Studies on temperature impact (sudden and gradual) of the white-leg shrimp Litopenaeus vannamei.

Abstract

In the present study, the effect of temperature shock (sudden and gradual) by increasing water temperature from 28°C to 40°C on survival, behavioral responses and immunological changes in Litopenaeus vannamei (L. vannamei) was studied. In sudden temperature shock, experimental groups were maintained at different temperature ranges such as 28°C- 31°C; 28°C-34°C; 28°C-37°C and 28°C-40°C along with 28°C as control. For gradual temperature shock experiments, the initial water temperature was maintained at 28°C for 24h in control and then increased to 1°C for every 24h until reaching 40°C. On reaching the final temperature of 40°C, it was kept stable for 120h. Results indicated that the increasing water temperature (sudden shock) affected survival, behavioral responses and immunological parameter. No shrimp survived at 40°C treatment (sudden), whereas in the gradual temperature shock experiment 20% of animals survived at 40°C. The increasing water temperature had no effects on behavioral responses up to 37°C (gradual), but at 40°C the observation of muscle cramps, low swimming rate, no feeding, muscle and hepatopancreas color turned whitish. Overall, the results suggest that L. vannamei can tolerate water temperature up to 34°C under sudden shock and 37°C under gradual shock conditions. This study reveals that shrimp L. vannamei can self-regulate to a certain extent of temperature variation in the environment.