Pacific whiteleg shrimps compromize their physiological needs to cope with environmental stress

The ongoing climate change is resulting in elevating temperatures and reduced pH levels in the marine environment. This work reports on the interactive effects of these two factors on growth and physiological responses of Pacific whiteleg shrimps (Litopenaeus vannamei), with a very important commercial shrimp specie. The study examines the interactive effects of temperature (28 versus34°C) and pH (6 versus 8) were examined at four combinations: (28°C and pH 8 (N28); 34°C and pH 8 (N34); 28°C and pH 6 (A28); and 34°C and pH 6 (A34), over a 30 days period. A combination of a high temperature and low pH (i.e., A34) was found to impose a high metabolic burden on the shrimp, resulting in an increased food intake and elevated osmorespiration responses relative to control, but no improvement in growth. The A34 stress combination increased ammonia excretion 2-fold relative to control, and increased a 40 % rise in metabolic oxygen uptake. Under A34 stress, glycogen and lipid reserves in both muscle and hepatopancreas were mobilized to support basal metabolic needs, resulting in growth suppression. The combined thermal-pH stress A34 did not affect the calcium and magnesium content of muscle and shell, which are essential minerals for exoskeleton and structural development. Although the shrimp can survive under high temperature-low pH stress conditions, their growth rate was compromised.