title: Potential climate change effects on the habitat of antarctic krill in the weddell quadrant of the southern ocean.
abstract: Antarctic krill is a cold water species, an increasingly important fishery resource and a major prey item for many fish, birds and mammals in the Southern Ocean. The fishery and the summer foraging sites of many of these predators are concentrated between 0° and 90°W. Parts of this quadrant have experienced recent localised sea surface warming of up to 0.2°C per decade, and projections suggest that further widespread warming of 0.27° to 1.08°C will occur by the late 21(st) century. We assessed the potential influence of this projected warming on Antarctic krill habitat with a statistical model that links growth to temperature and chlorophyll concentration. The results divide the quadrant into two zones: a band around the Antarctic Circumpolar Current in which habitat quality is particularly vulnerable to warming, and a southern area which is relatively insensitive. Our analysis suggests that the direct effects of warming could reduce the area of growth habitat by up to 20%. The reduction in growth habitat within the range of predators, such as Antarctic fur seals, that forage from breeding sites on South Georgia could be up to 55%, and the habitat's ability to support Antarctic krill biomass production within this range could be reduced by up to 68%. Sensitivity analysis suggests that the effects of a 50% change in summer chlorophyll concentration could be more significant than the direct effects of warming. A reduction in primary production could lead to further habitat degradation but, even if chlorophyll increased by 50%, projected warming would still cause some degradation of the habitat accessible to predators. While there is considerable uncertainty in these projections, they suggest that future climate change could have a significant negative effect on Antarctic krill growth habitat and, consequently, on Southern Ocean biodiversity and ecosystem services.
authors.affiliation: British Antarctic Survey, Natural Environment Research Council, Cambridge, United Kingdom. sih@bas.ac.uk
authors.forename: Simeon L
authors.initials: SL
authors.lastname: Hill
authors.forename: Tony
authors.initials: T
authors.lastname: Phillips
authors.forename: Angus
authors.initials: A
authors.lastname: Atkinson
mesh_terms: D000818:Animals; D000864:Antarctic Regions; D057231:Climate Change; D003080:Cold Temperature; D017753:Ecosystem; D033201:Euphausiacea / Q000254:growth & development / Q000502:physiology; D005247:Feeding Behavior; D008962:Models, Theoretical; D009792:Oceans and Seas