Risk maps for Antarctic krill under projected Southern Ocean acidification

Marine ecosystems of the Southern Ocean are particularly vulnerable to ocean acidification. Antarctic krill (Euphausia superba; hereafter krill) is the key pelagic species of the region and its largest fishery resource. There is therefore concern about the combined effects of climate change, ocean a...

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Bibliographic Details
Published in:Nature Climate Change
Main Authors: Kawaguchi, S, Ishida, A, King, R, Raymond, B, Waller, N, Constable, A, Nicol, S, Wakita, M, Ishimatsu, A
Format: Article in Journal/Newspaper
Language:English
Published: Nature Publishing Group 2013
Subjects:
Biological Sciences
Ecology
Marine and Estuarine Ecology (incl. Marine Ichthyology)
Antarctic
Southern Ocean
Weddell
Weddell Sea
Antarc*
Antarctic Krill
Euphausia superba
Ocean acidification
Online Access:https://doi.org/10.1038/nclimate1937
http://ecite.utas.edu.au/88093
Description
Summary:Marine ecosystems of the Southern Ocean are particularly vulnerable to ocean acidification. Antarctic krill (Euphausia superba; hereafter krill) is the key pelagic species of the region and its largest fishery resource. There is therefore concern about the combined effects of climate change, ocean acidification and an expanding fishery on krill and ultimately, their dependent predators - whales, seals and penguins. However, little is known about the sensitivity of krill to ocean acidification. Juvenile and adult krill are already exposed to variable seawater carbonate chemistry because they occupy a range of habitats and migrate both vertically and horizontally on a daily and seasonal basis. Moreover, krill eggs sink from the surface to hatch at 700-1,000 m (ref.), where the carbon dioxide partial pressure (p CO 2) in sea water is already greater than it is in the atmosphere. Krill eggs sink passively and so cannot avoid these conditions. Here we describe the sensitivity of krill egg hatch rates to increased CO 2, and present a circumpolar risk map of krill hatching success under projected p CO 2 levels. We find that important krill habitats of the Weddell Sea and the Haakon VII Sea to the east are likely to become high-risk areas for krill recruitment within a century. Furthermore, unless CO 2 emissions are mitigated, the Southern Ocean krill population could collapse by 2300 with dire consequences for the entire ecosystem. 2013 Macmillan Publishers Limited. All rights reserved.

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