Impacts of short-term salinity and turbidity stress on the embryonic stage of red sea bream Pagrus major

Abstract

Heavy rainfall can reduce salinity and increase turbidity in coastal waters, creating stressful conditions for the organisms found there, especially for the early stages of their ontogeny. The effects of salinity and turbidity on the embryonic stages of red sea bream Pagrus major were examined under controlled laboratory conditions. In the first experiment, eggs of red sea bream were exposed to different salinity stresses [34 (control), 30, 26, 22, 18, 14\xa0psu] for 3\xa0h. In the second experiment, eggs were exposed to higher turbidity levels of 100, 300, 500, and 700 NTU from 0 NTU (control) obtained by dissolving kaolin clay for the same duration as in the first experiment. The results showed that the embryos of red sea bream are tolerant to short-term exposure to low salinity stress. There were no significant differences in the hatching rate, yolk sac consumption of newly hatched larvae, or survival of larvae at 6\xa0days post-hatching. However, the short exposure to turbidity stress reduced the hatching rate, total length, and yolk sac volume of newly hatched larvae, and larval viability of red sea bream. Turbidity had a significant impact on the abnormality rate at hatching, with higher values observed for elevated turbidity.