The Yahoo News , 28 May 2006
Repeat hurricanes test coastal recovery
Pelican Shoal has never been much of an island — a quarter-acre patch of sand, bleached white coral and scrub seemingly adrift in crystal clear waters seven miles southeast of Key West.
But it was one of two places in Florida where the threatened roseate tern flew once a year from the Caribbean and South America to breed. Now, after two years of pounding hurricanes, it's under water.
Using decoys and recorded sounds, scientists are trying to lure the birds, which typically come in May, to an island in Dry Tortugas National Park. That's 70 miles away.
"The type of habitat they require for nesting is very limited in the state. Now they really don't have many places to nest, if any at all," said Ricardo Zambrano, a biologist with the Florida Fish and Wildlife Conservation Commission.
The tern's fate is one example of how repeated hurricanes not only displace people, but destroy wildlife habitat, kill plant life and rearrange coastal environments that have for centuries served as natural barriers.
Last year's Atlantic hurricane season was the busiest since record keeping began in 1851. The season included 27 named storms with 15 hurricanes, seven of which were Category 3 or higher. Category 4 Hurricane Katrina produced the worst devastation on record in Louisiana and Mississippi. Eight hurricanes have hit or impacted Florida since 2004.
With the six-month hurricane season starting June 1 and more severe storms predicted to come more often, nature is in for a series of debilitating blows the likes of which it hasn't endured in generations. Its ability to recover will be put to the test.
Throughout the Gulf Coast region from Texas to Florida, barrier islands were battered by wind and waves, leaving many fragmented and submerged.
The Chandeleur Islands off Louisiana's coast were stripped clean in Katrina, submerging much of the 40-mile long uninhabited chain and leaving the mainland more vulnerable in the coming hurricane season.
"It takes a long time for these dunes to re-establish naturally, so the next storm that comes along will have an easier job overtopping the islands and flooding inland areas," said oceanographer Abby Sallenger, of the.
Louisiana had already been losing coastal wetlands at a rate of about 25 square miles a year, scientists say. It's estimated that Katrina caused a loss of 118 square miles of wetland marshes.
"What potentially could happen if you take away the barrier islands, the wetlands could even disappear faster," Sallenger said. "The marsh itself will just disintegrate and it supports an incredibly rich ecosystem."
On Florida's Atlantic Coast, Hurricanes Frances and Jeanne delivered back-to-back blows in September 2004, eroding sand dunes and filling wetlands with sediment. In some places, mangrove roots are suffocating in silt as the repeated storms pile more sand and dirt around their bases.
"If you have a series of storms coming through and the return time becomes substantially less, you have all these cumulative impacts that affect the rate of recovery," said Ed Proffitt, a Florida Atlantic University biologist. "Whether the plants survive in the long run remains to be seen. It might take them a few years to die."
Thomas Doyle, a USGS environmental scientist, said it's too soon to tell how back-to-back hurricanes could begin affecting nature's ability to recover, adding that it "needs more scientific attention and scrutiny."
"Over the next hundred years, sea levels will rise, sea surface temperatures will rise, and it will potentially move more storms into hurricane status," Doyle said. "A lot of coastal forests, when they get knocked down, are being replaced by exotic species," reducing habitat for migratory birds.
"How it will impact them building energy for trans-Gulf flights, we just don't know yet," Doyle said. "We might see there's a significant pattern of decline in what comes back next season."
Coastal changes are inevitable in the coming years, but repeated blows could mean massive alterations.
"These hurricanes are just taking big chunks of our landscape," Doyle said.
"It could eventually be the threshold that tips the bucket and leads freshwater systems to become brackish ... and the whole system kind of collapses," Doyle added. "We now have this game board set with certain things in place and in combination with more frequent hurricanes, it can aggravate the situation in terms of sustainability in our social, agricultural and natural systems."
In Florida, where the Everglades has become a managed network of canals and levees, scientists are facing the daunting task of managing more water from frequent storms to keep developed areas from flooding and to cleanse agricultural runoff of fertilizers and pesticides before it bleeds into surrounding wetlands.
"Historically, the system expanded and contracted naturally," said Susan Sylvester, a director with the South Florida Water Management District.
Repeated storms batter the district's manmade marsh filter systems that cleanse pollutants before the water pushes south into the Everglades.
"I view the (marshes) as these really fragile kidneys," Sylvester said. "Those things are being taken off-line by having so much damage to vegetation ... You're overloading the system, and you've got to give it time to recover.
"Nobody anticipated the kind of damage we've seen from the hurricanes and the wind," she added.