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 Editorials | Environmental | February 2006 
Hurricanes Shape New Natural Order
 Cain Burdeau - Associated Press
| | Workers install pipes used to drain sand to recover the beaches devastated by Hurricane Wilma in the city of Cancun, Mexico. The government has initiated reconstruction of beaches destroyed by Hurricane Wilma. (AP/Israel Leal) |
Last year's record hurricane season didn't just change life for humans. It changed nature, too.
Everywhere scientists look, they see disrupted patterns in and along the Gulf of Mexico. Coral reefs, flocks of sea birds, crab- and shrimp-filled meadows and dune-crowned beaches were wrapped up in — and altered by — the force of hurricanes Katrina, Rita and Dennis.
"Nothing's been like this," said Abby Sallenger, a U.S. Geological Survey oceanographer, during a recent flight over the northern Gulf Coast to study shoreline changes.
For him, the changes are mind-boggling: Some barrier islands are nearly gone; on others, beaches are scattered like bags of dropped flour.
Hurricanes have been kneading the Gulf Coast like putty for eons, carving out inlets and bays, creating beaches and altering plant and animal life — but up to now, the natural world has largely been able to rebound. Trees, marine life and shoreline features tourists and anglers enjoyed in recent years were largely the same types as those 17th century buccaneers and explorers encountered.
But scientists say the future could be different. Nature might not be able to rebound so quickly. The reason: the human factor.
"Natural systems are resilient and bounce back," said Susan Cutter, a geographer with the University of South Carolina. "The problem is when we try to control nature, rather than letting her do what she does."
The seas are rising, the planet is getting hotter and commercial and residential development is snowballing. Add those factors to a predicted increase in nasty hurricanes and what results is a recipe for potentially serious natural degradation, some say.
"It may bring about a situation (in which) the change is so rapid, it's something that's very different from what the ecosystem experienced over the last three, four thousand years," said Kam-biu Liu, a Louisiana State University professor and hurricane paleoscientist. "We may be losing part of our beaches, we may lose our coastal wetlands, and our coastal forests may change permanently to a different kind of ecosystem."
Between 2004 and 2005, "we've basically demolished our coastline from Galveston (Texas) to Panama City, Fla.," said Barry Keim, the state climatologist in Louisiana. "It's getting to the point that we might have to rethink what our coastal map looks like."
The Gulf, scientists say, won't turn into an environmental wasteland, but it could be less rich in flora and fauna.
Surveys of the washed out Chandeleur Islands, an arc of barrier islands off the coast of Louisiana, found nesting grounds for brown pelicans, royal terns, sandwich terns and black skimmers gone.
"Hopefully the birds will be resilient enough to move to other areas," said Tom Hess, a biologist with the Louisiana Department of Wildlife and Fisheries. "We will have to see."
Salt water spread by Hurricanes Katrina and Rita killed marsh grasses across the Louisiana coast, leaving little left to eat for Louisiana's most hunted bird — the duck.
"Most of the marsh where that salt water sat for a long time looks dead. It looks like it is does extremely late in the winter and you've had several extreme frosts," said Robert Helm, a state waterfowl biologist. "Where we found birds, they seemed to be concentrated in the habitat that was not impacted by the storm."
Duck hunters ask themselves: If Louisiana's abundant wetlands keep getting knocked out, will the ducks head to greener fields?
"You don't go to the restaurant, find it empty, and hang around," said Charlie Smith, a duck hunter.
Katrina and Rita didn't only kill plants. They annihilated more than 100 square miles of wetlands in Louisiana alone, scattering huge chunks of soft marshy earth.
"The hurricanes may have changed habitat in ways that we have not even begun to assess," said Harriet Perry, a fishery expert with the University of Southern Mississippi.
A lot of things are happening under the water, too.
With their towering waves — well over 50 feet high during Katrina — hurricanes move huge volumes of mud and sediment on the ocean bottom, burying clam and oyster beds and seagrass meadows where crabs, shrimps and fish hide and feed. Can the sea plants spring back?
"It depends on the light penetration, how deep they are buried, and factors like that," said John Dindo, a marine scientist and assistant director of the Dauphin Island Sea Lab in Alabama.
Farther out, where the continental shelf drops off, the wild seas kicked up by the hurricanes damaged the Gulf's coral reefs.
After Rita's 30-plus-foot waves, surveys of the coral at the Flower Garden Banks National Marine Sanctuary 100 miles off the coast of Louisiana and Texas showed damage to about 5 percent of the reef. Brain and star coral was toppled and smashed into other coral heads. About 3 feet of sand was dispersed on sand flats in the reef where trigger fish and queen conch burrow and nest.
Also, a large plume of contaminated runoff from the mainland's towns and industries befouled the reef for a couple of days, said G.P. Schmahl, the sanctuary's manager.
Coral reefs are resilient, for the most part, but like much else in nature along the Gulf Coast they could be devastated by an onslaught of powerful hurricanes and warming seas. A coral reef near Jamaica, for example, was wiped out by Hurricane Allen in 1980, Schmahl said.
"If they're hit continually with a whole variety of stressors they may not be able to recover, and that's the big concern right now," he said.
Among fish, species shift locations when runoff from towns, septic systems and farms causes algae blooms or storms change salinity levels in coastal bays and channels. Still, not all changes are detrimental: When Gulf commercial and recreational fishermen are knocked out of the water in storms, overfished species like the red snapper get some breathing room.
Nor are the effects confined to the water or the shoreline. Go inland, and millions of trees — cypress, gum, pine, oak — were snapped like toothpicks. Wild fires fueled by fallen timber break out and kill even more trees. And plant diseases like citrus canker and soybean rust can be spread by hurricanes from one region to the next.
The Gulf is in the midst of flux — heavily developed, heavily fished and buffeted by climate change and storms. It's becoming a perfect place for oceanographers, marine biologists, geologists and geographers to study, said Steven F. DiMarco, an ocean researcher Texas A&M University.
"I think," he said, "people are looking to the Gulf of Mexico ever more as a microcosm of the world." |
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