ICHTHYOTOXIC PROPENSITIES OF SOME INDIAN MARINE GREEN-ALGAE (CHLOROPHYTES)

Twenty three extracts of chlorophytes have been assayed for ichthyotox icity against the common mosquito fish Gambusia affinis. The extracts generally have exhibited a wide range of effects. Of the twenty three species of chlorophytes, 35% exhibited ichthyotoxic properties causing mortality in fish and the remaining 65% were found to be nontoxic. Fu rther, Bryopsis plumosa was highly toxic, Caulerpa cupressoides, Bryop sis sp., and Halimeda gracilis were moderately toxic and Caulerpa ferg usonii, C.racemosa, C.peltata and C.taxifolia were found less toxic. T hese results suggest that some marine chlorophytes posses protective c hemical defense mechanism against herbivorous fishes.