SEASONAL ADAPTATIONS IN OXYGEN-TRANSPORT IN BROWN TROUT SALMO-TRUTTA FARIO

1. Blood parameters determining oxygen capacity and oxygen affinity we re measured in brown trout at different times of the year. 2. Haematol ogical data indicate a slight decrease in blood oxygen capacity during the warm seasons. 3. Oxygen affinity increases significantly during s ummer and decreases in winter. 4. The changes in P-50 exhibited a posi tive correlation with the amount of anodic haemoglobin components, and a negative correlation with the amount of cathodic haemoglobin compon ents. 5. The changes observed in the [ATP]/[Hb] molar ratio were not c orrelated with oxygen affinity and gave values near one. 6. We conclud e that the oxygen affinity increase could be a physiological adaptatio n to oxygen transport during the warmer period. A possible mechanism i s discussed.