Population ecology and community structure of subtidal soft sediment dwelling macroinvertebrates of Konkan, west coast of India

Abstract

Population density of benthos varied from 350 to 29,975.m-2 (XBAR = 4325, SD = +/- 5939) in the study area. The fauna was mainly composed of Polychaeta (76.96%), Mollusca (11.56%), Crustacea (4.93%), Echinodermata (4.36%) and other groups, viz. Echiurida, Nemertea and Sipuncula (1.59%). Twenty nine species of macro-invertebrates were observed. Among which, burrowing deposit feeding Axiothella obockensis, Clymene annandalei and surface deposit feeder Prionospio pinnata were dominant. The species diversity (Shanon Wiener index) varied from 0.44 to 3.58 (XBAR = 1.94, SD = +/- 0.89). Population and community structure were more stable in premonsoon months. Carnivorous species Glycera alba modified the community structure mainly due to prey-predator relationship. Deposit feeders were mainly confined to muddy substrata. Sediment composition, organic carbon content of the sediment and salinity of bottom waters were the key factors determining the population and community structure of soft sediment dwelling macro-invertebrates in the sub-tidal region of Konkan coast. The model put forward by Huston [Am Nat, 113 (1879) 101] is most convincing to explain the benthic population and community structure dynamics.