Acute toxicity of carbon dioxide on European seabass (Dicentrarchus labrax): Mortality and effects on plasma

European Seabass (Dicentrarchus labrax) weighing 40-120 g were exposed for 120 hr to six levels of CO2 (ag) in running seawater at 15 +/- 1 degrees C, 33-34%, and > 120 mmHg Po-2 (similar to 75% saturation). Mean water Pco(2) levels ranged from 0.6 mmHg (1.3 mg l(-1)) (control tank) to 62.3 mmHg (137.2 mg l(-1)). LC(50)'s were found to be 51.9, 51.6, 50.4, and 47.1 mmHg for 48, 72, 96 and 120 hr exposures respectively. Blood samples were taken from surviving fish after 120 h, and plasma analysis showed a significant decrease in [Cl-], from 160 +/- 2.9 (SD) mM (control value) to 115 +/- 1.8 mM (Pco(2) = 49 mmHg exposure). A smaller bur significant increase in [Na+] was observed, Na+ increased from 180 mM (control value) to 200 mM (Pco(2) = 50 mmHg exposure). The variation in plasma ions is in accordance with earlier observations of compensation for respiratory acidosis. No significant effects on plasma lactate concentration were observed. Copyright (C) 1996 Elsevier Science Inc.