Publications
Publications from USGS science centers throughout the Southeast Region.
Filter Total Items: 9969
Marsh submergence vs. marsh accretion: Interpreting accretion deficit data in coastal Louisiana
The apparent imbalance between relative sea-level rise and vertical marsh accretion is frequently cited as a major factor in the problem of wetland loss in Louisiana. Rates of relative sea-level rise are high in Louisiana due to high rates of subsidence. Although marsh accretion rates are also high, they are usually insufficient to maintain the relative elevation of the marsh surface. This situati
Authors
Denise J. Reed, Donald R. Cahoon
The examination of a competition matrix for transitivity and intransitive loops
Recent examinations of competition matrices for transitivity (species A > species B > species C) have used techniques that can be subject to certain biases. First, recent theoretical and empirical analyses have shown that traditional measures of competitive performance are biased in favor of the larger species. It is argued that this size bias has the potential to bias analyses of transitivity. Se
Authors
James B. Grace, Glenn R. Guntenspergen, Janet R. Keough
The role of epiphytes in seagrass production and survival: Microcosm studies and simulation modeling
No abstract available.
Authors
Hilary A. Neckles
Large-scale dialysis of sample lipids
The use of a semipermeable membrane device (SPMD) for dialysis in an organic solvent phase is an efficient alternative approach to separation of contaminants from large amounts of lipid (up to 50 grams or more) prior to organic chemical analysis. Passive separation of contaminants can be accomplished with a minimum of equipment and a comparatively small volume of solvent. This study examines the e
Authors
Jill Meadows, Donald E. Tillitt, James Huckins, D. Schroeder
The effects of low pH and elevated aluminum on yellowstone cutthroat trout (Oncorhynchus clarki bouvieri)
Although acid deposition is not considered a problem in the western United States, surface waters in high elevations and fish inhabiting these waters may be vulnerable to acidification. This study examined the sensitivity of a western salmonid to acid and aluminum stress. Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri; YSC) were exposed for 7 d during each of four early life stages, or
Authors
Aïda M. Farag, Daniel F. Woodward, Edward E. Little, B. L. Steadman, Frank A. Vertucci
Bioaccumulation of organic and inorganic selenium in a laboratory food chain
Aquatic organisms accumulated selenium (Se) from inorganic and organic Se species via aqueous and food-chain exposure routes. We measured aqueous and food-chain Se bioaccumulation from selenate, selenite, and seleno-L-methionine in a laboratory food chain of algae (Chlamydomonas reinhardtii), daphnids (Daphnia magna), and fish (bluegill, Lepomis macrochirus). Selenium concentrations were monitored
Authors
John M. Besser, Timothy J. Canfield, Thomas W. La Point
Using a Geographic Information System to determine the relation between stream quality and geology in the Roberts Creek watershed, Clayton County, Iowa
A geographic information system (GIS) was used to determine the relation between the stream-water quality and underlying geology in Roberts Creek watershed, Clayton County, Iowa, for base-flow conditions during the spring and summer of 1988–90. Geologic, stream, basin and subbasin boundaries, and water-quality sampling-site coverages were created by digitizing available maps. A contour coverage wa
Authors
Stephen J. Kalkhoff
Hydrologic and land-use factors associated with herbicides and nitrate in near-surface aquifers
Selected herbicides, atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) metabolites, and NO−3 were examined in near-surface unconsolidated and bedrock aquifers in the midcontinental USA to study the hydrogeologic, spatial, and seasonal distribution of these contaminants. Groundwater samples were collected from 303 wells during the spring and late summer of 1991. At least one herbicide or
Authors
Michael R. Burkart, Dana W. Kolpin
Application of a geographic information system in analyzing the occurrence of atrazine in groundwater of the mid-continental United States
The US Geological Survey, US Department of Agriculture, and US Environmental Protection Agency are conducting research and regional assessments in support of policy alternatives intended to protect water resources from agricultural chemical contamination. The mid-continent was selected because of the intense row crop agriculture and associated herbicide application in this region. An application o
Authors
M. R. Burkart, D.W. Kolpin
Application of semipermeable membrane devices (SPMDs) as passive air samplers
The semipermeable membrane device (SPMD), consisting of a neutral lipid (triolein) enclosed in polyethylene layflat tubing, is demonstrated to be a highly efficient passive air sampler. These devices readily sequester lipophilic organic contaminants from the vapor phase. Specifically, the SPMDs are shown to concentrate polychlorinated biphenyl (PCB) residues from a laboratory atmosphere in a linea
Authors
Jimmie D. Petty, James N. Huckins, James L. Zajicek
Survival of female canvasbacks wintering in coastal Louisiana
Annual survival probabilities of female canvasbacks (Aythya valisineria) are lower than those of males, but sources and timing of mortality are poorly understood. To further elucidate causes of reduced annual survival in female canvasbacks, we estimated survival rates for radio-tagged females in coastal Louisiana during winters 1988-91. Survival estimates for winters 1988-91 were 0.946 ± 0.072 (es
Authors
William L. Hohman, Ronald D. Pritchert, Joseph Moore, D.O. Schaeffer