COLUMN ONE : Galapagos Imperiled by Influx : The pristine islands’ unique flora and fauna have drawn naturalists since Darwin’s time. But a growing human presence threatens the fragile environment.

As the Pacific crashes on the lava rocks at secluded Darwin Bay, a partially submerged Ian Noble peers through his face mask amid one of the world’s most pristine ecological laboratories.

Noble’s eyes grow wide as a 400-pound sea lion and her offspring dart past his legs, burst from the surface and swim directly at him before turning swift underwater backflips. Nearby, scores of red-footed boobies nest amid Cryptocarpus bushes along the beach.

“We might as well get out,” says Noble, a schoolteacher from South Norwood, England, and a veteran bird-watcher. “It’s not going to get any better than that.”

But it may get worse as legions of vacation naturalists follow Noble to this fabled archipelago. The Galapagos, made famous by Charles Darwin, who traveled here in 1835 as a young scientist, have been long renowned as a naturalist’s dream.

But fascination with the islands’ unique flora and fauna--which evolved for eons insulated from human disruption--has also planted the seeds of their possible demise.

Today, this fragile environment 600 miles off the coast of Ecuador faces a surge of new tourism and immigration that threatens to destroy the environmental purity of volcanic islands that Darwin once called “a little world within itself.”

With such natural frontiers dwindling worldwide, there are mounting pressures on debt-ridden Ecuador to take short-term economic advantage of the archipelago.

Tourism, which generates more than $175 million a year, is a potential growth industry for Ecuador--and much of it is tied to the islands. Yet an unrestricted influx imperils the very environment that makes it such an attraction.

Right now, authorities here are at a crossroads. The Ecuadorean government is drafting a comprehensive new conservation policy that is expected to determine the future of additional hotel construction, tour boat operations and development.

“If the government wants to continue reaping the benefits of tourism over a long period of time, it is going to have to bite the bullet and establish some extremely strong policies” restricting tourism and immigration, says Craig MacFarland, president of the Charles Darwin Foundation for the Galapagos Isles, which was set up in 1959 to help foster conservation on the islands.

“The bottom line is that the reason people go to the Galapagos is not for rest and relaxation, not for sun and sand,” MacFarland says. “They go there to see the animals and the ecosystem.”

Indeed, the strains already have begun to show.

* Tourism has exploded, taxing both the Galapagos’ ecology and the ability of the financially strapped Ecuadorean government to protect it. Proposals to build huge luxury resorts loom as a major challenge to environmentalists.

* Lured by tourist dollars, immigrants are moving to the islands from the Ecuadorean mainland, increasing the pressures on the Galapagos’ already scarce resources--from fresh water and sand to seafood.

* The influx has brought alien plants and animals that endanger species that are found nowhere else. Scientists worry that newly introduced fire ants, for example, could upset the delicate balance of the insect population, which in turn serves as the diet of many birds.

“This is ecotourism gone awry,” says Mary Lou Higgins, a World Wildlife Fund program officer. “There can be great economic advantage of preserving areas because of the tourism potential, but you can also kill a place. There is just constant growth, and the islands can’t take it.”

Although visitors, who are supervised by well-trained guides, are largely restricted to marked trails, some of the 45 paths are so badly eroded that there is talk of closing them. And the growing number of boats and cars has taken a toll.

“We used to play a game when we rowed into town in the dinghy,” recalls Jacqueline de Roy, who came to Academy Bay on Santa Cruz Island from Belgium 35 years ago. “We’d count the number of chocolate chip starfish we could see along the rocks at low tide. There would be many, many of them. Now, there are none.”

More ominously, in the last five years more than 100 new plant species have been introduced to the islands, many inadvertently by cargo boats and newcomers. These include aggressive species such as leafy green lantana--which overwhelms endemic plants--and the guava tree, which forms a canopy that prevents the sun from nurturing indigenous seedlings.

“It is just such a pristine area that no matter what comes in, it will alter the native populations,” says Daniel Gerzon, a Galapagos naturalist guide who has temporarily left the islands to pursue a master’s degree in environmental management at Duke University.

