In late 2012, I spent a month in the Brazilian Amazon, researching the effect of dams on rivers, their species and ecosystems.
The Boto, a pink river dolphin endemic to the Amazon river and its tributaries, feeds on about 50 species of fish and is an important part of the flooded forest ecosystem. It is affected by dams' impact on oxygen content of the water, and on the general impact on seasonal flooding levels. The giant catfish depicted here, Brachyplatystoma rousseaxuii, has the longest reproductive migration of any freshwater fish, traveling from the mouth of the Amazon 3,400 miles to the spawning areas in the western tributaries of the Amazon. Newly constructed dams, such as the Santo Antonio and Jirau, on the Madeira River, are impacting those migrations.