Effect of light intensity on digestion and immune responses, plasma cortisol and amino acid composition ofScylla paramamosainduring indoor overwintering

Overwintering is one of an important stage for aquatic animals, and light intensity has an important effect on the conservation ofScylla paramamosainduring overwintering. Three different light intensity levels (0, 1.43 and 40.31 mu mol m(-2) s(-1)) were used to explore the effects of light intensity on digestion and immune responses, plasma cortisol and amino acid composition ofS. paramamosain. This is the first report that the adultS. paramamosaincan be effect by the light intensity. The results showed thatS. paramamosainhas a strong stress response under high light intensity. Compared with darkness condition, digestive enzyme activity was higher under light condition.S. paramamosainreared under low light conditions had enhanced immunity, and it raised in light conditions exhibited superior qualities to those cultured in dark conditions. The results of this study demonstrated that low light levels are most suitable for breeding and improving the quality ofS. paramamosain.