Burgeoning Starfish Population Ravaging Coral of Great Barrier Reef

Armies of coral-killing starfish are ravaging the Great Barrier Reef, threatening to turn a wonderland of living color into a white and lifeless landscape.

As millions of spiky echinoderms devour the blooms of the sea, alarmed marine scientists are blaming greedy shell collectors and fishermen who unwittingly help the “crown of thorns” starfish by eliminating its predators.

“If we don’t take action, I fear were going to lose the bulk of the Great Barrier Reef by the year 2000,” zoologist Robert Endean said.

The associate professor at the University of Queensland and his colleagues report that destruction of the world’s largest coral reef system is far worse than originally thought.

Wilderness of Skeletons

Since the early 1980s, a third of the 2,500 reefs along the Queensland coast have been affected, Endean said, with some popular diving spots transformed from ecological splendor to a wilderness of skeletons.

“We have a very serious situation,” said Endean, who has spent 20 years studying the 1,200-mile profusion of reefs. “The most damage has been done in the middle third of the chain, but pockets of starfish have started in the northern and southern thirds.”

The reddish-brown starfish, which are covered with venomous spines and crawl along on stubby legs, emerged in vast numbers across the Pacific in the 1960s in one of the strangest biological phenomena of the century. Millions attacked the reef with a vengeance, then mysteriously stopped for a time only to renew their attack.

Although some scientists regard the outbreaks as natural cyclical events, Endean believes the onslaughts were interrupted only because “the starfish had literally eaten themselves out of house and home.”

Prolific Breeders

They stay in one place devouring every polyp in sight, leaving reefs devoid of their once resplendent coral. And the starfish breed prolifically, with a female laying an estimated 20 million eggs a year.

A small fraction of the eggs survive being transported by ocean currents to other reefs, accounting for the second infestation, said Endean, who believes the present onslaught is far worse than the first.

“In the ‘60s it was principally the rapid-growing branching corals that were attacked, and some of these re-established quite quickly,” he said. “But in the ‘80s it’s been the massive hemispherical corals which have been destroyed.

“Some of them live a very long time, up to 10,000 years, and their destruction represents a very serious phase.”

53 Research Programs

The government is subsidizing 53 research programs to ensure the survival of the reef, which is not only a national asset but an officially designated World Heritage site.

While researchers differ on the extent of the damage and the prognosis, no one questions the danger from the starfish threat, which also threaten reefs around the Japanese-owned Ryukyu Islands, Fiji, Guam, Yap and the vast U.S. Trust Territory.

Marine biologist Leon Zenn agreed that the starfish constitute a “major problem” but is not convinced that their rampages are as potentially grim as Endean said.

“This is such a complicated phenomenon,” said Zenn, an officer with the government’s Great Barrier Reef Marine Park Authority. “We haven’t come up with the answers. We know so little about reefs at this stage.”

Maintaining that only 7% of the reefs are significantly infested, Zenn said, even if nothing daunts the attacks of the determined creatures, “The reef will still be in pretty good shape by the year 2000.”

Tourists Unaware

Endean said that many tourists are unaware of the damage “because they are taken to a few select spots where the starfish haven’t attacked or have been kept at bay.”

One exception is Green Island, 12 miles offshore from Cairns, the first coral island to be developed as a resort along the reef and a prime destination for visitors. Once a vista of living coral accessible to hikers, snorkelers or passengers in glass-bottomed boats, the sight has been transformed into a brown, algae-covered blur.

“After the first outbreak, there were many who still thought there was no real need for concern, that the situation would stabilize and the coral would grow back,” Endean said. ‘They were most surprised when the starfish returned, devastating reefs for the second time. It’s a horrible mess.”

Underwater Fences

Last September the Great Barrier Reef Marine Park Authority started testing different types of underwater fences. One consisted of fishing nets strung between fence posts driven into the seabed, with a string of buoys to keep the net afloat. Another was a nylon-coated wire mesh, while still other varieties involved strings of tangle nets.

Zenn said the major application of the fences was for rich coral patches that play an important part in the tourist trade. But a recent netting program failed dismally when the starfish simply clambered over the enclosure to reach the coral.

Another possibility to combat the problem is to poison the starfish with copper sulfate injections. But the procedure is a labor-intensive, expensive and raises fears among some environmentalists about releasing poison into the environment.

Endean argued that the only effective controls are the starfish’s own natural predators.

Tritons Disappearing

“The giant Triton, which eats young starfish, has been collected in such huge numbers that it is becoming a rare sight,” Endean said. Despite a ban on its collection by the Queensland government, Tritons continue to disappear as the shells sell briskly in the United States.

Endean and his team fenced off a colony of Tritons to try and breed them, but even those were stolen by poachers.

The other main predators are such large fish as cod and grouper, Endean said, but professional spear fishermen have drastically reduced their numbers.

“We find reefs nearest to human populations are the ones first and most severely affected,” Endean said, recommending Coast Guard-type patrols to stop the removal of the Tritons and overfishing.

“The predators have been over-collected by humans,” he said. “Unless we move quickly to stop it, there is every likelihood the remaining reefs will come under attack and the coral destroyed.

“Time is running out for the eighth natural wonder of the world.”