Nest predation increases with parental activity: Separating nest site and parental activity effects
T. E. Martin, J. Scott, C. Menge
2000, Proceedings of the Royal Society B: Biological Sciences (267) 2287-2293
Alexander Skutch hypothesized that increased parental activity can increase the risk of nest predation. We tested this hypothesis using ten open-nesting bird species in Arizona, USA. Parental activity was greater during the nestling than incubation stage because parents visited the nest frequently to feed their young during the nestling stage....
Spatial and temporal variability of picocyanobacteria Synechococcus sp. in San Francisco Bay
X. Ning, J. E. Cloern, B.E. Cole
2000, Limnology and Oceanography (45) 695-702
We collected samples monthly, from April to August 1998, to measure the abundance of autotrophic picoplankton in San Francisco Bay. Samples taken along a 160-km transect showed that picocyanobacteria (Synechococcus sp.) was a persistent component of the San Francisco Bay phytoplankton in all the estuarine habitats, from freshwater to seawater...
Periphyton dynamics in a subalpine mountain stream during winter
G.W. Gustina, J.P. Hoffmann
2000, Arctic, Antarctic, and Alpine Research (32) 127-134
We conducted two experiments to determine the activity of and factors which control periphyton during winter in Stevensville Brook, Vermont. The first experiment during winter/spring 1994 examined the effect of a 300 to 450% difference in light and doubling of flow (low and high light, slow and fast flow) on...
Strontium isotope geochemistry of groundwaters and streams affected by agriculture, Locust Grove, MD
J.K. Böhlke, M. Horan
2000, Applied Geochemistry (15) 599-609
The effects of agriculture on the isotope geochemistry of Sr were investigated in two small watersheds in the Atlantic coastal plain of Maryland. Stratified shallow oxic groundwaters in both watersheds contained a retrievable record of increasing recharge rates of chemicals including NO3−, Cl, Mg, Ca and Sr that were correlated...
Fractures and their distribution in the tills of Ohio
C.S. Brockman, J.P. Szabo
2000, Ohio Journal of Science (100) 39-55
Fractures in till may be horizontal, parallel high- to low-angle, or polygonal (when viewed on a horizontal surface). They have been attributed to several geologic processes, the most important of which are desiccation, freeze-thaw, glaciotectonics, and lodgement till deposition. A literature review, a field study, and core examinations have identified...
Forest clearing and regional landsliding
D. R. Montgomery, K. M. Schmidt, H. M. Greenberg, W. E. Dietrich
2000, Geology (28) 311-314
The influence of forest clearing on landsliding is central to long-standing concern over the effects of timber harvesting on slope stability. Here we document a strong topographic control on shallow landsliding by combining unique ground-based landslide surveys in an intensively monitored study area with digital terrain modeling using high-resolution laser...
The use of earthquake rate changes as a stress meter at Kilauea volcano
J. Dieterich, V. Cayol, P. Okubo
2000, Nature (408) 457-460
Stress changes in the Earth's crust are generally estimated from model calculations that use near-surface deformation as an observational constraint. But the widespread correlation of changes of earthquake activity with stress has led to suggestions that stress changes might be calculated from earthquake occurrence rates obtained from seismicity catalogues. Although...
U.S. Geological Survey, remote sensing, and geoscience data: Using standards to serve us all
Michael G. Benson, John Faundeen
2000, Conference Paper, Proceedings of International Geoscience and Remote Sensing Symposium (IGARSS)
The U.S. Geological Survey (USGS) advocates the use of standards with geosciences and remotely sensed data and metadata for its own purposes and those of its customers. In activities that range from archiving data to making a product, the incorporation of standards makes these functions repeatable and understandable. More important,...
Potential oil and gas resources of the Arctic National Wildlife Refuge in Alaska: 1002 area
K. J. Bird
2000, Polar Geography (24) 13-34
A geologist with extensive experience in the study of northern Alaska's petroleum resources provides an overview of the first comprehensive reassessment of the petroleum potential of section 1002 of the Arctic National Wildlife Refuge since the original study of 1987. The paper surveys the region's geology, and provides a description...
