Egginton, S orcid.org/0000-0002-3084-9692, Axelsson, M, Crockett, EL et al. (2 more authors) (2019) Maximum cardiac performance of Antarctic fishes that lack haemoglobin and myoglobin: Exploring the effect of warming on nature’s natural knockouts. Conservation Physiology, 7 (1). coz049. ISSN 2051-1434
Abstract
Antarctic notothenioids, some of which lack myoglobin (Mb) and/or haemoglobin (Hb), are considered extremely stenothermal, which raises conservation concerns since Polar regions are warming at unprecedented rates. Without reliable estimates of maximum cardiac output (Q˙Q˙), it is impossible to assess their physiological scope in response to warming seas. Therefore, we compared cardiac performance of two icefish species, Chionodraco rastrospinosus (Hb−Mb+) and Chaenocephalus aceratus (Hb−Mb−), with a related notothenioid, Notothenia coriiceps (Hb+Mb+) using an in situ perfused heart preparation. The maximum Q˙Q˙, heart rate (fH), maximum cardiac work (WC) and relative ventricular mass of N. coriiceps at 1°C were comparable to temperate-water teleosts, and acute warming to 4°C increased fH and WC, as expected. In contrast, icefish hearts accommodated a higher maximum stroke volume (VS) and maximum Q˙Q˙ at 1°C, but their unusually large hearts had a lower fH and maximum afterload tolerance than N. coriiceps at 1°C. Furthermore, maximum VS, maximum Q˙Q˙ and fH were all significantly higher for the Hb−Mb+ condition compared with the Hb−Mb− condition, a potential selective advantage when coping with environmental warming. Like N. coriiceps, both icefish species increased fH at 4°C. Acutely warming C. aceratus increased maximum Q˙Q˙, while C. rastrospinosus (like N. coriiceps) held at 4°C for 1 week maintained maximum Q˙Q˙ when tested at 4°C. These experiments involving short-term warming should be followed up with long-term acclimation studies, since the maximum cardiac performance of these three Antarctic species studied seem to be tolerant of temperatures in excess of predictions associated with global warming.
Metadata
Authors/Creators: |
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Copyright, Publisher and Additional Information: | © The Author(s) 2019. Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. |
Keywords: | Cardiac output, cardiac work, heart rate, icefishes, thermal adaptation, warming |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Biological Sciences (Leeds) > School of Biomedical Sciences (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 02 Jul 2019 10:31 |
Last Modified: | 25 Jun 2023 21:53 |
Status: | Published |
Publisher: | Oxford University Press |
Identification Number: | https://doi.org/10.1093/conphys/coz049 |