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United States Geological Survey: Staff Publications

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Full-Text Articles in Earth Sciences

Divergent Patterns Of Abundance And Age-Class Structure Of Headwater Stream Tadpoles In Burned And Unburned Watersheds, Blake R. Hossack, Paul Stephen Corn, Daniel B. Fagre Jan 2006

Divergent Patterns Of Abundance And Age-Class Structure Of Headwater Stream Tadpoles In Burned And Unburned Watersheds, Blake R. Hossack, Paul Stephen Corn, Daniel B. Fagre

United States Geological Survey: Staff Publications

Wildfire is a potential threat to many species with narrow environmental tolerances like the Rocky Mountain tailed frog (Ascaphlls montanlls Mittleman and Myers, 1949), which inhabits a region where the frequency and intensity of wildfires are expected to increase. We compared pre- and post-fire counts of tadpoles in eight streams in northwestem Montana to determine the effects of wildfire on A. montanus. All streams were initially sampled in 2001, 2 years before four of them bumed in a large wildfire, and were resampled during the 2 years follo\ving the fire. Counts of tadpoles were similar in the 1\\'0 …


Gastrointestinal Morphology Of Female White-Tailed And Mule Deer: Effects Of Fire, Reproduction, And Feeding Type, Teresa J. Zimmerman, Jonathan A. Jenks, David M. Leslie Jr. Jan 2006

Gastrointestinal Morphology Of Female White-Tailed And Mule Deer: Effects Of Fire, Reproduction, And Feeding Type, Teresa J. Zimmerman, Jonathan A. Jenks, David M. Leslie Jr.

United States Geological Survey: Staff Publications

We assessed variation in length, width, density, and surface enlargement factor of papillae; rumen and intestinal digesta weight; intestinal length; and intestinal tissue weight of reproductive and nonreproductive female white-tailed (Odocoileus virginianus) and mule deer (O. hemionus) using similar burned and unburned habitat. Deer were collected from study areas in Custer and Pennington counties, South Dakota, in and adjacent to a wildfire burn. Length of papillae and enlargement factor of papillae surface of white-tailed deer and mule deer were greater in burned than unburned habitat, and dry weight of rumen digesta of white-tailed deer was greater …


The Geochemical Record Of The Last 17,000 Years In The Guaymas Basin, Gulf Of California, Walter E. Dean Jan 2006

The Geochemical Record Of The Last 17,000 Years In The Guaymas Basin, Gulf Of California, Walter E. Dean

United States Geological Survey: Staff Publications

Sediments deposited on the western slope of the Guaymas Basin in the central Gulf of California are composed predominantly of detrital clastic material and biogenic silica (biopal), with minor organic material (average of 2.8% organic carbon) and calcium carbonate. The CaCO3 is derived from calcareous plankton and is highly variable ranging from 0% to 16%. In general, the CaCO3 content of the sediments varies inversely with the biopal content, reflecting the relative abundance of calcareous and siliceous plankton in the photic zone. Siliceous plankton dominate when winds are predominantly out of the northwest producing strong upwelling. Calcareous plankton …


A Continuous 250,000 Yr Record Of Oxygen And Carbon Isotopes In Ostracode And Bulk-Sediment Carbonate From Bear Lake, Utah-Idaho, Walter E. Dean, Jordon Bright, Darrell S. Kaufman, Richard M. Forester Jan 2006

A Continuous 250,000 Yr Record Of Oxygen And Carbon Isotopes In Ostracode And Bulk-Sediment Carbonate From Bear Lake, Utah-Idaho, Walter E. Dean, Jordon Bright, Darrell S. Kaufman, Richard M. Forester

