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Glasstire: Visual Art News and Reviews

Description: This is the official website for Glasstire, an online magazine that covers visual art in Texas and Southern California. Founded in 2001, Glasstire was one of the earliest online art journals in the United States. It is a non-profit publication supported in part by grants from The Houston Endowment, The Brown Foundation, the the National Endowment for the Arts, the Greater Houston Community Foundation, the City of Houston through Houston Arts Alliance, and the Texas Commission for the Arts. It includes articles, news about local art events, videos, and classifieds.
Date: 2013
Creator: Glasstire
Partner: UNT Libraries Digital Projects Unit

An evaluation of known remaining oil resources in the state of California: Project on advanced oil recovery and the states. Volume 2

Description: The Interstate Oil and Gas Compact Commission (IOGCC) has conducted a series of studies to evaluate the known, remaining oil resource in twenty-three (23) states. The primary objective of die IOGCC`s effort is to examine the potential impact of an aggressive and focused program of research, development, and demonstration (RD&D) and technology transfer on future oil recovery in the United States. As part of a larger effort by the IOGCC, this report focuses on the potential economic benefits of improved oil recovery in the state of California. Individual reports for seven other oil producing states and a national report have been separately published by the IOGCC. Several major technical insights for state and Federal policymakers and regulators can be reached from this analysis. Overall, well abandonments and more stringent environmental regulations could limit economic access to the nation`s known, remaining oil resource. The high risk of near-term abandonment and the significant benefits of future application of improved oil recovery technoloy, clearly point to a need for more aggressive transfer of currently available technologies to domestic oil producers. Development and application of advanced oil recovery technologies could leave even greater benefits to the nation. A collaborative, focused RD&D effort, integrating the resources and expertise of industry, state and local governments, and the Federal government, is clearly warranted. With effective RD&D and a program of aggressive technology transfer to widely disseminate its results, California oil production could be maximized. The resulting increase and improvement in production rates, employment, operator profits, state and Federal tax revenues, energy security will benefit both the state of California and the nation as a whole.
Date: November 1, 1993
Partner: UNT Libraries Government Documents Department

An evaluation of known remaining oil resources in the United States: Appendix. Volume 10

Description: Volume ten contains the following appendices: overview of improved oil recovery methods which covers enhanced oil recovery methods and advanced secondary recovery methods; the benefits of improved oil recovery, selected data for the analyzed states; and list of TORIS fields and reservoirs.
Date: November 1, 1993
Partner: UNT Libraries Government Documents Department

Photovoltaic balance-of-system designs and costs at PVUSA

Description: This report is one in a series of 1994-1995 PVUSA reports that document PVUSA lessons learned at demonstration sites in California and Texas. During the last 7 years (1988 to 1994), 16 PV systems ranging from 20 kW to 500 kW have been installed. Six 20-kW emerging module technology (EMT) arrays and three turnkey (i.e., vendor designed and integrated) utility-scale systems were procured and installed at PVUSA`s main test site in Davis, California. PVUSA host utilities have installed a total of seven EMT arrays and utility-scale systems in their service areas. Additional systems at Davis and host utility sites are planned. One of PVUSA`s key objectives is to evaluate the performance, reliability, and cost of PV balance-of-system (BOS). In the procurement stage PVUSA encouraged innovative design to improve upon present practice by reducing maintenance, improving reliability, or lowering manufacturing or construction costs. The project team worked closely with suppliers during the design stage not only to ensure designs met functional and safety specifications, but to provide suggestions for improvement. This report, intended for the photovoltaic (PV) industry and for utility project managers and engineers considering PV plant construction and ownership, documents PVUSA utility-scale system design and cost lessons learned. Complementary PVUSA topical reports document: construction and safety experience; five-year assessment of EMTs; validation of the Kerman 500-kW grid-support PV plant benefits; PVUSA instrumentation and data analysis techniques; procurement, acceptance, and rating practices for PV power plants; experience with power conditioning units and power quality.
Date: May 1, 1995
Creator: Reyes, A.B. & Jennings, C.
Partner: UNT Libraries Government Documents Department

Science & Technology Review, April 2001

Description: Serial publication produced by Lawrence Livermore National Laboratory regarding the institution's research in technology to address concerns about energy, bioscience, and the environment. "Science & Technology Review is published 10 times a year to communicate, to a broad audience, the Laboratory's scientific and technological accomplishments in fulfilling its primary missions. The publication's goal is to help readers understand these accomplishments and appreciate their value to the individual citizen, the nation, and the world" (inside cover).
Date: April 2001
Creator: Lawrence Livermore National Laboratory
Partner: UNT Libraries Government Documents Department

Selenium isotope geochemistry: A new approach to characterizing the environmental chemistry of selenium. Final report

Description: High levels of selenium in the environment will be a prominent water quality issue in the western United States for many years. Selenium accumulation is linked to increased rates of death and deformity in migratory birds, blind staggers in livestock, and selenosis in humans. In California, agricultural drain waters and oil refinery effluent contribute to high selenium content in the San Joaquin Valley and the San Francisco Bay. The importance of these industries to California`s economy precludes simple abatement, while the complexity of selenium cycling precludes simple remediation. The purpose of this project is to measure variations in the isotopic composition of selenium in water and soil samples caused by natural processes and to show, for the first time, the value of isotopic measurements in characterizing selenium pollution. The research seeks to identify sources of selenium pollution, determine processes in the selenium cycle, and support selenium remediation studies. The project required the successful integration of three components: (1) appropriate sampling a field setting showing Se enrichment and possibly isotopic fractionation, (2) analytical chemical methods for isolating and purifying the various species of Se in waters and sediment, and (3) mass spectroscopic instrumentation for high precision isotope abundance measurements.
Date: February 5, 1997
Creator: Volpe, A.M. & Esser, B.K.
Partner: UNT Libraries Government Documents Department

Base case and perturbation scenarios

Description: This report describes fourteen energy factors that could affect electricity markets in the future (demand, process, source mix, etc.). These fourteen factors are believed to have the most influence on the State� s energy environment. A base case, or most probable, characterization is given for each of these fourteen factors over a twenty year time horizon. The base case characterization is derived from quantitative and qualitative information provided by State of California government agencies, where possible. Federal government databases are nsed where needed to supplement the California data. It is envisioned that a initial selection of issue areas will be based upon an evaluation of them under base case conditions. For most of the fourteen factors, the report identities possible perturbations from base case values or assumptions that may be used to construct additional scenarios. Only those perturbations that are plausible and would have a significant effect on energy markets are included in the table. The fourteen factors and potential perturbations of the factors are listed in Table 1.1. These perturbations can be combined to generate internally consist.ent. combinations of perturbations relative to the base case. For example, a low natural gas price perturbation should be combined with a high natural gas demand perturbation. The factor perturbations are based upon alternative quantitative forecasts provided by other institutions (the Department of Energy - Energy Information Administration in some cases), changes in assumptions that drive the quantitative forecasts, or changes in assumptions about the structure of the California energy markets. The perturbations are intended to be used for a qualitative reexamination of issue areas after an initial evaluation under the base case. The perturbation information would be used as a �tiebreaker;� to make decisions regarding those issue areas that were marginally accepted or rejected under the base case. Hf a quantitative scoring ...
Date: October 1, 1998
Creator: Edmunds, T
Partner: UNT Libraries Government Documents Department

Electromagnetic induction tomography field experiment at Lost Hills, CA

Description: We have collected borehole to surface electromagnetic induction field data for a shallow steam injection that is underway at Mobil Oil� s Lost Hills-3 field in San Joaquin Valley. Earlier work had been done at the same site by Wilt et al. (1996). This site is an interesting test for techniques under development for environmental engineering, because it can be viewed as an excellent analog of a shallow environmental remediation using steam injection. Surface magnetic field data (vertical and radial fields, magnitude and phase) were collected using 18 receiver stations along two profiles which ran radially from the EM transmitter well from 5 m to 120 m. The data at each surface station were collected while the EM transmitter was raised slowly from a depth of 120 m to a final depth of 20 m. As part of this experiment, a calibration of the EM transmitter was also performed. Magnetic field data from Lost Hills were successfully collected, including both vertical and horizontal (surface radial) magnitude and phase data along a northerly profile and along a westerly profile. We have observed that the radial receiver data appear to be better behaved than the vertical receiver data, suggesting that these data may be less sensitive to environmental clutter (numerous metallic pipes crisscrossing the site at the surface) than are the vertical data. Some simple 1-D modeling has been done to confirm that the expected conductivity change in the steam zone should produce an observable anomaly in the measured data when comparing the pre-steam to the post-steam conditions. Results of this test were positive. Further analyses of these data making use of a new code developed in a companion paper are in progress and will presented separately.
Date: November 3, 1998
Creator: Berryman, J G & Buettner, H M
Partner: UNT Libraries Government Documents Department

