In Sani Isla, one of the most biodiverse corners of the world, the arrival of Ecuador’s biggest oil firm has pitted sister against sister

Children swim in the shadow of oil pipelines in a river near Yasuni national park in Ecuador

While they were growing up in their remote community deep in the Ecuadorean Amazon, Blanca Tapuy and her sister Innes were inseparable.

As children, they would play together while their parents hunted monkeys and tapir with blowpipes and spears. After they married, they regularly met to drink chicha and keep up with the latest gossip as western modernity crept ever closer to their indigenous Kichwa community.

Today, however, the sisters are at loggerheads, divided by an offer from the country’s biggest oil company, Petroamazonas, to start seismic surveys in their homeland of Sani Isla. Blanca declares she is willing to die to stop its advances. Innes passionately counters at community meetings that petrodollars are vital for the future prosperity of the community.

“It makes me very sad,” says Blanca. “We never fought before. We used to be so close. But now we barely talk.”

This is no simple sibling spat, but a difference of views on how to respond to an existential threat. The sisters, like their community and many others in the Amazon, are being driven apart by some of the world’s most powerful macroeconomic forces. Their long-ignored corner of the Amazon – one of the most biodiverse places on Earth – is now at the centre of a battle between conservationists and miners, shifting Ecuadorean political priorities, and a planned trade route between Brazil, the world’s biggest commodity supplier, and China, the greatest manufacturer.

Sani Isla is only just coming to terms with the developmental tsunami heading its way, the first waves of which are already churning up the local political waters. In the last census, there were only 422 residents in this area of 43,000 hectares. Many have to paddle along the Napo river or hike through the forest to attend meetings but, in the past six months, this tiny community has been riven by accusations of bribery, interference by outsiders and even preparations for armed resistance against what they expect to be a vastly bigger and better armed invading force. The tumult has shaken a community that as recently as two generations ago numbered just half a dozen families, who had only recently made contact with the outside world – first with missionaries, then the state, then loggers, oil companies and tourists.

Despite the increase in river traffic, particularly of boats carrying oil trucks and construction equipment, Sani remains home to some of the most ecologically precious habitats on Earth.

Their land – an area of forest, swamps, creeks and lagoons just south of the equator – overlaps with the Yasuni national park. A single hectare in this part of the Amazon contains more plant and insect species than all of Europe.

Outsiders now come in many forms. The main source of income and employment is the tourists who visit the Sani Ecolodge, which was built with money from the Occidental oil company during a previous failed attempt to prospect in the area.

The community has received satellite dishes, computers and solar energy from the European Union. International NGOs, such as the Rainforest Partnership, have helped to build a women’s centre and foster commerce in artisanal crafts. At least two of Sani’s men have foreign wives. One of them is Mari Muench, a British businesswoman, who married the Sani Isla shaman and former president, Patricio Jipa. He says he saw her in a vision when he was 15. The couple run the community’s ecolodge and are spearheading the fight to halt the oil firm.

“You can’t have an ecolodge and oil. It’s one or the other,” says Jipa. “We need to protect the forest, not just for ourselves but for future generations – for the world.”

He is opposed by his uncle, Pablo Licuy – another former president – who signed an agreement with Petroamazonas last year to allow seismic studies in return for $40 (£26.60) a hectare and a verbal promise to build a new school, communal kitchen, better toilets, a new football pitch and houses.

Opponents say he signed without the approval of the community. Some speculate that this is because he has a nephew in Petroamazonas, others that he has been bribed (there are rumours that some community members have been offered motorboats if they accept). Pablo denies these accusations and insists he was working in the interests of the community because the oil company can provide more than the ecolodge.

“The lodge was supposed to help us, but it only benefits some people. For the rest of us, it means we can’t hunt or fish,” he said. “Families are divided over this. I don’t want to see that. But the opponents are making things very tense.”

In some ways, the community is a microcosm of the conservation debate taking place across the world. On one side are short-term economic pragmatists. On the other are eco-idealists concerned about long-term sustainability. Advocates of oil, such as Pablo Licuy, say that life is much better now that the community has computers and football. Many opponents, including Blanca and Licuy Vergas, say they would like to go back to a purer era when they were cut off from the outside world.

It was not long ago. At 71 years old, Oscar Fernano Licuy Vergas is one of the few who can remember how rapidly the changes unfolded.

“When I was young, it was pure nature. Now, there’s more pollution, more illness and people don’t live in peace any more. Now we have fighting inside the community between those who want oil and those who don’t,” he says, during a break at a community meeting. “We’re under a great deal of pressure now because of all these big projects, but we feel a responsibility to look after nature.”

Contact has increased with the expansion of the nearest city, Coca, which was a cattle ranch 50 years ago but is now a busy municipality of more than 30,000 traders, plantation workers and oilmen that can be reached within three hours by motor canoe.

The interaction has brought mixed benefits, according to Guadalupe Aviles, 55. “When I was a little girl we had almost no contact with outsiders. If I saw them, I would run into the forest,” she said.

