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Researchers seek to turn the tide on problem of acid seas

Nature volume 430, page 820 (19 August 2004) | Download Citation


Rising carbon dioxide levels could devastate marine ecosystems


Sea change: falling pH levels caused by carbon dioxide emissions could devastate oceanic ecosystems. Image: NATUREPL.COM

Researchers met last week to map out plans to study a serious but largely neglected environmental problem — the gradual acidification of the oceans.

Since the industrial revolution, sea surface pH levels have dropped by around 0.1 units as the oceans absorb atmospheric carbon dioxide. This is already enough to trouble some marine species, but researchers warn that values could fall by a further 0.5 units by 2100. If steps are not taken to cut CO2 emissions, pH could drop even further, perhaps to levels that are thought to have triggered catastrophic extinction events in Earth's history (Nature 425, 365; 2003).

“We're taking a huge risk,” says Ulf Riebesell, a marine biologist at the Leibniz Institute of Marine Sciences in Kiel, Germany. “Chemical ocean conditions 100 years from now will probably have no equivalent in the geological past, and key organisms may have no mechanisms to adapt to the change.”

Aspects of the threat are already being studied, but marine scientists met at the Plymouth Marine Laboratory, UK, on 11–13 August to start work on a comprehensive research plan. The scheme, to be finalized later this year, will list key scientific questions and provide a blueprint for funding agencies and researchers.

Their efforts were due to be boosted on 17 August by news that Britain's Royal Society is to probe the likely changes to marine ecosystems following a rise in ocean acidity.

Studies of the effects of acidification on marine organisms will play a prominent part in the research plan. Last month, researchers showed that the shells and hard skeletons of plankton and corals will begin to dissolve as the oceans become more acid (R. A. Feely et al. Science 305, 362–366; 2004). The loss of these creatures would have incalculable consequences for the entire marine food chain.

Carol Turley, a senior scientist at the Plymouth lab, says researchers will investigate the growth, reproduction and adaptation capability of marine species ranging from bacteria to vertebrates. Results from these experiments will help to shape protocols for open-ocean studies. With the help of measurement tools such as pH sensors attached to profiling floats, researchers will try to track the subtle ecosystem interactions between the sea surface and the sea floor, and between coastal areas and the open ocean.

Modelling the likely changes in ocean chemistry, and determining how they may affect temperature, salinity and nutrient availability, will be another priority, says Turley. Researchers will also add CO2 to the ocean to simulate long-term changes. Together, these studies should show how biogeochemistry, species diversity and evolution will change in an acidic ocean.

Riebesell hopes that the initiatives, which will be overseen by the Integrated Marine Biogeochemistry and Ecosystem Research project, will influence funding agencies. “We know quite a lot about the ocean of the past,” he says. “But we owe it to people to tell them more about the ocean of the future.”

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