Geothermal resource requirements for an energy self-sufficient spaceport

Description: Geothermal resources in the southwestern United States provide an opportunity for development of isolated spaceports with local energy self-sufficiency. Geothermal resources can provide both thermal energy and electrical energy for the spaceport facility infrastructure and production of hydrogen fuel for the space vehicles. In contrast to hydrothermal resources by which electric power is generated for sale to utilities, hot dry rock (HDR) geothermal resources are more wide-spread and can be more readily developed at desired spaceport locations. This paper reviews a dynamic model used to quantify the HDR resources requirements for a generic spaceport and estimate the necessary reservoir size and heat extraction rate. The paper reviews the distribution of HDR resources in southern California and southern New Mexico, two regions where a first developmental spaceport is likely to be located. Finally, the paper discusses the design of a HDR facility for the generic spaceport and estimates the cost of the locally produced power.
Date: January 1, 1997
Creator: Kruger, P.; Fioravanti, M.; Duchane, D. & Vaughan, A.
Partner: UNT Libraries Government Documents Department

The hot dry rock geothermal potential of the Susanville (CA) area

Description: A portion of northeastern California that lies within the Basin and Range Province represents a large, untapped geothermal energy resource in the form of hot, but essential impermeable, rock. If a means of developing sufficient permeability in the deep, granitic basement can be demonstrated, the electric power generation potential would be considerable. The objective of this study is to look at the specific geographical region extending from northeast to southeast of the village of Litchfield to the Nevada border as a target area for the first commercial application of Hot Dry Rock reservoir stimulation techniques. The ultimate goal is to provide background information that could lead to the creation of a commercial-scale, engineered geothermal reservoir in granitic basement rock of low permeability.
Date: October 1, 1996
Creator: Brown, D.W.
Partner: UNT Libraries Government Documents Department

Heat flow and hot dry rock geothermal resources of the Clearlake Region, northern California

Description: The Geysers-Clear Lake geothermal anomaly is an area of high heat flow in northern California. The anomaly is caused by abnormally high heat flows generated by asthenospheric uplift and basaltic magmatic underplating at a slabless window created by passage of the Mendocino Triple Junction. The Clear Lake volcanic field is underlain by magmatic igneous bodies in the form of a stack of sill-form intrusions with silicic bodies generally at the top and basic magmas at the bottom. The tabular shape and wide areal extent of the heat sources results in linear temperature gradients and near-horizontal isotherms in a broad region at the center of the geothermal anomaly. The Hot Dry Rock (HDR) portion of The Geysers-Clear Lake geothermal field is that part of the geothermal anomaly that is external to the steamfield, bounded by geothermal gradients of 167 mW/m2 (4 heat flow units-hfu) and 335 mW/m2 (8 hfu). The HDR resources, to a depth of 5 km, were estimated by piece-wise linear summation based on a sketch map of the heat flow. Approximately, the geothermal {open_quotes}accessible resource base{close_quotes} (Qa) is 1.68E+21 J; the {open_quotes}HDR resource base{close_quotes} (Qha) is 1.39E+21 J; and the {open_quotes}HDR power production resource{close_quotes} (Qhp) is 1.01E+21 J. The HDR power production resource (Qhp) is equivalent to 2.78E+ 11 Mwht (megawatt hours thermal), or 1.72E+11 bbls of oil.
Date: August 1, 1996
Creator: Burns, K.L.
Partner: UNT Libraries Government Documents Department

Neotectonics and seismicity of the Clearlake region in northern California

Description: Geological, topographic, and seismic methods were used to locate faults in the vicinity of Clearlake in northern California. The geological method, which seeks faults as discontinuities in the lithotope, found faults in the Tertiary-Cretaceous rocks east of Burns Valley. The topographic method, which is used to produce Fault Evaluation Reports, found a very active fault zone, the Konocti Bay fault zone, south of Highlands arm. It also found some active faults north of Highlands arm, in the eastern part of Burns Valley and on the lakeshore near Oak Park. The seismic method is the most enduring of the three methods but is limited by location accuracy; the results improve as monitoring continues because of increases in the density of events and improvements in the crustal velocity model. The seismic method identified faulting along the valley at Borax Lake and possibly also on a line running northeast from the city of Clearlake. The latter may be associated with the Burns Valley fault or with the line of scoria domes which runs parallel to it. Seismic observations over longer periods at higher resolution will be required in order to determine the location of active faults near the city. 47 refs., 13 figs.
Date: April 1, 1996
Creator: Burns, K.L.
Partner: UNT Libraries Government Documents Department

Effects of minerals on the pyrolysis of Kern River 650 F{sup +} residuum

Description: Kern River 650 F{sup +} residuum (Kern Co, CA) and mixtures of Kern River 650 F{sup +} residuum with solids were examined by micropyrolysis at nominal constant heating rates from 1 to 50 C/min from temperatures of 100 to 700 C to establish evolution behavior, pyrolysate yields, and kinetics of evolution. The profiles for all samples generally exhibited two regimes of evolution: (1) low temperature (due to distillation), and (2) high temperature (due to cracking and distillation). The pyrolysate yields of the residuum alone and residuum with solids exhibited, with increasing sample size, a broad maximum at 0.005 to 0.010 g of {approximately} 1,000 mg pyrolysate/g residuum (relative to Green River oil shale Fischer Assay yield) as well as shifting of distribution from distillation to cracking regime. For kinetic parameters, because much of the low temperature evolving data was due to volatilization and not cracking, determinations were limited mostly to the discrete method. The best fits exhibited very similar parameters for all the samples have principal E{sub discrete} of 50 to 51 kcal/mol (accounting for {approximately}30% of total energy) and A{sub discrete} around 10{sup 12} to 10{sup 13} sec{sup {minus}1}. These results indicate the use of heat carriers, such as alumina or dolomite, in pyrolysis processing of heavy oils may effect the overall yields of the pyrolysate, but will probably not effect the pyrolysis cracking rates.
Date: April 1, 1995
Creator: Reynolds, J.G. & King, K.J.
Partner: UNT Libraries Government Documents Department

Preliminary report on isotope abundance measurements in groundwater samples from the Talbert Injection Barrier Area, Orange County Water District

Description: This report discusses isotope abundance measurements made on a collection of groundwater samples from the Orange County Water District. The water samples were collected in May, 1994 as part of a preliminary study conducted by LLNL to assess the feasibility of tracing and dating reclaimed water used in the Talbert Injection Barrier. A set of samples were collected both near to and far from the barrier and also at different depths in available monitoring wells. A variety of elements were selected for isotopic analysis; hydrogen (tritium), helium, neon, carbon, chlorine and strontium. The tritium abundance combined with the {sup 3}He and {sup 20}Ne abundance provides a method for age dating young (< 40 yr.) groundwater. The abundance of {sup 14}C provides an age dating technique for older (1,000--50,000 yr.) groundwater. The concentrations of {sup 36}Cl and {sup 87}Sr/{sup 86}Sr give information on sea water mixing and water-rock chemical interactions.
Date: February 1, 1995
Creator: Hudson, G.B.; Davisson, M.L.; Velsko, C.; Niemeyer, S.; Esser, B. & Beiriger, J.
Partner: UNT Libraries Government Documents Department

Real-time earthquake alert system for the greater San Francisco Bay Area: a prototype design to address operational issues

Description: This paper describes a prototype for this EAS (real time) in the Bay area. Approach is pragmatic, attempting to establish a prototype system at a low cost and quickly. A real-time warning system can protect the public and mitigate earthquake damage. The proposed system is a distributed network of real-time strong-motion monitoring stations that telemetered data in real time to a central analysis facility which could transmit earthquake parameter information to an area before elastic wave energy arrived. Upgrades and issues that should be resolved before an operational EAS can be established, are listed.
Date: May 29, 1996
Creator: Harben, P.E.; Jarpe, S. & Hunter, S.
Partner: UNT Libraries Government Documents Department

Quantitative precipitation and river flow predictions over the southwestern United States

