Inhibitory effects of four typical bloom-forming algae species on metamorphosis of the abalone Haliotis discus hannai

Abstract

In recent years, harmful algal blooms (HABs) have occurred frequently along the coast of China and have caused massive shellfish mortality. However, little is known about the impacts of HABs on the metamorphosis of shellfish. In this study, the effects of 4 typical harmful algae species present in Chinese waters (Karenia mikimotoi, Alexandrium catenella, Aureococcus anophagefferens, and Prorocentrum donghaiense) on the survival and metamorphosis of abalone Haliotis discus hannai larvae were investigated. After 96 h of treatment, un-metamorphosed larvae (veligers) were significantly affected by K. mikimotoi, A. catenella, and P. donghaiense, as mean ± SD survival rates were 5.2 ± 2.1, 27.7 ± 1.4, and 63.8 ± 6.9%, respectively, compared with 86.0 ± 4.1% for the control treatment (the non-toxic alga Skeletonema costatum). Survival rates of metamorphosed larvae were significantly affected by K. mikimotoi, A. catenella, and A. anophagefferens (4.5 ± 2.8, 22.3 ± 5.8, and 26.5 ± 3.6%, respectively, compared with 46.2 ± 1.3% for the control), and metamorphosis was significantly inhibited by K. mikimotoi and A. catenella (5.0 ± 2.2 and 24.5 ± 3.1%, respectively, compared with 49.3 ± 1.5% for the control). A. anophagefferens was more toxic to metamorphosed larvae than to un-metamorphosed larvae. These results suggest that all 4 species of harmful algae have detrimental effects on the metamorphosis of H. discus hannai and that K. mikimotoi and A. catenella are more toxic to abalone larvae than A. anophagefferens and P. donghaiense.