Blooms of Trichodesmwm thiebautii and their effect on Experimental pearl culture at Veppalodai

Abstract

Blooms of the blue-green alga, Tricltodesmiiim thiebautii, were observed at the pearl culture farm off Veppalodai in the Gulf of Mannar in March-April and September, 1973. Although the alga occurred in high concentration, it did not cause any unusual mortality of pearl oysters in the open-sea farm. However, a few hu.ndreds of experimental oysters kept in bloom-laden water in the laboratory died due to the death and decay of t'he algal filaments. It is pointed out that in a widespread bloom situation, as in the present instance, work on pearl culture is hampered as it is not possible to draw clear, bloom-free water for "seeding" operations.