Toxicity of the dinoflagellate Gambierdiscus sp. for the marine copepod Tigriopus japonicus

Abstract

It is known that Gambierdiscus toxicus is a benthic ciguatoxin-producing armored dinoflagellate, often attached to macroalgae in marine and the microalga is the primary causative organism of ciguatera fish poisoning occurred in tropical or subtropical regions. Recently, Gambierdiscus sp. has been observed in the southern sea of Korea by global warming. The purpose of this study was to examine the toxicity of Gambierdiscus sp. for the marine copepod Tigriopus japonicus which is primary consumer in marine ecosystem. Gambierdiscus sp. was isolated from Jeju island in Korea and have been cultured in laboratory. T. japonicus adult females and nauplii were exposed to various concentrations of the algae or their cultured medium for the assessment of toxicity and the analysis of gene expression in the copepod. In the toxicity test, Gambierdiscus sp. induced an increase in the mortality of nauplius and the immobility of adult female. 96h-LC50 level and NOEC of Gambierdiscus sp. for the nauplius were 435 cells/mL and 100 cells/mL, respectively. EC50 level and NOEC of Gambierdiscus sp. for the adult female were 1358 cells/mL and 400 cells/mL for 96 hours, respectively. The survival and mobility of T. japonicus were not affected by the cultured medium without Gambierdiscus sp. cells over all concentrations in the toxicity test. However, in the analysis of gene expression in the copepod, exposure of the copepod to the medium caussubtropical regions. Recently, Gambierdiscus sp. has been observed in the southern sea of Korea by global warming. The purpose of this study was to examine the toxicity of Gambierdiscus sp. for the marine copepod Tigriopus japonicus which is primary consumer in marine ecosystem. Gambierdiscus sp. was isolated from Jeju island in Korea and have been cultured in laboratory. T. japonicus adult females and nauplii were exposed to various concentrations of the algae or their cultured medium for the assessment of toxicity and the analysis of gene expression in the copepod. In the toxicity test, Gambierdiscus sp. induced an increase in the mortality of nauplius and the immobility of adult female. 96h-LC50 level and NOEC of Gambierdiscus sp. for the nauplius were 435 cells/mL and 100 cells/mL, respectively. EC50 level and NOEC of Gambierdiscus sp. for the adult female were 1358 cells/mL and 400 cells/mL for 96 hours, respectively. The survival and mobility of T. japonicus were not affected by the cultured medium without Gambierdiscus sp. cells over all concentrations in the toxicity test. However, in the analysis of gene expression in the copepod, exposure of the copepod to the medium caus