Effects of low-salinity stress on locomotor activity and feeding behavior in the Chinese shrimp (Fenneropenaeus chinensis)

Low-salinity stress disrupts the osmoregulatory system of crustaceans and thereby alters their energy-allocation strategies and behavioral patterns. Previous studies on low-salinity stress have mostly focused on physiological or molecular-level changes, with fewer investigations of behavioral responses. In this study, we examined changes in locomotor activity and feeding behavior in Fenneropenaeus chinensis under low-salinity stress. Three salinity groups were established: a control group (CG, 30 psu), a medium-salinity group (MG, 15 psu), and a low-salinity group (LG, 5 psu). Shrimp in the experimental arena were observed for 20 min, and video recordings were analyzed using automated tracking software (EthoVision XT v. 17.5). In the locomotor-activity observation, we analyzed changes in locomotor behavior, stress responses, and social behavior on days 1–3 after exposure; shrimp in the low-salinity group exhibited significantly reduced activity, whereas no significant difference was found between the medium-salinity and control groups. Stress responses and social behavior in the experimental groups displayed complex, dynamic, non-linear patterns. In the feeding-behavior observation, we examined feeding behavior under the three salinity conditions and found that both the number of feeding individuals and the amount of feed consumed were significantly lower in the low-salinity group than in the other two groups. These results highlight the effects of low-salinity stress on the behavior of F. chinensis and provide reference indicators for selective breeding and aquaculture practices.