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Continuous measurement of oxygen tensions in the air-breathing organ of Pacific tarpon (Megalops cyprinoides) in relation to aquatic hypoxia and exercise

Citation

Seymour, RS and Farrell, AP and Christian, K and Clark, TD and Bennett, MB and Wells, RMG and Baldwin, J, Continuous measurement of oxygen tensions in the air-breathing organ of Pacific tarpon (Megalops cyprinoides) in relation to aquatic hypoxia and exercise, Journal of Comparative Physiology. B, 177, (5) pp. 579-587. ISSN 0174-1578 (2007) [Refereed Article]

DOI: doi:10.1007/s00360-007-0156-5

Abstract

The Pacific tarpon is an elopomorph teleost fish with an air-breathing organ (ABO) derived from a physostomous gas bladder. Oxygen partial pressure (PO2) in the ABO was measured on juveniles (238 g) with fiber-optic sensors during exposure to selected aquatic PO2 and swimming speeds. At slow speed (0.65 BL s−1), progressive aquatic hypoxia triggered the first breath at a mean PO2 of 8.3 kPa. Below this, opercular movements declined sharply and visibly ceased in most fish below 6 kPa. At aquatic PO2 of 6.1 kPa and swimming slowly, mean air-breathing frequency was 0.73 min−1, ABO PO2 was 10.9 kPa, breath volume was 23.8 ml kg−1, rate of oxygen uptake from the ABO was 1.19 ml kg−1 min−1, and oxygen uptake per breath was 2.32 ml kg−1. At the fastest experimental speed (2.4 BL s−1) at 6.1 kPa, ABO oxygen uptake increased to about 1.90 ml kg−1 min−1, through a variable combination of breathing frequency and oxygen uptake per breath. In normoxic water, tarpon rarely breathed air and apparently closed down ABO perfusion, indicated by a drop in ABO oxygen uptake rate to about 1% of that in hypoxic water. This occurred at a wide range of ABO PO2 (1.726.4 kPa), suggesting that oxygen level in the ABO was not regulated by intrinsic receptors.

Item Details

Item Type:Refereed Article
Keywords:fish respiration, air-breathing, bimodal gas exchange, oxygen receptors
Research Division:Biological Sciences
Research Group:Zoology
Research Field:Animal Behaviour
Objective Division:Environment
Objective Group:Flora, Fauna and Biodiversity
Objective Field:Coastal and Estuarine Flora, Fauna and Biodiversity
UTAS Author:Clark, TD (Dr Timothy Clark)
ID Code:103470
Year Published:2007
Web of Science® Times Cited:16
Deposited By:IMAS Research and Education Centre
Deposited On:2015-10-13
Last Modified:2015-10-13
Downloads:0

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