Description: Accurate predictions of local precipitation and river flow are crucial in the western US steep terrain and narrow valleys can cause local flooding during short term heavy precipitation. Typical size of hydrologically uniform watersheds within the mountainous part of the western US ranges 10{sup 2} to 10{sup 3} km{sup 2}. Such small watershed size, together with large variations in terrain elevations and a strong dependence of precipitation on terrain elevation, requires a find-resolution and well-localized NWP to improve QPF and river predictions. The most important aspects of accurate QPF and river flow predictions in the western US are: (1) partitioning the total precipitation into rainfall and snowfall, (2) representing hydrologic processes within individual watersheds, and (3) map watershed areas onto the regularly-spaced atmospheric grid model grid. In the following, we present the QPF and river flow calculations by the CARS system during two winter seasons from Nov. 1994 to Apr. 1995.
Date: September 1, 1996
Creator: Kim, J. & Miller, N.L.
Partner: UNT Libraries Government Documents Department

Independent seismic evaluation of the 24-580-980 south connector ramps

Description: The interchange for highways 24, 580, and 980 (the Stack) in Oakland, California, lies 4.3 km from the surface expression of the Hayward fault and 26 km from the San Andreas fault. The purpose of this project is to compute realistic, linear, strong ground motion (rock outcrop motion) likely to affect this interchange during a hazardous earth-quake on the Hayward fault. With the exception of very long period ( >20 sec) motion, the Hayward fault will be the controlling deterministic ground motion hazard to this structure. We identified a magnitude M = 7.25 earthquake that ruptures 82 km of the Hayward fault as the principal hazard to the Stack; it has a moment of 8.5 x 10{sup 26} dyne-cm. Moment magnitudes (Hanks and Kanamori, 1979) are used in this report. Our goal is to produce realistic synthesized ground motion for three components and the full wavetrain and for frequencies from 0.05 to 33.0 Hz.
Date: May 1, 1997
Creator: Hutchings, L.J.; Kasameyer, P.W.; Jarpe, S.P. & Foxall, W.
Partner: UNT Libraries Government Documents Department

Independent seismic evaluation of the 24-580-980 south connector ramps response to the south connector ramps to a magnitude 7.25 Hayward Fault earthquake. Volume 3

Description: The 24/580/980 interchange is located near Oakland California on the Eastern perimeter of the San Francisco Bay (Fig. 1 and Fig. 2). This interchange is a major artery in the Eastern San Francisco Bay area and provides a critical link between major bay area highways. The main Concord line of the Bay Area Rapid Transit System (BART), with ridership of approximately 270,000 per day, runs underneath the interchange. The interchange site is approximately 4 Km from the Hayward fault and 16 Km from the San Andreas fault. The reinforced concrete interchange was designed and constructed in the mid 1960`s and thus the asphalt structure has many of the vulnerabilities associated with typical pre-1970`s concrete structures (Roberts [1], Zefinski [2], Chai et. al. [3], Priestly and Seible [4]). In 1980 some of the seismic vulnerabilities were addressed as the interchange was retrofit with deck hinge restrainers as part of the California Department of Transportation (Caltrans) state-wide seismic retrofit of bridge expansion joints. The interchange was subjected to earthquake motion during the 1989 Loma Prieta earthquake and sustained minor damage in some of the concrete diaphragms which support the hinge restrainer forces [5]. Caltrans engineers, working together with their external consultants Imbsen and Associates, have recently completed a seismic retrofit design for portions of the interchange. The retrofit is primarily intended to fix inadequacies in many of the 1960`s vintage reinforced concrete elements which constitute the bridge superstructure and foundations.
Date: November 1996
Creator: McAllen, David B.; Gerhard, Michael A.; Trummer, David J. & Murray, Robert C.
Partner: UNT Libraries Government Documents Department

Environmental isotope investigation of groundwater flow in the Honey Lake Basin, California and Nevada

Description: The hydrology of Honey Lake Basin was studied using environmental isotope measurements of approximately 130 water samples collected during 1995 and 1996. The principal analytical methods included hydrogen, oxygen and carbon stable isotope ratio measurements, radiocarbon and tritium dating, and measurements of dissolved noble gas abundances.
Date: July 1, 1997
Creator: Rose, T.P.; Davisson, M.L.; Hudson, G.B. & Varian, A.R.
Partner: UNT Libraries Government Documents Department

