The Brazilian Shield

The Brazilian Shield shares some if its ancient geologic history with the Guiana Shield. Bedrock underlying both regions is part of the cratonic nucleus of South America, having participated in the ancient supercontinents Gondwana, Pangaea

and Columbia. In contrast to its northern neighbor, the Brazilian Shield lacks the thick overlying sedimentary formations that form table-top mountains. This has led to fewer and smaller waterfalls, but much more extensive and ubiquitous bedrock rapids. These rapids harbor some of the most diverse fish primary consumer assemblages of any river in the world, including many endemic and spectacularly colored benthic species. Amazon Basin tributaries that drain the Brazilian Shield, including the Tapajós, Xingú and Tocantíns rivers, all have clear water from watersheds dominated by shield bedrock. Combinations of clear water with solid substrates, shallow rapids and diverse colorful fish assemblages create freshwater ecological conditions comparable to those of a coral reef.

Brazil

 

I have participated in two expeditions to the Brazilian Shield in Para State, Brazil, and co-authored a NSF Biodiversity Discovery and Analysis Grant (DEB-1257813, the iXingu Project) that allowed for extensive aquatic biodiversity inventories and trophic ecological research to be conducted in the lower Xingu River, a river that drains most of the central Brazilian Shield. This grant provided me one year of post-doctoral support. The incredibly diverse and complex habitats of the lower Xingu River are imperilled by imminent completion of the enormous Belo Monte Dam complex, making the iXingu Project's observations of intact biodiversity and natural ecological conditions incredibly important for future generations. Specimens that I collected in the Brazilian Shield have contributed to several new species description, one of which I authored. For a website with photos of fishes collected during the 2007 Serra do Cachimbo Expedition, click here. For more information on my fieldwork in rivers of the Brazilian Shield, click on the following: