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) — The U.S. Supreme Court has begun hearing arguments over the constitutionality of President Donald Trump’s order to end birthright citizenship for children born in the United States to someone in the country illegally or temporarily.

The birthright citizenship order, which Trump signed on Jan. 20, 2025, the first day of his second term, is part of his Republican administration’s broad immigration crackdown.

Trump is in attendance; he is the first sitting president to attend oral arguments at the nation’s highest court.

Every lower court to have considered the issue has found the order illegal and prevented it from taking effect. A definitive ruling by the nation’s highest court is expected by early summer.

Here’s the latest:

More than an hour in, it’s the opponents’ turn

The ACLU’s Wang has begun her presentation in defense of birthright citizenship.

Sauer noted that the government is “not asking you overrule Wong Kim Ark,” which extended citizenship to children born in the U.S. to foreign parents.

But he added that it was “totally unambiguous” that the 1898 ruling “relates to domiciled aliens,” and not what he called “sojourners,” or temporary visitors.

Judge Alito is asking Sauer about the humanitarian issue of people who have been in the U.S. for a long time and are “subject to removal” but in “their minds” have made a permanent home in America.

Alito also says that immigration laws in the U.S. have been “ineffectively and in some cases unenthusiastically” enforced over the years.

He’s asking Sauer to address the “humanitarian problem” that arises with how to deal with those people when it comes to birthright citizenship.

Sauer is saying that when it comes to birthright citizenship the U.S. is an “outlier among modern nations” and is pointing to places in Europe who don’t allow birthright citizenship and suggesting there doesn’t seem to have been any humanitarian fallout there.

Kavanaugh says Congress might have used different language in laws enacted in 1940 and 1952 if it wanted to make clear that children of people here illegally or temporarily were not entitled to citizenship.

Much of the early discussions revolved around the concepts of “domicile,” or a person’s permanent residence, and to which government that person owes “allegiance.”

Solicitor General D. John Sauer began his arguments by noting that the citizenship clause “was adopted just after the Civil War to grant citizenship to the newly freed slaves and their children, whose allegiance to the United States had been established by generations of domicile here.”

It did not, he said, “grant citizenship to the children of temporary visitors or illegal aliens who have no such allegiance.”

Sauer insists that Trump’s order would apply “only prospectively.”

But Justice Sonia Sotomayor says the logic of the administration’s argument would allow a future president to try to strip citizenship from U.S.-born children years from now.

Sauer was asked by Chief Justice John Roberts about how significant is the issue of “birth tourism.”

Critics of birthright citizenship have long said that it attracts people from other countries who come to the U.S. in order to give birth so that their children can become American citizens. Then they go back to their home country.

Sauer was asked by Roberts about any data on how many people come to the U.S. for this reason. “No one knows for sure,” Sauer said, and cited “media estimates” for various numbers.

Thomas recounts that the aim of the 14th amendment was to make citizens of the freed slaves. “How much of the debates around the 14 Amendment had anything to do with immigration?”

Conservative and liberal justices are questioning Sauer’s history of the debates that led to the adoption of the 14th Amendment. Justice Neil Gorsuch says there’s precious little discussion about domicile, a key part of Sauer’s argument.

Justice Elena Kagan says part of Sauer’s case rests “on some pretty obscure sources.”

Many of the arguments in today’s case go back to the Supreme Court’s 1898 ruling in the case of Wong Kim Ark, which said a U.S.-born child of Chinese nationals was a citizen.

In that ruling, Justice Horace Gray wrote that Fourteenth Amendment “affirms the ancient and fundamental rule of citizenship by birth within the territory. That, he wrote, is “including all children here born of resident aliens.”

Roberts says it’s not clear how the recognized exceptions to citizenship, children of ambassadors and foreign invaders, can be applied to “a whole class of illegal aliens.”

Roberts says he’s not sure “how you get to that big group from such tiny and idiosyncratic examples.”

Sauer, Trump’s top Supreme Court lawyer, is at the lectern, defending the president’s birthright citizenship order. Trump is in the courtroom.

On American Samoa, an island cluster in the South Pacific roughly halfway between Hawaii and New Zealand, native-born children are considered “U.S. nationals” — a distinction that gives them certain rights and obligations while denying them others.

American Samoans are entitled to U.S. passports and can serve in the military. Men must register for the Selective Service. They can vote in local elections in American Samoa but cannot hold public office in the U.S. or participate in most U.S. elections.

Those who wish to become citizens can do so, but the process costs hundreds of dollars and can be cumbersome. In 2022, the Supreme Court rejected an appeal seeking to extend birthright citizenship to American Samoa.

An Alaska appeals court is weighing whether to dismiss criminal charges against an Alaska resident born in American Samoa after she was elected to a local school board.

Crowds watched from the sidewalks as Trump’s motorcade drove along Constitution and Independence Avenues, passing the Washington Monument and the National Mall on the way to the court building.

