Effect of temperature on agonistic behavior and energy metabolism of the swimming crab (Portunus trituberculatus)

Fighting and cannibalism between crabs are key factors that restrict increases in production and economic benefits. Temperature is an important environmental factor that affects the agonistic behavior and physiological activities of crustaceans. To explore the response mechanism of energy metabolism associated with agonistic behavior, we quantified the agonistic behavior and the concentrations of glycogen and key metabolites of the swimming crab (Paramus trituberculatus) at different temperatures (16 degrees C, 24 degrees C and 32 degrees C). The main results revealed the following: (1) fighting intensity, fighting duration time, and the frequency of the agonistic behavioral performances tended to increase with the increase in temperature. The frequency of move to and contact behavior at 24 degrees C and 32 degrees C of winners was significantly higher than those of losers, while the frequency of move away at 16 degrees C, 24 degrees C and 32 degrees C of winners was significantly lower than that of losers. (2) Before fighting, the concentrations of glucose and lactate in the hemolymph increased with the increase in temperature, and the concentration of lactate was significantly higher in the 32 degrees C group than in the 16 degrees C group. After fighting, the concentration of glucose in the hemolymph tended to increase at first and then decrease with the increase in temperature. The glucose concentration was significantly higher in the 24 degrees C group than in the other groups. After fighting, the concentration of lactate tend to increase continuously with the increase in temperature, and the concentration was significantly higher in the 32 degrees C group than in the other groups. (3) After fighting, the glucose concentrations in the hemolymph in the 16 degrees C and 24 degrees C groups were significantly higher than before fighting, and the lactate concentrations in the 16 degrees C, 24 degrees C and 32 degrees C groups were significantly higher than before fighting. (4) The glycogen concentration in the claw muscle of winners in the 16 degrees C and 24 degrees C groups were significantly lower than those of the losers, while the glucose concentration in the hemolymph of winners in the 16 degrees C and 24 degrees C groups were significantly higher than those of the losers. The concentrations of pyruvate and citrate in the hemolymph of the winners in the 32 degrees C group were significantly higher than those of the losers. These preliminary results showed that temperature significantly affected the agonistic behavior and energy metabolism of the swimming crab, and that the agonistic behavior resulted in significant changes in key metabolites.