After analyzing their data, Wang and colleagues found that, despite a "dead zone" of low oxygen and high acidity outside the mouth of the Mississippi, the Gulf of Mexico on the whole showed a high ratio of alkalinity to DIC, meaning it would be more resistant to acidification. As the team traveled farther north, however, they saw the ratio steadily decreases north of Georgia. The waters in the Gulf of Maine, Wang says, on average had the lowest alkalinity to DIC ratio of any region along the eastern seaboard, meaning that it would be especially vulnerable to acidification should CO2 levels rise in those waters.
While it's unclear exactly why the ratio of alkalinity to DIC is low in those northern waters, Wang thinks part of the issue may be linked to alkalinity sources to the region. For example, the Labrador Coastal Current brings relatively fresh, low alkalinity water down from the Labrador Sea to the Gulf of Maine and Middle Atlantic Bight.
If this current is the major source of alkalinity to the region, he says, it may mean that the Gulf of Maine's fate could be linked to changes in global climate that, through melting sea ice and glaciers, increase the flow of fresh water to the Gulf of Maine. However, whether this freshening is accompanied by a decreases in seawater alkalinity and "buffer" capacity remains unknown.
Since the waters of the northeast U.S. are already susceptible to rising acidity, Wang says this raises big questions about how species of marine lifemany of which are important to the commercial fishing and shellfish industry therewill fare in the future. "For example, how are oysters going to do? What about other shellfish? If the food chain changes, how are fish going to be impacted?" Wang asks. "There's a whole ra
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Woods Hole Oceanographic Institution