Differences in topographic characteristics computed from 100- and 1000-m resolution digital elevation model data
D.M. Wolock, G.J. McCabe
2000, Hydrological Processes (14) 987-1002
Topographic characteristics computed from 100- and 1000-m resolution digital elevation model (DEM) data are compared for 50 locations representing varied terrain in the conterminous USA. The topographic characteristics are three parameters used extensively in hydrological research and modelling - slope (S), specific catchment area (A(s)) and a wetness index computed...
Fish remains from Homestead Cave and lake levels of the past 13,000 years in the Bonneville basin
J.M. Broughton, D.B. Madsen, Jay Quade
2000, Quaternary Research (53) 392-401
A late Quaternary ichthyofauna from Homestead Cave, Utah, provides a new source of information on lake history in the Bonneville basin. The fish, represented by 11 freshwater species, were accumulated between ~11,200 and ~1000 14C yr B.P. by scavenging owls. The 87Sr/86Sr ratio of Lake Bonneville varied with its elevation;...
Seasonal movement and habitat use by striped bass in the Combahee River, South Carolina
Kimberly A. Bjorgo, J. Jeffery Isely, C.S. Thomason
2000, Transactions of the American Fisheries Society (129) 1281-1287
Adult striped bass Morone saxatilis (N = 30, 656-906 mm total length) were captured by electrofishing during January-March 1998 in the Combahee River, South Carolina, and fitted with radio transmitters. Their exact locations were recorded biweekly through December. From January to early April, striped bass were located in the tidally...
Identifying the usage patterns of methyl tert-butyl ether (MTBE) and other oxygenates in gasoline using gasoline surveys
M.J. Moran, R.M. Clawges, J.S. Zogorski
2000, Conference Paper, ACS National Meeting Book of Abstracts
Data on the volumes of oxygenates and other compounds in gasoline are available from several sources collectively referred as gasoline surveys. The gasoline surveys provide the most definitive knowledge of which oxygenate, if any, and what volumes of that oxygenate are being used in various areas of the country. This...
Carbonate-shelf depositional environments of the Ordovician Viola formation in South-Central Kansas
K.D. Newell
2000, The Compass: Earth Science Journal of Sigma Gamma Epsilon (75) 90-100
The Upper Ordovician Viola Formation, an important petroleum reservoir in the Midcontinent, is a carbonate unit present over much of the subsurface in Kansas. The Viola is composed of two fining-upward sedimentary packages that are separated from each other by a minor karstic surface representing a brief period of exposure....
Post-early cretaceous landform evolution along the western margin of the Bancannia trough, western NSW
D.L. Gibson
2000, Rangeland Journal (22) 32-43
Previously undated post-Devonian sediments outcropping north of Fowlers Gap station near the western margin of the Bancannia Trough are shown by plant macro- and microfossil determinations to be of Early Cretaceous (most likely Neocomian and/or Aptian) age, and thus part of the Eromanga Basin. They are assigned to the previously...
Facies patterns and conodont biogeography in Arctic Alaska and the Canadian Arctic Islands: Evidence against juxtaposition of these areas during early Paleozoic time
Julie A. Dumoulin, A. G. Harris, D. C. Bradley, T. A. De Freitas
2000, Polarforschung (68) 257-266
Differences in lithofacies and biofacies suggest that lower Paleozoic rocks now exposed in Arctic Alaska and the Canadian Arctic Islands did not form as part of a single depositional system. Lithologic contrasts are noted in shallow- and deep-water strata and are especially marked in Ordovician and Silurian rocks. A widespread...
Kelp forest fish populations in marine reserves and adjacent exploited areas of central California
M.J. Paddack, J. A. Estes
2000, Ecological Applications (10) 855-870
Population structure (density and size distribution) of 10 species of epibenthic kelp forest fishes was compared between three marine reserves and adjacent exploited areas in central California. We also contrasted substrate relief, algal turf cover, and kelp population density among these areas. Densities of fishes were 12–35% greater within the...
