AME 65:261-270 (2012)  -  DOI: https://doi.org/10.3354/ame01555

ABSTRACT: Ostreopsis ovata is a benthic dinoflagellate that produces palytoxin and its analogues. Since the end of the 1990s, toxic blooms of O. ovata have been recorded in many tropical and temperate marine waters. These blooms often kill benthic invertebrates and cause health problems for humans. We hypothesize that increases in seawater temperature might induce these blooms. A strain of O. ovata isolated from the southern coast of Japan was selected for study. O. ovata cells were exposed to 7 different temperatures from 24 to 30°C for 30 d, and growth rates were noted. The specific growth rate was found to be highest at 25°C, next highest at 24°C and lower at 26, 28, 27, 30 and 29°C, in that order. The hypothesis that increased seawater temperature causes increases in growth rate was thus not supported. The cell toxicity and carbohydrate production of O. ovata were highest at the temperature range that is optimal for cell growth. Increasesing sea surface temperature, as a result of global warming, is therefore not likely to have a substantial effect on the bloom formation and toxicity of this Japanese strain of O. ovata.

KEY WORDS: Ostreopsis ovata · Benthic dinoflagellate · Palytoxin · Toxicity · Climate change · Carbohydrate production