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Effects of hypoxia on oxygen consumption, swimming velocity and gut evacuation in southern bluefin tuna (Thunnus maccoyii)

Citation

Fitzgibbon, QP and Seymour, RS and Buchanan, J and Musgrove, R and Carragher, J, Effects of hypoxia on oxygen consumption, swimming velocity and gut evacuation in southern bluefin tuna (Thunnus maccoyii), Environmental Biology of Fishes, 89, (1) pp. 59-69. ISSN 0378-1909 (2010) [Refereed Article]


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The original publication is available at http://www.springerlink.com

Official URL: http://www.springerlink.com/content/p0p338532t88gq...

DOI: doi:10.1007/s10641-010-9690-1

Abstract

Of the few measurements of the behavioural and physiological responses of tuna to hypoxia, most are restricted to shallow diving tropical species. Furthermore, when wild tuna experience low dissolved oxygen, they are likely to have an increased oxygen demand associated with the metabolic cost of food digestion and assimilation (specific dynamic action). However the response of postprandial tuna to hypoxia has never been examined. This study focuses on the metabolic and behavioural responses of both fasted and postprandial southern bluefin tuna (Thunnus maccoyii) to low dissolved oxygen. Fasted T. maccoyii were exposed to dissolved oxygen levels of 4.44, 3.23, 2.49 and 1.57 mg·l−1 for 20–21 h. In moderate hypoxia (4.44 and 3.23 mg·l−1), swimming speed was enhanced (1.5 and 1.3 times normoxic speed, respectively) presumably to increase ventilation volume. Routine metabolic rate (Rr) was similarly elevated (1.3 and 1.2 times normoxic Rr, respectively), most likely due to increased metabolic demand of faster swimming. At 2.49 mg·l−1, swimming speed increased to over double the normoxic speed, possibly as an escape response. At 1.57 mg·l−1, both swimming speed and Rr were reduced (0.8 and 0.9 times normoxic level, respectively), and tuna failed to survive the entire 20 h exposure period. This reveals that the critical oxygen level of T. maccoyii is between 1.57 and 2.49 mg·l−1, demonstrating that they are remarkably well adapted to low dissolved oxygen. Feeding did not greatly influence their hypoxia tolerance with tuna surviving exposure to dissolved oxygen levels of 2.96 and 1.81 mg·l−1 for 21 h, after ingesting a ration of 6.7% body weight of sardines (Sardinops sagax). In a subsequent experiment to determine the effects of hypoxia on digestion rate, T. maccoyii were fed to satiation and exposed to a dissolved oxygen level of 2.84 mg·l−1 for 6.5–8 h. There was no significant difference in swimming speed, Rr and gastric evacuation rates of tuna in hypoxia compared to those in normoxia. This demonstrates that in moderate to severe hypoxia, T. maccoyii are still capable of aerobically supporting maintenance metabolism, routine swimming and specific dynamic action. It is hypothesized that adaptations which support the large metabolic scope of tuna are also likely to be beneficial for oxygen extraction and delivery in conditions of hypoxia.

Item Details

Item Type:Refereed Article
Keywords:Southern bluefin tuna . Hypoxia Metabolic rate . Feeding . Dissolved oxygen
Research Division:Agricultural and Veterinary Sciences
Research Group:Fisheries Sciences
Research Field:Aquaculture
Objective Division:Animal Production and Animal Primary Products
Objective Group:Fisheries - Aquaculture
Objective Field:Aquaculture Tuna
Author:Fitzgibbon, QP (Dr Quinn Fitzgibbon)
ID Code:66615
Year Published:2010
Web of Science® Times Cited:2
Deposited By:TAFI - Marine Research Laboratory
Deposited On:2011-02-03
Last Modified:2017-06-20
Downloads:0

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