Design-based and model-based inference in surveys of freshwater mollusks
R.M. Dorazio
1999, Journal of the North American Benthological Society (18) 118-131
Well-known concepts in statistical inference and sampling theory are used to develop recommendations for planning and analyzing the results of quantitative surveys of freshwater mollusks. Two methods of inference commonly used in survey sampling (design-based and model-based) are described and illustrated using...
Basin waves on a seafloor recording of the 1990 Upland, California, earthquake: Implications for ground motions from a larger earthquake
D.M. Boore
1999, Bulletin of the Seismological Society of America (89) 317-324
The velocity and displacement time series from a recording on the seafloor at 74 km from the 1990 Upland earthquake (M = 5.6) are dominated by late-arriving waves with periods of 6 to 7 sec. These waves are probably surface waves traveling across the...
Temporal and spatial variability of the sediment grain-size distribution on the Eel shelf: The flood layer of 1995
D.E. Drake
1999, Marine Geology (154) 169-182
Sediment grain-size characteristics observed on the Eel shelf have been analyzed using a wet-sieving technique that minimizes breakage of aggregates. At several sites on the 70-m isobath north of the river, where a 1995 flood layer attained a maximum thickness of about 9 cm, replicate box cores were collected on...
The use of modeling in restoration ecology: The Everglades case
Donald L. DeAngelis
1999, Conference Paper, Perspectives in ecology : a glance from the VII International Congress of Ecology, Florence 19-25 July 1998
No abstract available....
Seismic activity of the San Francisco Bay region
W. H. Bakun
1999, Bulletin of the Seismological Society of America (89) 764-784
Moment magnitude M with objective confidence-level uncertainties are estimated for felt San Francisco Bay region earthquakes using Bakun and Went-worth's (1997) analysis strategy for seismic intensity observations. The frequency-magnitude distribution is well described for M ≧ 5.5 events since 1850 by a Gutenberg-Richter relation with a b-value of...
Application of spatially referenced regression modeling for the evaluation of total nitrogen loading in the Chesapeake Bay watershed
Stephen D. Preston, John W. Brakebill
1999, Water-Resources Investigations Report 99-4054
The reduction of stream nutrient loads is an important part of current efforts to improve water quality in the Chesapeake Bay. To design programs that will effectively reduce stream nutrient loading, resource managers need spatially detailed information that describes the location of nutrient sources and the watershed factors that affect...
Calculation of broadband time histories of ground motion: Comparison of methods and validation using strong-ground motion from the 1994 Northridge earthquake
S. Hartzell, S. Harmsen, A. Frankel, S. Larsen
1999, Bulletin of the Seismological Society of America (89) 1484-1504
This article compares techniques for calculating broadband time histories of ground motion in the near field of a finite fault by comparing synthetics with the strong-motion data set for the 1994 Northridge earthquake. Based on this comparison, a preferred methodology is presented. Ground-motion-simulation...
Individual-based models in ecology: An overview
Donald L. DeAngelis, D. M. Fleming, L.J. Gross, W.F. Wolff
James G. Sanderson, Larry D. Harris, editor(s)
1999, Book chapter, Landscape ecology: A top-down approach
No abstract available....
Water-sediment controversy in setting environmental standards for selenium
Steven J. Hamilton, A. Dennis Lemly
1999, Ecotoxicology and Environmental Safety (44) 227-235
A substantial amount of laboratory and field research on selenium effects to biota has been accomplished since the national water quality criterion was published for selenium in 1987. Many articles have documented adverse effects on biota at concentrations below the current chronic criterion of 5 μg/L. This commentary will present...
Multi-year persistence of oil mousse on high energy beaches distant from the Exxon Valdez spill origin
Gail V. Irvine, Daniel H. Mann, Jeffrey W. Short
1999, Marine Pollution Bulletin (38) 572-584
For at least 5 yr after the Exxon Valdez spill, relatively unweathered oil mousse has persisted on the exposed rocky shores of Shelikof Strait 500 km from Prince William Sound, Alaska. Previously it was thought that oil would be rapidly removed from such geomorphic settings by wave action. Oil mousse...
