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Heart rate responses to temperature in free-swimming Pacific bluefin tuna (Thunnus orientalis)


Clark, TD and Farwell, CJ and Rodriguez, LE and Brandt, WT and Block, BA, Heart rate responses to temperature in free-swimming Pacific bluefin tuna (Thunnus orientalis), Journal of Experimental Biology, 216, (Part 17) pp. 3208-3214. ISSN 0022-0949 (2013) [Refereed Article]

DOI: doi:10.1242/jeb.086546


The bluefin tuna heart remains at ambient water temperature (Ta) but must supply blood to warm regions of the body served by countercurrent vascular heat exchangers. Despite this unusual physiology, inherent difficulties have precluded an understanding of the cardiovascular responses to Ta in free-swimming bluefin tunas. We measured the heart rate (f(H)) responses of two captive Pacific bluefin tunas (Thunnus orientalis; 9.7 and 13.3 kg) over a cumulative period of 40 days. Routine f(H) during fasting in the holding tank at a Ta of 20C was 45.18.0 and 40.76.5 beats min(-1) for Tuna 1 and Tuna 2, respectively. f(H) decreased in each fish with a Q10 temperature coefficient of 2.6 (Tuna 1) and 3.1 (Tuna 2) as Ta in the tank was slowly decreased to 15C (~0.4C h(-1)), despite a gradual increase in swimming speed. The same thermal challenge during digestion revealed similar thermal dependence of f(H) and indicated that the rate of visceral cooling is not buffered by the heat increment of feeding. Acutely decreasing Ta from 20 to 10C while Tuna 1 swam in a tunnel respirometer caused a progressive increase in tail-beat frequency and oxygen consumption rate (M(O2)). f(H) of this fish decreased with a Q10 of 2.7 as Ta decreased between 20 and 15C, while further cooling to 10C saw a general plateau in f(H) around 35 beats min(-1) with a Q10 of 1.3. A discussion of the relationships between f(H), and haemoglobin-oxygen binding sheds further light on how bluefin cardiorespiratory systems function in a changing thermal environment.

Item Details

Item Type:Refereed Article
Keywords:ambient temperature, cardiorespiratory, cardiovascular, oxygen consumption rate, swimming speed, tail beat-frequency, thermal biology, visceral temperature
Research Division:Biological Sciences
Research Group:Zoology
Research Field:Animal behaviour
Objective Division:Environmental Management
Objective Group:Coastal and estuarine systems and management
Objective Field:Coastal or estuarine biodiversity
UTAS Author:Clark, TD (Dr Timothy Clark)
ID Code:103354
Year Published:2013
Web of Science® Times Cited:16
Deposited By:IMAS Research and Education Centre
Deposited On:2015-10-06
Last Modified:2017-10-31

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