Location

Click here for a location map of the project

Our study is based in the Mamirauá Sustainable Development Reserve, which is situated in the heart of the Brazilian Amazon at 3o 3’ South, 64o 51’ West. The reserve is a magnificent area of flooded forest – so called because for half of the year it is inundated with floodwater and becomes an inland sea almost covered in forest. The Reserve is bounded by the Amazon river itself on one side (but called the Solimoes river as far inland as this) and its mighty tributary the Japura river. These huge waterways, each a kilometre or more across, merge at the entrance to the Reserve and create an even larger river, braided by islands.

The land between the rivers is lower than on either side, which is why this area always floods during the rainy season and for a month or two thereafter. The flood adds 10–15m to the height of the water; sufficient to submerge all land. This predictable, annual occurrence dominates all life here, whether it be large animal or small, trees, flowers, insects, birds, fish, fungi or human.

Dolphins, of course, have to adapt rather less to this change than do most land-based animals. They naturally rise and fall with the water level, and mostly have to take care not to become trapped as the water rushes out of the reserve in July, August and September. Fish are available year-round, so food is not usually a problem, and in fact prey becomes more concentrated when all water is forced into channels and streams within the forest.

Unlike many Reserves, Mamirauá was deliberately set up to function with its human inhabitants remaining in place rather than being removed. Only commercial resource extraction operations were banned, while locals are encouraged to manage the forest’s bountiful harvest in a sustainable way. And the experiment is working – the iconic Pirarucu, the world’s largest freshwater fish, has made a dramatic recovery here and can be seen by the hundreds during the season when males display for mates. The Reserve is also home to many other well-known Amazonian specialities such as piranha, jaguar, caiman, anaconda and more species of fish and bird than you can imagine!

Satellite image of the Amazon rainforest around the Mamirauá Reserve, showing the location of our study site (arrowed).