LOS ANGELES -- The world's coral reefs made a partial recovery last year after a dismal 1998 but remain threatened by overfishing and climate changes, scientists say. One marine biologist was concerned for Hawaii's reefs, which he said were being manhandled and trampled by tourists.
A 1998 survey indicated that 15 percent of the world's reefs had died off, but the latest survey by Reef Check found that a third of those reefs actually recovered from bleaching.
Gregor Hodgson, founder and global coordinator of Reef Check, said one reason the reefs' prospects brightened a little is that they are beginning to thrive in hundreds of marine parks around the world - including the Florida Keys National Marine Sanctuary. In those areas, lobsters and other important sea creatures are coming back.
Hodgson announced the findings at the University of California, Los Angeles, Ocean Discovery Center in Santa Monica. UCLA will become Reef Check's new home after leaving Hong Kong this summer.
The group, which recently released its third annual report, relies on the volunteer efforts of more than 1,500 divers and marine scientists to document the health of more than 250 reefs in more than 50 countries.
Their cause is important because, by some measures, coral reefs have even more diverse life than rain forests, said Michael Crosby, senior science adviser for marine and coastal ecosystems for the U.S. Agency for International Development and the National Oceanographic and Atmospheric Administration.
All those species contain "a wealth of information we're only beginning to tap into," he said. One coral reef species is being used in bone grafts, and another has helped develop pesticides, Crosby said.
And reefs affect not just ocean health, but coastal health as well. They serve as natural breakwaters protecting land from typhoons and erosion, Crosby said.
The beauty of coral reefs, and all the life within them, is both a reason to save them and a way to protect them. Hodgson said that in developing countries like the Philippines and Indonesia - homes of some of the most biologically diverse reefs - ecotourism can help people strike a better balance with the environment while continuing to make a living.
On most of the reefs surveyed by Reef Check, important species that should be there - lobster, grouper, sea cucumbers - are missing, Hodgson said. Without such algae-eating creatures, algae becomes so dominant it overwhelms the ecosystem.
The opposite problem hit many reefs in 1998, an El Nino year that saw the warmest ocean temperatures on record. The warmer conditions killed the algae the coral needs to survive, bleaching the reefs white.
Coral structures are colonies of animals, and they get their color from algae. In bleaching, the animals expel most of the algae. Usually, the remaining algae can repopulate the coral later on and restore its color.
An otherwise healthy reef can bounce back from a bleaching. But for those already stressed, "a bleaching event can push them over the edge," Crosby said.
Reef problems triggered by climate changes are continuing. In early April, Fiji began seeing major coral bleaching, Hodgson said. Nearly two-thirds of the coral reefs around the islands are bleached, and 15 percent are dead, he said.
In separate findings reported in the May 4 issue of the journal Nature, scientists found that for the first time in the Caribbean, a large population of coral was killed by bleaching.
Since the 1998 bleaching was blamed on unusually warm sea temperatures, the coral death is another signal to be concerned about global climate change, said Rich Aronson, a senior marine scientist at the Dauphin Island Sea Lab on Dauphin Island, Ala.
In coastal reefs in Belize, coral animals themselves were killed by the severe bleaching in 1998, Aronson and colleagues found in recent studies. For the dominant kind of coral in an area covering at least 140 square miles, he said, "it was just a complete wipeout."
The killing ranged from depths of three feet to the floor of the reef about 70 feet down, he said. That range reinforces the idea that the high water temperature was responsible, Aronson said.
Efforts to monitor and protect the 425,000 acres of coral reefs in the United States have gained steam since 1998, when President Clinton created a task force to tackle the problem, Crosby said.
More than $10 million this year and a proposed $26 million next fiscal year will help map and protect U.S. reefs, Crosby said. He said that although Reef Check's work has been important in measuring the extent of reef problems, most of the nation's and the world's reefs remain inadequately mapped.
In Hawaii, where the vast majority of U.S. reefs are found, scientists believe reef-hopping snorkelers are destroying the corals.
Corals, on average, grow by about an inch a year. Hawaii's corals grow at a slower rate than most because the islands are at the northern edge of the Pacific's coral-growing region, said Alton Miyasaka, an aquatic biologist with the state Department of Land and Natural Resources Division of Aquatic Resources.
The shallow waters of Oahu's Hanauma Bay, one of the most heavily used marine parks in the world, are dotted with balding coral heads, a sign of coral death, he said. But healthy corals proliferate in deeper waters beyond the nearshore reef.
Miyasaka said tourists must be educated that corals are colonies of animal and plant species that need sunlight to fully grow, and die if they are overly manhandled.
Facts about coral reefs:
-Corals are animals that have plant life - algae - living inside them. The algae are what give corals their brownish-green color, and they're what give the corals enough energy to build a skeletons of calcium carbonate.
-Coral reefs are the largest structures made by living organisms and are result of many living and dead skeletons fusing together.
-Coral reefs can be found off the coasts of about 100 countries.
-Coral reefs are home to thousands of species of life, from algae to sea cucumbers to fish to crustaceans. For instance, some Pacific reefs hold more than 1,300 species of reef fish alone.
Source: Reef Check.
On the Net:
Oahu Visitors Bureau: http://www.visit-oahu.com/aloha.htm. Click on Beaches. Click on Hanauma Bay.