Harpacticoid copepod distribution on a sandy shore in the vicinity of a power plant discharge, at Kalpakkam, along the east coast of India

Abstract

Harpacticoid copepods were sampled monthly from December 1988 to November 1990 at seven experimental stations in the vicinity of a power plant discharge on the east coast of India. Seasonally copepods were abundant during summer (Feb.-May) and less during monsoon (June-Aug.). High water temperatures were recorded at stations nearer to the discharge point. Warm water in nearby stations elevated the sand (substratum) temperature and reduced copepod density. The maximum density at the farthest station (st. 7) was 3722 no. 10 cm(-2), where the seasonal temperature ranged from 26.9 to 29.8 degrees C. Contrarily, at stations nearer to the discharge (sts 3, 4 and 5) wherein often temperatures above 34 degrees C prevailed, the density was drastically reduced. The population of copepods were restored in all stations during a plant shutdown period when normal temperatures prevailed. Salinity and dissolved oxygen level did not show any influence on copepod abundance.