Good News for Chesapeake Bay Seagrass Facing Climate Change?

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Good News for Chesapeake Bay Seagrass Facing Climate Change?

This summer, Virginia Sea Grant-funded researchers reported a surprising finding about climate change and seagrass in Chesapeake Bay.

Seagrass meadow. ©Heather Dine/NOAA

Seagrass meadow. ©Heather Dine/NOAA

By Janet Krenn and Katharine Sucher, Staff Writers

This summer, Virginia Sea Grant-funded researchers reported a surprising finding about the effect of climate change on seagrass. According to the study, the increase of carbon dioxide we’re expecting from climate change may help seagrass to survive despite rising temperature.

For those involved in efforts to restore seagrass in Chesapeake Bay, this new finding may come as a surprise—seagrasses are notoriously intolerant of heat. But combine those warm waters with increased CO2 and seagrass growth might actually be enhanced.

Dick Zimmerman, Old Dominion University (ODU) researcher and co-author of the report, explains that this relates to the fact that seagrass are photosynthetic. Having more carbon dioxide available means it’s easier for the plants to gather CO2 for photosynthesis and produce more sugar for every particle of light absorbed.

“Ultimately, plants are doing more photosynthesis because they’re more efficient,” Zimmerman says. “They’re placing less effort into light harvesting and more into growth and reproduction.”

Zimmerman and his research colleagues Victoria Hill (ODU) and Charles Gallegos of the Smithsonian Environmental Research Center made the discovery while developing a new model to predict seagrass growth. Models like this could help improve restoration of seagrass, which provides habitat for important species like blue crab and bay scallops but have been slow to recover since disease decimated population in the 1930s.

“Carbon dioxide, light, and temperature all interact in complex ways. Their impacts on eelgrass can be hard to interpret in a natural environment where everything is constantly varying unless you have a predictive model,” Zimmerman says. Eelgrass is the type of seagrass found in Chesapeake Bay.

For their model, Zimmerman, Hill and Gallegos used water quality data that are readily available, thanks to long-term data gathering efforts throughout the Chesapeake Bay. The team found that combining seagrass and water quality models could accurately predict light conditions, which in turn accurately predicted seagrass distribution. Because water quality data are available, the model, called GrassLight Version 2.11, can also be applied to many estuaries where there is concern about the survival of seagrass.

Since the model’s completion, its versatility has been acknowledged by the environmental managers. In 2014, it was one of five accepted into  Chesapeake Bay Program’s modeling efforts. The process of transferring the model to the program began in 2014 and will take approximately two years.

It was in developing and testing this model that the research team learned that seagrass might have a shot at surviving the combined effects of climate change.

“This is really cool science,” Zimmerman says. “This is breaking new ground on acclimation patterns.”

Abstract for the paper “Predicting Efforts of Ocean Warming, Acidification, and Water Quality on Chesapeake Region Eelgrass” can be found at the Limnology and Oceanography website: