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New research: Acid zone in Chesapeake Bay could harm oysters

John Lee

Water in the Chesapeake Bay that’s about 30 to 50 ft. deep is becoming more acidified, according to new research.


That means carbon dioxide is dissolving in the water, which could potentially hurt oysters and clams.


There aren’t as many oysters in the Chesapeake Bay as there used to be. And University of Delaware Wei-Jun Cai says he may know why.


Shellfish need a compound called calcium carbonate to help build their shells.


"And if pH is low, and carbonate saturation state is low, that would be harmful, and they have to be above a certain level to be saturated in the carbonate," Cai said.


If it’s undersaturated, the shell would dissolve, and an oyster may not be able to rebuild it.

Cai is part of a 16-person research team that collected water samples in the Chesapeake Bay to study oxygen and pH in America’s largest estuary. They analyzed changes changes in water chemistry by collecting water samples to measure pH, oxygen and dissolved inorganic carbon. The pH of the water, Cai said, is near 7.2, an acidic pH for water.

Cai says the team will next look at how to apply their research to preserving shellfish in the bay.

"To restoring the bay, we need a different aspect [approach]. For example, we need to reduce nutrient input," Cai said.

They’re also building a model to predict how pH changes in the surface water.

Journal reference: Wei-Jun Cai, Wei-Jen Huang, George W. Luther III, Denis Pierrot, Ming Li, Jeremy Testa, Ming Xue, Andrew Joesoef, Roger Mann, Jean Brodeur, Yuan-Yuan Xu, Baoshon Chen, Najid Hussain, George W. Waldbusser, Jeffrey Cornwell, & W. Michael Kemp. Redox reactions and weak buffering capacity lead to acidification in the Chesapeake Bay. Nature Communications: 8:369. DOI: 10.1038/s41467-017-00417-7.

Additional information: This study received funding through the National Oceanic and Atmospheric Administration, National Science Foundation, NASA, Delaware Sea Grant and University of Delaware.


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