High dietary lipid level promotes low salinity adaptation in the marine euryhaline crab (Scylla paramamosain)

The physiological processes involved in adaptation to osmotic pressure in euryhaline crustaceans are highly energy demanding, but the effects of dietary lipids (fat) on low salinity adaptations have not been well evaluated. In the present study, a total of 120 mud crabs (Scylla paramamosain, BW = 17.87 ± 1.49 g) were fed control and high-fat (HF) diets, at both medium salinity (23‰) and low salinity (4‰) for 6 wk, and each treatment had 3 replicates with each replicate containing 10 crabs. The results indicated that a HF diet significantly mitigated the reduction in survival rate, percent weight gain and feed efficiency induced by low salinity (P P P P < 0.05). In summary, high dietary lipid levels improved energy provision to facilitate mitochondrial biogenesis, which increased ATP provision for osmotic pressure regulation of mud crabs. This study also illustrates the importance of dietary lipid nutrition supplementation for low salinity adaptations in mud crabs.