First published online July 20, 2007
Journal of Experimental Biology 210, 2618-2626 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.003855
Differential heating and cooling rates in bigeye tuna (Thunnus obesus Lowe): a model of non-steady state heat exchange
Hans Malte1,
Christina Larsen1,*,
Michael Musyl2 and
Richard Brill3,
,
1 Department of Zoophysiology, Institute of Biological Sciences, University
of Aarhus, Denmark
2 Joint Institute for Marine and Atmospheric Research, Pelagic Fisheries
Research Program, University of Hawai`i at Manoa, Honolulu, HI 96822,
USA
3 Honolulu Laboratory, Southwest Fisheries Science Center, National Marine
Fisheries Service, NOAA, Honolulu, HI 96822, USA
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Fig. 1. 3-day depth record for Fish 241, illustrating the typical pattern observed
in bigeye tuna not associated with floating objects or seamounts (from
Musyl et al., 2003 ). The black
horizontal bars indicate the night time.
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Fig. 2. Ambient (Ta) and sensor (Ts)
temperature records (the latter located within the body of an archival tag
placed in the visceral cavity) during a typical daytime period for Fish 241,
along with the fitted Ts data. (A) An entire daytime
period; (B) the 300–400 min portion in A expanded.
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Fig. 3. The fitted values of khigh and klow
for each daytime period of each fish from the entire data records. Missing
values typically resulted from the fish being associated with a Buoy 3 (Fish
301, Fish 390, Fish 392) or Cross Seamount (Fish 224), making fitting
impossible. Fish 224 had an apparent constant displacement of the recorded
ambient temperature. When this was adjusted by a constant value, such that the
night-time sensor temperature excess was similar to that of the other fish, it
gave similar fitted values for klow and
khigh and therefore the results were included in the
figure.
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Fig. 5. (A) Red muscle temperature (Trm) of Fish 241
(calculated from the measured sensor temperature) as a function of ambient
temperature (Ta) during one day. The data points are
joined to illustrate the behavior of the fish and how this affects its
Trm. (B) The distribution of calculated
Trm for an ambient temperature interval of
10.0–25.5°C. (C) Density plot of the number of observations (i.e.
the number of observations per °C2) of a given combination of
ambient and calculated red muscle temperature. This plot is based on the
combined set of observations (all days and nights for the entire time of
deployment) for Fish 241, Fish 290, Fish 292, Fish 301 and Fish 625, for a
total of 921,592 observations. The dotted straight lines in A and C show
Ta=Trm.
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Fig. 6. Vertical swimming speed as a function of depth during one day for Fish 241.
As indicated by the arrows, the left side of the figure shows descents and
right side ascents.
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Fig. 7. Mean of all the observed maximal ascent and descent speeds (± s.e.m)
during vertical excursions for (from left to right) Fish 390, Fish 392, Fish
301, Fish 298, Fish 625, Fish 241 and Fish 224, plotted as a function of size
(fork length, FL). The regression lines were fitted with a weighted
linear least-square procedure using the reciprocals of the s.e.m. as weight
and are: y=3.627–0.0192x (for descents,
r2=0.985, P=0.00015) and
y=3.439–0.0195x (for ascents,
r2=0.945, P=0.001). Note that the s.e.m. for each
point is so small that it is not distinguishable from the symbol. Also the
maximal vertical speeds observed for each fish during their entire tag
deployment period are shown (filled triangles).
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© The Company of Biologists Ltd 2007
