Photoperiod affects gamete production, and protein and lipid metabolism in male narrow-clawed Crayfish Pontastacus leptodactylus (Eschscholtz, 1823)

Abstract

Understanding effects of photoperiod on the reproductive efficiency and physiological responses of Pontastacus leptodactylus is important for successful management of the crayfish hatcheries. Spermatozoal number, gonado-somatic index (GSI), hepatosomatic index (HSI), testicular index (TI), vas deferens index (VDI), and total protein, amino and fatty acid profiles of the hepatopancreas were evaluated in male narrow-clawed crayfish P. leptodactylus. Animals (30–70 g) were maintained utilizing five different photoperiodic regimens (3 L:21D, 6L:18D, 24 L:0D, 0L:24D, and natural photoperiod (9 L:15D)) for 5 weeks. Different photoperiods affected spermatozoal number, GSI, and total protein, amino acid and fatty acid profiles of the hepatopancreas (P < 0.05). The greatest spermatozoal number and GSI were recorded in darkness (P < 0.05). There was the least spermatozoal number (3.5 × 106 ± 0.5) and GSI (2 ± 0.1%) when imposing the 9 L and 24 L photoperiodic regimens, respectively. In addition, maintenance in constant light as compared with other lighting regimens resulted in a greater total protein (43.68 ± 4.83 mg/g), phenylalanine (7.23 ± 0.35%), and total single unsaturated fatty acids (ΣMUFA) (48.07 ± 2.30%), but lesser total polyunsaturated fatty acids (ΣPUFA) (23.36 ± 1.07%), serine (1.53 ± 0.02%), Σn-6 (11.24 ± 1.18%), 20:4 (n-6) (2.7 ± 0.14%), and 20:2 (0.67 ± 0.17%) contents in the hepatopancreas (P < 0.05). The results of the present study indicate total darkness increases the spermatozoal production and imposing longer dark periods improved the reproductive efficiency and physical conditions in male P. leptodactylus.