Endangered pink river dolphins face a rising mercury threat in the Amazon

PUERTO NARINO, Colombia (AP) — A flash of pink breaks the muddy surface of the Amazon River as scientists and veterinarians, waist-deep in the warm current, patiently work a mesh net around a pod of river dolphins. They draw it tighter with each pass, and a spray of silver fish glistens under the harsh sun as they leap to escape the net.

When the team hauls a dolphin into a boat, it thrashes as water streams from its pink-speckled sides and the crew quickly ferries it to the sandy riverbank where adrenaline-charged researchers lift it onto a mat. They have 15 minutes — the limit for how long a dolphin can safely be out of the water — to complete their work.

Fernando Trujillo, a marine biologist leading the effort, kneels beside the animal’s head, shielding its eye with a small cloth so it can’t see what’s happening. He rests his hand gently on the animal and speaks in low tones.

“They’ve never felt the palm of a hand. We try to calm them,” said Trujillo, sporting a pink dolphin bandana. “Taking a dolphin out of the water, it’s a kind of abduction.”

One person counts the dolphin's breaths. Another wets its skin with a sponge while the others conduct multiple medical tests that will help show how much mercury is coursing through the Amazon’s most graceful predators.

Trujillo directs the Omacha Foundation, a conservation group focused on aquatic wildlife and river ecosystems, and leads health evaluations of river dolphins. It's a painstaking operation involving experienced fishermen, veterinarians and locals that takes months of planning and happens a couple of times a year.

“We take blood and tissue samples to assess mercury,¨ Trujillo told The Associated Press from the Colombian riverside town of Puerto Narino. “Basically, we’re using dolphins as sentinels for the river’s health.”

Mercury contamination comes mainly from illegal gold mining — a growing industry across the Amazon Basin — and forest clearing that washes mercury that naturally occurs in soil into waterways.

The miners use mercury to separate gold from sediment, then dump the sludge back into rivers, where it enters fish eaten by people and dolphins. Rising global gold prices have fueled a mining boom, and mercury pollution in remote waterways has increased.

Mercury can damage the brain, kidneys, lungs and immune system and cause mood swings, memory loss and muscle weakness in people, according to the World Health Organization and the U.S. Environmental Protection Agency. Pregnant women and young children are most at risk, with prenatal exposure linked to developmental delays and reduced cognitive function.

“The maximum any living being should have is 1 milligram per kilogram,” Trujillo said. “Here, we’re seeing 20 to 30 times that amount.”

In previous years, his team found 16 to 18 milligrams per kilogram of mercury in dolphins, which can suffer the same neurological damage, organ damage and other problems as humans. In Colombia’s Orinoco River, levels in some dolphins have reached as high as 42, levels scientists say are among the most extreme ever recorded in the species.

Trujillo said it's difficult to prove the toxin is directly killing dolphins. Further studies are underway, he added, noting that “any mammal with a huge amount of mercury will die.”

When Trujillo and his team tested their own blood three years ago, his results showed more than 36 times the safe limit — 36.4 milligrams per kilogram — a level he attributes to decades working in mercury-affected areas and a diet heavy in fish. With medical assistance, his levels have dropped to about 7 milligrams.

“Mercury is an invisible enemy until it builds up to a sufficient amount, then it starts to affect the central nervous system,” Trujillo told AP after his team managed to capture and test four pink dolphins. “We’re already seeing evidence of it in Indigenous communities.”

A series of scientific studies and reports — including work by the International Pollutants Elimination Network and academic researchers — have found high mercury exposure among Indigenous peoples across the Amazon, including in Brazil, Peru, Colombia, Suriname and Bolivia. Hair samples showed averages well above WHO's safe threshold of 1 part per million, with one Colombian community registering more than 22 milligrams per kilogram.

Dolphin populations in this part of the Amazon have plunged, with Trujillo’s monitoring showing a 52% decline in pink dolphins and a 34% drop in gray river dolphins, a different species, in recent decades. The International Union for Conservation of Nature listed the pink dolphin as endangered in 2018. Trujillo said exact numbers for the Amazon are unknown, but his organization estimates 30,000 to 45,000 across the basin.

Pink river dolphins also face threats from overfishing, accidental entanglement in nets, boat traffic, habitat loss and prolonged drought.

Colombia says it's tackling illegal mining and mercury pollution. It banned mercury use in mining in 2018, ratified the Minamata Convention aimed at reducing mercury in the environment and submitted an action plan in 2024. Authorities cite joint operations with Brazil and recent enforcement sweeps, but watchdogs say efforts remain uneven and illegal mining persists across much of the country.

Other Amazon nations say they’re stepping up. Brazil has launched raids and moved to restrict satellite internet used by illegal gold-mining camps that use mercury, aiming to disrupt logistics and supply lines. Peru recently seized a record 4 tons of smuggled mercury. Ecuador, Suriname and Guyana have filed action plans to cut mercury use in small-scale gold mining.

The dolphin testing operation relies on José “Mariano” Rangel, a charismatic former fisherman from Venezuela. He leads the charge when it’s time to haul the animals — which can weigh as much as 160 kilograms (about 353 pounds) — into the small boats. It's a moment that can end with a stinging blow to the jaw as the dolphins thrash to break free.

“The most difficult part of the captures is enclosing the dolphins,” Rangel said.

A portable ultrasound machine scans lungs, heart and other vital organs for disease. The team checks for respiratory problems, internal injuries and signs of reproduction, photograph the animals' skin and scars, swab blowholes and genital openings for bacterial cultures, and collect tissue for mercury testing. Microchips are implanted so researchers can identify each animal and avoid duplicating tests.

Omacha has recorded antimicrobial resistance — bacteria that can’t be killed by common medicines — and respiratory problems. They have also identified possible emerging diseases, such as papilloma virus, that could pose risks to both dolphins and humans.

After a long morning hauling and testing dolphins, the scientists return to a laboratory in Puerto Narino that's covered with posters of dolphins and manatees and the bones and skulls of dolphins and other animals. They test some samples, prepare others to send to larger facilities and end their day repairing nets and refilling kits to do it all again at dawn.

For Trujillo, each capture, scan and blood test is part of a larger fight.

“We are one step away from being critically endangered and then extinct,” Trujillo said.

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Scientists and veterinarians free a pink river dolphin after a health check in Puerto Narino, Colombia, Sunday, Sept. 7, 2025. (AP Photo/Fernando Vergara)

Scientists and veterinarians weigh a pink river dolphin after a health check in Puerto Narino, Colombia, Sunday, Sept. 7, 2025. (AP Photo/Fernando Vergara)

Scientists examine blood samples that were drawn from pink river dolphins in the Amazon River to determine mercury levels in Puerto Narino, Colombia, Sunday, Sept. 7, 2025. (AP Photo/Fernando Vergara)

A veterinarian draws a blood sample in a pink river dolphin in the Amazon River during health checks in Puerto Narino, Colombia, Sunday, Sept. 7, 2025. (AP Photo/Fernando Vergara)

Veterinarian Maria Jimena Valderrama implants a microchip into a pink river dolphin after a health check in Puerto Narino, Colombia, Sunday, Sept. 7, 2025. (AP Photo/Fernando Vergara)

Scientists and veterinarians examine a pink river dolphin in Puerto Narino, Colombia, Sunday, Sept. 7, 2025. (AP Photo/Fernando Vergara)

Scientists and veterinarians examine a pink river dolphin in Puerto Narino, Colombia, Sunday, Sept. 7, 2025. (AP Photo/Fernando Vergara)

Scientists and veterinarians capture a pink river dolphin in the Amazon River for health checks in Puerto Narino, Colombia, Sunday, Sept. 7, 2025. (AP Photo/Fernando Vergara)

Scientists and veterinarians capture a pink river dolphin in the Amazon River for health checks in Puerto Narino, Colombia, Sunday, Sept. 7, 2025. (AP Photo/Fernando Vergara)

Scientists and veterinarians capture a pink river dolphin in the Amazon River to perform health checks in Puerto Narino, Colombia, Sunday, Sept. 7, 2025. (AP Photo/Fernando Vergara)

Fishers help scientists and veterinarians to capture pink river dolphins in the Amazon River for health checks in Puerto Narino, Colombia, Sunday, Sept. 7, 2025. (AP Photo/Fernando Vergara)

Scientists and veterinarians examine a pink river dolphin in Puerto Narino, Colombia, Sunday, Sept. 7, 2025. (AP Photo/Fernando Vergara)

WASHINGTON (AP) — Senate Democratic leaders believe they have a path to winning the majority in November, though it's one with very little wiggle room.

The party got a new burst of confidence when former Rep. Mary Peltola announced Monday she'll run for the Senate in Alaska. Her bid gives Democrats a critical fourth candidate with statewide recognition in states where Republican senators are seeking reelection this year. Nationally, Democrats must net four seats to edge Republicans out of the majority.

That possibility looked all but impossible at the start of last year. And while the outlook has somewhat improved as 2026 begins, Democrats still almost certainly must sweep those four seats. First they must settle some contentious primaries, the mark of a party still struggling with its way forward after Republicans took full control of Washington in 2024. Importantly, they must also beat back challenges to incumbents in some of the most competitive states on the map.

And though some of Senate Minority Leader Chuck Schumer's top Democratic Senate recruits were lauded for their statewide success in pivotal states, some are nearly 70 or older, hardly the key to a lasting Democratic transformation.

Republicans doubt the chances Democrats can pull off such a task, considering most of the 2026 contests are in states that Donald Trump easily won in 2024.

Still, independent voters have drifted in Democrats' direction over the past year, according to a new Gallup poll, a slight breeze at Democrats' back they didn't expect a year ago when there was little path at all.

“I say it’s a much wider path than the skeptics think, and a much wider path than it was three months ago and certainly a year ago,” Schumer told The Associated Press Tuesday.

Republicans currently hold 53 seats, while the Democratic caucus has 47 members, including two independents.

Schumer argues that Peltola, elected twice statewide to Alaska's at-large House seat, puts the typically Republican-leaning state in play as a potential pickup for Democrats.

