Brazilian Shield Amazonian Rivers & Streams - A Global Ecoregion
Largest, most distinctive clear-water river ecosystem of South America
Snapshot: Ecoregion 154
Size:
2,500,000 sq. km (1,000,000 sq. miles)
Habitat type:
Large River Headwaters
Geographic Location:
Central South America: Brazil, Bolivia, and Paraguay
Conservation Status:
Vulnerable
Quiz Time!
Why is the Dourada Zebra so called?
Answer:
The dourada zebra is a large catfish that has zebra-like stripes and hence the name. It is rarely caught and is found only in the upper Rio Madeira and the Caquetá region of Columbia.
About the Area
The Brazilian Shield is the pre-cambrian geologic formation lying primarily south of the Amazon River. The ancient sedimentary rocks of the Brazilian Shield are well weathered, and the tributaries draining them tend to be nutrient-poor "clearwater" rivers, named for their transparency.
Hundreds of rivers and streams flow through this area on their way to the Amazon River. Despite the low nutrient content of the water, these rivers are believed to contain exceptional levels of aquatic diversity, with a large number of migratory fish species.Local Species
Similar to the Upper Amazon Rivers and Streams, this ecoregion includes species from a number of fish families.
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
This ecoregion comprises the most altered part of the Amazon basin. Threats include petroleum and mineral exploration, logging, construction of dams, agricultural expansion, pasture development, and overexploitation of aquatic species.
Resources
• NationalGeographic.com
