Temperature and salinity effects and toxicity of Gambierdiscus caribaeus (Dinophyceae) from Thailand

Abstract

:Species of the benthic dinoflagellate genus Gambierdiscus are the putative producer of the toxins causing ciguatera fish poisoning (CFP) in tropical and subtropical areas. Although CFP events and distribution of G. caribaeus have been reported in Thailand, little is known about the conditions that enhance the growth of Gambierdiscus in Thailand. Hence, this study was aimed at determining the effects of temperature and salinity and their interactions on the growth of Thai G. caribaeus. The strain tested showed the highest cell yield in IMK/2 medium. Based on growth rate (μ), Thai G. caribaeus grew in the temperature range of 20°C–35°C and the salinity range of 20–40. The suboptimal condition (≥ 80% of the maximal growth rate) for the strain tested was 20.5°C–30.5°C and salinity of 25.0–37.5. The optimal condition was 25°C and salinity of 30. Furthermore, the Thai G. caribaeus revealed high toxicity to mice. Our results suggest that tolerance of up to 35°C may allow these organisms to be distributed in tropical areas, including Thailand, where the water temperature often exceeds 30°C.