Protecting our Paradise

The South's exquisite barrier islands give us places to play, shelter from storms, and incredibly diverse wildlife. Now they need our help.

Strings of pearls, rings of diamonds, and chains of gold. All command fortunes, yet all pale in value when compared with the South's offshore bounty of barrier islands.

From Assateague Island in Maryland to Padre Island in Texas, our region owns the lion's share of America's barrier system, by far the most extensive on Earth. It is a world of breathtaking beauty, amazing violence, pristine wilderness, and misguided exploitation. It cannot be confined, for it dies in captivity. Only by understanding its whims and meeting its needs can we ensure its survival.

How Barrier Islands Form

Most barrier islands are geologic babies, less than 5,000 years old. Ours generally fall into one of three categories. The first, coastal plain islands, resulted from sea levels that have risen hundreds of feet since the last ice age, flooding river valleys and eroding what were once the ridges in between the valleys. Sand has eroded from these ridges and formed spits of beach growing laterally across the mouths of estuaries and sounds. When storms cut inlets through the spits, barrier islands ensued. North Carolina's Outer Banks are the classic example.

Cumberland Island in Georgia exemplifies the second kind. Called a composite barrier island, it combines a modern island with one that formed more than 100,000 years ago.

Delta islands are the third kind. They form as waves slice apart river deltas, dispersing silt and leaving behind the heavier sand. Grand Isle in Louisiana typifies this.

Why We Need Them

Anyone gazing anxiously at a satellite view of a monstrous hurricane churning toward the coast instinctively knows the value of barrier islands. Like nature's punching bags, they absorb the first big blows of waves and wind, lessening the damage behind them.

The second benefit isn't as obvious, but it's just as vital. In the shallow water between island and mainland, lagoons form, stabilized by salt marshes and mangrove swamps. Marshes and mangroves serve as incubators for a vast array of wildlife, especially birds, fish, crustaceans, and reptiles.

"Eighty percent of the commercial catch off the Southeast coast is linked to salt marshes," states Fred Whitehead, naturalist for the Greyfield Inn on Cumberland Island. "Take away the marshes, and you take away the shrimp and other species."

Salt marshes and mangroves also blunt hurricanes. They reduce the heights of storm surges, soaking up floodwaters like sponges.

Shifting Sands

Those considering building on a barrier island should recognize one fundamental truth: Barrier islands are dynamic structures, designed to move as waves, wind, and currents act upon them. Living fast and dying young, they form, migrate, disappear, and then re-form. Although Padre Island is building out toward the sea, most barrier islands gradually migrate landward as storms pick up sand from the seaward edge and deposit it landward. Ultimately, they may merge with the mainland, as Myrtle Beach and Virginia Beach have done.

However, many people don't want to hear about migration. They'd rather stake a claim to the natural beauty by building houses, hotels, roads, and resorts.

This requires man-made structures, such as seawalls and jetties, to hold down the islands. It doesn't work for long. Seawalls transfer the energy of crashing waves down the beach. The first beach without a seawall gets devoured. Jetties that are used to keep inlets open instead snare the sand carried by currents moving along the shore. On one side, the beach feasts; on the other, it starves. Jetties built to protect the inlet between Fenwick Island in Delaware and Assateague Island in Maryland have shifted the latter island almost a half mile inland.

"All of these strategies try to maintain the status quo," says Orrin Pilkey, professor emeritus of geology at Duke University. "But on a barrier island, there is no status quo."

That Sinking Feeling

While the future seems dicey for some coastal plain islands, for Louisiana's delta islands, the outlook is dire. They're literally sinking into the Gulf at an alarming rate. "We're losing a football field of marsh every 45 minutes," warns the Nature Conservancy's Jean Landry, who has lived on Grand Isle since 1962. "During the last 60 years, we've lost enough marsh to cover the state of Delaware."

The reason? Levees, dams, and the deep navigation channel dredged out of the Mississippi River have cut off the delta's sediment supply. Instead of replenishing islands and wetlands, 120 million tons of sediment is shot like a cannonball off the continental shelf every year, lost to the marshes forever. Rising sea levels exacerbate the crisis.

Additional channels dug for navigation and oil-and-gas exploration pose another threat. They allow saltwater from the Gulf to invade freshwater wetlands, killing sheltering vegetation. "Once you kill the plants, the root systems disappear, and there's nothing to hold organic soil together," notes Kerry St. Pe, director of the Barataria-Terrebonne National Estuary Program. "They erode away. Higher coastal areas, such as ridges, follow. Oaks die, and you lose habitat."