United States Geological Survey: Staff Publications

Oxygen and carbon isotopes from a continuous, 120-m-long, carbonate-rich core from Bear Lake, Utah-Idaho, document dramatic fluctuations in the hydrologic budget of the lake over the last 250,000 yr. Isotopic analyses of bulk sediment samples capture millennialscale variability. Ostracode calcite was analyzed from 78 levels, mainly from the upper half of the core where valves are better preserved, to compare the isotopic value of purely endogenic carbonate with the bulk sediment, which comprises both endogenic and detrital components. The long core exhibits three relatively brief intervals with abundant endogenic aragonite (50±10%) and enriched δ18O and δ13C. …


Unusual Holocene And Late Pleistocene Carbonate Sedimentation In Bear Lake, Utah And Idaho, Usa, Walter E. Dean, Joseph Rosenbaum, Gary Skipp, Steven Colman, Richard Forester, An Liu, Kathleen R. Simmons, James Bischoff Jan 2006

Unusual Holocene And Late Pleistocene Carbonate Sedimentation In Bear Lake, Utah And Idaho, Usa, Walter E. Dean, Joseph Rosenbaum, Gary Skipp, Steven Colman, Richard Forester, An Liu, Kathleen R. Simmons, James Bischoff

United States Geological Survey: Staff Publications

Bear Lake (Utah–Idaho, USA) has been producing large quantities of carbonate minerals of varying mineralogy for the past 17,000 years. The history of sedimentation in Bear Lake is documented through the study of isotopic ratios of oxygen, carbon, and strontium, percent organic carbon, percent CaCO3, X-ray diffraction mineralogy, HCl-leach inorganic geochemistry, and magnetic properties on samples from three piston cores. Historically, the Bear River, the main source of water for Great Salt Lake, did not enter Bear Lake until it was artificially diverted into the lake at the beginning of the 20th century. However, during the last glacial …


Reply To The Discussion By F. Lagroix And S.K. Banerjee Of “Geochemical Evidence For The Origin Of Late Quaternary Loess In Central Alaska”, Daniel R. Muhs, James R. Budahn Jan 2006

Reply To The Discussion By F. Lagroix And S.K. Banerjee Of “Geochemical Evidence For The Origin Of Late Quaternary Loess In Central Alaska”, Daniel R. Muhs, James R. Budahn

United States Geological Survey: Staff Publications

We thank F. Lagroix and S.K. Banerjee (2006) for their Muhs and Budahn 1895 interest in our recent paper and welcome this opportunity to clarify our thoughts on the issues they raise. ...

The loess deposits of central Alaska contain a long and detailed record of sedimentation and soil formation. However, we are convinced that this history is a complex one and, therefore, we again thank Lagroix and Banerjee (2006) for the opportunity to articulate some additional thoughts on the geologic record here. We applaud the use of new methods, such as those of Lagroix and Banerjee (2002, 2004), in …


Introduction To "The Endangered Species Act At Thirty, Volume 2", Frank W. Davis, J. Michael Scott, Dale D. Goble Jan 2006

Introduction To "The Endangered Species Act At Thirty, Volume 2", Frank W. Davis, J. Michael Scott, Dale D. Goble

United States Geological Survey: Staff Publications

More than thirty years after its passage, the Endangered Species Act (ESA) of 1973 continues to be a corners tone of U.S. biodiversity policy and among our most powerful environmentallaws. The ESA set the nation's biodiversity conservation policy on a path that emphasized species-based conservation and triggered action only when a species faced imminent extinction. However, promoting recovery has proven more challenging than the original designers of the law anticipated. The number of listed species has mushroomed from 78 in 1973 to 1,267 in 2005, while in that time only 13 species have recovered sufficiently to be removed from the …


Introduction To "The Endangered Species Act At Thirty, Volume 1", J. Michael Scott, Dale D. Goble, Frank W. Davis Jan 2006

Introduction To "The Endangered Species Act At Thirty, Volume 1", J. Michael Scott, Dale D. Goble, Frank W. Davis

