Study Shows Long-term Effects of Ocean Acidifcation on Algae

Sophie McCoy works with algae on Tatoosh Island in 2010 (photo by Cathy Pfister)

Sophie McCoy works with algae on Tatoosh Island in 2010 (photo by Cathy Pfister)

Sophie McCoy, who earned a PhD in from the Department of Ecology and Evolution at the University of Chicago this year, has moved on to become a post-doctoral fellow at the Plymouth Marine Laboratory (PML) in the United Kingdom, but not before publishing one more paper on her work studying the effects of ocean acidification in the Pacific Northwest.

For her PhD project, McCoy studied crustose coralline algae, a group of species living in the waters around Tatoosh Island off the coast of Washington state. These algae grow skeletons made of calcium carbonate, much like other shelled organisms such as mussels and oysters. As people burn fossil fuels and release carbon into the atmosphere, the ocean absorbs a big chunk of it, causing pH levels to drop and make the water more acidic. Crustose coralline algae and shellfish have difficulty producing their skeletons and shells in such an environment, and can provide an early indicator of how increasing ocean acidification affects marine life.

Tatoosh Island, Washington (photo from the Pfister Lab)

Tatoosh Island, Washington (photo from the Pfister Lab)

Science Life spoke to McCoy in January about how this changing environment affects competition among different species of algae, setting up a “rock, paper, scissors” dynamic where no one species has a clear advantage. Her new study, published on June 15 in Nature Climate Change, looked at how the increasingly acidic ocean waters affect the thickness (and competitive fitness) of the algae, and showed that some algae are half as thick as they used to be 15-20 years ago.

‚ÄúThis is strong evidence of a significant impact on these important seaweed species and the same story is likely to be found elsewhere around the world as our seas become more acidic,” McCoy said in a press release from PML. “Anything that makes them more stressed and less able to survive could have ramifications across coastal ecosystems and affect other organisms along marine food chains.”

While at UChicago, McCoy worked with Cathy Pfister and Tim Wootton, who have been studying Tatoosh for the past 20 years. In 2011, Science Life spoke to them about how they figured out how to track historical pH levels in the ocean by using mussel shells. And if you’re thinking there might be some other explanation for ocean acidification besides increased carbon in the atmosphere, they covered that too.

McCoy S.J. (2014). Skeletal trade-offs in coralline algae in response to ocean acidification, Nature Climate Change, DOI:

About Matt Wood (433 Articles)
Matt Wood is a senior science writer for the University of Chicago Medicine and editor of the Science Life blog.

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