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https://hdl.handle.net/2440/44142
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Type: | Journal article |
Title: | Continuous measurement of oxygen tensions in the air-breathing organ of Pacific tarpon (Megalops cyprinoides) in relation to aquatic hypoxia and exercise |
Author: | Seymour, R. Farrell, A. Christian, K. Clark, T. Bennett, M. Wells, R. Baldwin, J. |
Citation: | Journal of Comparative Physiology B: biochemical, systemic, and environmental physiology, 2007; 177(5):579-587 |
Publisher: | Springer |
Issue Date: | 2007 |
ISSN: | 0174-1578 1432-136X |
Statement of Responsibility: | Roger S. Seymour, Anthony P. Farrell, Keith Christian, Timothy D. Clark, Michael B. Bennett, Rufus M. G. Wells and John Baldwin |
Abstract: | The Pacific tarpon is an elopomorph teleost fish with an air-breathing organ (ABO) derived from a physostomous gas bladder. Oxygen partial pressure (PO(2)) in the ABO was measured on juveniles (238 g) with fiber-optic sensors during exposure to selected aquatic PO(2) and swimming speeds. At slow speed (0.65 BL s(-1)), progressive aquatic hypoxia triggered the first breath at a mean PO(2) of 8.3 kPa. Below this, opercular movements declined sharply and visibly ceased in most fish below 6 kPa. At aquatic PO(2) of 6.1 kPa and swimming slowly, mean air-breathing frequency was 0.73 min(-1), ABO PO(2) 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 PO(2) (1.7-26.4 kPa), suggesting that oxygen level in the ABO was not regulated by intrinsic receptors. |
Keywords: | Fish Respiration Air-breathing Bimodal gas exchange Oxygen receptors |
Description: | The original publication can be found at www.springerlink.com |
DOI: | 10.1007/s00360-007-0156-5 |
Published version: | http://www.springerlink.com/content/90239m328x4119nx/ |
Appears in Collections: | Aurora harvest Earth and Environmental Sciences publications |
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