Acute response of Pacific white shrimp Litopenaeus vannamei to high-salinity reductions in osmosis-, metabolism-, and immune-related enzyme activities

Abstract

This study investigates the acute responses of pacific white shrimp Litopenaeus vannamei to an abrupt reduction of salinity in osmosis-, metabolism-, and immune-related enzyme activities in the hemolymph of L. vannamei previously reared at 56‰ salinity. Three salinity reductions (56 to 54‰, 56 to 52‰, and 56 to 48‰) were used, and L. vannamei was directly transferred from the salinity of 56 to 54‰, 52‰, and 48‰, respectively. The hemolymph was collected from five shrimp in each group at 1 h, 6 h, 12 h, 18 h, 24 h, 36 h, and 48 h to detect the change of ATPase (including Na+/K+-ATPase and T-ATPase), alkaline phosphatase (AKP), acidic phosphatase (ACP), and superoxide dismutase (SOD) activities. Our results showed that no shrimp death occurred after an abrupt reduction of salinity. However, ATPase, SOD, ACP, and AKP enzyme activities in three salinity reductions all changed significantly, and the activities of T-ATPase and Na+/K+-ATPase showed a single peak trend during the process of experiment. The SOD activity peaked at 24 h after the salinity was decreased. ACP activities remained an increasing trend within 48 h after salinity was decreased in the three salinity treatments. A single peak trend was found in AKP activity and peaked at 18 h and then decreased significantly. The results indicate that an abrupt decrease in salinity significantly affected ATPase, SOD, ACP, and AKP activities. Osmotic, metabolism, and immune-related enzyme activities of L. vannamei are sensitive parameters to respond to an abrupt drop of salinity.