Chesapeake Quarterly Volume 11 Number 1

Acid Test for the Great Shellfish Bay?

March 2012 • Volume 11, Number 1

An Acidifying Estuary? The "Other CO2 Problem"

Stephen P. Nash

As CO₂ levels are rising in the atmosphere, acidity levels are rising in the ocean, which may be slowing growth rates for coral reefs, oysters, and other shell-building species. Could changes in acidity threaten the survival of oysters in the Chesapeake Bay at a time when oyster farming here is on the rise? To find out more, two researchers have come on a late-June morning to the shore of Maryland's Severn River, not far from the Bay, to set up experiments. To create a kind of time machine, the researchers will pump CO₂ into a marked-off square of river water, creating acidity levels as they will be in the future, circa 2050 and 2100. The Severn River project is part of a suite of new and recent research on the effects of rising CO₂ levels on the Chesapeake. Whitman Miller is studying how acidifying waters would affect oysters; Tom Arnold is looking at what would happen to seagrasses. more . . .

Chemistry 101 — How Rising Carbon Dioxide Threatens Shell-Builders

Excess atmospheric CO₂ turns marine waters acidic. In the Chesapeake additional CO₂ may come from nutrients. more . . .

Chemistry 102 — The pH Scale: Yardstick for Acidity

pH Scale. Source: Figure Adapted from Current: the Journal of Marine Education, Volume 25, Number 1, 2009.

Shell Game

When the larvae a Mike Congrove's oyster hatchery began dying in large numbers last June, he wasn't sure why. Larval production dropped from 100 million larvae a week down to 10 million. He had worked in the business long enough to know there could be multiple causes. In this dieoff, however, one major change drew his attention: the river water he was using had lower levels of pH. The Piankatank River — at least for awhile — had become more acidic. more . . .

Crab vs. Oyster

In the Chesapeake Bay and the open ocean, waters with rising acidity may be poison for some species and tonic for others. Recent laboratory studies examined how Bay species were affected by water with different levels of pH, the laboratory scale that describes acidity, and results for oysters and crabs were strikingly different. That's

important because of predictions that the Bay and the open ocean will slowly become more acidic in coming decades. more . . .

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issue cover. Photograph by Michael W. Fincham.

Should We Regulate Acidity in the Bay? If So, How?

According to state and federal regulators, there isn't yet enough proof to say the Bay has an acid problem. One national environmental group, however, disagrees. more . . .