Scientists fear that an ecological disaster may be unfolding off the coast of North Carolina, following in the wake of Hurricanes Dennis and Floyd, which dumped some three feet of rain on the eastern third of the state in September. Flooding from the hurricanes washed loads of pollution and organic matter out to sea — including raw sewage, hog waste, fertilizers, decomposing vegetation, and topsoil — threatening the biologically rich waters between the mainland and the Outer Banks barrier islands, the second largest estuary in the U.S. When the water in the estuary warms up next spring or summer, vast areas of the estuary could rapidly be drained of oxygen because of the nutrient overload, killing large numbers of fish and other creatures and drastically limiting habitat for surviving wildlife.