Study of Macrobenthos in Relation to Eutrophication at Chilika Lagoon, East Coast of India

In order to find out hydrographical parameters influences over macrobenthic density and diversity, fifteen stations were sampled in Chilika lagoon. They were grouped into macrophytes dominated areas from Station 1 to Station 10 (St1 to St10) and Phragmites karka dominated areas from Station 11 to Station 15 (St 11 to St 15).The value of Pearson’s correlation matrix in the macrobenthic density was found to be positive significant relationship with transparency (r=0.548, p<0.05), depth (r=0.8006, p<0.01) and pH (r=0.72, p<0.01). Whereas macrobenthic biomass was significant positive relationship with transparency (r=0.656, p<0.01), depth (r=0.8006, p<0.01), pH (r=0.516, p<0.05) and dissolved oxygen (r=0.671, p<0.01). The diversity index values were found highest in between St1 to St10 and decreased sharply in between St11 to St15. The Non-metric Multidimensional Scaling (NMDS) resulted three clusters of stations in the study area which were characterized as live macrophyte, live and dead macrophyte and Phargmites karka in Cluster I, Cluster II and Cluster III respectively. Progressive decreasing trend was observed in macrobentic density and diversity with the hydrographical parameters of depth, transparency and dissolved oxygen from cluster I to Cluster III. The total numbers and biomass of wet weight of macrobenthic were observed 26075 no m^-2 (1738 ± 3341) and 277 gm m^-2 (18.47±38.83) in the sampling stations. Bivalves followed by Polychaets were dominated in the first group of stations where as Polychaet and Chronomid was dominated in the second group of stations.