Eelgrass absorbs and stores carbon and provides habitat for baby fish and lobsters.

A new state law will establish a system to map eelgrass and salt marsh vegetation —aquatic plants important to the economy and environment as both “carbon sinks” and fish nurseries.

State Rep. Joyce “Jay” McCreight, D-Harpswell, introduced L.D. 593, “An Act To Restore Regular Eelgrass Mapping in the State,” and shepherded the bill through the Legislature. The law takes effect in October, although work will not start until funding kicks in next year.

“Both resources provide critical benefits for our coastal ecosystem,” McCreight said in her testimony to the Legislature’s Committee on Environment and Natural Resources. “They have been described as carbon ‘sinks’ — powerhouses of carbon absorption and storage that hold carbon that would otherwise be released into the atmosphere, helping to mitigate greenhouse gas emissions.”

“They provide critical habitat for young aquatic creatures, foraging areas and shelter for young fish and invertebrates, food for migratory waterfowl and spawning surfaces for many aquatic species. … They also provide a buffer that helps mitigate shoreline erosion, and protect water quality by filtering polluted runoff and removing excess nutrients.”

The Friends of Casco Bay and The Nature Conservancy were among several supporters of the bill to testify at a public hearing in March.

Eelgrass and salt marsh vegetation “have a higher capacity to store carbon than our forests, although they are not as abundant,” said Ivy L. Firgnoca, Casco Baykeeper with the Friends of Casco Bay.

“By storing carbon in the nearshore environment, eelgrass beds also buffer against ocean acidification, which is detrimental to Maine’s valuable shellfish,” Firgnoca said.

The effects of development can harm eelgrass, as can the invasive European green crab. Better known as a clam predator, the abundant crabs also consume eelgrass.

Rob Wood, director of government relations and climate policy for The Nature Conservancy in Maine, described eelgrass and salt marsh as “keystone habitats” that “form the foundation of the food web along Maine’s coast.”

“Many sea-run fish that the state and The Nature Conservancy are working to protect use eelgrass beds to aid their transition between fresh and salt water,” Wood said.

Eelgrass, or Zostera marina, primarily grows “in shallow, protected intertidal and subtidal locations,” the bill says.

Bailey Island resident Mary Ann Nahf was one of multiple local advocates to testify. Nahf chairs Harpswell’s conservation commission and its climate resilience implementation task force.

“The townspeople recognize the importance of healthy eelgrass beds and coastal marshes,” Nahf said. “(They value) the habitat they provide, how they act as nurseries for baby lobsters and various shellfish species and are an indicator of clean water.”

Nahf gave the example of Long Marsh, a salt marsh that stretches for a mile at the head of Doughty Cove and serves as “a significant carbon sink” for Harpswell.

Marine biologist Phil Colarusso has studied eelgrass for more than 30 years.

“Maine, due to its extensive coastline, protected inlets and cold water, possesses the greatest acreage of eelgrass in New England, but its effort to map this important resource lags behind all of its neighbors,” Colarusso said in testimony to the committee.

New Hampshire maps its eelgrass every other year, Massachusetts in cycles of three to five years, Connecticut and Rhode Island every six to seven years, according to Colarusso.

Maine, meanwhile, has mapped its entire coast only twice: once from 1992-1997 and once from 2001-2010, according to the Friends of Casco Bay. The state used oil spill response funds for those efforts. Only Casco Bay has been mapped since, in 2013 and 2018.

“Without funding for mapping, Maine is missing critical information it needs to protect its valuable coastal and marine resources,” said Firgnoca, the Casco Baykeeper. “Without mapping, Maine cannot achieve goals set forth in its climate action plan and be resilient to climate change.”

For McCreight, it was her second attempt to pass the bill. She introduced similar legislation during her previous term and saw unanimous support from the committee, only to see the bill die when the coronavirus pandemic sidelined the Legislature.

This year, the committee’s eight Democrats and five Republicans again endorsed the bill unanimously. The House of Representatives and Senate passed it without opposition, and Gov. Janet Mills signed it July 8.

The bill will map the plants along the Maine coast in a five-year cycle. The work will start in the area between Phippsburg and St. George. Scientists with the Maine Department of Environmental Protection will work their way Down East over the next three years before they map Southern Maine, from Eliot to Phippsburg, last. Mapping for this section of coast, which includes Harpswell, must be complete by Nov. 1, 2027.

The bill aligns with the Maine Climate Council’s 2020 report titled “Maine Won’t Wait: A Four-year Plan for Climate Action.”

“Maine’s forests, saltmarshes, and coastal eelgrasses provide many economic benefits and ecosystem services, but their ability to absorb and store large amounts of carbon at low cost is reason alone to conserve these areas,” the plan states.

McCreight’s bill will enable that conservation, according to testimony by the DEP.

“Knowledge of the location of these critical habitats and their health over time will inform actions to conserve and restore these important resources,” said Brian Kavanah, director of the DEP’s Bureau of Water Quality.

The bill will create two full-time positions in state government, for a biologist and an environmental technician. With wages and aerial photography among its primary expenses, the bill will cost $285,014 in its first year, fiscal year 2022-23.

While the DEP did not take a position on the bill, Kavanah called the value of eelgrass and salt marsh habitat to the economy and environment “undeniable.”

In addition to conservation and restoration, McCreight expects the state to reference the maps when it reviews applications for aquaculture leases and responds to oil spills. The DEP will also post the maps online for public use.

A grant from the Broad Reach Fund supports the Harpswell Anchor’s reporting on climate change.