Saturday, May 21, 2011

Ocean Acidification: Killing Marine Life

The acidification of the world's oceans could have major consequences for the marine environment. New research shows that coccoliths, which are an important part of the marine environment, dissolve when seawater acidifies.

Associate Professor Tue Hassenkam and colleagues at the Nano-Science Center, University of Copenhagen, are the first to have measured how individual coccoliths react to water with different degrees of acidity.

Coccoliths are very small shells of calcium carbonate that encapsulate a number of species of alga. Algae plays an important role in the global carbon-oxygen cycle and thus in our ecosystem. Our seawater has changed because of our emissions of greenhouse gases and therefore it was interesting for Hassenkam and his colleagues to investigate how the coccoliths react to different types of water.

"We know that the world's oceans are acidifying due to our emissions of CO2 and that is why it is interesting for us to find out how the coccoliths are reacting to it. We have studied algae from both fossils and living coccoliths, and it appears that both are protected from dissolution by a very thin layer of organic material that the algae formed, even though the seawater is extremely unsaturated relative to calcite. The protection of the organic material is lost when the pH is lowered slightly. In fact, it turns out that the shell falls completely apart when we do experiments in water with a pH value that many researchers believe will be the found in the world oceans in the year 2100 due to the CO2 levels," explains Tue Hassenkam, who is part of the NanoGeoScience research group at the Department of Chemistry, University of Copenhagen. (read more)