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

PUERTO NARINO, Colombia — 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.