United States Geological Survey: Staff Publications

This book examines one legislative effoft to resolve the dilemma, the Endangered Speeies Aet of 1973 (ESA 1973). The ESA was an idealistic and perhaps naive attempt to preserve humanity by preserving other species in the ecological support system that makes life possible. In the words of the House report accompanying the bill:

A certain humility, and a sense of urgency seem indicated .... One might analogize the case to one in which one copy of all the books ever printed were gathered together in one huge building. The position in which we find ourselves today is that of custodians …


By The Numbers, J. Michael Scott, Dale D. Goble, Leona K. Svancara, Anna Pidgorna Jan 2006

By The Numbers, J. Michael Scott, Dale D. Goble, Leona K. Svancara, Anna Pidgorna

United States Geological Survey: Staff Publications

The current endangered species list has its administrative beginnings in 1964 when the Department of the Interior's Committee on Rare and Endangered Wildlife Species published a preliminary list of 62 species at risk of extinction (Goble, forthcoming). Following the enactment of the Endangered Species Preservation Act of 1966 (ESPA), the secretary of the interior in 1967 published the first official list of 78 "native fish and wildlife threatened with extinction" (ESPA sec. l(c); U.S. Department of the Interior 1967; Wilcove and McMillan, this volume). By the time the Endangered Species Act (ESA) was adopted in 1973, there were 392 species …


Endangered Species Time Line, Leona K. Svancara, J. Michael Scott, Dale D. Goble, Frank W. Davis, Donna Brewer Jan 2006

Endangered Species Time Line, Leona K. Svancara, J. Michael Scott, Dale D. Goble, Frank W. Davis, Donna Brewer

United States Geological Survey: Staff Publications

The Endangered Species Act (ESA) is embedded in a web of statutes designed to regulate relationships between humans and other species that stretch back nearly a millennium (Goble, this volume; Goble and Freyfogle 2002). This chapter presents a time line of federal actions taken to protect wildlife beginning with passage of the Land and Water Conservation Fund Act in 1963 (Act of May 28, 1963). Earlier laws to protect wildlife are discussed elsewhere (Goble, this volume). The time line emphasizes federal actions that conserve species at risk of extinction and significant events in the course of implementing the Endangered Species …


The Agricultural Productivity Of Chaco Canyon And The Source(S) Of Pre-Hispanic Maize Found In Pueblo Bonito, Larry Benson, John Stein, Howard Taylor, Richard Friedman, Thomas C. Windes Jan 2006

The Agricultural Productivity Of Chaco Canyon And The Source(S) Of Pre-Hispanic Maize Found In Pueblo Bonito, Larry Benson, John Stein, Howard Taylor, Richard Friedman, Thomas C. Windes

United States Geological Survey: Staff Publications

Agricultural productivity estimates suggest that the core area of Chaco Canyon could have sustained only a few hundred individuals. Modern analogues of existing Pueblo populations and their domestic habitations with Chaco structures suggest that Chaco at times had a resident population exceeding 2000 people. These data suggest that maize would have had to be imported to feed permanent residents and those visiting Chaco during ritual–political gatherings and those who participated in the accelerated construction and modification of great houses between AD 1030 and 1130. Comparison of strontium-isotope and trace-element ratios of synthetic soil and natural waters from sites within the …


Abundance And Distribution Of Selected Elements In Soils, Stream Sediments, And Selected Forage Plants From Desert Tortoise Habitats In The Mojave And Colorado Deserts, Usa, M. A. Chaffee, K. H. Berry Jan 2006

Abundance And Distribution Of Selected Elements In Soils, Stream Sediments, And Selected Forage Plants From Desert Tortoise Habitats In The Mojave And Colorado Deserts, Usa, M. A. Chaffee, K. H. Berry

