Officials with the U.S. Geological Survey who flew over the Gulf Coast from Florida to Louisiana said Thursday that most of the Chandeleur chain of barrier islands _ the first line of storm defense for eastern Louisiana and western Mississippi _ appears to be gone. What is usually a continuous line of dunes is now just marshy outcrops, said Ann Tihansky, a hydrologist with the survey. "It's unbelievable," she said, after reviewing the results of an aerial video survey.

"It just makes the coastline more and more susceptible because more of that storm surge can move further inland," said Glenn Guntenspergen, a U.S. Geological Survey landscape ecologist who has studied the effect of hurricanes on Gulf Coast ecosystems.

With the loss of the islands and wetlands that buffer the region, he said, "It becomes less and less likely for the systems to be able to recover from these kinds of storms. The systems as a whole are rapidly losing their ability to recover."