Evolution at Sea: Long-Term Experiments Indicate Phytoplankton Can Adapt to Ocean Acidification

10:27:23 AM, Monday, April 09, 2012

“ScienceDaily (Apr. 8, 2012) — Fossil fuel derived carbon dioxide has a serious impact on global climate but also a disturbing effect on the oceans, know as the other CO2 problem. When CO2 dissolves in seawater it forms carbonic acid and results in a drop in pH, the oceans acidify. A wealth of short-term experiments has shown that calcifying organisms, such as corals, clams and snails, but also micron size phytoplankton are affected by ocean acidification. The potential for organisms to cope with acidified oceanic conditions via evolutionary adaptations has so far been unresolved.

Scientists of the Helmholtz Centre for Ocean Research Kiel (GEOMAR) have now for the first demonstrated the potential of the unicellular algae Emiliania huxleyi to adapt to changing pH conditions and thereby at least partly to mitigate negative effects of ocean acidification. These results raised by the biologists Kai Lohbeck, Prof. Ulf Riebesell and Prof. Thorsten Reusch are published in the current issue of Nature Geoscience.

Experimental Emiliania huxleyi strains were isolated in Norwegian coastal waters and cultured in the laboratory under projected future ocean CO2 conditions. After about one year, which translates into 500 generations in this rapidly reproducing species, the biologists detected adaptation to high CO2 – adapted populations grew and calcified significantly better than non adapted control populations when tested under ocean acidification condition.

“From a biogeochemical perspective the most interesting finding was probably a partly restoration in calcification rates” GEOMAR scientist Prof. Ulf Riebesell notes. Emiliania huxleyi covers its cell surface with minute calcite scales that were found to decrease in weight under increased CO2 concentrations. “This is what we expected from the literature. But we were fascinated to find impaired calcification to partly recover after only 500 generations” says biologist Kai Lohbeck…”

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