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

•The dinoflagellate Gambierdiscus sp. was identified in the temperate area.•The dinoflagellates caused immobilization or mortality in Tigriopus japonicus.•The algae and culture medium induced stress or detoxification-related gene expression.

The toxic dinoflagellate Gambierdiscus sp. has recently been observed in temperate areas in the Southern Sea of the Republic of Korea. The purpose of this study was to examine the toxicity of Gambierdiscus sp. toward the marine copepod Tigriopus japonicus. T. japonicus adult females and nauplii were exposed to various concentrations of algae or culture medium to assess toxicity and analyze gene expression patterns in the copepod. Based on the toxicity tests, Gambierdiscus sp. increased the mortality of nauplii and the immobility of adult females. The survival and mobility of T. japonicus were not affected by culture medium lacking Gambierdiscus sp. cells in the toxicity test. However, based on the analysis of gene expression in the copepod, exposure of the copepod to culture medium affected the expression of stress or detoxification-related genes. Further studies to identify toxins in Gambierdiscus sp. are required to increase our understanding of dinoflagellate toxicity.