Impact of Short-Term Salinity and Turbidity Changes on Hatching and Survival Rates of Japanese Sea Cucumber, Apostichopus japonicus (Selenka, 1867), Eggs

The increased frequency and intensity of extreme rainfall events attributed to global climate change could lead to changes in salinity and turbidity levels in coastal waters which may negatively impact the survival of organisms, particularly during the early developmental stages. In this study, the influences of salinity and turbidity on the early life stage of Japanese sea cucumber, Apostichopus japonicus (Selenka, 1867), were studied in a series of small-scale laboratory experiments. During the first half of the experiments, A. japonicus fertilised eggs were exposed to various levels of salinity stresses (34: control, 30, 26, 22, 18, 14 PSU) for a single period of 3 h. In the second half of the experiments, following the same duration as the first experiment, fertilised eggs were exposed to different levels of turbidity, 0 (control), 100, 300, 500, and 700 NTU. The results showed that the hatching and survival rates significantly decreased as salinity dropped. As for turbidity, there were significant adverse effects on hatching and survival rates of A. japonicus. This study shows that short-term low salinity and high turbidity influenced events could potentially reduce larvae survival of A. japonicas. These factors could affect the robustness of future adult populations.