Subtidal benthic macrofauna of the Mangalore Coast, west coast of India

Abstract

Subtidal macrobenthic fauna from the Mangalore Coast was studied from the shelf areas between the old Mangalore Port and Suratkal, covering an area of approximately 40 km sup(2). Benthic bivalves were the most abundant group, (36160/m sup(2)) in December. During the same period, gastropods which also coexisted, showed their highest density (6400/m sup(2)), followed by a lean period up to April. Peak abundance of polychaetes was during May (3380/m sup(2)) with consequent reduction during the time of bivalve dominance and vice versa. Other groups recorded occasionally were amphipods, heteropods, holothurians, juvenile star fishes, stomatopods, cephalochordates, sipunculids, oligochaetes, cumaceans and decapods. The area between the old Mangalore Port and New Mangalore Port appeared to be more productive compared to the suratkal area in the north. The striking difference noticed was the shift in the benthic production from the 5 m contour. In all the earlier workd 5 m contour line was found to be most productive, with a decrease in biomass with depth. In the present observations 5 m contour line was least productive with an increasing trend up to 20 m, both in biomass and numerical density.