BAR HARBOR, Maine -- Jane Disney steered her kayak along an edge of Frenchman Bay a mile or so north of here. "Look, there's a great blue heron," she said, gesturing toward the shoreline, where the elegant bird perched on a rock.

It was a postcard scene in a setting that is increasingly feeling man's imprint, especially underwater. For generations, Mainers have scoured the depths of this bay for pleasure and profit. Abundant populations of fish have long since disappeared due to overfishing. But the bay continues to supply ample mussels, clams and lobsters.

Commercial fishing continues to help drive this area's economy, but it has also left parts of the aquatic ecosystem that supports healthy sea life and stores carbon dioxide either battered or gone.

Disney, a scientist at the Mount Desert Island Biological Laboratory, estimates that around 80 percent of Frenchman Bay's underwater eelgrass has disappeared since 1996, primarily from activities such as raking for clams or mussels. In some areas, the sea grass, which used to cover the muddy or sandy subtidal areas near shore, is missing.

Individual rakes, she said, do little damage. But the collective devastation of thousands of fishing expeditions over the years has taken a heavy toll.

Eelgrass (Zostera marina) does a number of valuable things. It pulls nitrogen and phosphorus from the water, helping to counteract the damage caused by fertilizer-infused soil runoff that can spawn deadly algae blooms.

Eelgrass also provides a habitat for all sorts of marine animals -- not least of which are lobsters and mussels. And the structure of the grass helps stabilize sediment on the bay floor, keeping the water clear and creating a nursery for eggs and juvenile animals to thrive.

Volunteers replant eelgrass

But eelgrass and other coastal and subsea ecosystems like sea grass, salt flats and mangroves also have vast potential as a tool to help mitigate the impacts of global warming. Just like forests and other terrestrial biomass, the undersea plants store carbon dioxide, which is why they're sometimes called "blue carbon sinks."

Conversely, the destruction of marine ecosystems emits carbon dioxide, exacerbating global warming (ClimateWire, Sept. 7).

The U.N. Environment Programme (UNEP) estimates that 93 percent of the Earth's carbon dioxide passes through the oceans. Ocean grasses, the agency says, account for 50 to 71 percent of the carbon storage capacity of ocean sediments, which is equal to half the emissions from the entire global transportation sector.

UNEP says halting the destruction and degradation of blue carbon sinks would equal at least 10 percent of the reductions needed to keep atmospheric concentrations of carbon dioxide below 450 parts per million.

Standing in bright yellow boots on the shore of Hadley Point in Frenchman Bay, Disney said 140 acres of deteriorated or destroyed eelgrass habitat is targeted for restoration.

Below the water's surface, Disney and groups of volunteers have placed flat metal grids, about 2 feet square, on the bay surface. About a thousand eelgrass plants per year are introduced into the subtidal zone through this method. The most recent grids that Disney and the volunteers have submerged into the cold late-summer water are made of wood and biodegrade, making labor less intensive.

A decade of decline

"Some said that restoration would cost $250,000 per acre," she said, "We've spent, maybe, tens of thousands."

The historical dynamics of the eelgrass habitat in Frenchman Bay are difficult to pin down because not until 1996 was any thorough mapping conducted. Anecdotal information from people living in the area suggests the grasses were abundant until 1996, the same year the first survey of eelgrass was conducted. Between 1996 and 2008, though, 70 percent of the eelgrass habitat disappeared.

At Hadley Point, Disney said, eelgrass coverage might reach 80 percent of what it was in 1996 by 2022.

The decline in eelgrass is the result, she said, of a cultural tradition in the area of seeking economic gain -- from fishing, cruise ships or building around the bay -- without considering the long-term consequences. She said the net result risks tipping the bay into widespread ecosystem collapse.

Eelgrass habitats are in decline all along the Atlantic Coast, according to Disney. The grass is almost completely gone from the Chesapeake Bay, and along with it, most of the wild oysters that were once iconic to Maryland but are now farmed rather than fished.

Disney fears that, if the trend is left unchecked, Maine might reach a similar point and its watermen could be relegated to posing for tourists at cruise terminals rather than continuing to prosper in a commercially viable and sustainable business.

Because many of the same species that are affected by eelgrass degradation are also of commercial interest, Disney said many fishermen support efforts to restore habitats. Chief among those supporters are the lobster fishermen, whose buoys marking the location of their pots are scattered across the bay. More difficult to convince have been the clam and mussel fishermen whose methods have degraded the eelgrass.

Getting fishermen to 'take ownership'

Disney's past career as a public schoolteacher has aided her. By her estimate, she taught 900 children, many of whom are now fishermen or have the ear of a mother or father in the industry.

Jerilyn Bowers, a development and public relations director at Disney's laboratory, said, "It's not uncommon in these traditional fishing communities for there to be 12-, 15-, 16-year-old boys who have their own boats, their own industries essentially, and they are generating a significant amount of revenue. So it's really critical to get them to take ownership of this bay at a very young age."

Bowers is a seventh-generation Mainer on both sides of her family.

It's the type of day-to-day, down-in-the-trenches effort, Disney said, that's required to change people's thinking about conservation and building sustainable commercial practices. It's wives talking to husbands and children speaking to parents, she said.

The need to address the eelgrass problem becomes only more urgent with the quickening pace of global warming, Disney said.

"People are beginning to understand that these vegetative marine habitats are playing a major role in mitigating the impacts of climate change and that we really need to restore them where we can and protect them," she said.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500