Comparative effects of long-term hypoxia on growth, feeding and oxygen consumption in juvenile turbot and European sea bass

When juvenile turbot Scophthulmus maximus and sea bass Dicentrarchus labrax were fed to satiation, growth and food intake were depressed under hypoxia (3.2 +/- 0.3 and 4.5 +/- 0.2 mg O-2 l(-1)). However, no significant differ ence in growth was observed between fishes maintained in hypoxia and fed to satiation and fishes reared in normoxia (7.4 +/- 0.3 mg O-2 l(-1)) and fed restricted rations (same food intake of fishes at 3.2 mg O-2 l(-1)). Routi ne oxygen consumption of fishes fed to satiation was higher in normoxia tha n in hypoxia due to the decrease in food intake in the latter. Of the physi ological parameters measured, no significant changes were observed in the t wo species maintained in hypoxia. This study confirms the significant inter action between environmental oxygen concentrations, feeding and growth in f ishes. Decrease in food intake could be an indirect mechanism by which prol onged hypoxia reduces growth in turbot and sea bass, and may be a way to re duce energy and thus oxygen demand. (C) 2001 The Fisheries Society of the B ritish Isles.