Effect of light condition on the growth performance and biochemical compositions of post-mating female mud crab (Scylla paramamosain)

Abstract

Understanding factors affecting the reproductive performance of mud crab (Scylla paramamosain) is important for the optimization of the culture conditions. There are some indications that complete darkness could enhance and accelerate the spawning in female decapods, but sometimes it may lead to low larval quality. Therefore, the present study was carried out to clarify the effect of different light conditions on female S. paramamosain during the post-mating period. To accomplish this, proximate compositions, total carotenoid content, amino acid and fatty acid profiles were investigated in female S. paramamosain cultured under two different light conditions: complete darkness (0 ± 0 lx; 0 h light: 24 h dark) and normal light condition (7.00 ± 1.50 lx; 12 h light: 12 h dark; this light condition is regular in S. paramamosain hatcheries). Further, weight gain ratio (WGR), specific growth rate (SGR), gonado-somatic index (GSI), and hepatosomatic index (HSI) were also investigated. Different light conditions affected carotenoid, protein, amino acid, and fatty acid contents, but not growth parameters. Female S. paramamosain cultured under complete darkness had lower amino acids and protein contents in the muscle in comparison with those under the normal light condition. Moreover, complete darkness decreased the ovarian protein and carotenoid. The changes in fatty acids profiles were variable under the two light conditions. These results indicated that the lowering of carotenoid and protein contents in the ovary under complete darkness could be the potential limiting factors affecting the reproductive performance of post-mating female S. paramamosain.