A tougher toll to calculate


Storms: Concerns about the environmental impact of hurricanes often have been overshadowed by the extensive property damage they cause.

October 07, 2002|By Dennis O'Brien | Dennis O'Brien,SUN STAFF

When Hurricane Lili and Tropical Storm Isidore slammed into Louisiana's Gulf Coast this fall, news reports focused on flooded homes and shops, flattened fields and millions of dollars in property damage.

But for some scientists studying hurricanes, the focus is shifting from the search for ways to reduce property damage toward ways to reduce their impact on waterways, woods, grasses and marine life.

As this year's hurricane season peaks, some scientists say the long-term environmental damage caused by hurricanes has been overlooked and is little understood.

"We're just starting to take a look at the major effects that hurricanes have on the environment," says Stephen P. Leatherman, director of the International Hurricane Center and Laboratory for Coastal Research at Florida International University in Miami.

Hurricanes have torn out trees that protect barrier beaches along Florida's coast, destroyed canopy-like clusters of trees in Miami's parks, carved out waterways on Long Island, and dumped so much water into the bays of North Carolina and Maryland that their effects on underwater grasses, crabs and other shellfish last for decades, scientists say.

The Great Hurricane of August 1933, which made its debut 20 years before storms were named, smashed into the Outer Banks of North Carolina, swept through southeastern Virginia and brought 30-foot waves that carved the inlet at Ocean City.

Five years later, a hurricane smashed into the south shore of Long Island, N.Y., creating 13 inlets before it headed north and uprooted millions of trees in the Connecticut River Valley. Leatherman says many of the inlets on Long Island exist today.

Tropical Storm Agnes dumped so much fresh water and silt into the Chesapeake Bay in 1972 that its effects on the bay grasses essential to marine life are still being studied.

"You had everything you could think of coming into the bay -- cows, trees, dirt," says John Page Williams, a senior naturalist for the Chesapeake Bay Foundation. "What you had was a monstrous water machine."

Agnes' effects on the Chesapeake have been extensively documented.

But scientists in other states are just beginning to examine the long-term effects that hurricanes and tropical storms have on things such as Florida's mangrove trees and the amount of shellfish in the waters of North Carolina.

David Eggleston, an associate professor of marine science at North Carolina State University, says better land management practices are needed to reduce the damage hurricanes inflict on water quality and shellfish.

"We need to have adaptive management to take into account how fisheries respond to these large-scale natural events," says Eggleston, who is researching the effects of hurricanes for the National Oceanic and Atmospheric Administration's Sea Grant program and plans to publish a paper in the next few months.

Scientists say that concerns about the environmental impact of hurricanes have often been overshadowed by the extensive property damage they cause.

"We haven't emphasized the environmental effects because when it comes to hurricanes, the property damage issue has been a priority," says Leatherman, a former University of Maryland coastal geology professor and an expert on beaches. "What difference does a few trees being uprooted make to a guy who's just lost his house?"

The property losses can be enormous. Federal officials and insurance industry analysts say the single most expensive natural disaster in U.S. history was Hurricane Andrew, which caused $26 billion in damage when it hit South Florida with winds up to 165 mph in 1992.

But unlike property costs, the environmental toll is often more difficult to calculate.

"The problem is we don't know how much human activity has changed things, but we do know the land is more exposed than ever before," says Hans Paerl, a water quality expert at the University of North Carolina's Institute of Marine Sciences.

Paerl, with a team of researchers, found in a recent study that the cumulative effects of three hurricanes that hit coastal North Carolina in 1999 --Dennis, Floyd and Irene -- had a "cascading effect" on Pamlico Sound. The amount of fresh water the storms dumped into the sound's salty water reduced catches of clams, oysters and blue crabs for years, he said.

"Their habitats were either moved or destroyed," Paerl says. Their findings were published last year in Proceedings of the National Academy of Sciences.

Paerl says that while there is no scientific proof, he believes development has probably worsened the damage -- environmental as well as property -- caused by hurricanes.

"We've modified that land so the water has nowhere to go. In a lot of areas you don't have a wooded watershed to filter and absorb what a hurricane brings," he says. "The conversion of forest to cropland, for one, means more nutrients in the water."

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