Abstract:Toxic microalgae outbreaks have caused significant economic losses in the Chinese aquaculture industry, including the aquaculture of shrimp. Blooms that involve phycotoxins, especially paralytic shellfish poison(PSP), are dangerous, harm the shrimps and cause losses in marine production. Previous studies mainly focused on the toxic effects on shellfish and fish, rather than shrimp. This study investigated the inductive effect of the toxic dinoflagellate (ATHK), a producer of PSP, on oxidative stress and the expression of a caspase gene (Fenneropenaeus chinensis, an important mariculture species in China. A. tamarense, and individuals cultured with filtered seawater were set as control. Superoxide dismutase (SOD) activity, glutathione S-transferase (GST) activity, malonyldialdehyde (MDA) content and expression in the gills were analyzed at 3, 6, 12, 24, 48, 72 and 96 h after exposure. The results showed that SOD activity, GST activity, MDA content and generally increased at first and then decreased with increasing exposure time. However, when exposed to 1000 cells/mL of , SOD activity increased and then decreased with increasing exposure time, and was significantly(P<0.05) inhibited, except at 3- and 48 h-post treatment. The changes in SOD and GST activities of in this study suggest that these enzymes were actively involved in the detoxification process in gills of F. chinensis exposed to 1 000 cells/mL of increased with increased exposure time, and displayed a time-dependent response relationship. The exposed to was positively and linearly correlated with the MDA content. The current study revealed that exposure to, causing lipid peroxidation (LPO) and upregulation of in gills of the shrimp. The findings from this study demonstrated that SOD, GST and MDA were sensitive and suitable potential oxidative biomarkers of A. tamarense in the short term. Further studies are needed to clarify the mechanism of toxicity of to aquatic invertebrates.