United States Geological Survey: Staff Publications

A baseline and background chemical survey was conducted in southeastern California, USA, to identify potential sources of toxicants in natural and anthropogenically-altered habitats of the threatened desert tortoise (Gopherus agassizii). Soil, stream sediment, and plant samples were collected from six tortoise habitat study areas in the Mojave and Colorado deserts and analysed for up to 66 different elements. The chemical analyses provided new information on the abundances and distributions of selected elements in this region. Soil, stream-sediment, and plant analyses showed distinct variations in bulk chemistries from locality to locality. Variations were, in general, consistent with the many …


Mineralogical Characterization Of Protolith And Fault Rocks From The Safod Main Hole, John G. Solum, Stephen H. Hickman, David A. Lockner, Diane E. Moore, Ben A. Van Der Pluijm, James P. Evans Jan 2006

Mineralogical Characterization Of Protolith And Fault Rocks From The Safod Main Hole, John G. Solum, Stephen H. Hickman, David A. Lockner, Diane E. Moore, Ben A. Van Der Pluijm, James P. Evans

United States Geological Survey: Staff Publications

Washed cuttings provide a continuous record of the rocks encountered during drilling of the main hole of the San Andreas Fault Observatory at Depth (SAFOD). Both protolith and fault rocks exhibit a wide variety of mineral assemblages that reflect variations in some combination of lithology, P-T conditions, deformation mechanisms, and fluid composition and abundance. Regions of distinct neomineralization bounded by faults may record alteration associated with fluid reservoirs confined by faults. In addition, both smectites occurring as mixed-layer phases and serpentine minerals are found in association with active strands of the San Andreas Fault that were intersected during drilling, although …


Seasonal And Spatial Patterns Of Metals At A Restored Copper Mine Site. I. Stream Copper And Zinc, Dustin G. Bambic, Charles N. Alpers, Peter G. Green, Eileen Fanelli, Wendy K. Silk Jan 2006

Seasonal And Spatial Patterns Of Metals At A Restored Copper Mine Site. I. Stream Copper And Zinc, Dustin G. Bambic, Charles N. Alpers, Peter G. Green, Eileen Fanelli, Wendy K. Silk

United States Geological Survey: Staff Publications

Seasonal and spatial variations in metal concentrations and pH were found in a stream at a restored copper mine site located near a massive sulfide deposit in the Foothill copper-zinc belt of the Sierra Nevada, California. At the mouth of the stream, copper concentrations increased and pH decreased with increased streamflow after the onset of winter rain and, unexpectedly, reached extreme values 1 or 2 months after peaks in the seasonal hydrographs. In contrast, aqueous zinc and sulfate concentrations were highest during low-flow periods. Spatial variation was assessed in 400 m of reach encompassing an acidic, metal-laden seep. At this …


Use Of Mammal Manure By Nesting Burrowing Owls: A Test Of Four Functional Hypotheses, Matthew D. Smith, Courtney J. Conway Jan 2006

Use Of Mammal Manure By Nesting Burrowing Owls: A Test Of Four Functional Hypotheses, Matthew D. Smith, Courtney J. Conway

United States Geological Survey: Staff Publications

Animals have evolved an impressive array of behavioural traits to avoid depredation. Olfactory camouflage of conspicuous odours is a strategy to avoid depredation that has been implicated only in a few species of birds. Burrowing owls, Athene cunicularia, routinely collect dried manure from mammals and scatter it in their nest chamber, in the tunnel leading to their nest and at the entrance to their nesting burrow. This unusual behaviour was thought to reduce nest depredation by concealing the scent of adults and juveniles, but a recent study suggests that manure functions to attract arthropod prey. However, burrowing owls routinely …


Eolian Additions To Late Quaternary Alpine Soils, Indian Peaks Wilderness Area, Colorado Front Range, Daniel R. Muhs, James B. Benedict Jan 2006

Eolian Additions To Late Quaternary Alpine Soils, Indian Peaks Wilderness Area, Colorado Front Range, Daniel R. Muhs, James B. Benedict

