Animal Conservation

Kelp Mitigate Ocean Acidification, Key to Health and Abundance of Important Shellfish |

Mike Doall and oyster farmer Paul McCormick with kelp grown on the Great Gun Oyster Farm. Photo courtesy of Professor Christopher Gobler

Stony Brook-led study, published in Frontiers in Marine Science, reveals results that combat climate change and apply to new oyster farming methods

STONY BROOK, NY, May 25, 2022 – While kelp is known as a nutritious food for sea creatures and humans, harvesting kelp may be a new way to help keep bivalves such as clams and oysters – a more common food source and a staple of the marine industry – healthy and more plentiful. A new study led by Christopher Gobler, PhD, and a team of scientists from the Stony Brook University School of Marine and Atmospheric Sciences (SoMAS) shows that the presence of kelp significantly reduces ocean acidification, a result of climate change.

Published in Frontiers in Marine Science, the study also demonstrated that deploying kelp on an oyster farm reverses ocean acidification and therefore protects bivalves from acidification. The process may also have additional ecosystem and aquaculture benefits, including carbon and nitrogen sequestration and extraction, and protection against harmful algal blooms.

For shellfish, one of the most serious threats from climate change is ocean acidification. Levels of carbon dioxide or CO2 in the Earth’s atmosphere continue to rise, seeping into the oceans where they cause chemical reactions that lower pH and cause ocean acidification. Over the past two decades, one of the strongest findings from ocean climate change research has been that rising CO2 levels in surface waters threaten shellfish that rely on higher pH waters. to grow and survive. This threat is particularly acute in coastal areas where additional sources of acidity can further reduce pH and slow shell formation in shellfish, especially bivalves. And while many wild bivalve populations have crashed, a booming wave of aquaculture in the United States and around the world has grown global seafood production through aquaculture and now surpasses wild capture.

pH scale measurements with and without kelp. The graph shows continuous pH bubbling (NBS scale) and the addition of 4 x 104 mL-1 cells of Isochrysis galbana added daily to simulate daily bivalve feeding. Image courtesy of Professor Christopher Gobler

“Despite this wave of aquaculture, increasing ocean acidification now threatens bivalve aquaculture and required a solution,” says Professor Gobler, Endowed Chair of Coastal Ecology and Conservation at SoMAS . “We believe our work is the basis for a solution.”

In the study, titled “Seaweed (Saccharina latissima) attenuates coastal ocean acidification and increases growth of North Atlantic bivalves in laboratory experiments and on an oyster farm,” Professor Gobler and colleagues conducted six experiments to assess the effects of elevated CO2 and the presence of kelp (S. latissima) on the growth rates of three different species of bivalves: (Oriental oysters (Crassostrea virginica), blue mussels (Mytilus edulis ), and clams/northern quahogs (Mercenaria mercenaria).

In each of the experiments, acidification was significantly reduced with kelp culture. They continued the research with the ultimate test – a field experiment at the Great Gun Oyster Farm in Moriches Bay, New York.

They found that during a month-long deployment, oysters surrounded by kelp benefited from higher pH water and grew significantly faster than individual shellfish located further away where the water pH was lower. significantly lower.

Professor Gobler and his colleagues point out that these findings have powerful implications for oyster farming in coastal areas.

“We have been witnessing coastal ocean acidification for years and have documented its ability to slow the growth of, and even kill, shellfish. We started growing kelp on oyster farms to just expand aquaculture to After seeing its ability to rapidly absorb CO2 and improve low pH conditions, we knew it had the potential to benefit shellfish undergoing acidification. was exciting, being able to improve oyster growth on an oyster farm undergoing coastal acidification proves that this approach can have very wide applications,” says Professor Gobler.

Overall, the research clearly shows, according to the authors, that “kelp farming provides an environmentally friendly way to protect shellfish from current and future ocean acidification and other coastal stressors.” .

Building on work, helping oyster farms

“We’ve helped grow kelp at 10 oyster farms in New York City since 2018 and more aquaculturists are hoping to incorporate kelp into their farms,” ​​says Mike Doall, Associate Director of Shellfish Restoration and Aquaculture at Stony Brook University. “In addition to providing crop diversification and additional revenue streams, kelp’s ability to combat ocean acidification gives these oyster farmers all the more reason to add kelp as a second crop.”

The recent study builds on other research from the same SoMAS group, which published a study in Harmful Algae in 2021. This study demonstrated that kelp has the ability to deter the intensity of harmful algal blooms , another environmental threat to shellfish farming.

Such scenarios with kelp seem to create a win-win scenario for oyster farmers like Paul McCormick, owner of the Great Gun oyster farm where the current study was carried out.

“The kelp seems like the perfect complement to the oysters on my farm,” says McCormick. “It grows in the winter and spring, when the oysters need less attention, and there’s a lot of restaurant interest in the kelp. If it provides protection for my oysters against poor water quality, well that’s another good reason to add it to my farm.

Photo captions:

Mike Doall and oyster farmer Paul McCormick with kelp grown on the Great Gun Oyster Farm. Photo courtesy of Chris Gobler

pH scale measurements with and without kelp. The graph shows continuous pH bubbling (NBS scale) and the addition of 4 x 104 mL-1 cells of Isochrysis galbana added daily to simulate daily bivalve feeding. Image provided by Chris Gobler

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