Insight: Amazon rainforest gold mining is poisoning scores of threatened species

LOS AMIGOS BIOLOGICAL STATION, Peru, Aug 5 (Reuters) – In a camping tent in the Peruvian jungle, four scientists crowded around a tiny patient: An Amazonian rodent that could fit in the palm of a human hand.

The researchers placed the small-eared pygmy rice rat into a plastic chamber and piped in anesthetic gas until it rolled over, asleep. Removing the creature from the chamber, they fitted it with a miniature anesthetic mask and measured its body parts with a ruler before gently pulling hairs from its back with tweezers.

The hairs, bundled into a tiny plastic bag, would be carried to a nearby lab at the Los Amigos Biological Station for testing to determine whether the rat is yet another victim of mercury contamination.

Los Amigos lies in the rainforest of southeastern Peru’s Madre de Dios region where some 46,000 miners are searching for gold along river banks in the country’s epicenter of small-scale mining.

Tests like this are providing the first extensive indications that mercury from illegal and poorly regulated mining is affecting terrestrial mammals in the Amazon rainforest, according to preliminary findings from a world-first study shared with Reuters.

Absorbing or ingesting mercury-contaminated water or food has been found to cause neurological illness, immune diseases and reproductive failure in humans and some birds.

But scientists don’t yet know its full effects on other forest animals in the Amazon, where more than 10,000 species of plants and animals are at a high risk of extinction due to destruction of the rainforest.

Reuters accompanied the researchers in Madre de Dios over three days in late May and reviewed their previously unreported findings. Their data showed mercury contamination from informal gold mining making its way into the biodiversity hotspot’s mammals — from rodents to ocelots to titi monkeys.

Leaders from the eight countries around the Amazon meeting in Brazil next week will discuss how to end illegal gold mining.

The rapid expansion of mining in the rainforest over the past 15 years is seen by regional governments as an environmental and health threat. Colombia has proposed a regional pact to end illegal mining, although has not suggested a deadline to reach that goal, a government spokesperson told Reuters.

A research team from the San Diego Zoo Wildlife Alliance, the California nonprofit Field Projects International and Peruvian partner Conservación Amazônica have collected fur and feather samples from more than 2,600 animals representing at least 260 species, including emperor tamarins and brown capuchins, in the 4.5 square kilometer (1.7 square mile) area around the Los Amigos station.

While the scientists began testing for mercury at Los Amigos in 2021, some of the samples were gathered as early as 2018.

Of the 330 primate samples tested so far, virtually all showed mercury contamination — and in some cases the levels were “astounding,” said biologist Mrinalini Erkenswick Watsa of the San Diego Zoo Wildlife Alliance.

Erkenswick Watsa said they could not share specific readings before their findings are published in peer-reviewed journals.

But a study last year led by biogeochemist Jacqueline Gerson of the University of Colorado Boulder, drawing on the same data generated at Los Amigos, found that songbirds living around the station had mercury levels as much as 12 times higher than those in a forest farther away from gold mining.

During Reuters’ visit to Los Amigos, scientists caught rodents in metal traps baited with peanut butter and snagged birds and a bat in mist nets floating through the forest.

A MINING BOOM

The vast majority of small-scale or artisanal miners in the Amazon are mining illegally in protected areas, or working informally – outside reserves but without explicit permission from the government.

Informal miners even in government-designated mining corridors, which includes much of the Madre de Dios region, operate with little regulatory oversight.

Some researchers say this means that many small-scale mining operations disregard environmental laws restricting deforestation and the use of toxic liquid mercury to separate precious metal from sediment.

Some of that mercury is then absorbed into the environment and, in some cases, into endangered species.

“When someone buys their gold engagement ring, they could be causing the Amazon to get a little bit sicker,” said Erkenswick Watsa.

Peruvians have mined gold for centuries. Artisanal mining boomed in the Madre de Dios region during the 2008 Great Recession as gold prices spiked, driven up by investors fleeing financial markets and national currencies for a safe place to put their money.