United States Geological Survey: Staff Publications

Surface horizons of many alpine soils on Quaternary deposits in high-mountain settings are enriched in silt. The origin of these particles has been debated, particularly in the Rocky Mountain region of North America. The most common explanations are frost shattering of coarser particles and eolian additions from distant sources. We studied soil A horizons on alpine moraines of late-glacial (Satanta Peak) age in the Colorado Front Range. Surface horizons of soils on these moraines are enriched in silt and have a particle size distribution that resembles loess and dust deposits found elsewhere. The compositions of sand and silt fractions of …


A Cool Eastern Pacific Ocean At The Close Of The Last Interglacial Complex, Daniel R. Muhs, Kathleen R. Simmons, George L. Kennedy, Kenneth R. Ludwig, Lindsey T. Groves Jan 2006

A Cool Eastern Pacific Ocean At The Close Of The Last Interglacial Complex, Daniel R. Muhs, Kathleen R. Simmons, George L. Kennedy, Kenneth R. Ludwig, Lindsey T. Groves

United States Geological Survey: Staff Publications

New high-precision thermal ionization mass-spectrometric (TIMS) U-series ages of solitary corals (Balanophyllia elegans) from several marine terrace localities along the California and southern Oregon coasts date to the ~80,000 yr BP high stand of sea, correlative with marine isotope substage 5a, late in the last interglacial complex. Ages of multiple corals from localities north of Point Año Nuevo (central California) and San Nicolas Island (southern California) suggest that this high sea stand could have lasted at least 8000 yr, from ~84,000 to ~76,000 yr BP. These ages overlap with those from marine deposits on tectonically stable Bermuda and …


Paleoclimatic Evidence For Future Ice-Sheet Instability And Rapid Sea-Level Rise, Jonathan T. Overpeck, Bette L. Otto-Bliesner, Gifford H. Miller, Daniel R. Muhs, Richard B. Alley, Jeffrey T. Kiehl Jan 2006

Paleoclimatic Evidence For Future Ice-Sheet Instability And Rapid Sea-Level Rise, Jonathan T. Overpeck, Bette L. Otto-Bliesner, Gifford H. Miller, Daniel R. Muhs, Richard B. Alley, Jeffrey T. Kiehl

United States Geological Survey: Staff Publications

Sea-level rise from melting of polar ice sheets is one of the largest potential threats of future climate change. Polar warming by the year 2100 may reach levels similar to those of 130,000 to 127,000 years ago that were associated with sea levels several meters above modern levels; both the Greenland Ice Sheet and portions of the Antarctic Ice Sheet may be vulnerable. The record of past ice-sheet melting indicates that the rate of future melting and related sea-level rise could be faster than widely thought.


Ice Sheets And Sea Level, Johannes Oerlemans, Dorthe Dahl-Jensen, Valérie Masson-Delmotte, Jonathan T. Overpeck, Bette L. Otto-Bliesner, Gifford H. Miller, Richard B. Alley, Daniel R. Muhs, Shawn J. Marshall Jan 2006

Ice Sheets And Sea Level, Johannes Oerlemans, Dorthe Dahl-Jensen, Valérie Masson-Delmotte, Jonathan T. Overpeck, Bette L. Otto-Bliesner, Gifford H. Miller, Richard B. Alley, Daniel R. Muhs, Shawn J. Marshall

United States Geological Survey: Staff Publications

The estimate of the contribution of the Greenland Ice Sheet (GIS) to the higher sea level stand in the Eemian interglacial (between 2.2 and 3.4 m) is based on the assumption that there was no ice at the location of the Dye-3 ice core in southern Greenland. However, Eemian ice has been found at the base of this ice core. The presence of Eemian ice in south and coastal Greenland implies that the GIS was essentially intact in a much warmer climate and could not have contributed more than 1 to 2 m to sea-level rise.


