Fig. 2. Fragmentation of Andes-to-Amazon connectivity by hydropower dams.

(A) Freshwater ecoregions of the Andean Amazon (20), where most existing and proposed dams are concentrated in the Amazonas High Andes ecoregion. (B and C) Fragmentation for individual sub-basins under two scenarios: (B) dams existing and under construction and (C) all dams existing, under construction, and proposed. Color gradation from blue to red denotes increasing fragmentation, represented by decreasing total length of the individual river network. That is, fragmentation is increasing as rivers go from blue (big, connected river networks) to red (small, isolated river networks).