Analysis of Key Physiological Characteristics of Portunus trituberculatus in Response to Short-Term Low Salinity Stress

Salinity is a significant environmental factor that can affect the survival,metamorphosis,growth and feeding of Portunus trituberculatus.In order to analyze the key physiological characteristics of P.trituberculatus in response to short-term low salinity stress,the experiments of gradually decline and recovery as well as abrupt decline in salinity were carried out.The results showed that P.trituberculatus could survive in a certain low salinity range in the short term,and salinity 12 was the lowest tolerable salinity under the present experimental conditions.The change of the hemolymph osmotic pressure displayed significant positive correlations with water salinity,and the pressure was always higher than seawater osmotic pressure.Short-term low salinity stress changed the structure and morphology of gill tissue.The expansion of gill filament ends and epithelial cell shedding were conducive to osmotic adjustment.The activities of key ion transport enzymes such as Na^(+)-K^(+)-ATPase,carbonic anhydrase and V-ATPase also changed with the osmotic regulation,while Na^(+)-K^(+)-ATPase played a dominant role.In summary,as an osmotic adjustment species,P.trituberculatus rapidly adapt to the short-term low-salinity environment by osmotic adjustment in vivo,but salinity below salinity 12 is not conducive to its survival.Our result enriched the theoretical mechanism of osmotic regulation of P.trituberculatus,providing reference for the development of aquaculture technology of P.trituberculatus.