Southern Ocean acidification and the effect on pteropods and krill

• Main Author: Schwalger-Smith, Briar
• Format: Other/Unknown Material
• Language: English
• Published: University of Canterbury 2014
• Subjects: Antarctic; Southern Ocean; Antarc*; Ocean acidification
• Online Access: http://hdl.handle.net/10092/13870

Increasing anthropogenic carbon dioxide in the atmosphere decreases the pH of the ocean and the carbonate ion concentration. Colder temperatures and winds causing the upwelling of deep sea water are two factors that will increase the rate of ocean acidification in the Southern Ocean, relative to lower latitudes. Pteropods and krill are both important species in Antarctic ecosystems and this review outlines the current understanding of how they are affected by projected changes to ocean chemistry. All species of thecosomata (shelled pteropod) experienced degrees of shell dissolution as a result of ocean acidification and aragonite undersaturation. Other physiological factors and survival rate varied between pteropod species but predominately showed a negative impact. Aragonite undersaturation is projected to occur in the Southern Ocean by 2050 and by 2030 in winter. The effects of ocean acidification on pteropods have been more widely researched than the effects on the key ecosystem species, krill. Increased carbon dioxide levels detrimentally affected the hatch rate of krill eggs and population collapse is projected for 2300, with severe and widespread consequence to the entire ecosystem. This review highlights current gaps in the research and identifies the urgent need for a more comprehensive understanding of the ecological impacts of declining or disappearing pteropod and krill populations.