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Changes in cardiac output during swimming and aquatic hypoxia in the air-breathing Pacific tarpon


Clark, TD and Seymour, RS and Christian, K and Wells, RMG and Baldwin, J and Farrell, AP, Changes in cardiac output during swimming and aquatic hypoxia in the air-breathing Pacific tarpon, Comparative Biochemistry and Physiology. Part A, 148, (3) pp. 562-571. ISSN 1095-6433 (2007) [Refereed Article]

DOI: doi:10.1016/j.cbpa.2007.07.007


Pacific tarpon (Megalops cyprinoides) use a modified gas bladder as an air-breathing organ (ABO). We examined changes in cardiac output (b) associated with increases in air-breathing that accompany exercise and aquatic hypoxia. Juvenile (0.49 kg) and adult (1.21 kg) tarpon were allowed to recover in a swim flume at 27 C after being instrumented with a Doppler flow probe around the ventral aorta to monitor b and with a fibre-optic oxygen sensor in the ABO to monitor air-breathing frequency. Under normoxic conditions and in both juveniles and adults, routine air-breathing frequency was 0.03 breaths min− 1 and b was about 15 mL min− 1 kg− 1. Normoxic exercise (swimming at about 1.1 body lengths s− 1) increased air-breathing frequency by 8-fold in both groups (reaching 0.23 breaths min− 1) and increased b by 3-fold for juveniles and 2-fold for adults. Hypoxic exposure (2 kPa O2) at rest increased air-breathing frequency 19-fold (to around 0.53 breaths min− 1) in both groups, and while b again increased 3-fold in resting juvenile fish, b was unchanged in resting adult fish. Exercise in hypoxia increased air-breathing frequency 35-fold (to 0.95 breaths min− 1) in comparison with resting normoxic fish. While juvenile fish increased b nearly 2-fold with exercise in hypoxia, adult fish maintained the same b irrespective of exercise state and became agitated in comparison. These results imply that air-breathing during exercise and hypoxia can benefit oxygen delivery, but to differing degrees in juvenile and adult tarpon. We discuss this difference in the context of myocardial oxygen supply.

Item Details

Item Type:Refereed Article
Keywords:air-breathing fish, aerial respiration, cardiac output, cardiac stroke volume, exercise, compact myocardium, heart rate, Megalops cyprinoides
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:103464
Year Published:2007
Web of Science® Times Cited:12
Deposited By:IMAS Research and Education Centre
Deposited On:2015-10-12
Last Modified:2015-10-12

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