Two experiments were conducted to examine the simultaneous effects of water temperature and Na +:K + ratio on growth, survival, and hemolymph osmolality of Litopenaeus vannamei reared in 4‰ salinity well-water. In one study, a factorial experiment was conducted with levels of water temperature of 26 and 30°C, and Na +:K + ratios of 40:1, 80:1, and 120:1. Growth of shrimp was significantly higher at the Na +:K + ratio of 40:1 than at 120:1, but not higher than at 80:1. Also, growth of shrimp was statistically greater at 30°C than at 26°C. Survival rate of shrimp was neither affected by Na +:K + ratio nor by temperature. In another factorial experiment, a lower range of experimental temperatures (20 and 24°C) and Na +:K + ratios of 40:1 and 120:1 were tested. Both growth and survival of L. vannamei reared at the Na +:K + ratio of 40:1 were significantly higher than at the ratio of 120:1. In turn, survival rate of shrimp, but not growth, was significantly higher at 24°C than at 20°C. No differences among treatments were observed for shrimp hemolymph osmolality measurements in both experiments. Results of the present study agree with previous reports of negative effects of high aqueous Na +:K + ratio (or K + deficient levels) on shrimp performance. At the same time, they represent the first report of a strong sensitivity of L. vannamei survival to the aqueous Na +:K + ratio at low temperature.
Bibliographical noteFunding Information:
This research was supported by the National Sea Grant College Program of the U.S. Department of Commerce's National Oceanic and Atmospheric Administration under NOAA Grants NA06OAR4170078 , the Mississippi-Alabama Sea Grant Consortium , project number R/SP-20 and Auburn University . The mention of trademarks or proprietary products does not constitute an endorsement of the product by Auburn University and does not imply its approval to the exclusion of other products that may also be suitable. The authors would like to extend their gratitude to the Alabama Agricultural Experiment Station and the National Oceanic and Atmospheric Administration , Grant NOAA NAO60AR4170191 . Dr. Martin Perez-Velazquez and Dr. Mayra L. González-Félix were sponsored by the National Council for Research and Technology (CONACYT), Mexico , Grants 93931 and 93934 , respectively.
- Litopenaeus vannamei
- Na : K ratio