Response of the blue shrimp Litopenaeus stylirostris to temperature decrease and hypoxia in relation to molt stage

In a second experiment, temperature was decreased from 28 to 22 °C in 24 h, before a severe hypoxia of 0.5±0.1 mg O2 l−1 was applied. Mortality and OC were studied in relation to molt stages. Half of the shrimps died after respectively 100 min at 0.5 mg O2 l−1 at 28 °C and 153 min at 0.4 mg O2 l−1 at 22°C. Mortality was significantly higher in stages D2 and B compared to stages C and D0. Control shrimps in stage D2 had a lower hypo-OC than shrimps in stages C and D0 both at 28 and 22 °C. Temperature decrease had no effect on hypo-OC. Hypoxia reduced hypo-OC for all stages, whatever the temperature, but the effect was greater in stage C at 27 °C (68% decrease) compared to 22 °C (49%) and stage D2 at both temperatures (respectively, 43% and 58% at 27 and 22 °C). Combination of temperature and hypoxia had a significant effect on hypo-OC. Low temperature reduced the effect of hypoxia presumably by slowing down the metabolism. Results are discussed in relation to pond observation.