Effect of salinity on the physiology and bioenergetics of adult Chinese mitten crabs Eriocheir sinensis

Abstract

Rates of physiological processes and bioenergetics of the Chinese mitten crab Eriocheir sinensis were determined during a 7-day experiment on adult males (mean wet weight 147.27±20.86g) exposed to salinities of 0.5, 7 and 25. Salinity did not significantly affect food consumption rate (p>0.05). The rate of faeces production rose between salinities of 0.5 and 25 (p<0.05), whereas the rate of ammonia excretion decreased. At salinities of 7 and 25 crabs consumed 1.6 and 1.3 times more oxygen respectively than at a salinity of 0.5 (p<0.05). E. sinensis was able to maintain a positive energy balance at salinities of 0.5 and 25, and the scope for growth reached 66.07±45.23 and 47.79±31.42Jd−1g−1 dry wt, respectively. Although the high inter-individual variability significantly influenced the obtained results, the lower metabolic expenses and higher scope for growth indicate that freshwater environments (S<7) are more “profitable” for adult of Chinese mitten crabs from a bioenergetical point of view than saline waters.