Upper Amazon Rivers and Streams - A Global Ecoregion

One of the most species rich freshwater ecosystem on earth

About the Area
The Amazon River has over 1,000 tributaries. Those originating in the Andes on the western perimeter of the basin are sediment-rich and appear muddy (called "whitewater" rivers), while the ones in Guiana Highlands to the north of the Amazon River tend to be nutrient-poor and appear black (called "blackwater" rivers).

These interconnected waterways form the Upper Amazon Rivers and Streams ecoregion, where hundreds of endemic fish live making it the most species rich freshwater ecosystem on earth.

Local Species
The entire Amazon region has more than 1,300 described fish species with many more that remain to be discovered. The Amazon's piedmont streams have not been well investigated, but it is known that they harbor an incredible array of aquatic species, particularly fish.

For example, More than 500 species are known from just one of the rivers in this region - the Napo River.

Fish groups with high numbers of species representation include Characins (e.g., tetras, piranhas, pacus), Catfishes (e.g., doradids, loricariids, pimelodids), Gymnotoids ("electric eels"), Osteoglossids (relic "bony-tongues"), and Cichlids. Other aquatic species are expected to show high levels of diversity as well.

Threats
Hydroelectric dams, deforestation of headwater catchments for logging, and conversion to agriculture and pasture is a potentially serious problem leading to erosion and altered hydrologic regimes, further disturbing the movements of migratory fish species.

Other serious threats include oil development, pipelines, mining activities, and construction of roads and railroads that open up access to the region and increase levels of hunting and fishing. Habitat protection is severely hampered in the northwest portion of the basin where illegal narcotics activities predominate.

Resources
• NationalGeographic.com