Hurricane Katrina severely disrupted the Gulf Coast's natural landscape by sweeping away barrier islands, polluting waterways and ripping up wetlands vital to shrimp, crabs and oysters.
The National Oceanic and Atmospheric Administration has declared a widespread failure of the $700 million-a-year Gulf Coast fishing industry because habitats and fishing boats were ruined.
"Louisiana is known for its seafood - oysters, shrimp and fish - and all of this could be severely affected by this event," said Harry Roberts, director of coastal studies at Louisiana State University. "This storm is going to have a long-term impact on the environment here."
The Gulf of Mexico region, from Texas to Florida, produces more seafood than any other part of the United States, including about two-thirds of the oysters slurped in the Chesapeake region. Louisiana alone produces about 100 million pounds of shrimp each year and 12 million pounds of oyster meat, according to that state's statistics.
The storm's immediate fallout includes rising prices and limited availability of seafood, although fish populations sometimes rebound after storms, industry observers said.
Islands swept away
Barrier islands along the Gulf Coast, including the Chandeleur Islands off Louisiana and Dauphin Island off Alabama, were swept away or chopped up, according to the U.S. Geological Survey. This destruction removed protection from future storms for cities and marshes along the coast, and it eliminated critical habitat for the endangered brown pelican and other species, scientists said.
"It's the most damage I've ever seen from any storm," said Abby Sallenger, a USGS oceanographer who examined the coast from an airplane after the storm. "What happened to the Chandeleur Islands was catastrophic; they were almost completely destroyed."
Videotape of the ravaged coast, taken by agency scientists, shows mostly open water, with a few remaining nubs of sand where the Chandeleurs' 40-mile-long strip of unpopulated dunes and grass once lay 70 miles east of New Orleans. The island's lighthouse is missing.
The video also shows Dauphin Island ripped in half, with a new inlet through its middle. Scores of homes are wrecked, the main road is buried in sand, and a broken oil rig has washed up on shore, spilling a trail of black ooze.
"There are unbelievable amounts of debris floating in the water along the coast," said Andy Coburn, associate director of a shoreline study program at Duke University, who also surveyed the storm's damage from an airplane. "Anything you had in communities - trailers, building materials, paper, barges - is floating out there."
Some of the junk flushed out by the storm will rot and could cause an increase in low-oxygen zones along the Louisiana coast, said Donald Boesch, president of the University of Maryland Center for Environmental Science and a New Orleans native.
"It might make the dead zone in the gulf worse next year," Boesch said. "But that will be a short-term effect."
More permanent might be the damage to the already-fragile Mississippi Delta wetlands, which had been shrinking for decades because of the construction of levees and oil platforms. These marshes lost much of their remaining area, although how much is still unknown, said Noel Kinler, a manager with the Louisiana Department of Wildlife and Fisheries.
Walls of water driven by the hurricane folded up many marshes "like accordions" and threw them onto shores and highways, leaving broad areas of open water, Kinler said.
"When you damage these wetlands, you are damaging their capacity to support a wide variety of wildlife species," he said. "Shrimp, oysters and fish will be tremendously impacted."
Polluted, bacteria-ridden floodwater - tainted with lead, sewage and oil - is being pumped out of New Orleans into Lake Pontchartrain, an estuary connected to the Gulf of Mexico. This diseased brew could flow into adjacent Lake Borgne and then wetlands along the gulf that breed shrimp, oysters and crabs, Roberts and other scientists fear.
Many of the fishing boats along the coast are damaged, so little seafood is likely to come from the gulf in the near future, authorities said. But as a precaution, the Louisiana health department has closed all oyster beds, said Bob Johannessen, a spokesman for the agency.
"The water is known to be infected with bacteria, and we've had quite a few cases of rescue workers and flood victims getting sick with diarrhea" after spending time in the water, Johannessen said.
NOAA is sending teams of researchers into the coastal wetlands to check pollution levels in the water and in marine life, said Susan Buchanan, a spokeswoman for the agency.
Hurricanes have battered the Gulf Coast for hundreds of years and marshes and fish have recovered afterward, said Len Bahr, an ecologist from Maryland who is director of a coastal science program in Louisiana Gov. Kathleen Babineaux Blanco's office.
Decades of construction