EXPERIMENTAL EVIDENCE FOR THE POTENTIAL OF SOUTHERN OCEAN ACIDIFICATION TO AFFECT ANTARCTIC KRILL

Abstract : Antarctic krill Euphausia superba are a key species of the Southern Ocean ecosystem. While it has been known for some time that the early effects of ocean acidification will be more pronounced in the polar regions due to the increased solubility of carbon dioxide and calcium carbonate in cold water, this is the first experimental evidence of a potential impact on Antarctic krill and therefore the ecosystem. Our research has been conducted in a unique purpose built aquarium designed to rear Antarctic krill through maturation and all stages of the larval life cycle. This has permitted us to examine the effects of ocean acidification on both eggs, larvae and adult krill. It is clear from our research that Antarctic krill face critical boundaries in ocean acidification due to the vertical distribution of larval stages in their life cycle. While larvae and adults may be able to cope with increased pCO2 concentrations at the surface, they may not be able to tolerate the amplified effects of ocean acidification at their hatching depth of 1000 metres. There is therefore potential for a considerable disruption to the Southern Ocean ecosystem and the fishery should the recruitment of krill be significantly affected through the combined effects of climate change and ocean acidification in the future.