Australia’s Great Barrier Reef Periled by Man, Nature : Environment: Flooding, voracious starfish and pollution take their toll on the 1,370-mile coral structure. Rescue efforts are under way.

Scientists have warned for nearly 40 years that the Great Barrier Reef, an 80,000-year-old coral structure off northeast Australia, is slowly being destroyed by natural and man-made problems.

Freshwater flooding combined with a new outbreak of coral-stripping starfish have heightened fears that it is in serious peril.

Scientists say flooding over the recent months in Queensland killed up to 85% of the coral and most of the fish around some of the state’s most popular tropical islands.

John Veron, a spokesman for the Great Barrier Reef Marine Park Authority said experts who checked the damage reported coral dying because of flooding from the Fitzroy River.

Fresh water, which kills coral and other marine life by lowering the salinity of seawater, is spread like a blanket on the ocean surface to a depth of about 6 feet in some places.

“You can already smell and see dead coral in some areas,” Veron said, and the reef may take seven years to recover fully from the worst coastal flooding since 1954.

Great Barrier Reef Marine Park stretches for 1,370 miles from the Torres Strait in Cape York on the far northeast tip of Australia to midpoint on the Queensland coast.

The reef, popular with scuba divers the world over, consists of about 3,000 individual reefs containing 4,000 species of mollusks and 1,500 fish varieties. It produces $780 million a year in tourism revenue.

Among the marine life is the Crown of Thorns starfish, having its second major outbreak in the reef in 15 years. The starfish eats at the coral like acid, stripping sections of their color.

A longer-term problem is the amount of nutrients and sediment building up in the reef. Scientists say its ability to nurture marine life is being inhibited by agricultural runoff rich in soil and fertilizers, including herbicides and pesticides from cane fields and fruit orchards in Queensland.

At its annual meeting in Perth last year, the World Conservation Union said toxic wastes from a mine in Papua New Guinea, across the Torres Strait from Australia, are damaging the reef.

Officials of Papua New Guinea have denied that toxic copper sediments from the mine reach the Pacific through the Fly River drainage system.

John Lucas of James Cook University is an expert on the Crown of Thorns starfish. He said evidence from 7,000 years of coral sediment shows Crown of Thorns outbreaks are becoming more frequent and nutrient levels may be the reason.

“A Crown of Thorns outbreak is like a bush fire, which can be a natural event started by lightning strike,” he said, “but humans can change the frequency of the fires.”

About 500,000 tourists visit the reef every year, according to authority figures.

Some travelers to Australia say they want to see the reef before it’s too late, but Lucas said: “The reef won’t disappear. It just won’t be as attractive.”

Several rescue efforts are under way.

Nearby resorts will be ordered to remove nitrogen and phosphorus from their sewage and new resorts will be required to have three-stage treatment systems.

The park authority spends 25% of its research money on water quality projects and will seek more money for pollution research.

Federal officials have proposed a 1% tax on commercial tourist activity on the reef, with the money going to research and park management. Queensland state, concerned about the effect on tourism, has opposed a tax.