'Losing Noah's Ark': largest wetland on Earth at risk from shipping route

As the evening sky turns violet, the animals of the Pantanal gather near the water. Capybaras swim in tight formation, roseate spoonbills add smudges of pink to the riverbanks, the rumble of a jaguar pulsates from the forest.

- Harriet Barber

This tropical wetland is the largest on Earth, stretching across Brazil, Paraguay and Bolivia, and plays host to some of the greatest gatherings of animals anywhere.

"The Pantanal is like Noah's Ark.

It is home to animals that are disappearing... a place where those at risk of extinction can survive," said Pierre Girard, a professor at the Federal University of Mato Grosso, Brazil.

But scientists say the survival of the entire biome is at risk. "The Pantanal, as we know it, could soon cease to exist," Girard said.

The 170,000 sq km (42m acre) wild expanse harbours one of the world's most biologically rich environments, with at least 380 species of fish, 580 types of birds and 2,272 different plants. It is one of the main refuges for jaguars and houses a host of vulnerable and endangered species, including giant river otters, giant armadillos and hyacinth macaws.

But there are fresh plans for the Paraguay River, one of the Pantanal's main arteries, to be turned into an industrial shipping route.

Political proponents say the waterway would reduce costs and time for exporting agricultural commodities to North America, Europe and Asia but critics warn that its creation - which involves building ports, possibly straightening bends and meanders, and large-scale dredging - would cause irreversible damage to the wetland and its wildlife.

"It seems a high price to pay: destroying the Pantanal, one of the world's unique systems, to reduce the price of grain," said Carolina Joana da Silva, a professor at Mato Grosso State University.

Inside a communal fishers' work shed in Cáceres, 64-year-old Elza Basto Pereira, the head of the community, said construction materials began arriving along the river six months ago.