NARRAGANSETT, R.I. — Oysters and coconuts seldom go together as a meal, but they are an excellent combination for helping the environment.

Coconuts, in this case, aren’t the kind you eat. Instead, they are large coconut-fiber logs that provide a foundation for a barrier to stop erosion. 

The oysters are simply the shells collected from local seafood restaurants and stuffed in bags. Together, they are the building blocks for low-priced, low-impact barriers that protect eroding marshes.

Rhode Island has plenty of deteriorating marshes, and these organic buffers might just help reverse the damage. The Ocean State has lost some 53 percent of its marshes in the past 200 years, and sea-level rise is accelerating that decay. Yet, there are few options for slowing an eroding marsh. Without room to migrate inland or upward, they simply dwindle over time.

Like many of the state’s coastal regions and waterways, the picturesque Narrow River is threatened by a combination of rising water and human activity. In recent years, motorboat wakes and extreme weather events such as Hurricane Sandy have destroyed 15 percent of the watershed’s marshland, according to officials.

To slow this trend, conservationists are testing this “living-shoreline” barrier to help restore vital wetlands. The project, run by The Nature Conservancy in partnership with the Department of Environmental Management and the U.S. Fish and Wildlife Service, builds and manages these natural barriers along the edge of the marsh. The low wall impedes waves and encourages sediment buildup, while the oyster shells and biodegradable fiber logs attract sea life such as shrimp and fish.

The first row of the experimental barrier was installed in April in three 100-foot sections below the Middlebridge area of the river. A second round was added Aug. 21. It’s too soon to tell if the living shoreline is regrowing the marsh, but the approach has helped eroding tidal regions in Delaware, New Jersey and the Chesapeake Bay in Maryland.

These coconut-fiber barriers, or coir logs, aren’t new. They are a state-approved material for erosion control. Larger logs, called burritos, contain sand and serve as an alternative to traditional seawalls made of stone, wood and/or steel. They are a preferred line of defense to hardened structures such as bulkheads and stone riprap, which typically exacerbate erosion in adjoining areas. Currently, 30 percent of Rhode Island’s shoreline is armored with such artificial barriers.

Oyster bags are also more common in restoration efforts. Some 150 tons of the recycled shells are now submerged in coastal waters through a shell collection and marine restoration program run by The Nature Conservancy. Oysters Gone Wild works with local seafood restaurants, such as the Matunuck Oyster Bar and the Newport Restaurant Group, to keep the shells out of the Central Landfill. Most of these collected shells are now providing a foundation, or reef, for new oyster beds at Ninigret and Quonochontaug saltwater ponds in Charlestown and Westerly.

If the project succeeds at the Narrow River site, oysters and other shellfish may rebound and additional barriers will be built along the 6.3-mile wetland.

“The hope is marsh grows out of it,” said John Torgan, director of ocean and coastal conservation for The Nature Conservancy. “We do this to learn and get better at it.”

Funds for the project are channeled through the state Coastal Resources Management Council (CRMC) as part of federal Sandy relief aid. Considering the modets investment — $37,000 from federal aid and $19,000 from The Nature Conservancy — the project is seen as a low-risk investment.

In an area popular with nature lovers and boaters, the projects also is an importamt part of the town’s vibrant tourism industry. “We are working to sustain nature and nature sustains us,” Torgan said.