Changes of haemocyanin, protein and free amino acid levels in the haemolymph of Penaeus japonicus exposed to ambient ammonia

Abstract

Haemolymph ammonia-N of Penaeus japonicus (15.6 ± 2.17 g) increased with increased ambient ammonia-N, as they were exposed individually in 30 ppt seawater to 0.003 (control), 0.367, 0.731, 1.439 and 3.665 mmol/1 ammonia-N after 24 hr. Ammonia-N excretion was inhibited and net ammonia-N uptake occurred, as shrimps were exposed to 0.367 mmol/1 ammonia-N or greater. Haemocyanin and protein levels in the haemolymph of shrimp decreased, whereas free amino acid levels increased with increased ambient ammonia-N in the range of 0.003–1.439 mmol/1 ammonia-N. Exposure of shrimp to ambient ammonia-N at 1.439 mmol/1 caused accumulation of haemolymph ammonia and urea, and caused catabolism of haemocyanin and protein to free amino acids. Urea, taurine and glutamine are the major organic constituents in the haemolymph of shrimp under ammonia stress.