'Coastal strongholds' against rising seas

Salt marsh along Long Island Sound in Connecticut.

From ecoRI News (ecori.org)

A new study conducted by The Nature Conservancy helps identify “coastal strongholds” — areas that because of their unique topographies, elevations and landforms give threatened habitats in Rhode Island a chance to escape rising sea levels and continue to provide vital services to people and wildlife.

The 280-page study also offers land managers and agencies a tool to gather comprehensive data, such as water quality, important wildlife areas, sediment and soil nitrogen levels, that can be used to develop targeted conservation plans that will have the greatest chance of protecting coasts and communities against sea-level rise.

Among the strongholds identified in the Ocean State are Prudence Island and the salt marshes along the Palmer River between Barrington and Warren based on the undeveloped lands that surround them. The report notes that even these areas are threatened.

With sea levels projected to rise as much as six feet by the next century, many coastal habitats — tidal marshes, sandy beaches, and seagrass beds — could disappear under rising waters.

But scientists say these “strongholds” provide escape routes that allow threatened habitats to migrate inland and survive sea-level rise. The authors of the study, however, warn that manmade development and pollution could cut off these escape routes and lead to habitats being drowned out of existence.

“This study illustrates the vulnerability of coastal wetlands and the need to conserve and restore them,” said John Torgan, state director of The Nature Conservancy in Rhode Island. “It also demonstrates the need to continue to implement nature-based solutions at all Rhode Island marshes that are highly vulnerable to sea-level rise because they don’t have room to migrate inland.”

During the past 18 months, the Conservancy and the U.S. Fish & Wildlife Service have raised the elevation of 40 acres of marsh at the John H. Chafee and Sachuest Point National Wildlife refuges. In July, the Conservancy received a $1 million Coastal Resilience grant from the National Oceanic and Atmospheric Administration to increase the use of nature-based infrastructure for flood protection in New England. The Conservancy plans to hire a regional coastal-resilience specialist and implement a large-scale restoration project in each of the five coastal New England states.

The coastal strongholds research is supported by federal funding for Hurricane Sandy recovery, in response to a need identified by a coalition of states, federal agencies and other conservation organizations for information to help land managers and communities make strategic decisions to help coastal systems and communities adapt to changing conditions.

Healthy coastal habitats, such as sand dunes and tidal marshes, can shield communities from storm surges while also providing feeding and nursing grounds for wildlife. Sandy beaches serve as breeding grounds for rare species while supporting local tourism economies. Salt marshes rival forests in carbon storage and provide habitat for one of the East Coast’s rarest birds: the saltmarsh sparrow.

The Atlantic Coast Joint Venture — a partnership of federal, regional, state and local agencies and organizations — is already planning to use the tool to identify priority habitat for the saltmarsh sparrow and two other species, black rail and American black duck, that depend on salt-marsh habitat by looking for parcels in migration corridors that may be eligible for funding through Natural Resources Conservation Service programs to support conservation on working lands.

“If these important habitats disappear, it will have severe impacts on our economy, our environment and the health of our communities,” Torgan said. “Sea-level rise is happening now. We must take conservation action now to ensure these coastal habitats that provide so many services to both people and nature don’t disappear forever.”

The study analyzed landforms, elevations, nitrogen and sediment inputs, manmade development and other characteristics of 11,000 coastal sites from Maine to Virginia. Areas with open spaces, low-lying landscapes, good freshwater flow, low nitrogen, and diverse shorelines with many inlets provided habitats the greatest chance to migrate and take root inland. Conversely, areas with steep cliffs or high elevations will block migration, and too much nitrogen can disrupt root development. Manmade structures such as seawalls or buildings can also cut off escape routes.

The study was funded by the U.S. Fish & Wildlife Service.

The Palmer River (oil), by Edward Mitchell Bannister (1828-1901).