Heart rate telemetry to study environmental influences on fish metabolic expenditure

Abstract

Routine metabolic rate (RMR) and heart rate (HR) were measured simultaneously in 15 °C-acclimated and free swimming European sea bass (Dicentrarchus labtax 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 LOC(MO2)-curve which describes the relationship between maximum sustainable oxygen consumption (MO2) and water oxygen concentration (C(w)O2). Heart rates values distributed below a LOC(HR)-curve which figures the relationship between the maximum HR and C(w)O2. A mathematical model describing this relationship is proposed. Using the LOC(MO2)- and LOC(HR)-curves, the range of the correlated changes of HR and MO2 is delimited. The influence of C(w)O2 on these limits is also considered and discussed. Two examples illustrating the limiting effect of low ambient oxygenation level on fish metabolic demand are described.