· A River from Many Places
· Special Features
· Did You Know?
· Wild Side
· Cause for Concern
· Looking Ahead

Global 200 Snapshot

The headwater streams of this tropical ecoregion are extremely species-rich, probably among the richest in the world.  

A River from Many Places

The Amazon River has more than 1,000 tributaries. Those originating in the Andes on the western perimeter of the basin, and in the Guiana Highlands to the north of the Amazon River, comprise the major aquatic habitats of this ecoregion. These interconnected waterways form the Upper Amazon Rivers and Streams ecoregion, where hundreds of endemic fish live.

Special Features

This enormous ecoregion includes the headwaters of two very species-rich rivers, the Amazon and the Orinoco. Tributaries to these rivers arising in the Andes are sediment-rich and appear muddy -- they are called "whitewater" rivers. Those formed in the Guiana Highlands in the north tend to be nutrient-poor and, thus, their waters are clear and appear black. These are called "blackwater" rivers.

Fish come from families, too. Several of the fish families, including charcins (Characidae), minnows (Cyprinidae), and siluroid catfishes (Siluridae), are part of a group called ostariophysan fishes. These fishes have an acute sense of hearing based on unusual adaptations of their anatomy: Their swim bladder, a gas-filled sac that helps fish remain buoyant, picks up sound waves from the water and resonates and amplifies them before sending them through several vertebrae to the ear.

Wild Side

Scientists have identified more than 1,300 fish species within the Amazon Basin, and they know many more remain to be discovered. The diversity of fishes found here is truly astounding. More than 500 species are known from just one of the rivers in this region--the Napo River. If you were to look beneath the water's surface, you’d think you'd walked into a huge tropical aquarium. Schools of small, colorful fish dart everywhere. You might also see different types of piranhas. Several members of larger fish also live here, including electric eels (gymnotids) and Loricariid catfishes. And if you got tired of seeing fish, you could look for the rare giant river otter and a variety of aquatic bird life.

Cause for Concern

Deforestation within the headwater areas for timber and conversion to agriculture and pasture is a potentially serious problem, leading to soil flowing off the land and into the rivers and streams. Hydroelectric dams in this ecoregion also modify the natural flow of the rivers and streams and block the movements of migratory fish species. Oil drilling and transport through pipelines occur primarily in the Cordillera Oriental in the Andean portion of the Amazon, and mining activities are relatively widespread. Roads and railroads 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 drug trade and related activities predominate.

Looking Ahead

Check back soon for more about the conservation of this ecoregion.