Justice Felix Frankfurter, a native of Austria, was the last of six justices who were born abroad. The current court is American from birth.

Still, the citizenship issue hits close to home for some justices.

Thomas and Ketanji Brown Jackson are descended from enslaved people who eventually had their citizenship established by the 14th Amendment.

Justice Sonia Sotomayor’s parents were born in Puerto Rico, where residents became citizens under a 1917 law enacted by Congress. The justice most closely tied to an immigrant is Alito, whose father was born in Italy.

Way back in 1841, former President John Quincy Adams represented a shipload of African men and women who had been sold into slavery in the famous Amistad case.

Former President William Howard Taft became chief justice nearly eight years after leaving the White House in 1913. Charles Evans Hughes left the Supreme Court for a presidential run in 1912, which he nearly won, then returned to the court in 1930 as chief justice.

In 1966, Richard Nixon argued his only Supreme Court case, which he lost.

Twenty-four Democratic state attorneys general put out a statement Wednesday morning saying they’re “proud to lead the fight against this unlawful order.”

While Democratic attorneys general have sued the Trump administration scores of times, the plaintiffs in this case are represented by the American Civil Liberties Union and other civil rights groups.

The Democratic attorneys filed court papers supporting their position. Twenty-five of their Republican counterparts filed a friend-of-the-court brief backing the Trump administration.

The only state sitting this one out is New Hampshire.

More than 250,000 babies born in the U.S. each year would not be citizens, according to research from the Migration Policy Institute and Pennsylvania State University’s Population Research Institute.

The order would only apply going forward, the administration has said. But opponents have said a court ruling in Trump’s favor could pave the way for a later effort to take away citizenship from people who were born to parents who were not themselves U.S. citizens.

The president and first lady Melania Trump showed up for the court ritual marking the arrival of a new justice following the confirmations of Justice Neil Gorsuch in 2017 and Justice Brett Kavanaugh a year later.

The ceremony for Trump’s third appointee, Justice Amy Coney Barrett, was delayed a year because of the COVID-19 pandemic and Trump, who was no longer in office, did not attend.

Traditionally the president has avoided attending arguments to maintain distance between the government branches — since the executive officer’s presence is seen by many as a way to pressure the independent court to rule in their favor.

Given the unusual nature of it all — Trump’s presence in the courtroom spotlights how high the stakes are for him, as the court’s decision will have massive consequences on his longstanding promise to crack down on immigration.

Last year, Trump said that he badly wanted to attend a hearing on whether he overstepped federal law with his sweeping tariffs, but he decided against it, saying it would have been a distraction.

Adam Winkler, a constitutional law professor at UCLA, told the The Associated Press that Trump’s attending SCOTUS oral arguments signals how important the president views this case.

However, Trump’s presence “is unlikely to sway the justices,” Winkler said, adding that the SCOTUS justices “pride themselves in their independence, even if some agree with much of Trump’s agenda.”

The fanfare of Trump being in the courtroom will make for a different experience for the justices themselves, however, as “Trump’s presence will make the atmosphere a little bit more circus-like,” Winkler said.

Solicitor General D. John Sauer is making his ninth Supreme Court argument and second in as many weeks. Sauer’s biggest win to date was the presidential immunity decision that spared Trump from being tried for his effort to overturn the 2020 election.

Sauer was a Supreme Court law clerk to Justice Antonin Scalia early in his legal career.

ACLU legal director Cecillia Wang, the child of Chinese immigrants, is presenting her second argument to the Supreme Court. In the first Trump administration, a 5-4 conservative majority ruled against Wang’s clients in another immigration case.

It’s not an April Fool’s joke. Alito was born this day in 1950. Only Thomas, who turns 78 in June, is older than Alito among the nine justices.

In the post-pandemic era, the other justices allow the 77-year-old Thomas, the longest-serving member of the court, to pose a question or two before the free-for-all begins.

In a second round of questioning, the justices ask questions in order of seniority. Chief Justice John Roberts, whose center chair makes him the most senior, gets the first crack.

The justices have routinely gone beyond the allotted time since returning to the courtroom following the Covid-19 pandemic.

A buzzer and the court marshal’s cry, “All rise,” signal the justices’ entrance from behind red curtains. The livestream won’t kick in for several minutes, until after the ceremonial swearing-in of lawyers to the Supreme Court bar.

FILE - The U.S. Supreme Court is seen in Washington on Feb. 24, 2026. (AP Photo/Matt Rourke, File)

People arrive to walk inside the U.S. Supreme Court, on Capitol Hill in Washington, Wednesday, April 1, 2026. The Supreme Court justices will hear oral arguments today on whether President Donald Trump can deny citizenship to children born to parents who are in the United States illegally or temporarily. (AP Photo/J. Scott Applewhite)