Scientists interpret this map of Tiana Beach in West Shinnecock on Long Island, NY as showing areas of dissolved oxygen-rich waters moving across meadows of sea grass. Credit: Bradley Peterson

— By Chris Gonzales, Freelance Science Writer, New York Sea Grant

Stony Brook, NY, August 21, 2023 - Sea grass meadows worldwide cover just 0.1 percent of the world’s ocean floor, yet they sequester 20% of the atmospheric carbon dioxide. This fact has generated much interest among ecologists, given the current carbon-linked climate crisis.¹

Scientists know that the significant reductions in carbon dioxide will improve water quality, increase available oxygen, and, for instance, create beneficial habitats for shellfish such as clams and scallops to survive. Furthermore, these shellfish themselves are valuable ecosystem members, filtering the water to make it clearer.

Stony Brook University (SBU) researchers working on a New York Sea Grant (NYSG)-funded project funded would like to see continued efforts and study to improve water quality across the South Shore Estuaries of Long Island and the Peconics. Sea grass meadows could be part of that solution. 

Scientists believe sea grass meadows could serve as sanctuaries for living things in an acidic ocean.

“Many people know that all plants need sunlight to photosynthesize, but do you know that they also need carbon?” asked Bradley Peterson, head of the Marine Community Ecology Lab at SBU’s School of Marine and Atmospheric Sciences (SoMAS) and the principal investigator on the project. “Eelgrass absorbs carbon dissolved in seawater when they photosynthesize. This means that the carbon dioxide in the water within the eelgrass canopy is less than in the surrounding water. Some of this modified water leaks out of the seagrass meadow to the surrounding areas.”

“With our award from New York Sea Grant, we measured this flow and observed what impact it had on those shellfish, like bay scallops, that recruit [reproduce] inside seagrass meadows.”

“In both the lab and the field, eelgrass significantly drew down the carbon dioxide, dramatically impacting the shellfish larvae that were associated with eelgrass. They grew more and survived longer. Eelgrass acts like a little ‘oasis’ for shellfish from ocean acidification.”

“That may be really, really important for the shellfish in our local waters,” he emphasized.


Aerial photographic analysis of Shinnecock Road (in the Hamptons, Long Island, NY) found that areas of sea grass meadows correspond to areas of high pH (low acidity)—a good thing. Credit: Bradley Peterson

Creating Clearer Waters

Typically, without any intervention, pH would oscillate dynamically over time. But with the presence of sea grass, the acidic pH could be offset, gradually reducing the acidity of the waters.

Scientists have found that with increasing biomass of sea grass, pH declines, thus becoming less acidic.

Partners for the Peterson Lab were Cornell Cooperative Extension, the National Park Service, the Nature Conservancy, and the Department of Environmental Conservation.


In these laboratory tanks and pipes, shoots of sea grass counteract the effects of carbon-induced acidic seawater. Credit: Bradley Peterson

Studying Sea Grass (Zostera marina)

The type of sea grass being studied was Zostera marina, a plant native to the coasts throughout the Northern Hemisphere.

In repeated experiments, scientists found highly significant drawdowns of carbon dioxide over a 12-hour period.

They raised clams (both larvae and juveniles) to assess how well they grew in the conditioned waters. When they reviewed their data, they found these clams were healthier.


A SBU-led team is assessing the ability of seagrass to draw down carbon dioxide from the aquatic environment. This could reduce the effects of ocean acidification, which would be a benefit to shellfish. Credit: Kaitlyn O’Toole

More Info: Spotlight on Ocean Acidification

As humans have released carbon dioxide into the atmosphere over the past century, it has led to the oceans absorbing about a third of this excess carbon dioxide, and the problem known as ocean acidification (OA). This excess carbon in the ocean’s waters leads to heightened levels of acidity, harming marine life. OA is particularly a problem for shellfish such as oysters, clams, and mussels. Their shells become brittle and easily broken. In addition, the shellfish have a harder time reproducing.

References

¹ Climate Change Science: Basics of Climate Change. U.S. Environmental Protection Agency.


More Info: New York Sea Grant

New York Sea Grant (NYSG), a cooperative program of Cornell University and the State University of New York (SUNY), is one of 34 university-based programs under the National Oceanic and Atmospheric Administration’s National Sea Grant College Program.

Since 1971, NYSG has represented a statewide network of integrated research, education and extension services promoting coastal community economic vitality, environmental sustainability and citizen awareness and understanding about the State’s marine and Great Lakes resources.

Through NYSG’s efforts, the combined talents of university scientists and extension specialists help develop and transfer science-based information to many coastal user groups—businesses and industries, federal, state and local government decision-makers and agency managers, educators, the media and the interested public.

The program maintains Great Lakes offices at Cornell University, SUNY Buffalo, SUNY Oswego and the Wayne County Cooperative Extension office in Newark. In the State's marine waters, NYSG has offices at Stony Brook University and with Cornell Cooperative Extension of Nassau County on Long Island, Brooklyn College and Cornell Cooperative Extension in NYC and Kingston in the Hudson Valley.

For updates on Sea Grant activities: www.nyseagrant.org has RSS, Facebook, Twitter, Instagram, and YouTube links. NYSG offers a free e-list sign up via www.nyseagrant.org/nycoastlines for its flagship publication, NY Coastlines/Currents, which is published quarterly.