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John D. Powell

Publications and source records attributed to John D. Powell.

4 recordsLinked to original sources
USGS2016

Genetic status and conservation of Westslope Cutthroat Trout in Glacier National Park

Invasive hybridization is one of the greatest threats to the persistence of Westslope Cutthroat Trout Oncorhynchus clarkii lewisi . Large protected areas, where nonhybridized populations are interconnected and express historical life history and genetic diversity, provide some of the last ecological and evolutionary strongholds for conserving this species. Here, we describe the genetic status and distribution of Westslope Cutthroat Trout throughout Glacier National Park, Montana. Admixture between Westslope Cutthroat Trout and introduced Rainbow Trout O. mykiss and Yellowstone Cutthroat Trout O. clarkii bouvieri was estimated by genotyping 1,622 fish collected at 115 sites distributed throughout the Columbia, Missouri, and South Saskatchewan River drainages. Currently, Westslope Cutthroat Trout occupy an estimated 1,465 km of stream habitat and 45 lakes (9,218 ha) in Glacier National Park. There was no evidence of introgression in samples from 32 sites along 587 km of stream length (40% of the stream kilometers currently occupied) and 17 lakes (2,555 ha; 46% of the lake area currently occupied). However, nearly all (97%) of the streams and lakes that were occupied by nonhybridized populations occurred in the Columbia River basin. Based on genetic status (nonnative genetic admixture ≤ 10%), 36 Westslope Cutthroat Trout populations occupying 821 km of stream and 5,482 ha of lakes were identified as “conservation populations.” Most of the conservation populations ( N = 27; 736 km of stream habitat) occurred in the Columbia River basin, whereas only a few geographically restricted populations were found in the South Saskatchewan River ( N = 7; 55 km) and Missouri River ( N = 2; 30 km) basins. Westslope Cutthroat Trout appear to be at imminent risk of genomic extinction in the South Saskatchewan and Missouri River basins, whereas populations in the Columbia River basin are widely distributed and conservation efforts are actively addressing threats from hybridization and other stressors. A diverse set of pro-active management approaches will be required to conserve, protect, and restore Westslope Cutthroat Trout populations in Glacier National Park throughout the 21st century.

Glacier National Park↗
USGS1985

Relation between ground-water quality and mineralogy in the coal-producing Norton Formation of Buchanan County, Virginia

The geochemical processes controlling ground-water chemistry in the coal-producing strata of southwestern Virginia include hydrolysis of silicates, dissolution of carbonates, oxidation of pyrite, cation exchange, and precipitation of secondary minerals, kaolinite and goethite. Core material from the Norton Formation of the Pennsylvania Period is composed of slightly more than one-half sandstone; siltstone and minor amounts of shale, clay, and coal account for the majority of the remainder. Petrographic analyses and x-ray diffraction studies indicate that the sandstone is about 75 percent quartz, 15 percent plagioclase feldspar, 2 percent potassium feldspar, 2 percent muscovite, 4 percent chlorite, and 1 percent siderite. Calcite is present in small amounts and in a few strata as clasts or cement. No limestone strata were identified. The siltstone is about 50 percent quartz, 10 percent plagioclase feldspar, 10 percent mica, 20 percent chlorite, and from 0 to 25 percent siderite. Pyrite is associated with some siltstone and, where present, generally accounts for less than 1 percent. Total sulfur generally constitutes less than 0.1 percent of core samples but about 4 percent in the more pyrite-rich layers. Three reaction models are used to account for the observed water chemistry. The models derive sulfate from pyrite, iron from pyrite and siderite, calcium from plagioclase and calcite, sodium from plagioclase and cation exchange, magnesium from chlorite, and carbon from carbon dioxide, calcite, and siderite. Kaolinite, chalcedony, and goethite are formed authigenically. Carbon-13 data define the relative contributions of carbon sources to models. Comparison of adjacent unmined and mined basins indicates that surface mining significantly increases the weathering reaction of pyrite in contrast to weathering reactions of other minerals. However, in the area studied, reactive pyrite does not appear to be present in sufficient quantities in strata associated with mined coal seams to cause acid mine drainage.

Virginia↗
USGS1983

Quality of ground water in southern Buchanan County, Virginia

In seven small contiguous stream basins in the coal area of southwest Virginia, ground water is predominantly bicarbonate in anion composition, with calcium as the major cation in the ridges and sodium the major cation in the lower altitudes. Sulfate is the major anion in water associated with coal seams and in stream waters draining areas extensively disturbed by mining activities. Water found along a major linear feature in the Big Prater Creek valley and water from deep wells in Levisa Fork basin contain chloride as the predominant anion. Hydrogen ion activities (pH) in the ground water range from 5.2 to 8.4. Iron concentrations as high as 14,000 micrograms per liter are present in domestic wells. The chemical composition of most streams changes with diminishing discharge and at baseflow is similar to the composition of local ground water. At high flows, streams draining mined areas are enriched with sulfate. (USGS)

Water-Resources Investigations Report↗