Effects of O₂ supersaturation on metabolism and growth in juvenile turbot (Scophthalmus maximus L.)

J. Person-Le Ruyet, K. Pichavant, C. Vacher, N. Le Bayon, A. Sévère, G. Bœuf-2002

Aquaculture, 205(3-4): 373-383
Abstract:

Effects of O₂ supersaturation on metabolism and growth were studied in juvenile turbot (Scophthalmus maximus L.). When fish were reared for 30 days in water containing O₂ at 147% or 223% air saturation, there were no significant differences in food intake, growth, food conversion or protein utilization compared to fish exposed to normoxia (100% air saturation in water outlet). Exposure to hyperoxia resulted in increased body fat deposition. Daily rates of O₂ consumption of resting fish were not affected by O₂-concentrations, and there were no significant differences in rates of nitrogenous excretion among fish exposed to the different O₂-concentrations. Turbot tolerated severe hyperoxia, 350% air saturation, for 10 days.

There were changes in acid-base balance that compensated for the respiratory acidosis resulting from O₂ supersaturation. Blood pH was regulated within 24 h (it averaged 7.69 over the 30-day experiment) by significant increases in plasma CO₂ content and pCO₂. Plasma CO₂ was dose dependent averaging 11.3 and 18.9 mmol l^-l under 147% and 224% O₂ saturation, respectively, compared to 6.7 mmol l^-l under normoxia. Over the 30-day experiment, the only change in hydromineral balance was a slight, but non-significant decrease in plasma chloride content in fish exposed to hyperoxia (137 mmol l^-l compared to 139 under normoxia). There were no changes in haematocrit, haemoglobin and red blood cell counts (they averaged 18.3%, 3.7 g dl^-1 and 1.37×10⁶ mm^-3, respectively) and no signs of stress (plasma cortisol averaged 3.8 ng ml^-1) related to exposure to O₂-supersaturation for 30 days.

(Ifremer, Centre de Brest, Station Ressources Vivantes, BP 70, 29280 Plouzané, France, Tel.: +33-2-98-22-4391; fax: +33-2-98-22-4366, e-mail : jperson@ifremer.fr)

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