Skip to main content
U.S. flag

An official website of the United States government

Polluted groundwater threatens coral reefs

Coral reefs already stressed by ocean acidification are particularly vulnerable to polluted groundwater, according to a recent study by USGS geologist Nancy Prouty and colleagues.

Rising atmospheric CO2 is causing a gradual decrease in ocean pH, making it more difficult for corals to grow calcium carbonate skeletons and enhancing rates of dissolution and bioerosion—the breakdown of coral by other organisms. The authors show that polluted groundwater discharging onto coral reefs off west Maui, Hawai‘i, further lowers seawater pH and exposes corals to nitrate concentrations 50 times higher than normal. Such land-based pollution could contribute to the collapse of coastal coral reef ecosystems sooner than predicted just on the basis of ocean acidification. The study was published in the American Geophysical Union (AGU) Journal of Geophysical Research: Oceans, featured on AGU’s GeoSpace blog, and reported by the Honolulu Star-Advertiser and the Associated Press.

CT scans and photographs of coral collected from reef near polluted groundwater seeps. One set shows more erosion than the other
Coral collected from reef near polluted groundwater seeps, A, shows more erosion than coral collected away from seeps, B, in these computerized tomography (CT) images and photographs. cm = centimeter. Location map of the island of Maui, Hawaii shows the study area on the western coast.(Public domain.)

Get Our News

These items are in the RSS feed format (Really Simple Syndication) based on categories such as topics, locations, and more. You can install and RSS reader browser extension, software, or use a third-party service to receive immediate news updates depending on the feed that you have added. If you click the feed links below, they may look strange because they are simply XML code. An RSS reader can easily read this code and push out a notification to you when something new is posted to our site.