that are vital components of the Amazon basin. Freshwater
ecosystems are connected via the hydrological cycle
to adjacent systems: laterally (water-land), longitudinally
(up- and down-stream), and vertically (atmospheresurface
water-ground water; Ward 1989, Pringle 2003).
The hydrological connectivity of freshwater ecosystems
makes them highly sensitive to a broad range of anthropogenic
impacts occurring in both aquatic and terrestrial
ecosystems at local and distant locations. Globally,
this hydrological connectivity has exacerbated the impacts
caused by the large populations typically found near
freshwater ecosystems, creating some of the most altered
systems on Earth (Malmqvist & Rundle 2002; Carpenter
et al. 2011).
How vulnerable are freshwater ecosystems in the Amazon
to leading anthropogenic pressures? This question is