Effects Of Four Typical Bloom Forming Algae On Metamorphosis And Activities Of Antioxidant Enzymes Of Abalone Haliotis Discus Hannai

Chinese abalone aquaculture was severely threatened by harmful algal blooms,which happened frequently and affected widely.And it caused economic loss more than 2 billion yuan.In order to explore the effects and mechanisms of harmful algae blooms on abalone,we investigated the acute toxicity of four different harmful algae(Karenia mikimotoi,Alexandrium catenella,Prorocentrum donghaiense and Aureococcus anophagefferens)on the survival of Haliotis discus hannai Ino,the metamorphosis of larvae and the activities of antioxidant enzymes.The results of the acute toxicity of harmful algae blooms on the survival of Haliotis discus hannai Ino suggested that K.mikimotoi and A.catenella could lead the larvae,juveniles and adults of H.discus hannai Ino to death.The survival rates of larvae reduced a lot in 96 h when exposed to K.mikimotoi culture.The survival rates of larvae,juveniles and adults were reduced when exposed to A.catenella culture.P.donghaiense and A.anophagefferens could lower the survival rates of larvae,but had no significant effect on that of juveniles and adults.Meanwhile,the results of effects of harmful algae blooms on the metamorphosis of larvae showed that K.mikimotoi,A.catenella and P.donghaiense could do harm to the metamorphosis of larvae.The metamorphosis rates of larvae almost reduced to 5 % and 25 % in 96 h when exposed to K.mikimotoi culture and A.catenella culture.And A.anophagefferens could lead larvae to death,which achieved metamorphosis,suggesting a potential threat to the recruitment of population.Besides,the finding of effects of harmful algae blooms on the activities of antioxidant enzymes indicated that K.mikimotoi and A.catenella inhibited SOD and CAT activities in the gills,and SOD and GSH-Px activities in the hepatopancreas of abalone,which suggested that these two algae would damage the immune system of abalone.However,P.donghaiense and A.anophagefferens had no influence on the three antioxidant enzymes of abalone.Therein,this study revealed that K.mikimotoi blooms and A.catenella blooms did harm to the survival of abalone,the metamorphosis of larvae and the activities of antioxidant enzymes;A.anophagefferens blooms could lead larvae to death,which achieved metamorphosis.All of three may be serious threats to abalone aquacultures and harm to natural population of abalone,and P.donghaiense may have potential negative impacts on abalone.