Modeling variability in replicated surveys at aggregation sites
Mark S. Udevitz
Gerald W. Garner, Steven C. Amstrup, Jeffrey L. Laake, Bryan F.J. Manly, Lyman L. McDonald, Donna G. Robertson, editor(s)
1999, Conference Paper, Marine mammal survey and assessment methods
Surveys of aggregation sites can provide unbiased estimates of annual trends in population size if the proportion of the population counted at these sites does not vary systematically among years. However, counts at these sites tend to be highly variable and resulting trend estimates typically have poor precision. I developed...
Global to local scale simulations of streamflow in the Merced, American, and Carson Rivers, Sierra Nevada, California
M. D. Dettinger, D.R. Cayan, K. Mo, A.E. Jeton
1999, Conference Paper
Atmospheric moisture transport and moisture budgets during winter (December-April) simulated by the National Centers for Environmental Prediction (NCEP) regional spectral model (RSM) are examined and used to simulate streamflow variations in the Sierra Nevada. The RSM was nested in 2"-latitude x 2"-longitude NCEPreanalyzed atmospheric-data fields (as a surrogate for a...
Riparian restoration using physical manipulation and natural seedfall
G.T. Auble
1999, Conference Paper, Riparian ecosystem restoration in the Gila River Basin: Opportunities and constraints : Workshop proceedings, April 8-9, 1999, Tucson, AZ
In many arid landscapes, riparian sites are the only places wet enough to support trees. The vertical structure of trees and shrubs is critical to many riparian habitat and aesthetic values (Brinson et al. 1981). Thus, woody vegetation is often an important objective and success measure for riparian restoration....
Transitions in forest fragmentation: implications for restoration opportunities at regional scales
James D. Wickham, K. Bruce Jones, Kurt H. Riitters, Timothy G. Wade, Robert V. O’Neill
1999, Landscape Ecology (14) 137-145
Where the potential natural vegetation is continuous forest (e.g., eastern US), a region can be divided into smaller units (e.g., counties, watersheds), and a graph of the proportion of forest in the largest patch versus the proportion in anthropogenic cover can be used as an index of forest fragmentation. If...
Biophysical mechanisms of trichloroethene uptake and loss in baldcypress growing in shallow contaminated groundwater
C.T. Nietch, J. T. Morris, D.A. Vroblesky
1999, Environmental Science & Technology (33) 2899-2904
Wetland vegetation may be useful in the remediation of shallow contaminated aquifers. Mesocosm experiments were conducted to describe the regulatory mechanisms affecting trichloroethene (TCE) removal rates from groundwater by flood-adapted wetland trees at a contaminated site. TCE flux through baldcypress [Taxodium distichum (L) Rich] seedlings grown in glass- carboys decreased...
Guidelines for proper care and use of wildlife in field research
M. Friend, D. E. Toweill, R.L. Borwnell Jr., V. F. Nettles, D.S. Davis, W.J. Foreyt
1999, Information and Technology Report 1999-0001
Public attitudes towards animals continue to change over time. These changes apply to wildlife along with other species, and in recent years, attitudes have been increasingly oriented toward assuring that all species receive proper care whenever human interactions are involved. Guidance regarding the application of euthanasia is provided in the...
Professional conduct of scientists during volcanic crises
IAVCEI Subcommittee for Crisis Protocols, Chris Newhall, Shigeo Aramaki, Franco Barberi, Russell Blong, Marta Calvache, Jean-Louis Cheminee, Raymundo Punongbayan, Claus Siebe, Tom Simkin, Stephen Sparks, Wimpy Tjetjep
1999, Bulletin of Volcanology (60) 323-334
Stress during volcanic crises is high, and any friction between scientists can distract seriously from both humanitarian and scientific effort. Friction can arise, for example, if team members do not share all of their data, if differences in scientific interpretation erupt into public controversy, or if one scientist begins work...
