From the mighty Amazon’s icy source to its plume reaching as far as the Caribbean, National Geographic Explorer teams conduct groundbreaking research to take the pulse of one of the planet’s integral and endlessly magical resources. From the health of river turtles and pink dolphins to the migration of Andean bears, extreme urgency is met by equally hopeful solutions. 　　Premieres October 10 at 9/8c on National Geographic 　　Streams next day on Disney+ and Hulu…