SAN DIEGO — A new study reveals a type of grass growing in San Diego Bay is a carbon-eating powerhouse in the fight against climate change.

Eileen Maher, director of environmental conservation for the Port of San Diego, was part of the team to release a study on carbon storage in eelgrass beds. Eelgrass is a type of marine plant that spends its entire life growing submerged in seawater.

What You Need To Know

  • The Port of San Diego is studying carbon storage in eelgrass beds

  • San Diego Bay has nearly 2,600 acres of eelgrass, which amounts to 50% of all the eelgrass in Southern California

  • The bay’s eelgrass beds currently contain 170,000 metric tons of carbon dioxide, which is equivalent to the same amount of CO2 emitted by more than 37,000 cars annually

  • If left undisturbed, carbon can remain trapped in eelgrass sediments for thousands of years

The study found that San Diego Bay’s eelgrass beds currently contain 170,000 metric tons of carbon dioxide, which is equivalent to the same amount of CO2 emitted by more than 37,000 cars annually. ,

Presently, San Diego Bay has nearly 2,600 acres of eelgrass, which amounts to 50% of all the eelgrass in Southern California and about 17% of eelgrass in the state. As much as 73% of the bay’s carbon is stored in the sediments of the South Bay.

“On land, forests help absorb carbon from the atmosphere,” Maher said. “But we’re finding that in the water, eelgrass is absorbing up to 10 times more carbon.”

The study was funded through the U.S. Maritime Administration’s Maritime Environmental and Technical Assistance Program, which supports and promotes emerging technologies to improve environmental sustainability in the maritime industry.

Over the next year, the port will continue studying the relationship between eelgrass and carbon storage. Through the META program, MARAD has committed $175,000 to a second year of research. A third partner, the U.S. Navy, has joined the effort, allowing the team to study carbon sequestration and storage in the Navy’s eelgrass restoration areas.

Jessica Curran, marine biologist for U.S. Navy, is proud to be part of the collaboration.  

“My job is finding a balance between ensuring that the Navy meets their mission requirements while being good caretakers of the environment,” Curran said.

Curran noted eelgrass has the unique ability to rapidly capture and store large amounts of carbon. Because eelgrass is submerged in water, it prevents the release of CO2 and can remain trapped in eelgrass sediments for thousands of years if left undisturbed. Eelgrass habitats cover a small fraction of the area as forests do on land, yet they can store carbon 30-50 times faster than terrestrial forests.

Maher believes creating or restoring eelgrass habitat could lead to more carbon storage, which could potentially support the port’s greenhouse gas emissions reduction efforts.

“Being able to restore eel grass beds, create new beds, create more saltmarshes, create more habitat for the fish and the birds, that’s what drives me,” Maher said. “That’s what gives me inspiration.”

In addition to storing carbon, eelgrass also helps improve water quality, provides protection from waves that erode shorelines, and is a vital habitat and food source for many animals in and around the bay, including endangered green sea turtles.