The distribution of species richness can be described at different spatial grain. Here, as an example, the Amazon Basin is divided into 23 major sub-basin units greater than 20 000 km2. At this spatial grain (Level 1), the Negro and Madeira river basins show the highest fish diversity with 1 126 and 1 373 species, respectively.
The map is interactive: click on each sub-basins area to see richness at a finer spatial resolution (Level 2). Click on the dark grey zone to go back to Level 1. Project in progress, given values are temporary.