It's a development similar to other states where Schumer believes Democrats have recruited strong candidates: former three-term Sen. Sherrod Brown in Ohio, former two-term Gov. Roy Cooper in North Carolina and two-term Gov. Janet Mills in Maine.

But they hardly represent a quartet of guarantees. Brown, a longtime pro-labor progressive in increasingly GOP-leaning Ohio, and Peltola, who was elected during a special election in 2022, both lost reelection in 2024. Mills, finishing her second term as governor, faces a competitive primary challenge from progressive veteran and oyster farmer Graham Platner.

None of the four had runaway popularity with voters in their states in 2024. Right around half of voters had somewhat or very favorable views of all of them, with Cooper slightly higher and Brown slightly lower, according to AP VoteCast, a survey of the electorate.

Age remains another issue. After President Joe Biden, in his early 80s, withdrew from the 2024 race amid concerns he was too old to serve, Democratic Senate leadership hasn't changed course. Schumer, 75, has recruited candidates who are older, with several top recruits – including Mills and Brown – well into their 70s.

“Voters sent a very clear message in 2024 that they’re sick of the gerontocracy. They’re sick of Democrats putting up old candidates and that they want some new blood,” said Lis Smith, a national Democratic strategist. “And some of the recruits, like in Maine, seem to completely ignore the message that voters sent in 2024.”

Schumer said winning back the Senate is paramount over all else.

“It's not young versus old. It's not left versus center. It's who can best win in the states,” he said. “So, these are all really good candidates, and I don't think you look at them through one narrow prism. You look at who can win.”

Before Democrats can test their general-election appeal, they must navigate some primaries that highlight lingering divisions within the party.

Platner, who has been endorsed by independent Sen. Bernie Sanders of Vermont, has demonstrated formidable fundraising for his Maine contest, despite controversies surrounding past social media posts and a tattoo linked to Nazi imagery. Some Democrats worry his insurgent appeal could be a liability in November if he is the nominee.

In Michigan, Democratic Sen. Gary Peters' retirement has opened a seat in a state Trump carried narrowly. Republicans have unified behind former Rep. Mike Rogers, while Democrats face a crowded August primary after failing to recruit Gov. Gretchen Whitmer.

Crowded or contentious primaries are also playing out in Minnesota, Texas and Iowa, forcing Democrats to devote resources even in states not central to their path to a majority.

Sen. Chris Van Hollen is part of an informal group of Democratic senators known as Fight Club that has been openly critical of party leadership’s approach to the midterms. Van Hollen said the group has objected to what it sees as the Senate Democrats’ campaign arm — controlled by Schumer — “wading into certain Democratic primaries.”

“So, yes, we’re taking a look at all of them,” Van Hollen said of endorsing more progressive candidates.

Betsy Ankney, political director for the National Republican Senatorial Committee in 2020, acknowledged Democrats’ desire to make the case for competitiveness but characterized Trump’s presidential victories in Alaska and Ohio in 2024 — by 13 and 11 percentage point margins, respectively — as enormous hurdles.

She said Republicans are “rightly focused, on real tangible targets in Georgia, in Michigan," calling them “very real pickup opportunities.”

Democrats’ shot at the majority almost certainly depends on Sen. Jon Ossoff winning reelection in Georgia, where Trump won in 2024 by 2.2 percentage points, and holding Michigan, where Peters' retirement creates an open seat in a state Trump carried by 1.4 percentage points.

"It’s not just about where the Democrats can play. It’s about where we can play, too,” Ankney said.

Despite the challenges, Democrats see reasons for optimism in the broader political climate.

A new Gallup survey found 47% of U.S. adults now identify with or lean toward the Democrats, while 42% are Republicans or lean Republican. That gives Democrats the advantage in party affiliation for the first time since Trump’s first term.

But the data strongly suggests that independents are moving toward Democrats because of their souring attitude toward Trump, rather than greater goodwill toward Democrats. The Democratic Party’s favorability is still low, and Gallup’s analysis found that, as more Americans identify as independents, they tend to gravitate toward the party that is out of political power — whether it’s the Democrats or the Republicans.

Still, that appears to be a dynamic in Democrats' favor, as economic unease creeps into the election year with little time before the feelings lock into voters' political thinking, veteran Republican pollster Ed Goeas said.

“That creates an environment that will affect these Senate races,” Goeas said, predicting House Republicans could lose their majority. He said Republicans are assuming the economy and the political environment are going to be better.

“I think they are going to end up getting frustrated going into the summer because, first of all, the economy is not on all levels improving. It’s going to be a target-rich environment for Democrats," he said.

“It’s going to be close.”

Beaumont reported from Des Moines, Iowa. Associated Press writer Amelia Thomson DeVeaux in Washington contributed to this report.

Senate Minority Leader Chuck Schumer, D-N.Y., speaks during the Senate Democrat policy luncheon news conference at the Capitol, Tuesday, Jan. 13, 2026, in Washington. (AP Photo/Rod Lamkey, Jr.)

FILE - Rep.-elect Mary Peltola, D-Alaska, is interviewed on Capitol Hill in Washington, Sept. 12, 2022. (AP Photo/Amanda Andrade-Rhoades, File)