Biological impact of photoperiod on fairy shrimp (Branchinecta orientalis): Life history and biochemical composition

Abstract

B. orientalis, fairy shrimp, is often among the most conspicuous invertebrates inhabiting temporary aquatic habitats with a typical variation in environmental conditions. Its life history characteristics and biochemical composition were studied under four different photoperiodic regimes (24L: 0D, 0L: 24D, 16L: 8D, and 12L: 12D). The significantly highest cumulative and initial hatching rates (48 h) were obtained at 24L: 0D (p < 0.05). Cultivating the larvae under different photoperiods did not significantly affect specific growth rate (SGR) (p > 0.05). However, higher final total body length and daily growth rate were recorded under constant darkness. Higher lipid content was found at 24L: 0D to the extent that it was more than two times higher than that at 16L: 8D and 12L: 12D (p < 0.05). There was also a remarkable increase in body crude protein content at 24L: 0D (p < 0.05). Body fatty-acid profiles of the fairy shrimps were also affected by culture condition (p < 0.05). Extension of lighting period resulted in a subtle increase in body contents of arginine, lysine, histidine, isoleucine, leucine, valine, methionine, and phenylalanine, especially in the group kept under a 16L: 8D regime. The highest and lowest digestive enzyme activity was observed at 0L: 24D and 24L: 0D, respectively (p < 0.05). In contrast, the highest and lowest soluble protein content was recorded at 24L: 0D and 0L: 24D, respectively (p < 0.05). Similarly, antioxidant status was significantly higher at 0L: 24D (p < 0.05). In conclusion, a 16L: 8D light-dark cycle might be an optimal condition in terms of growth performance and physio-biochemical characteristics. These findings could be helpful in optimizing the rearing conditions for upscaling B. orientalis production.