ABSTRACT
Samples of the cultured benthic dinoflagellates Gambierdiscus toxicus and Ostreopsis lenticularis, both isolated from a shalow back reef habitat in soutwestern Puerto Rico, were estracted in methanol, dried and resuspended in distilled water. After centrifugation, aliquots of the supernatant, or dilutions thereof, were added to suspensions of washed human and mouse red blood cells and incuated at different temperatures for different time periods. Further spectrophotometrical examinations of the samples showed a hemolytic activity aginst mouse and human red blood cells. The hemolytic activity of G. toxicus extract was 3 to 4 times greater than that of O. lenticularis and was less temperature-dependent. Such findings suggest that these two dinoflagellates produce chemically different hemolysins
