TEMPORAL DISTRIBUTION OF FISH ASSEMBLAGE IN KARNAFULLY RIVER ESTUARY, BANGLADESH

Abstract

This research aims at studying the temporal distribution of fish assemblage in the Karnafully river estuary, Bangladesh. To study the fish assemblage catch from Estuarine Set Bag Net (Behundi jal) as well water samples were collected in four seasons (winter, pre-monsoon, monsoon and post-monsoon) from April, 2013 to December, 2013. Multivariate analyses were performed using the software PRIMER V6 and Canonical Correspondence Analysis (CCA) was done using the SPSS V17. In the present study, 41 species of fish belonging 20 families were identified of which Harpodon nehereus (20.54%), Panna microdon (17.44%), Coilia ramkorati (14.42%), Johnius macropterus (10.90%) were found to be most dominant species. The Shannon-Wiener diversity index, Margalef richness index, Pielou’s evenness index and Simpson dominance index were found to be 2.67, 4.57, 0.95 and 0.97 respectively. The diversity index showed significant differences in temporal fish assemblage structure. At the similarity of 50.5%, three groups were attained while monsoon showed separate clustering from other groups. The Non-metric Multidimensional Scaling (nMDS) showed 20% similarity in all seasons based on Bray-Curtis similarity matrix. The CCA ordination indicated that temperature and dissolve oxygen (DO) were the two most important environmental parameters shaping the fish assemblage structure in the Karnafully river estuary.