Acidifying Southern Ocean Could Have Large Impact on Krill Populations
15.10.2010 - Atmosphere & Space, Water & Oceans, Flora & Fauna, Antarctic
Antarctic krill faces an increasing threat to their embryos as a result of ocean acidification, new research shows. Exposing krill to different levels of carbon dioxide, researchers from the Australian Antarctic Division (AAD) sought to investigate the possible impacts of acidification on the early development of krill. In the study, most of the krill embryos subjected to higher acidity levels were unable to develop and hatch successfully.
At the AAD’s krill aquarium, the researchers set up three sea water tanks with the current levels of carbon dioxide at 380 parts per million (ppm), a higher concentration of the greenhouse gas at 1000ppm and a very high concentration at 2000ppm. While no change was detected in the developing krill embryos from the first two tanks, the last one showed no surviving embryos. These results suggest that krill survival would be rendered difficult should carbon dioxide levels in the Southern Ocean rise significantly.
Since krill are major part of the Southern Ocean food chain, any impact on developing krill populations would have a major impact on the entire Southern Ocean ecosystem. Vertically migrating species such as krill – which spawn eggs at the surface before they sink and the larvae hatch and swim back to the surface – are more likely to see the highest impact on their populations and the highest mortality rates.
However, further studies still need to be undertaken to identify the exact carbon dioxide concentration “tipping point” and the potential impact of ocean acidification on the later stages of the life cycle of krill. Atmospheric levels of CO2 could rise to 788 ppm by the year 2100; concentrations in the Southern Ocean could rise to 1400 ppm.