Effects of seawater pH and temperature on foraging behavior of the Japanese stone crab Charybdis japonica.

We examined prey selection and foraging behaviors of the crab Charybdis japonica exposed to four combinations of pH (7.3 and 8.1) and temperature (18°C and 25°C). The order of prey selection by C. japonica was Potamocorbula laevis, Ruditapes philippinarum, Tegillarca granosa and Mactra veneriformis. Under high pCO, times for searching, breaking, eating and handling were all significantly longer than those at the normal pCO, and the prey profitability and predation rate under high pCO were significantly lower than normal pCO. Moreover, temperature significantly influenced the foraging behaviors, but its effects were not as strong as those of pH; times for searching, eating and handling under high temperature were significantly lower than the low temperature, and the prey predation rates under high temperature was significantly higher than low temperature. In conclusion, high pCO negatively affected the foraging behavior, but high temperature actively stimulated the foraging behaviors of crabs.