Acid-base balance, ammonia and lactate levels in the haemolymph of Penaeus japonicus during aerial exposure

Acid-base balance, ammonia and L-lactate levels were measured in the haemolymph of Penaeus japonicus subjected to aerial exposure at 6, 12 and 18 degrees C for up to 12-48 h. About 90% of P. japonicus survived at 6 and 12 degrees C after 36 h of aerial exposure, whereas no prawns survived at 18 degrees C after 24 h. Haemolymph pH and OH-/H+ decreased at 18 degrees C, but increased at 6 and 12 degrees C with increased exposure time. Haemolymph P-CO2, HCO3-, TCO2 (total carbon dioxide) and L-lactate levels were directly related to exposure time. After a 12-h emersion at 18 degrees C, P. japonicus accumulated, ammonia and L-lactate up to 0.645 and 11.77 mmol l(-1), which was three and four times higher than those at 6 degrees C, respectively. The ability of P. japonicus at low temperature (6 and 12 degrees C) to survive longer than those at 18 degrees C is considered to be due to lower accumulation of ammonia and L-lactate, and compensation buffer of HCO3.- (C) 1998 Elsevier Science Inc. All rights reserved.