Status Of Feral Pigs In Kansas And Nebraska, Philip S. Gipson, Charles D. Lee, Sam Wilson, James R. Thiele, Deke Hobbick Jan 2006

Status Of Feral Pigs In Kansas And Nebraska, Philip S. Gipson, Charles D. Lee, Sam Wilson, James R. Thiele, Deke Hobbick

United States Geological Survey: Staff Publications

Wild pigs have expanded their range markedly during the last 30 years. In Kansas feral pigs from domestic stock were first reported in 1994 on Fort Riley Army Base. During 2005, 2006, and 2007 the occurrence of reproducing wild pigs was confirmed on 18 sites throughout Kansas and 4 sites in Nebraska. One Nebraska population is in a county neighboring Kansas. Estimated numbers of pigs ranged from 8-10 individuals at each of 2 sites in Kansas to more than 30 on each of 3 other sites. The wild pig population in Kansas appears to be changing from 1 predominantly of …


Cougars In Kansas, Charles D. Lee, Alyssa E. Warneke, Mike Houts, Troy R. Livingston, Philip S. Gipson Jan 2006

Cougars In Kansas, Charles D. Lee, Alyssa E. Warneke, Mike Houts, Troy R. Livingston, Philip S. Gipson

United States Geological Survey: Staff Publications

The presence of the cougar (Puma concolor) in the state of Kansas is a controversial issue. Since 1999, 234 cougar sightings have been reported to the Extension Wildlife Specialist at Kansas State University. To those who have reported such sightings, the existence of cougars in Kansas is undeniable. Others, however, question the validity of such sightings as providing evidence of cougars. After surveying other governmental agencies and organizations, we discovered that acceptable identification criteria for rare or unusual felines included things beside sightings: voucher specimens, DNA from hair or scat, tracks, prey carcasses, and photographs or videos. The …


Simulation Of Solute Movement Through Wellbores To Characterize Public Supply Well Contaminant Vulnerability In The High Plains Aquifer, York, Nebraska, Brian R. Clark, Matthew K. Landon, Leon J. Kauffman, George Z. Hornberger Jan 2006

Simulation Of Solute Movement Through Wellbores To Characterize Public Supply Well Contaminant Vulnerability In The High Plains Aquifer, York, Nebraska, Brian R. Clark, Matthew K. Landon, Leon J. Kauffman, George Z. Hornberger

United States Geological Survey: Staff Publications

A ground-water flow and transport model simulating contaminant movement to public supply wells in the High Plains aquifer near York, Nebraska was developed as part of the U.S. Geological Survey National Water-Quality Assessment Program. Water-quality samples were collected from wells screened in unconfined and confined units. Samples collected from a public supply well and selected monitoring wells completed in the confined aquifer have chemistry and age-tracer concentrations consistent with a mix of young water from unconfined recharge areas combined with relatively older confined aquifer water. These results imply that there are preferential flow paths that permit shallow recharge water and …


Multi-Species Patterns Of Avian Cholera Mortality In Nebraska’S Rainwater Basin, Julie A. Blanchong, Michael D. Samuel, Gene Mack Jan 2006

Multi-Species Patterns Of Avian Cholera Mortality In Nebraska’S Rainwater Basin, Julie A. Blanchong, Michael D. Samuel, Gene Mack

United States Geological Survey: Staff Publications

Nebraska’s Rainwater Basin (RWB) is a key spring migration area for millions of waterfowl and other avian species. Avian cholera has been endemic in the RWB since the 1970s and in some years tens of thousands of waterfowl have died from the disease. We evaluated patterns of avian cholera mortality in waterfowl species using the RWB during the last quarter of the 20th century. Mortality patterns changed between the years before (1976–1988) and coincident with (1989–1999) the dramatic increases in lesser snow goose abundance and mortality. Lesser snow geese (Chen caerulescens caerulescens) have commonly been associated with mortality …


Regional Patterns In The Isotopic Composition Of Natural And Anthropogenic Nitrate In Groundwater, High Plains, U.S.A., P. B. Mcmahon, J. K. Bohlke Jan 2006

