The Environment In Focus
1:53 pm
Tue August 12, 2014

Rising Carbon Dioxide Levels May Feed Underwater Grasses

Some aquatic vegetation in the Chesapeake Bay and elsewhere may actually be helped by the rising carbon dioxide levels that are causing global warming, researchers suggest.


Underwater grass beds are critically important to the Bay and other waterways, because they produce oxygen, filter out sediment, feed ducks, and provide shelter for young crabs and fish.

Pollution smothered more than two thirds of the Bay’s grasses during the 1960s and 1970s, and the grasses have been up and down since then.  Some scientists worry that rising temperatures from global warming will kill off much of the Bay's southern grasses (a species called eelgrass).

But other researchers, including Richard Zimmerman, a professor of ocean and atmospheric sciences at Old Dominion University in Norfolk, have concluded that rising carbon dioxide levels in the water actually feed the growth of many underwater grasses.

“Rising CO2 levels in the bay waters that we might see over the next 50 to 100 years look like they should be able to offset the negative effects of temperature and allow sea grasses to survive even perhaps better than they are now," Zimmerman said.

I visited an underwater grass bed in the Honga River on Maryland's Eastern Shore with Lee Karrh, a biologist with the Maryland Department of Natural Resources.

He showed me a healthy bed of widgeon grass, and suggested that this species could actually grow faster and become more hardy with the increased carbon dioxide levels causing global warming.

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