for National Geographic News
A new study makes the provocative claim that Hurricanes Katrina and Rita actually helped stabilize coastal wetlands by depositing tons of silt and sedimenteven as the storms devastated dozens of square miles of the low-lying areas.
The new findings contradict long-held theories that rivers are the primary source of the sediment that forms wetlands, says research leader R. Eugene Turner, an ecologist at Louisiana State University (LSU) in Baton Rouge.
The study also counters beliefs that the loss of wetlandsespecially on the eastern Louisiana coastlinehas been caused by flood-prevention levees on the Mississippi River, he adds.
Coastal wetlands are breeding grounds for many marine animals. They also protect coastlines from hurricane sea swells, or storm surges.
Though sediments are a relatively small fraction of a wetland, such deposits are an important part of the physical framework supporting wetland plants.
In findings that could cause a stir among environmentalists, the LSU researchers ultimately conclude that hurricanes play an important role in maintaining the health of wetlands.
"I don't think most people expected that," said Mark Ford, deputy director of the Coalition to Restore Coastal Louisiana (CRCL) in Baton Rouge. "It does sound a little counterintuitive.
"I expect it to stir up a lot of conversation. But that's good."
The study, which was funded by a $25,000 grant from the National Science Foundation, appears today in the online edition of the journal Science.
Restoring Louisiana's diminished wetlands has become a major political issue in the state.
The U.S. Geological Survey estimates that Louisiana lost at least 100 square miles (260 square kilometers) of coastal wetlands because of Katrina and Rita. (Related: "Many Islands 'Gone,' Wetlands Gutted After Katrina, Experts Say" [September 2005].)
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