June 16, 2008
Keys’ Reefs Recovering After Back-to-Back Hurricanes
DRY TORTUGAS -- Before six hurricanes hit mainland Florida in 2004 and 2005, they first wreaked havoc on the Florida Keys' far western islands known as the Dry Tortugas.
Fort Jefferson, the lone man-made structure at the remote outpost, survived with minimal damage.
But under the sea, large sections of the precious coral reef were not so lucky.
"The gorgonians, that literally look like a forest, were just blasted to nothing," said Jerry Ault, professor of marine biology and fisheries at the University of Miami. "They looked like your favorite parking lot. Nothing survived."
The damage, Ault estimates, covered between 50 and 100 square miles of the coral reefs, which are much more than beautiful underwater landscape. They provide food and shelter for countless species and buffer coastlines from storms.
But Mother Nature has been busy in the intervening years. The corals are recovering, said University of North Carolina research scientist Mark Chiappone, who is based in Key Largo.
"We've seen all these baby gorgonians about yea high bouncing back," said Chiappone of the new two-inch high corals. "It's a good sign. That means recovery potential is there. It doesn't always happen. If you have a lot of ship grounding sites, often algae settles in there, or seaweed."
Ault and Chiappone are two of the 36 scientists from universities and federal and state agencies who worked together during the sixth biennial marine census, which ended last week, to document changes in fish abundance and habitat quality.
The purpose: to measure how the Tortugas Ecological Reserve -- a controversial 151-nautical-square mile no-fishing zone established in 2001 to help marine life rebound from decades of overfishing and man-made environmental changes -- is affecting the entire Keys ecosystem.
While the Dry Tortugas are remote, about 70 miles west of Key West, the sustainability and health of the marine life in its waters is critical to all of Florida's coral reef ecosystem and the state's economy.
The Dry Tortugas is a prime spawning area up-current from the rest of Florida and the gateway to three large ecosystems: Gulf of Mexico, Caribbean Sea and Atlantic Ocean.
Florida's coral reef ecosystem, the third-largest in the world, generates an estimated 91,000 jobs and $6 billion annually in fishing and tourism, Ault said.
This was the first census conducted since the 46-square mile "Research Natural Area," another controversial no-fishing zone adjacent to the Tortugas Ecological Reserve, went into effect in November 2007.
Some fishermen and groups, including the Coastal Conservation Association of Florida, opposed the no-take zones in the reserves, saying it was unfair to close off prime fishing areas permanently. They countered that size limits, bag limits and fishing seasons would have the same results of improving fish populations, but in a less draconian manner.
The scientists, while living on a 100-foot dive boat, collected data on a possible 300 species of fish, as well as on corals, sponges, algae and urchins, during 1,712 dives, some at 112 feet deep, over 20 days.
During the 2006 census, Ault said there was a big drop in the number of small reef fish, such as the bandtail puffers and purple reef fish that are not known for their swimming prowess.
It was the first signs of decline after steady improvement had been recorded in the previous biennial census studies. The scientists believe that hurricanes, especially Katrina and Wilma of 2005, were the primary cause of the population declines found during the 2006 census.
"The blue heads were just gone, just absolutely gone," Ault said. "What we're surmising is the currents must have been radical, like a washing machine, and the critical habitats they needed for camouflage were gone, so their cover was gone.
"Maybe they were eaten by predators," Ault added. "Maybe they were blown away. All we know for sure is they weren't there."
Others like the sharp nosed puffers and masked goby might have gotten lost with the churned sediment that made navigation difficult, said James Bohnsack, a scientist and director with the National Oceanic and Atmospheric Administration Fisheries Service in Miami.
Preliminary data from the 2008 data indicates the fish populations also are recovering.
SOME SPECIES GAIN
The hurricanes' wrath wasn't completely devastating. It proved beneficial to some species, with greater numbers of small snappers and groupers, especially red grouper, counted in 2006.
"The little guys have seemed to have gotten a competitive edge," Ault said. "We'll see this year how they fared."
Ault concedes the jury is still out about the long-term benefits of the reserves.
"I'm not here waving a banner, saying marine protected areas solve all our problems," Ault said. "A lot of this is exploratory. But the results are promising."
Ault said one reason fishing in the Keys has survived better that some areas is because of the remoteness of the Dry Tortugas, which can be reached only by boat or sea plane.
"Now you can get out here in two hours," Ault said. "People are willing to make the run. That's why we need to get a grip on it before they take the last fish out of the bucket."