Light Intensity and Photoperiod Interaction Affects the Survival, Development, Molting and Apoptosis-Related Genes of Swimming Crab Portunus trituberculatus Larvae

A 19-day experiment was conducted to investigate the optimal light intensity and photoperiod combination for larval swimming crabs Portunus trituberculatus in terms of survival, development, and apoptosis-related gene expression. Two photoperiods, i.e., 12 and 18 h photophases, and three light intensities, i.e., 126.08, 173.17, and 191.53 mu mol m (-2) s (-1), were used in the study. The results showed that the cumulative survival rate (CSR) of larvae decreased with the increasing light intensity, and the adverse effect of high light intensity was only observed in long photophase groups. On the contrary, a long photophase and low light intensity elevated the CSR from zoea III to juvenile crabs. A long photophase also accelerated the development of zoea III larvae and upregulated the molting-related (ecr and rxr) and apoptosis-related (jnk, p53, and bcl-2) gene expressions. Taken together, the present study suggested that the light intensity and the photoperiod had a combined effect on P. trituberculatus larvae. The optimal light intensity and photoperiod for P. trituberculatus larvae were 126.08 mu mol m (-2) s (-1), and an 18 h photophase, respectively.