First published online April 8, 2004
Journal of Experimental Biology 207, 1615-1624 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.00952
Metabolic rates of captive grey seals during voluntary diving
Carol E. Sparling* and
Michael A. Fedak
Sea Mammal Research Unit, Gatty Marine Laboratory, University of St
Andrews, St Andrews, Scotland, UK, KY16 8LB
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Fig. 1. Schematic diagram of the open-flow respirometry system. The arrows show the
direction of air-flow through the system.
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Fig. 2. Schematic of the pool used in the measurement of diving metabolic rate. The
entire surface of the pool is covered by aluminium mesh so that the seal can
only surface and breathe in the box situated in one corner. The pool is
divided into lanes using nets, so that during measurement the seals can travel
a maximum of 168 m away from the breathing box. The depth of the pool is 2.5
m.
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Fig. 3. The distribution of dive and surface times for all dives from all eight
seals (767 dives in total).
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Fig. 4. Frequency distribution of dive durations from satellite-tagged UK grey
seals (total number of dives was >219 000 from 108 seals).
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Fig. 5. Diving metabolic rates (DMR) in relation to mass. Each point is the mean
DMR of an individual seal (N=8 seals). The solid line is the line
fitted by least-squares regression, weighted by the number of dives from each
individual. The equation for this line is: log DMR = log mass (0.76-1.79)
(r2=0.92, P<0.0001). The broken line
represents Kleiber's prediction of BMR in terrestrial mammals.
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Fig. 6. Mean (+S.D.) metabolic rates (the multiple of the basal
metabolism predicted by Kleiber's allometric equation;
Kleiber, 1975 ) of seven grey
seals during diving (DMR) or during rest (RMR) at the water surface. Resting
values are for alert, inactive animals breathing continuously. These data are
compared with values for the same individuals, on the same day, during diving.
The difference is significant (paired t-test, t=3.86,
P=0.003).
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Fig. 7. 3-D surface plot of the relationship between diving metabolic rate (DMR),
dive duration and mean speed during a dive (from all dives from all animals).
Surface fitted to data using running median smoothing of the values at
neighbouring points.
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Fig. 8. Variation in metabolic rate as a function of dive duration. Metabolic rates
are oxygen consumption over the whole dive plus surface period expressed as a
multiple of Kleiber's (1975)
predicted basal metabolic rate. Dives from all eight seals are shown.
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Fig. 9. Log-transformed diving metabolic rate (DMR) plotted against dive duration
for all dives. Also indicated is the boundary defined by quantile regression
of the 95th percentile plus upper and lower 95% confidence limits to this
line. The regression is significant at P<0.05. The thick, broken
line represents the relationship between maximum possible aerobic log DMR and
dive duration, based on maximum utilisation of body oxygen stores during the
dive.
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© The Company of Biologists Ltd 2004
O2). Each point
is an individual dive, with a different symbol for each animal. The predicted
post-dive O2 is the