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The endemic and endangered Maugean Skate (Zearaja maugeana) exhibits short-term severe hypoxia tolerance

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Morash, AJ ORCID: 0000-0001-8486-4567, Lyle, JM ORCID: 0000-0001-9670-5854, Currie, S, Bell, JD ORCID: 0000-0002-1926-7501, Stehfest, KM ORCID: 0000-0002-6371-9296 and Semmens, JM ORCID: 0000-0003-1742-6692 2020 , 'The endemic and endangered Maugean Skate (Zearaja maugeana) exhibits short-term severe hypoxia tolerance' , Conservation Physiology, vol. 8, no. 1 , pp. 1-15 , doi: 10.1093/conphys/coz105.

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Abstract

The endangered and range-restricted Maugean skate (Zearaja maugeana) is subjected to large environmental variability coupled with anthropogenic stressors in its endemic habitat, Macquarie Harbour, Tasmania. However, little is known about the basic biology/physiology of this skate, or how it may respond to future environmental challenges predicted from climate change and/or increases in human activities such as aquaculture. These skate live at a preferred depth of 5–15 m where the dissolved oxygen (DO) levels are moderate (~55% air saturation), but can be found in areas of the Harbour where DO can range from 100% saturation to anoxia. Given that the water at their preferred depth is already hypoxic, we sought to investigate their response to further decreases in DO that may arise from potential increases in anthropogenic stress. We measured oxygen consumption, haematological parameters, tissue–enzyme capacity and heat shock protein (HSP) levels in skate exposed to 55% dissolved O2 saturation (control) and 20% dissolved O2 saturation (hypoxic) for 48 h. We conclude that the Maugean skate appears to be an oxyconformer, with a decrease in the rate of O2 consumption with increasing hypoxia. Increases in blood glucose and lactate at 20% O2 suggest that skate are relying more on anaerobic metabolism to tolerate periods of very low oxygen. Despite these metabolic shifts, there was no difference in HSP70 levels between groups, suggesting this short-term exposure did not elicit a cellular stress response. The metabolic state of the skate suggests that low oxygen stress for longer periods of time (i.e. >48 h) may not be tolerable and could potentially result in loss of habitat or shifts in their preferred habitat. Given its endemic distribution and limited life-history information, it will be critical to understand its tolerance to environmental challenges to create robust conservation strategies.

Item Type: Article
Authors/Creators:Morash, AJ and Lyle, JM and Currie, S and Bell, JD and Stehfest, KM and Semmens, JM
Keywords: hypoxia, metabolism, environmental stress, anaerobic metabolism, endangered species
Journal or Publication Title: Conservation Physiology
Publisher: Oxford University Press
ISSN: 2051-1434
DOI / ID Number: 10.1093/conphys/coz105
Copyright Information:

Copyright 2020 The Authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/

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