Regional Patterns In The Isotopic Composition Of Natural And Anthropogenic Nitrate In Groundwater, High Plains, U.S.A., P. B. Mcmahon, J. K. Bohlke

United States Geological Survey: Staff Publications

Mobilization of natural nitrate (NO3-) deposits in the subsoil by irrigation water in arid and semiarid regions has the potential to produce large groundwater NO3- concentrations. The use of isotopes to distinguish between natural and anthropogenic NO3- sources in these settings could be complicated by the wide range in δ15N values of natural NO3-. An ~10 000 year record of paleore-charge from the regionally extensive High Plains aquifer indicates that δ15N values for NO3- derived from natural sources ranged from 1.3 to 12.3‰ and …


Mountain Plover Population Responses To Black-Tailed Prairie Dogs In Montana, Stephen J. Dinsmore, Gary C. White, Fritz L. Knopf Oct 2005

Mountain Plover Population Responses To Black-Tailed Prairie Dogs In Montana, Stephen J. Dinsmore, Gary C. White, Fritz L. Knopf

United States Geological Survey: Staff Publications

We studied a local population of mountain plovers (Charadrius montanus) in southern Phillips County, Montana, USA, from 1995 to 2000 to estimate annual rates of recruitment rate (f) and population change (λ). We used Pradel models, and we modeled λ as a constant across years, as a linear time trend, as year-specific, and with an additive effect of area occupied by prairie dogs (Cynomys ludovicianus). We modeled recruitment rate (f) as a function of area occupied by prairie dogs with the remaining model structure identical to the best model used to estimate λ. Our results indicated …


Nonlinear Dynamics In Ecosystem Response To Climatic Change: Case Studies And Policy Implications, Virginia R. Burkett, Douglas A. Wilcox, Wilcox Stottlemyer, Wylie Barrow, Dan Fagre, Jill Baron, Jeff Price, Jennifer L. Nielsen, Craig D. Allen, David L. Peterson, Greg Ruggerone, Thomas Doyle Sep 2005

Nonlinear Dynamics In Ecosystem Response To Climatic Change: Case Studies And Policy Implications, Virginia R. Burkett, Douglas A. Wilcox, Wilcox Stottlemyer, Wylie Barrow, Dan Fagre, Jill Baron, Jeff Price, Jennifer L. Nielsen, Craig D. Allen, David L. Peterson, Greg Ruggerone, Thomas Doyle

United States Geological Survey: Staff Publications

Many biological, hydrological, and geological processes are interactively linked in ecosystems. These ecological phenomena normally vary within bounded ranges, but rapid, nonlinear changes to markedly different conditions can be triggered by even small differences if threshold values are exceeded. Intrinsic and extrinsic ecological thresholds can lead to effects that cascade among systems, precluding accurate modeling and prediction of system response to climate change. Ten case studies from North America illustrate how changes in climate can lead to rapid, threshold-type responses within ecological communities; the case studies also highlight the role of human activities that alter the rate or direction of …


The Impacts Of Sprawl On Biodiversity: The Ant Fauna Of The Lower Florida Keys, Elizabeth A. Forys, Craig R. Allen Aug 2005

The Impacts Of Sprawl On Biodiversity: The Ant Fauna Of The Lower Florida Keys, Elizabeth A. Forys, Craig R. Allen

United States Geological Survey: Staff Publications

Sprawling development can affect species composition by increasing the rate of invasion by non-native species, and decreasing the persistence of native species. This paper briefly reviews the scientific literature on the impacts of sprawl on biological diversity, with specific emphasis on the influence of sprawl on non-native species richness. We then explore the relationship between sprawl and biodiversity using a data set of ant species collected from 46 habitat patches located in the increasingly suburbanized Florida Keys, USA. We quantified sprawl as the proximity of roads and amount of development surrounding a habitat patch. Using bait transects, we identified 24 …


