TEMPERATURE SELECTION AND PREFERENCE OF JUVENILE ERIOCHEIR SINENSIS

Chinese mitten crabs are widely distributed from Fujian in southern China to Liaoning in northern China, and they are able to adapt to a range of temperatures. The study focused on the behavioral responses of juvenile mitten crabs sampled from the Yangtze River to changes in water temperature. This is an important stage of the life cycle of this species that often has low disease resistance and high mortality rates. A temperature gradient was established across the shuttlebox to enable the preference of juvenile crabs for either temperature to be established. The shuttlebox system ensures the stability of the temperature on either side of the box. Established experimental groups were set as follws: Group Ⅰ (8℃ and 14℃), Group Ⅱ (14℃ and 21℃), Group Ⅲ (21℃ and 28℃), and Group Ⅳ (28℃ and 35℃). Results showed that the juvenile Chinese mitten crab had a preferred temperature (T_pref) of 28℃. Neither time of day nor gender had any significant effects on the temperature preference. Further more, there were significant differences in the swimming velocity of the juvenile crabs in different groups under the same experimental temperatures. The juvenile crabs increased their swimming velocity to escape suboptimal water temperature, and there was a positive relationship between swimming velocity and the degree of temperature deviation from T_pref. Water temperature with an inverted U-shaped swimming parabolic rate. The fitting equation for temperature (x) and swimming velocity (y), y=0.0027x²–0.1045x+1.5875, R²=0.8615. The impact of gender differences in swimming speed was not significant (P>0.05), and there was no significant difference between day and night swimming rate (P>0.05). Thus, the results of this study will be useful for enhancing the survival and growth rates of this species in aquaculture settings as well as for controlling and protecting them in the wild.