Short-term fluctuations in salinity and turbidity: effects on the embryonic stage of two abalone species, Haliotis discus discus and Haliotis gigantea

Abstract

Marine gastropod eggs are often distributed in the intertidal zone, where they are potentially exposed to short-term salinity and turbidity changes due to heavy rains that may adversely affect their embryonic development. In this study, the embryos of two abalone species, disk abalone Haliotis discus discus and giant abalone Haliotis gigantea, were exposed to various salinities (34, 30, 26, 22, 18 and 14 psu) or turbidities (0, 100, 300, 500 and 700 NTU) for a single 3 h period, and subsequently maintained at normal control conditions (34 psu and 0 NTU). The short-term low salinity stress decreased the hatching and survival rates, and increased the abnormality rate for both species. As for turbidity stress, negative effects on hatching and survival rates were observed in both species when their embryos were exposed to increased turbidity. The abnormality rates of both species at turbidities of 500 and 700 NTU were significantly higher than those at turbidities of 0 and 100 NTU. Overall, exposure of embryos to low salinity or high turbidity for even a short period can clearly have substantial impacts on the embryonic development of the two abalone species, and disk abalone was more sensitive to salinity and turbidity stresses compared to giant abalone.