Distribution Patterns Of Lentic-Breeding Amphibians In Relation To Ultraviolet Radiation Exposure In Western North America, Michael J. Adams, Blake R. Hossack, Roland A. Knapp, Paul Stephen Corn, Stephen A. Diamond, Peter C. Trenham, Dan B. Fagre Jul 2005

Distribution Patterns Of Lentic-Breeding Amphibians In Relation To Ultraviolet Radiation Exposure In Western North America, Michael J. Adams, Blake R. Hossack, Roland A. Knapp, Paul Stephen Corn, Stephen A. Diamond, Peter C. Trenham, Dan B. Fagre

United States Geological Survey: Staff Publications

An increase in ultraviolet-B (UV-B) radiation has been posited to be a potential factor in the decline of some amphibian population. This hypothesis has received support from laboratory and field experiments showing that current levels of UV-B can cause embryo mortality in some species, but little research has addressed whether UV-B is influencing the distribution of amphibian populations. We compared patterns of amphibian presence to sitespecific estimates of UV-B dose at 683 ponds and lakes in Glacier, Olympic, and Sequoia–Kings Canyon National Parks. All three parks are located in western North America, a region with a concentration of documented amphibian …


Estimated Ultraviolet Radiation Doses In Wetlands In Six National Parks, Stephen A. Diamond, Peter C. Trenham, Michael J. Adams, Blake R. Hossack, Roland A. Knapp, Stacey L. Stark, David Bradford, P. Stephen Corn, Ken Czarnowski, Paul D. Brooks, Dan Fagre, Bob Breen, Naomi E. Detenbeck, Kathy Tonnessen Jul 2005

Estimated Ultraviolet Radiation Doses In Wetlands In Six National Parks, Stephen A. Diamond, Peter C. Trenham, Michael J. Adams, Blake R. Hossack, Roland A. Knapp, Stacey L. Stark, David Bradford, P. Stephen Corn, Ken Czarnowski, Paul D. Brooks, Dan Fagre, Bob Breen, Naomi E. Detenbeck, Kathy Tonnessen

United States Geological Survey: Staff Publications

Ultraviolet-B radiation (UV-B, 280–320-nm wavelengths) doses were estimated for 1024 wetlands in six national parks: Acadia (Acadia), Glacier (Glacier), Great Smoky Mountains (Smoky), Olympic (Olympic), Rocky Mountain (Rocky), and Sequoia/ Kings Canyon (Sequoia). Estimates were made using ground-based UV-B data (Brewer spectrophotometers), solar radiation models, GIS tools, field characterization of vegetative features, and quantification of DOC concentration and spectral absorbance. UV-B dose estimates were made for the summer solstice, at a depth of 1 cm in each wetland. The mean dose across all wetlands and parks was 19.3 W-h m-2 (range of 3.4–32.1 W-h m-2). The mean …


Patterns Of Fish Use And Piscivore Abundance Within A Reconnected Saltmarsh Impoundment In The Northern Indian River Lagoon, Florida, Philip W. Stevens, Clay L. Montague, Kenneth J. Sulak Apr 2005

Patterns Of Fish Use And Piscivore Abundance Within A Reconnected Saltmarsh Impoundment In The Northern Indian River Lagoon, Florida, Philip W. Stevens, Clay L. Montague, Kenneth J. Sulak

United States Geological Survey: Staff Publications

Nearly all saltmarshes in east-central, Florida were impounded for mosquito control during the 1960s. The majority of these marshes have since been reconnected to the estuary by culverts, providing an opportunity to effectively measure exchange of aquatic organisms. A multi-gear approach was used monthly to simultaneously estimate fish standing stock (cast net), fish exchange with the estuary (culvert traps), and piscivore abundance (gill nets and bird counts) to document patterns of fish use in a reconnected saltmarsh impoundment. Changes in saltmarsh fish abundance, and exchange of fish with the estuary reflected the seasonal pattern of marsh flooding in the northern …