When fish numbers diminished in the Ecuadoran Amazon, the Siona Indigenous people blamed envious, rival shamans for blocking the animals' passage through the rivers of Cuyabeno, a biodiverse wetland. A study by Ecuador's National Biodiversity Institute in February revealed "heavy metals accumulation in fish" in several Amazonian rivers -- including the Aguarico and Cuyabeno that cross the reserve and are a source of food for indigenous peoples.