TEMPORAL DISTRIBUTION OF FISH ASSEMBLAGE IN THE SANGU RIVER ESTUARY, CHITTAGONG WITH SPECIAL REFERENCE TO SOME ENVIRONMENTAL PARAMETERS

Abstract

This research aimed at studying the temporal distribution of fish assemblage in the Sangu river estuary, Bangladesh. Fish samples were collected from Estuarine Set Bag Net (Behundi jal) over four seasons such as (winter, pre-monsoon, monsoon and post-monsoon) from April, 2014 to December, 2014 and water samples were collected from the estuary during the four seasons. Multivariate analyses were performed using the software PRIMER V6 and Canonical Correspondence Analysis (CCA) was done using the SPSS V17. In the present study, 34 species of fish belonging 21 families were identified of which Gudusia chapra (18.09%), Harpodon nehereus (17.92%), Trypauchen vagina (13.71%) and Liza subviridis (5.65%) were found to be most dominant species where most of the young individual and the adult of small species. The assemblage was dominated by marine and brackish water species. The Shannon-Wiener diversity index, Margalef richness index, Pielou’s evenness index and Simpson dominance index were found to be 3.03, 7.05, 0.94 and 0.97 respectively. The diversity index showed significant differences in temporal fish assemblage structure. At the similarity of 58% three groups were attained while monsoon showed separate clustering from other groups. The Non-metric Multidimensional Scaling (nMDS) showed 43% similarity in all seasons based on Bray-Curtis similarity matrix. The CCA ordination indicated that dissolved oxygen (DO) and salinity were the two most important environmental parameters shaping the fish assemblage structure in the Sangu river estuary.