“I learned a lot from the missionaries, but I wish we had never had contact with the oil companies. The big change now is that they offer individual families jobs or engines for their canoes. That is dividing people.”

Most of the supporters of oil feel they are not getting their fair share of the benefits from the lodge. Their opponents say tourism promises long-term benefits and a clean environment, whereas the oil will only last a few decades, provide a brief economic boost and then leave with the environment ruined.

There are precedents. Ecuador is seeking $27bn in compensation from Texaco for the damage the US company’s Chevron subsidiary did in the Amazon in the 1970s and 80s, yet the government continues to promote exploration by Petroamazonas, Repsol and other oil firms. The Quito-based environmental campaigners Acción Ecológica have taken community members on “toxic tours” to affected areas.

After this, in a marathon session last month, the community voted by a large majority to reject the oil company and seek alternative sources of income through the ecolodge, of which Mari Muench is now in charge. But Petroamazonas, which owns exploration rights in Sani, continues to look for an opening.

Representatives of the company and the agriculture ministry visited while the Guardian was in Sani. They said they were there to deliver invitations to workshops on sustainable fishing and farming and declined to comment about oil exploration.

Although the government and oil company have yet to respond directly to the Guardian about Sani, they say drilling in the Amazon is necessary to raise money for poverty alleviation, improved state infrastructure and better public services. Today’s technology, they argue, is much more environmentally friendly than in the days of Chevron.

Ecuador has won international kudos in recent years for its seemingly progressive environmental policies, including the world’s first constitution that recognises the rights of nature, and the ITT initiative. This promises not to exploit oil in a 180,000-hectare area of the Yasuni national park – just downstream of Sani – if the international community can raise half the estimated $7.6bn value of the fossil fuel.

By comparison, the campaign for Sani Isla is a grassroots affair that has only just started to attract the attention of the domestic media. It lacks high-level political support and the finances needed to fight a legal battle. Locals are aware they are fighting an uphill battle.

“We don’t have money. That’s the problem. We’re just a small lodge against a multibillion-dollar company,” says the president, Leonardo Tapuy. “It’s difficult to be president of a divided community. To unite them, we need to be well organised and to explain our reasoning clearly.”

But Sani has picked up support from environmental and indigenous groups in Ecuador, as well as the global campaign group Avaaz, which collected more than a million online signatures in a petition to the Ecuadorean president, Rafael Correa, to halt oil drilling in Sani.

But Correa too is influenced by outside forces and economic pressures. Since he renegotiated the country’s debts in 2008, Ecuador has been unable to access finance on international markets. Instead it has sold more oil and borrowed more from China – both of which add to the impetus to exploit fossil fuels in the Amazon.

Alberto Acosta – Correa’s former right-hand man, author of the constitution and a rival in the recent presidential election – estimates the nation’s debt to Beijing at $17bn.

“China lends money to the government. The government repays with oil,” he said in explaining why the push to exploit resources in the Amazon had accelerated in recent years.

That is not the only threat to this small community from global geopolitical shifts. The Napo river, which runs through Sani’s territory and marks the border of the Yasuni national park, is being eyed as part of a new trade route from Ecuador’s Manta port to Brazil’s Manaus, 2,000km to the east. A mix of river and road transport has long been seen as an alternative to the Panama Canal. It would cut the journey times and costs of sending raw materials from Brazil to its biggest customers in Asia: China, South Korea and Japan. Many politicians believe the plan is on hold, but construction work to build ports and roads along the Napo is moving ahead.

“Compared to other big projects, it’s being done in a low-key fashion,” said Santiago del Hierro, an architect who is leading research on the impacts of the Manta-Manaus corridor at the Catholic University in Quito. “It is moving ahead slowly but steadily, catalysing colonisation and deforestation in a similar way to the impact of oil extraction during recent decades.”

Already in the midst of one battle to protect their land, the people of Sani are now wondering whether they will be overwhelmed by this second front of development, which is likely to bring dredgers, riverbank erosion and increased traffic not just to them, but to the ITT initiative, the Yasuni national park and its last two uncontacted tribes, the Tagaeri and Taromenane.

Unlike the Kichwa, those tribes remain deep in the forest and violently, often murderously, resist any approaches.

“I guess the river project could be an even bigger threat than the oil company,” says Freddy Aviles, the outgoing manager of Sani Lodge, as he surveys the future challenges facing the community.

I ask him if he ever wished his community too had resisted contact with the outside world. His answer suggests the conflict in Sani is within as well as among people.

“I think about that a lot,” he said. “If we’d never made contact, we would be free but we wouldn’t have education or the chance for foreign travel. It depends on the type of contact. The lodge brings foreign visitors and they do affect the forest, but not like oil companies do.

“It’s more sustainable. Other tribes that have worked closely with the oil companies have been changed. They now have cars and homes with metal roofs. Maybe we move more slowly. But there are some that have not made contact at all. And yes, I’m envious of them. Their lives are pure.”