Ocean Acidification In The Caribbean Significant, Yet Variable

ScienceDaily (Nov. 28, 2008) — A new study, which confirms significant ocean acidification across much of the Caribbean and Gulf of Mexico, reports strong natural variations in ocean chemistry in some parts of the Caribbean that could affect the way reefs respond to future ocean acidification.

Such short-term variability has often been underappreciated and may prove an important consideration when predicting the long-term impacts of ocean acidification to coral reefs.

Conducted by scientists from NOAA and the University of Miami's Rosenstiel School of Marine and Atmospheric Science, the study was published in the Oct. 31, 2008 issue of the Journal of Geophysical Research – Oceans.

Previous NOAA studies have shown that a quarter of the carbon dioxide that humans place in the atmosphere each year ends up being dissolved into the ocean. The result is the ocean becomes more acidic, making it harder for corals, clams, oysters, and other marine life to build their skeletons or shells. A number of recent studies demonstrate that ocean acidification is likely to harm coral reefs by slowing coral growth and making reefs more vulnerable to erosion and storms.

In the new study, NOAA scientists used four years of ocean chemistry measurements taken aboard the Royal Caribbean Cruise Line ship Explorer of the Seas together with daily satellite observations to estimate changes in ocean chemistry over the past two decades in the Caribbean region. The resulting new ocean acidification tracking products are available online along with animations of the changes since 1988.

"Ocean acidification has become an important issue to coral reef managers and researchers,” said Tim Keeney, deputy assistant secretary for oceans and atmosphere and co-chair of the United States Coral Reef Task Force. “These new tools provide these communities with better information to guide future research. This is the first time that anyone has been able to track ocean acidification on a monthly basis."

The study supports other findings that ocean acidification is likely to reduce coral reef growth to critical levels before the end of this century unless humans significantly reduce carbon dioxide emissions. While ocean chemistry across the region is currently deemed adequate to support coral reefs, it is rapidly changing as atmospheric carbon dioxide levels rise.

“The study demonstrates a strong natural seasonal variability in ocean chemistry in waters around the Florida Keys that could have important consequences for how these reefs respond to future ocean acidification," says NOAA's Dwight Gledhill, Ph.D., lead author of the study.

C. Mark Eakin, Ph.D., coordinator of NOAA’s Coral Reef Watch, said “Organisms from highly variable environments are often better adapted to changes like we have seen in the last 20 years. The real question is how far corals can adapt and if this natural variability will be enough to protect them."

Co-authors of the paper are Rik Wanninkhof, Ph. D., NOAA Research's Atlantic Oceanographic and Meteorological Laboratory, Frank J. Millero, Ph. D, University of Miami's Rosensteil School of Marine and Atmospheric Science, and Eakin, NOAA National Satellite and Information Service's Coral Reef Watch.