ATHENS, Ga., Oct. 24 (UPI) -- Some marine creatures in the Gulf of Mexico face a double threat from agricultural runoff and atmospheric carbon dioxide, U.S. researchers say.
Increasing acidification in coastal waters from the combined effects of fertilizer runoff carried by the Mississippi River into the northern gulf and excess atmospheric carbon dioxide from burning fossil fuels could compromise the ability of oysters and other marine creatures to form and keep their shells, they said.
"Before, scientists only worried about low oxygen in waters along the coast," Wei-Jun Cai, a University of Georgia, Athens, professor of marine sciences, said in a university release Monday.
"Our paper basically says not only do we need to worry about low oxygen, we also need to worry about acidification."
An increase in ocean acidity means sea creatures that form carbonate shells or skeletons, including to oysters and corals, have problems producing and maintaining these structures, the researchers said.
They said measurements on the Changjaing (Yangtze) River, the largest river in Asia, produced similar results.
"Many of our fisheries resources, especially shellfish, are concentrated in areas where rivers discharge onto the coast, like the northern Gulf and the East China Sea, and thus are at risk," UGA marine scientist James T. Hollibaugh said. "And of course there are likely ramifications for fish and animals further up the food chain that depend on these same shellfish for food."