Preliminary changes in the humoral and cellular response of shrimp Litopenaeus vannamei during the acclimatization to different salinity

In Nayarit Mexico, the shrimp Litopenaeus vannamei (Boone, 1931) is one of the most widely used species grown on farms, due to its tolerance to a wide range of salinity, probably caused by salinity decreased in the shrimp ponds during rainy season from 35 to 5 practical salinity units (psu) The purpose of this work was to evaluate the response of shrimp to the acclimatization process during both decreasing salinity (10 psu, 7 psu, 5 psu and 2 psu) and its gradual increase (2 psu, 5 psu, 7 psu and 10 psu). The variables determined were, hemocyanin concentration, total count, and differential count of hemocytes in juvenile shrimp. Shrimp clotting time from both experiments was not altered. Hemocyanin increased significantly (P <0.05) with the reduction of salinity while hemocytes tended to decrease as salinity decreased, and to increase when salinity increased. Hyaline hemocytes showed a higher percentage when salinity increased, showing significant differences (P <0.05) in shrimp from both experiments. Finally, the acclimatization process did not affect survival, and the differences between the determined variables could be related to the decrease in salinity.