 9 species of arthropoda-bivalvia, few crustacea-isopoda, crustaceae-tanaidaceae and nemartina taxa. The relative abundance was not significantly different in Mongla and Koromjal. A significant seasonal effect on the relative abundance was found by performing the Kolmogorov-Smirnov test, at p < 0.05. The monsoon gave rise to more diverse macrobenthic species than the dry season. To study the relations between the macrobenthic species, relative abundances, and the environmental parameters, redundancy multivariate analysis was applied. The overall results indicate relative species abundance is influenced by the combined effects of environmental parameters and biological parameters. Further research is necessary to understand the species and system dynamics. The research of non-forestry product of the Sundarbans is necessary for the future management of the Sundarbans in a sustainale manner.