Osmo-ionic regulation in whiteleg shrimp, Penaeus vannamei, exposed to climate change-induced low salinities

Abstract

Most shrimp aquaculture systems rely to a large extent on the ecosystem services, and therefore, the species are inherently vulnerable to climate change effects. To study the adaptability of Penaeus vannamei under the change in salinity caused by climatic events like heavy rainfall, shrimp were exposed to salinity stress by reducing the salinity gradually and drastically. Shrimp survival rate, water and serum osmolality, ionic regulation and Na+‐K+‐ATPase activity were examined to ascertain the adaptability. Survival was 100% in all the treatments of gradual salinity reduction and 95% up to 5 ppt when salinity was reduced drastically. In both the stress experiments, P. vannamei effectively regulated its serum osmolality within a narrow range of 727–484 mOsm/kg in gradual and 713–510 mOsm/kg in drastic experiments against the wide range of medium osmolality by increasing its osmoregulatory capacity. The ionic profile in the shrimp tissue (Ca>K>Na>Mg) was entirely different from the profiles of the serum (Na>Ca>K>Mg) and medium (Na>Mg>Ca>K). In summary, P. vannamei being a strong hyper osmoregulator retains the essential ions at requisite concentrations through active transport by increasing the Na+‐K+‐ATPase enzyme activity to endure and survive under low salinities. This excellent osmoregulatory property places P. vannamei as the best contender for climate‐resilient aquaculture where salinity may vary due to climatic events such as heavy rainfall.