Soc for experimental Biol Annual Meeting - Salzburg 2012

Bjørn Tirsgaard (University of Copenhagen, Denmark) and John Fleng
Steffensen (University of Copenhagen, Denmark)

Aerobic and anaerobic oxygen consumption was measured for 13 Sparus
aurata swimming at incremental increasing swimming speeds until fatigue
at 10°C. The anaerobic swimming cost was measured as the excess postexercise
oxygen consumption (EPOC) following each swimming speed.
To determine tail-beat frequency, amplitude and burst and coast behaviour,
the peduncle position was determined at 25 s·' by video tracking.
The data showed that S. aurata swam exclusively using aerobic
metabolism up to 88% of their critical swimming speed (Ucrit
). Above
88% Ucrit' the contribution from the anaerobic swimming cost increased
exponentially and represented 12%, 59% and 70% of the total swimming
cost at 90%, Ucritand fatigue, respectively, and resulted in a total anaerobic
capacity of 170 mg O2 kg·'. Normalized tail-beat amplitude and frequency
both predicted the swimming speed but only tail-beat frequency was able
to predict the aerobic swimming cost. The change to burst and coast
swimming was correlated to the first measurements of EPOC and both
the burst frequency (bursts min·') and burst distance (percentage burst
distance) were found to predict EPOC by linear regressions. The low
temperature used in the present study resulted in a prolonged recovery
time, which increased with the anaerobic contribution to 10 hours after
fatigue. Due to the late initiation time, the contribution from the anaerobic
swimming cost did not affect the optimal swimming speed or the minimum
cost of transport. In contrast, the cost of swimming above 88% Ucrit
increased by 334% at fatigue.
Email addressforcorrespondence:btirsgaard@bio.ku.dk