HEART-RATE TELEMETRY TO STUDY ENVIRONMENTAL-INFLUENCES ON FISH METABOLIC EXPENDITURE

Routine metabolic rate (RMR) and heart rate (HR) were measured simulta neously in 15 degrees C-acclimated and free swimming European sea bass (Dicentrarchus labrax L.) in normoxic and hypoxic conditions. The RMR fell within the boundaries previously reported for that species, i.e. the standard metabolic rate and the LOCMO2-curve which describes the relationship between maximum sustainable oxygen consumption (MO2) and water oxygen concentration (CwO2). Heart rates values distributed belo w a LOCHR-curve which figures the relationship between the maximum HR and CwO2. A mathematical model describing this relationship is propose d. Using the LOCMO2- and LOCHR-curves, the range of the correlated cha nges of HR and MO2 is delimited. The influence of CwO2 on these limits is also considered and discussed. Two examples illustrating the limit ing effect of low ambient oxygenation level on fish metabolic demand a re described.