A Closer Look at Sea Level Rise at Cape Romain National Wildlife Refuge
|An ominous sign of past events at Cape Romain. This post once marked an island fully above water. The sign uselessly warns, "No pets allowed." Photo: USFWS.|
Cape Romain National Wildlife Refuge near Charleston, South Carolina, is a living exhibit for anyone seeking to understand the impacts of rising sea levels in a changing climate.
Begin at Boneyard Beach on Bulls Island. Here, on the refuge’s largest barrier island, the sea is slowly consuming a forest. Waves break around dead oak, cedar and pine trees, their barren, outstretched limbs bleached by the sun.
“Tourists love to come here because it’s so beautiful, but really it’s the loss of a maritime forest,” said Raye Nilius, the U.S. Fish and Wildlife Service’s project leader for the South Carolina Lowcountry Refuges Complex. “Boneyard Beach is a record of what happens to the forest when sea levels rise and shoreline erodes away. For scientists and land managers seeking answers, the best approach may be to study these transitions from one type of habitat to another.”
The three-mile-long beach is losing ground at the rate of 25 to 30 feet a year. Behind it, the sea is slowly laying claim to its next targets: treetops on the forest edge are scarred from salt spray as the ocean moves in.
Farther back from the beach sits a 600-acre, freshwater impoundment built in 1927 that has become important coastal habitat for endangered wood storks and other wading birds, shorebirds and waterfowl. Part of the levee is just one or two big storms away from giving in to the sea. Waves have sliced away at a section built in 1988, leaving a four-foot cliff where a road used to be.
Once the sea begins creeping into Jack’s Creek, the freshwater pond will transform to saltwater marsh. That will mean the loss of habitat diversity, the biological equivalent of big-box stores pushing out the mom-and-pop shops on Main Street. Ducks and geese that now find food on the island will have to look elsewhere.
Across Bull Bay, there’s another sign of a rising sea, literally. A brown USFWS sign tells visitors to keep dogs off the refuge, but it’s sitting atop a wooden post in the water. Until last year, the sign had topped a small island called Sandy Point at the mouth of Five Fathom Creek, perfect nesting grounds for American oystercatchers, Wilson’s Plovers and terns. Just ten years ago, the island was about a mile long. Today it’s open water.
The final feature in the living exhibit is on Cape Island, the northernmost barrier island on the refuge and one of the most important loggerhead sea turtle nesting areas on the Atlantic Coast. From 1999 to 2006, the beach receded 180 feet. Many of the loggerheads began nesting in areas that expose eggs to high tides and groundwater intrusion, resulting in mass mortality. Because of these and other threats to the population, the Service is considering a proposal to up-list the loggerhead from threatened to endangered under the Endangered Species Act.
In recent years, with help from sea turtle experts at the South Carolina Department of Natural Resources and the South Carolina Aquarium, along with dozens of volunteers, the refuge’s Turtle Recovery Team has been relocating an ever increasing number nests. The nests are dug up and moved to safe areas, away from wash-over areas and high enough to prevent groundwater intrusion. Hatchling success has dramatically improved, from 25 percent to 78 percent.
But as the coastal refuge slowly erodes, Nilius is thinking about the future. Ninety-five percent of Cape Romain is less than 5 feet above sea level. The refuge’s habitat is expected to transition from island and salt marsh habitat to an increasing amount of open water and rapidly advancing tidal creeks throughout the marsh. As the refuge’s islands erode, suitable nesting beaches for sea turtles, shorebirds, and seabirds will become rare. Freshwater wetlands that nourish migratory waterfowl will be lost, making those that remain even more valuable. As sea level rises, the marsh may recede inland, where urban development continues to accelerate.
“The ocean encroaches on one side, human population increases on the other and the islands are caught in the middle” Nilius said.
Nilius questions whether in 50 years, Cape Romain will provide the habitat that species depend upon today. The refuge’s future existence may depend on conserving land on the mainland now, before spreading urban development takes away that option.
Time is running out.
- by Stacy Shelton