Energy expenditure of swimming bottlenose dolphins (Tursiops truncatus)

The aim of our investigations was to determine, via oxygen and carbon-dioxi de respirometry, how much energy dolphins (Tursiops truncatus) require when swimming at different speeds. Experiments were conducted on two female bot tlenose dolphins (mean mass 162 kg) in the dolphinarium in Nuremberg Zoo, G ermany, between March and August 1997. Animals were stationed in a respirat ion chamber for a minimum of 90 s after performing a variety of activities. We measured respiration frequency and oxygen requirements during (1) resti ng, (2) swimming at various velocities and (3) leaping to various heights. Resting metabolic rate of our bottlenose dolphins (2.15 W kg(-1)) was compa rable to previously published data. Metabolic rate in swimming dolphins inc reased to 2.47 W kg(-1) at 2 m s(-1), while leaps to 2.2 and 3 m height req uired a power input of 3.5 and 4 W kg(-1), respectively. Transport costs of swimming dolphins were lowest (1.16 J kg(-1) m(-1), corresponding to 0.12 J N-1 m(-1)) at a speed of 2.5 m s(-1), yielding an optimal range speed of between 1.9 and 3.2 m s(-1) (corresponding to minimum cost of transport +/- 10%). Breathing rates during all experiments correlated very well with oxyg en consumption (r(2) > 0.89) and could be used to derive metabolic rates in unencumbered dolphins at sea.