Pesticide transport in the San Joaquin River Basin
Neil M. Dubrovsky, Charles R. Kratzer, Sandra Y. Panshin, JoAnn M. Gronberg, Kathryn M. Kuivila
2000, Conference Paper, Agrochemical fate and movement
Pesticide occurrence and concentrations were evaluated in the San Joaquin River Basin to determine potential sources and mode of transport. Land use in the basin is mainly agricultural. Spatial variations in pesticide occurrence were evaluated in relation to pesticide application and cropping patterns in three contrasting subbasins...
Landscape-based spatially explicit species index models for everglades restoration
J. L. Curnutt, J. Comiskey, M.P. Nott, L.J. Gross
2000, Ecological Applications (10) 1849-1860
As part of the effort to restore the ∼10 000-km2 Everglades drainage in southern Florida, USA, we developed spatially explicit species index (SESI) models of a number of species and species groups. In this paper we describe the methodology and results of three such models: those for the Cape Sable Seaside Sparrow...
Sensitivity of species habitat-relationship model performance to factors of scale
J.W. Karl, P.J. Heglund, E.O. Garton, J. M. Scott, N.M. Wright, R.L. Hutto
2000, Ecological Applications (10) 1690-1705
Researchers have come to different conclusions about the usefulness of habitat-relationship models for predicting species presence or absence. This difference frequently stems from a failure to recognize the effects of spatial scales at which the models are applied. We examined the effects of model complexity, spatial data resolution, and scale...
Contribution of landbird migration to the biological diversity of the northwest gulf coastal plain
W.C. Barrow Jr., R.B. Hamilton, M.A. Powell, K. Ouchley
2000, Conference Paper, Texas Journal of Science
This study examined seasonal diversity and feeding behavior of those avian species utilizing that region of the Northwest Gulf Coastal Plain known as the Chenier Plain. Field observations were conducted at three forested locations on coastal cheniers for three years (1993-95) in the spring and at one location for three...
Statistical evaluation of effects of riparian buffers on nitrate and ground water quality
T.B. Spruill
2000, Journal of Environmental Quality (29) 1523-1538
A study was conducted to statistically evaluate the effectiveness of riparian buffers for decreasing nitrate concentrations in ground water and for affecting other chemical constituents. Values for pH, specific conductance, alkalinity, dissolved organic carbon (DOC), silica, ammonium, phosphorus, iron, and manganese at 28 sites in the Contentnea Creek Basin were...
Using an analytical geometry method to improve tiltmeter data presentation
Wen-June Su
2000, Environmental & Engineering Geoscience (6) 227-245
The tiltmeter is a useful tool for geologic and geotechnical applications. To obtain full benefit from the tiltmeter, easy and accurate data presentations should be used. Unfortunately, the most commonly used method for tilt data reduction now may yield inaccurate and low-resolution results. This article describes a simple, accurate, and...
Sea-cliff erosion at Pacifica, California, caused by 1997-98 El Niño storms
Charles B. Snell, Kenneth R. Lajoie, Edward W. Medley
2000, Conference Paper, Proceedings of sessions of Geo-Denver 2000 - Slope stability 2000
Twelve homes were constructed in 1949 at the top of a sea cliff along Esplanade Drive in the City of Pacifica, located on the northern coast of San Mateo County, California. The rear yards of those properties were bounded by an approximately 20-meter (70-foot) high cliff that has retreated episodically...
Younger Dryas interval and outflow from the Laurentide ice sheet
T.C. Moore Jr., J.C.G. Walker, David K. Rea, C.F.M. Lewis, L.C.K. Shane, A. J. Smith
2000, Paleoceanography (15) 4-18
A boxmodel of the Great Lakes is used to estimate meltwater flow into the North Atlantic between 8000 and 14,000 calendar years B.P. Controls on the model include the oxygen isotopic composition of meltwaters and lake waters as measured in the shells of ostracodes. Outflow rates are highest when oxygen...
