The effect of temperature and salinity on oxygen consumption in the brachyuran crab Cyclograpsus punctatus (Crustacea: Decapoda: Grapsidae)

Abstract

The aquatic oxygen consumption of the estuarine brachyuran crab, Cyclograpsus punctatus, was investigated after a 24-hour acclimation period at different temperature (12.5, 20, 30°C) and salinity (9, 17.5, 35, and 44‰) combinations . Salinity had no significant effect on oxygen consumption at 12.5 and 20°C in both large and small crabs. At 30°C and 44‰, however, the rate of oxygen consumption declined in large crabs (from 0.233 to 0.176 mg O2 g wwt/h) and increased in small crabs (0.300 to 0.469 mg O2 g wwt/h). There was also a significant increase in the oxygen consumption (0.300 to 0.536 mg O2 g wwt/h) of small crabs at the high temperature/ low salinity combination. Temperature had a significant effect on the rate of oxygen consumption at all salinities, with Q10 values ranging from 1.16 to 2.85. In all cases the mass-specific oxygen consumption rate of small crabs was higher than that of large crabs. The results suggest that the confinement of this species to the lower reaches of estuaries may, in part, be due to physiological constraints on juveniles and small individuals.

Key words: estuarine crab, aquatic metabolism.