Morphometric adaptations of sea bass gills to different dissolved oxygen partial pressures

The total respiratory surface area (RSA) of sea bass Dicentrarchus labrax (initial mass 153 ± 27 g), reared in a brackish water recirculation system at 24° C for 3 months under three different oxygen partial pressures of 60, 90 and 140% saturation (87.0, 130.0 and 203.1 torr. respectively), was 351.98 (± 8.90), 264.86 (± 48.20) and 212.90 (± 57.22) mm² g⁻¹ body mass. RSA was negatively correlated with oxygen availability in the water. In the same experiment, no significant differences in the total length of filaments or frequency of lamellae were observed, although the total length of filaments was shorter in fish cultured under hyperoxia.