Indeed, many Galapagos conservationists fear that the isles may end up akin to Hawaii, where the introduction of alien species and lack of conservation have resulted in destruction of much of the islands’ lush rain forests and native plants and animals.

“Nobody wants the Galapagos to become a Hawaii,” says Lisa Minichiello, administrator of the Smithsonian Institution’s Galapagos program. “Galapagos is one of the last places where it’s still possible to try to control the damage, and even preserve it to a great degree.”

The battle to preserve the Galapagos appeared to have been won in 1959, when an international alliance of conservation groups took a giant step in its bid to protect this window on the evolutionary past.

That year, the Ecuadorean government designated the 90% of the islands’ 3,000 square miles that was not colonized at the time a national park, and the Darwin Foundation was chartered to help protect their natural assets.

But the struggle has proved to be dynamic--with new conflicts arising even as old skirmishes end.

Interest in the islands has grown dramatically since organized tourism began in 1969. About 50,000 outsiders are expected to visit the 13 major islands this year, more than twice the number that came here five years ago. The local population has increased from 6,119 to about 14,000 in the last eight years and is growing at 12% a year.

Authorities have opened a second airstrip on the islands and are building a third. And some Ecuadoreans are urging the government to permit increased urbanization.

Meanwhile, the budget for the national park was severely sliced in the early 1980s and is only slowly being restored. The number of park rangers has fallen from 75 to 46. There are four patrol boats, but tour guides say that only one usually operates.

Most visitors travel throughout the islands on touring yachts, converted fishing boats or larger vessels, and sleep in their berths at night. But small hotels have opened--particularly in the islands’ main settlement, Puerto Ayora on Santa Cruz--which cater primarily to mainland Ecuadoreans.

The former fishing village is typical of the new trend. It is undergoing a building boom, with a growing string of souvenir shops, restaurants and discos.

One staple is jewelry made of black coral, itself an endangered species. Although residents still lack such basics as 24-hour electricity and a hospital, crime and prostitution have also arrived in Puerto Ayora.

In recent years, politically well-connected entrepreneurs have sought to build luxury resorts, which preservationists say would seriously deplete scarce natural resources and could open the developmental floodgates. Most recently, Ecuadorean President Rodrigo Borja Cevallos issued a decree suspending efforts to build a five-star hotel on the island of San Cristobal until a high commission proposes a new tourism policy.

“Conservationists have had a hard but successful time in convincing the government” that it should reject these proposals, says Peter Kramer, field program director of the World Wildlife Fund International in Gland, Switzerland. “Once you build big beach hotels you’re getting into the league with Hawaii and the Caribbean and the South Pacific.”

Ecuador’s ambassador to the United States, Jaime Moncayo, asserts that ecological and scientific concerns, rather than economic incentives, will continue to drive the government’s policy in the Galapagos.

But he notes that Ecuadoreans are legally permitted to move to wherever they wish--including the islands. “Part of the species of the islands are the people who are already there,” he says.

No such species were there in 1535, when a sailing ship carrying the Spaniard Tomas de Berlanga, then the bishop of Panama, ran into doldrums and was carried out to the previously undiscovered islands on its way from Panama to Peru. His account of the islands included the first descriptions of the tortoises and iguanas--both of which are found nowhere else--and noted the birds’ unusual tameness.

The islands first appeared on a map in 1570 as the Isolas de Galapagos or Islands of the Tortoises. From the late 1500s to the early 1700s, they were a hideaway for British buccaneers, who stocked up on fresh water and tortoise meat. Exploitation increased in the 18th Century as whalers and hunters nearly eliminated the fur seals and wiped out some tortoise species.

The Galapagos were officially annexed by Ecuador in 1832 and a small colony established on the island of Floreana, which would soon become a penal settlement. Darwin arrived three years later on the vessel Beagle, visiting four islands for a total of five weeks.

