Mortality of marine organisms associated with offshore summer blooms of the toxic dinoflagellate Gonyaulax monilata Howell at Galveston, Texas

Occurrence of blooms of the toxic dinoflagellate Gonyaulax monilata, in the offshore coastal waters of Texas at Galveston in 1971 and 1972, is documented. The types and quantities of organisms noted during the blooms were quite similar. They consisted of 29 spp, including coelenterates, annelids, molluscs, crustaceans, echinoderms, and fishes, all of which were either sessile, sedentary, or weakly motile, suggesting that the more mobile spp were able to avoid the area of the bloom before accumulating lethal amounts of toxin. Despite extensive monitoring in late July and Aug of 1973, on G. monilata were noted in the offshore area of Galveston Island. The absence of the red tides during these yr is evidently related to relatively low salinities and temps in the Galveston Bay drainage area during the month of Aug