Mercury and selenium accumulation in the Colorado River food web, Grand Canyon, USA.

Using Otolith Chemistry Tags and Growth Patterns to Distinguish Movements and Provenance of Native Fish in the Grand Canyon

Fish otolith and water chemistry were assessed in the Grand Canyon reach of the Colorado River and its tributaries. Aqueous strontium and selenium (in ratio to calcium) and carbon stable isotopic ratios were identified as markers with excellent potential to track the provenance and movements of the endangered humpback chub Gila cypha. Although otolith dC and Sr/Ca varied proportionately to wate...

The Biogeographic Significance of a Large, Deep Canyon: Grand Canyon of the Colorado River, Southwestern USA

Factors Affecting Condition of Flannelmouth Suckers in the Colorado River, Grand Canyon, Arizona

—The impoundment of the Colorado River by Glen Canyon Dam, Arizona, in 1963 created a highly regulated environment in the Grand Canyon that altered the native fish populations, including the flannelmouth sucker Catostomus latipinnis. Flannelmouth suckers were sampled from 1991 to 2001 to determine seasonal, annual, and spatial trends in fish condition (i.e., relative weight [Wr]). Mean Wr peake...

The mystery of the pre–Grand Canyon Colorado River— Results from the Muddy Creek Formation

The Colorado River’s integration off the Colorado Plateau remains a classic mystery in geology, despite its pivotal role in the cutting of Grand Canyon and the region’s landscape evolution. The upper paleodrainage apparently reached the southern plateau in the Miocene, and recent work supports the longstanding idea that the river was superimposed over the Kaibab uplift by this time. Once off th...

Numerical modeling of the late Cenozoic geomorphic evolution of Grand

The late Cenozoic geomorphic evolution of Grand Canyon has been infl uenced by three primary tectonic and drainage adjustment events. First, 1 km of relief was produced along the Grand Wash–Wheeler Fault system beginning at 16.5 Ma. Second, the ancestral Colorado River became integrated with the lower Colorado River through Grand Canyon between 5.5 and 6 Ma. Third, the Colorado River was infl u...