Dynamics of free amino acids in the hemolymph of Pacific whiteleg shrimp Litopenaeus vannamei exposed to different types of stress

We analyzed the dynamics of amino acids, ammonia-N, and carbohydrates in hemolymph when Pacific whiteleg shrimp Litopenaeus vannamei was subjected to air-exposure and low-salinity stresses. Glycine, l-arginine, and d- and l-alanine levels in hemolymph were increased under both stress conditions. Ammonia-N, a product of amino acid catabolism, also increased in level. These results suggest that the above-mentioned amino acids are used as energy sources. Levels of total carbohydrates, the sum of glucose and other carbohydrates, in the hemolymph showed different dynamics between the two types of stress and were not always high. This suggests that other energy sources, such as amino acids, are important when animals are subjected to stress. It is possible that particular amino acids act as energy sources under various stress conditions.