Scientists look to coral insides for evidence of environmental damage

"This study gives us a sense of how big the changes have been over the last 60 years and how population growth is leading to the degradation of the reefs," said researcher Kiho Kim

By Brooks Hays

June 7 (UPI) -- Researchers at American University are using a novel sampling and imaging technique to study the insides of coral. The scientists are the first to survey coral skeletons for evidence of environmental damage caused by humans.

A plethora of scientific studies have highlighted the peril faced by the planet's coral reefs. Rising water temperatures, ocean acidification, overfishing and pollution all threaten coral and the ecological benefits the fragile organisms provide.


"This study gives us a sense of how big the changes have been over the last 60 years and how population growth is leading to the degradation of the reefs," Kiho Kim, a marine ecologist at American, said in a news release.

Researchers collected coral samples from Guam, where reefs are polluted by sewage-derived nitrogen -- the result of poor wastewater infrastructure. The scientists used a diamond-tipped drill bit to extract the skeletal cores. Surprisingly, the process doesn't hurt the coral.

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As Guam's population continues to grow, as expected, wastewater treatment facilities will be further taxed, yielding potentially devastating consequences for the island nation's coastal ecosystems.

By studying coral skeletons, researchers hope to be able to tease out the health effects of different factors -- separating the impact of global warming from local pollution. Environmental conditions leave measurable marks on coral skeletons, just as temperature and precipitation influence a tree's growth rings.


Scientists have previously used coral skeletal analysis to trace ocean temperature changes, but a new analysis method developed by Princeton scientists, called stable isotope analysis, has allowed researchers to isolate the impact of nitrogen pollution.

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Analysis of the skeletal cores collected off the coast of Guam showed increases in nitrogen pollution corresponded neatly with the country's population growth over the last 60 years. Researchers shared their findings in the journal Marine Pollution Bulletin.

If coral is going to survive the impacts of global warming, researchers say it's imperative local communities ensure other environmental hazards are dramatically curbed.

"Coral reefs on Guam face the simultaneous challenges of multiple -- and sometimes conflicting -- user needs and impacts from declining water quality. Yet they remain of critical importance to Guam's economy," Kim said. "This situation is common to tropical islands throughout the world. Lessons learned regarding coping with these challenges may provide guidance for other islands in the region."

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