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Cardiorespiratory collapse at high temperature in swimming adult sockeye salmon


Eliason, EJ and Clark, TD and Hinch, SG and Farrell, AP, Cardiorespiratory collapse at high temperature in swimming adult sockeye salmon, Conservation Physiology, 1, (1) Article cot008. ISSN 2051-1434 (2013) [Refereed Article]


Copyright Statement

Copyright 2013 The Author. Licenced under the terms of the Creative Commons Attribution License

DOI: doi:10.1093/conphys/cot008


Elevated summer river temperatures are associated with high in-river mortality in adult sockeye salmon (Oncorhynchus nerka) during their once-in-a-lifetime spawning migration up the Fraser River (British Columbia, Canada). However, the mechanisms underlying the decrease in whole-animal performance and cardiorespiratory collapse above optimal temperatures for aerobic scope (Topt) remain elusive for aquatic ectotherms. This is in part because all the relevant cardiorespiratory variables have rarely been measured directly and simultaneously during exercise at supra-optimal temperatures. Using the oxygen- and capacity-limited thermal tolerance hypothesis as a framework, this study simultaneously and directly measured oxygen consumption rate (MO2), cardiac output Vb, heart rate (fH), and cardiac stroke volume (Vs), as well as arterial and venous blood oxygen status in adult sockeye salmon swimming at temperatures that bracketed Topt to elucidate possible limitations in oxygen uptake into the blood or internal delivery through the oxygen cascade. Above Topt, the decline in MO2max and aerobic scope was best explained by a cardiac limitation, triggered by reduced scope for fH. The highest test temperatures were characterized by a negative scope for fH, dramatic decreases in maximal Vb and maximal Vs, and cardiac dysrhythmias. In contrast, arterial blood oxygen content and partial pressure were almost insensitive to supra-optimal temperature, suggesting that oxygen delivery to and uptake by the gill were not a limiting factor. We propose that the high-temperature-induced en route mortality in migrating sockeye salmon may be at least partly attributed to physiological limitations in aerobic performance due to cardiac collapse via insufficient scope for fH. Furthermore, this improved mechanistic understanding of cardiorespiratory collapse at high temperature is likely to have broader application to other salmonids and perhaps other aquatic ectotherms.

Item Details

Item Type:Refereed Article
Keywords:aerobic scope, cardiovascular, climate change, heart rate, migration, oxygen- and capacity-limited thermal tolerance
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:103366
Year Published:2013
Web of Science® Times Cited:78
Deposited By:IMAS Research and Education Centre
Deposited On:2015-10-07
Last Modified:2017-10-31
Downloads:553 View Download Statistics

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