Ocean Acidification Puts Corals At Risk

Scientists in Japan have discovered that ocean acidification inhibits the formation of calcium carbonate skeletons in corals, highlighting yet another detrimental impact of human activity on ocean ecosystems.

AsianScientist (Dec. 26, 2017) – A team of researchers at the University of Tokyo, Japan, have revealed that ocean acidification negatively impacts the formation of corals’ skeletons. They published their findings in Scientific Reports.

Ocean acidification is a global environmental problem caused by elevated levels of carbon dioxide dissolving in seawater. Most studies until now have evaluated the effects of ocean acidification on coral calcification by examining the response of aquarium-cultured corals. This may not reflect the conditions found in the corals’ native environments.

In this study, a team of researchers led by Professor Yusuke Yokoyama at the Atmosphere and Ocean Research Institute at the University of Tokyo collected coral skeletons from Japan’s Chichijima and Kikaijima islands in the Ogasawara and Amami archipelagoes, respectively. They analyzed the boron isotope ratios in these skeletons, which reflect the pH (acidity) of the skeletons’ calcification fluid.

They found that a decrease in seawater pH—that is, ocean acidification—leads to a corresponding decrease in the pH of calcification fluid in corals. This inhibits the calcification of corals, which is a critical process for coral growth and survival.

“We didn’t expect such beautiful reproducibility in boron isotope records of Porite coral skeletons collected from these two islands so far apart,” said Dr. Kauru Kubota of the University of Tokyo, who is the first author of the paper. “We are very excited that the high-precision measurements allowed us to detect recent subtle changes in the boron isotopes of the skeletons.”

“However, given the impact on corals, we cannot consider our report good news, because the lower pH of calcification fluid prevents the corals from building calcium carbonate skeletons. I think we can say that ocean acidification indeed poses an imminent threat to coral reef ecosystems,” he added.

The article can be found at: Kubota et al. (2017) Rapid Decline in pH of Coral Calcification Fluid Due to Incorporation of Anthropogenic CO2.


Source: University of Tokyo; Photo: Yusuke Yokoyama.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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