“Both in time and space,” Darwin wrote of the Galapagos, “we seem to be brought somewhat near to that great fact--that mystery of mysteries--the first appearance of new beings on Earth.”

Darwin’s discoveries here stimulated him to ponder the basis for evolution, leading to his theory that the fittest of any species survive through a process of natural selection.

The Galapagos proved such a fertile field laboratory for Darwin, as well as for the generations of scientists to follow, because all plant and animal life arrived by wind and current and evolved insulated from human incursion. In addition, as a result of the islands’ isolation from each other, diverse species emerged.

At the same time, the lack of natural predators led to the animals’ fearlessness.

By the time the park was established in 1959, however, predators introduced by humans were proliferating. A year later, conservation groups established the Charles Darwin Research Station on Santa Cruz to spearhead preservation and educational efforts and supervise scientific endeavors. And, on many fronts, progress has been made.

An effective breeding program has the giant tortoises multiplying again. Abundant colonies of sad-eyed fur seals frolic offshore.

Authorities have undertaken successful campaigns to eradicate hundreds of feral goats, which were introduced to serve as fresh meat but which also wiped out much of the native vegetation on some islands.

Rats, which attack penguin chicks and tortoise eggs and hatchlings, have nearly been eliminated on Pinzon Island. Wild dogs no longer threaten land iguana populations.

In 1986, the waters surrounding the islands were declared a Marine Resources Reserve. And last year, after an outcry by naturalists over the slaughter of sharks for their fins, primarily by Asian fishermen, a law was passed prohibiting shark and gill-net fishing.

Even the ferocious-looking white-tipped sharks have returned to the southern beach of Bartolome Island, where they glide 10 abreast in water so clear and shallow they can be seen from the shore. They had been scared away by people until swimming was prohibited.

In general, Galapagos wildlife is so benign to visitors, said guide Julian Echeverria, that “there’s more danger of breaking a leg embarking from the dinghy than of being attacked by an animal.”

Rather, it is the behavior of humans that concerns conservationists.

“Ten tourists, if they behave badly, could easily destroy the Galapagos,” says the Wildlife Fund’s Kramer, a former Darwin Foundation president, “whereas, 80,000 could be fine if they are well-managed.”

Examples of such indiscretions abound. Only last August, in a bid to lure hammerhead sharks, one visitor threw out a fishing line, snaring a giant frigate bird with the hook and entangling another in the line.

Another tourist trampled on sea turtle nests along a secluded sandy beach. Others in his group frightened nearby animals by making loud noises and motioning with their hands.

A young sea lion on Seymour Island was found with a piece of twine around its neck--a plaything that could become a deadly noose. Even touching a young sea lion is taboo: It alters the pup’s scent and could prompt its mother to reject it, resulting in its starvation.

But for the respectful nature enthusiast, the opportunity to view so many kinds of rare animals at such close range in such striking settings remains nothing short of remarkable.

“The tourists who come here now,” quipped a tour boat purser, “they are all little Darwins.”

On Hood Island, Ian Noble wanders along the rugged volcanic landscape surrounded by creatures he previously had only dreamed of. He had journeyed from Africa to the Amazon in search of unusual birds, but now he has entered an avian haven unlike any other.

Scores of blue-footed boobies--which, one writer quipped, prove that God has a sense of humor--whistle and honk in their seriocomic mating dance, high-stepping with their bright blue feet as though strutting with flippers. Colonies of snow-white masked boobies atop black lava cliffs peer at Noble like ornithological Zorros.

Rare waved albatrosses practice their courtship ritual--stretching their necks, opening their long beaks in a V to emit a high-pitched “whoo-oo,” then ducking down to engage in an intense, clattering round of beak-jousting with their training mate.

And, all along the coastline, prehistoric-looking marine iguanas, miniature Godzillas, provide a creepy reptilian backdrop to the bird riot.

“I’d always heard that the Galapagos were a paradise for bird-watchers,” Noble confides as he steps around boobies, booby nests and booby chicks along the rocky trail. “But I never expected anything like this.”