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Lake Powell retains most of the phosphorus that it receives, leading to downstream phosphorus limitation. These data were compiled to examine controls on phosphorus cycling below Lake Powell in the Colorado River and from storm inputs from the Paria River. Objectives of our study were to determine how several forms of phosphorus, both organic and inorganic, were cycled under varying dissolved oxygen concentrations and pH, reflecting the range of values observed in the river over the years. These data represent nitrogen, phosphorus, calcium, and carbon concentrations, water quality parameters (pH, dissolved oxygen, temperature), sediment composition, total protein, and extracellular enzyme activity (alkaline phosphatase)....
Categories: Data; Tags: Aquatic Biology, Arizona, Colorado River, Ecology, Geochemistry, All tags...
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These data were acquired from 7 study sites distributed across the range of Gopherus agassizii. Data were collected from 1997 to 2002 as part of three separate studies, although data were not collected at all sites in each year. Radio-transmitters were attached to the carapace of 151 females and VHF radio-telemetry was used to relocate animals to assess reproductive status. Egg production was determined from X-radiographs taken weekly/biweekly intervals (depending on the study) using a portable X-ray machine between April and July or August of each year. In addition, the mean carapace length (MCL) of each tortoise was measured at each time of capture or recapture using calipers (mm). A nesting event was recorded...
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Lake Mead National Recreation Area, Nevada. Boulder Canyon dam site (Hoover Dam), showing barges used in diamond drill work. Plate 9-A, U.S. Geological Survey Water-Supply Paper 556.
Lake Mead National Recreational Area (LMNRA) serves as critical habitat for several federally listed species and supplies water for municipal, domestic, and agricultural use in the Southwestern U.S. Contaminant sources and concentrations vary among sub-basins within LMNRA. To investigate whether environmental contaminant exposure is associated with alterations in male common carp (Cyprinus carpio) gamete quality and endocrine- and reproductive parameters, data were collected among sub-basins (n = 7) over 7 years (1999 to 2006). Endpoints included the sperm quality parameters of motility, viability, mitochondrial membrane potential, count, morphology, and DNA fragmentation; plasma components were vitellogenin (VTG),...
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Lake Mead National Recreation Area, Nevada. The "Temple," a butte of conglomerate above the mouth of the Virgin River. The Virgin River enters the Colorado just above the point where the major stream makes its final sharp right angle turn, flowing due south. Colorado River Survey of 1923 (Birdseye).
    map background search result map search result map Lake Mead National Recreation Area, Nevada. The "Temple," a butte of conglomerate above the mouth of the Virgin River. Lake Mead National Recreation Area, Nevada. Boulder Canyon dam site (Hoover Dam), showing barges used in diamond drill work. Mojave Desert Tortoise (Gopherus agassizii) Morphometrics and Egg Data from Seven Sites across the Mojave, (1997-2002) Phosphorus, nitrogen, carbon, calcium, pH, and dissolved oxygen data from incubations of Colorado River water and sediment and associated ambient river water measurements Lake Mead National Recreation Area, Nevada. The "Temple," a butte of conglomerate above the mouth of the Virgin River. Lake Mead National Recreation Area, Nevada. Boulder Canyon dam site (Hoover Dam), showing barges used in diamond drill work. Phosphorus, nitrogen, carbon, calcium, pH, and dissolved oxygen data from incubations of Colorado River water and sediment and associated ambient river water measurements Mojave Desert Tortoise (Gopherus agassizii) Morphometrics and Egg Data from Seven Sites across the Mojave, (1997-2002)