Effect of salinity on the growth performance, osmolarity and metabolism-related gene expression in white shrimp Litopenaeus vannamei

An 8-week feeding trial was conducted to study the effect of long-term low-salinity stress on the growth performance, and expression of osmolarity and metabolism-related genes (Na+-K+-ATPase α-subunit and in gills, trypsin and chymotypsin in hepatopancreas) in white shrimp (L. vannamei). Four groups of the white shrimp (mean initial weight, 0.31 ± 0.02 g) were cultivated at salinity of 2, 10, 20 and 30 psu for 8-week. All treatments were conducted in triplicate of 40 each. The results indicated that shrimps reared at salinity 20 psu and 30 psu were significantly higher in final weight, weight gain and specific growth ratio than the other treatments (p < 0.05 when compared to 2 and 10), and those reared at salinity 2 psu were significantly lower than the other treatments in growth performance and survival (p < 0.05 when compared to other treatments). Quantitative real-time PCR (qRT-PCR) results indicated that Na+-K+-ATPase α-subunit and carbonic anhydrase mRNA levels at salinity 2 psu and 10 psu were increased significantly 1.79-, 1.65-fold and 3.22-, 2.31-fold respectively according to salinity 20 psu, chymotrypsin and trypsin mRNA level at salinity 10 psu and 2 psu decreased significantly 15%, 36% and 72%, 45% respectively according to salinity 30 psu. In conclusion, low salinity could, to some extent, reduce growth performance and survival significantly, and influence transcript levels of Na+-K+-ATPase α-subunit, carbonic anhydrase in gills and chymotrypsin, trypsin in hepatopancreas.