The influence of seagrass on shell layers and Florida Bay mudbanks
E. J. Prager, R. B. Halley
1999, Journal of Coastal Research (15) 1151-1162
Aerial photography indicates that sometime since the early 1970's, an emergent ridge of shell debris developed on a mudbank north of Calusa Key in Florida Bay. Coarse shell deposits on and within the Bay's shallow mudbanks are believed to be the product of transport during major storm events and subsequent...
Biochemical analysis of plant protection afforded by a nonpathogenic endophytic mutant of Colletotrichum magna
R. S. Redman, S. Freeman, D.R. Clifton, J. Morrel, G. Brown, R. J. Rodriguez
1999, Plant Physiology (119) 795-804
A nonpathogenic mutant of Colletotrichum magna (path-1) was previously shown to protect watermelon (Citrullus lanatus) and cucumber (Cucumis sativus) seedlings from anthracnose disease elicited by wild-type C. magna. Disease protection was observed in stems of path-1-colonized cucurbits but not in cotyledons, indicating that path-1 conferred tissue-specific and/or localized protection. Plant...
Post audit of a numerical prediction of wellfield drawdown in a semiconfined aquifer system
M. Stewart, C. Langevin
1999, Groundwater (37) 245-252
A numerical ground water flow model was created in 1978 and revised in 1981 to predict the drawdown effects of a proposed municipal wellfield permitted to withdraw 30 million gallons per day (mgd; 1.1 × 105 m3/day) of water from the semiconfined Floridan Aquifer system....
Estimation of potential runoff-contributing areas in the Kansas-Lower Republican River basin, Kansas
Kyle E. Juracek
1999, Water-Resources Investigations Report 99-4089
Digital soils and topographic data were used to estimate and compare potential runoff-contributing areas for 19 selected subbasins representing soil, slope, and runoff variability within the Kansas-Lower Republican (KLR) River Basin. Potential runoff-contributing areas were estimated separately and collectively for the processes of infiltration-excess and saturation-excess overland flow using a...
Geology of Unga Island and the northwestern part of Popof Island: Chapter 2 in A geological and geophysical study of the gold-silver vein system of Unga Island, Southwestern Alaska
James R. Riehle, Frederic H. Wilson, Nora B. Shew, Willis H. White
1999, Open-File Report 99-136-2
The first geologic map of Unga Island was published by Atwood (1911; scale 1:250,000), who correctly inferred the middle Tertiary age of the volcanic rocks and made the important distinction between the lava flows and the intrusive domes. Although Burk's (1964) reconnaissance map of the Alaska Peninsula (scale 1:250,000) has...
The mathematics of movement
Douglas H. Johnson
1999, Prairie Naturalist (31) 125-127
Review of: Quantitative Analysis of Movement: Measuring and Modeling Population Redistribution in Animals and Plants. Peter Turchin. 1998. Sinauer Associates, Sunderland, MA. 306 pages. $38.95 (paper)....
The relative importance of light and nutrient limitation of phytoplankton growth: A simple index of coastal ecosystem sensitivity to nutrient enrichment
J. E. Cloern
1999, Aquatic Ecology (33) 3-16
Anthropogenic nutrient enrichment of the coastal zone is now a well-established fact. However, there is still uncertainty about the mechanisms through which nutrient enrichment can disrupt biological communities and ecosystem processes in the coastal zone. For example, while some estuaries exhibit classic symptoms of acute eutrophication, including enhanced production of...
Cooling rates and crystallization dynamics of shallow level pegmatite-aplite dikes, San Diego County, California
Karen L. Webber, William B. Simmons, Alexander U. Falster, Eugene E. Foord
1999, American Mineralogist (84) 708-717
Pegmatites of the Pala and Mesa Grande Pegmatite Districts, San Diego County, California are typically thin, sheet-like composite pegmatite-aplite dikes. Aplitic portions of many dikes display pronounced mineralogical layering referred to as "line rock," characterized by fine-grained, garnet-rich bands alternating with albite- and quartz-rich bands. Thermal modeling was performed for...
