Calcibiocavitological investigations

Abstract

Calcibiocavitation is a major poroblem in the marine environment and a detailed study on these aspects has been undertaken and the salient findings are presented here. Gregarious molluscs such as the sacred chank Xancus pvrum, mussels (both green and brown), rock oysters (Crassostrea spp.), pearl oysters, Thais rudolphi (Lam.) and corals which inhabit the southwest coast of Kerala and the Gulf of Mannar have been investigated. The wide fluctuations noted in the abundance and population structure of the various pests in the molluscan beds during the short period of two years clearly indicated that they were in severe competetion for suitable substrata and the shells of gregarious mollusks which inhabit this area provide ample opportunities for the pests to flourish. The incidence of boring sponges is found to be rather high among raft-cultured pearl oysters both at Tuticorin and Vizhinjam. It is difficult to control the infection of boring animals in the natural beds, but the low rate of incidence recorded year after year under suggests that the nature controls this to lower level.Another important observation was the wide distribution of the boring sponge C.vastifica in the Ashtamudi Lake, Quilonwhich may form a major threat to our future rock oyster farms along the estuaries.