Institute of Geophyics and Planetary Physics. Annual report for FY 1994

Description: The Institute of Geophysics and Planetary Physics (IGPP) is a Multicampus Research Unit of the University of California (UC). IGPP was founded in 1946 at UC Los Angeles with a charter to further research in the earth and planetary sciences and in related fields. The Institute now has branches at UC campuses in Los Angeles, San Diego, Riverside, and Irvine and at Los Alamos and Lawrence Livermore national laboratories. The University-wide IGPP has played an important role in establishing interdisciplinary research in the earth and planetary sciences. For example, IGPP was instrumental in founding the fields of physical oceanography and space physics, which at the time fell between the cracks of established university departments. Because of its multicampus orientation, IGPP has sponsored important interinstitutional consortia in the earth and planetary sciences. Each of the six branches has a somewhat different intellectual emphasis as a result of the interplay between strengths of campus departments and Laboratory programs. The IGPP branch at Lawrence Livermore National Laboratory (LLNL) was approved by the Regents of the University of California in 1982. IGPP-LLNL emphasizes research in seismology, geochemistry, cosmochemistry, high-pressure sciences, and astrophysics. It provides a venue for studying the fundamental aspects of these fields, thereby complementing LLNL programs that pursue applications of these disciplines in national security and energy research. IGPP-LLNL is directed by Charles Alcock and is structured around three research centers. The Center for Geosciences, headed by George Zandt and Frederick Ryerson, focuses on research in geophysics and geochemistry. The Center for High-Pressure Sciences, headed by William Nellis, sponsors research on the properties of planetary materials and on the synthesis and preparation of new materials using high-pressure processing.
Date: September 29, 1995
Creator: Ryerson, F.J.
Partner: UNT Libraries Government Documents Department

Science and technology review: June 1996

Description: The first feature article is a survey of four research projects showing how theory and modeling efforts by scientist in the Chemistry and Materials Science Directorate at LLNL are advancing the understanding of the property of materials with consideration of underlying structures. The second feature article discusses Livermore and DOE`s Oakland Operations Office teaming up to decontaminate, decommission, and close out--on time and under budget--the Ann Arbor Inertial Confinement Fusion Facility in Michigan. Two research highlights on Mammoth Mountain CO{sub 2} mystery and osteoporosis are also included.
Date: June 1, 1996
Creator: Failor, B. & Stull, S.
Partner: UNT Libraries Government Documents Department

Methods for Using Ground-Water Model Predictions to Guide Hydrogeologic Data Collection, with Applications to the Death Valley Regional Ground-Water Flow System

Description: Calibrated models of ground-water systems can provide substantial information for guiding data collection. This work considers using such models to guide hydrogeologic data collection for improving model predictions, by identifying model parameters that are most important to the predictions. Identification of these important parameters can help guide collection of field data about parameter values and associated flow-system features that can lead to improved predictions. Methods for identifying parameters important to predictions include prediction scaled sensitivities (PSS), which account for uncertainty on individual parameters as well as prediction sensitivity to parameters, and a new ''value of improved information'' (VOII) method, which includes the effects of parameter correlation in addition to individual parameter uncertainty and prediction sensitivity. The PSS and VOII methods are demonstrated using a model of the Death Valley regional ground-water flow system. The predictions of interest are advective-transport paths originating at sites of past underground nuclear testing. Results show that for two paths evaluated, the most important parameters include a subset of five or six of the 23 defined model parameters. Some of the parameters identified as most important are associated with flow-system attributes that do not lie in the immediate vicinity of the paths. Results also indicate that the PSS and VOII methods can identify different important parameters. Because the methods emphasize somewhat different criteria for parameter importance, it is suggested that parameters identified by both methods be carefully considered in subsequent data collection efforts aimed at improving model predictions.
Date: July 31, 2001
Creator: Tiedeman, Claire R.; Hill, M.C.; D'Agnese, F.A. & Faunt, C.C.
Partner: UNT Libraries Government Documents Department


Description: GOPHERLTS AGAISSIZII (Desert Tortoise). Predation. A variety of predators, most notably coyotes (Canis Iatrans) and Common Ravens (Corvis corau) have been reported to prey on hatchling desert tortoises (Emst et al. 1994). Turtles of the United States and Canada (Smithsonian Institution Press, Washington, D.C. 578 pp.). Here, we report an observation of a hatchling tortoise, fitted with a radiotransmitter, that was preyed upon by native fire ants (Solenopsis sp.) in the eastern Mojave Desert at Yucca Mountain, Nevada (36 degrees 50 minutes N, 116 degree 25 minutes E). On 8/27/94, tortoise No.9315 (carapace length = 45 mm, age = 5 d) was found alive with eyes, chin, and parts of the head and legs being eaten by ants. The tortoise was alive, but lethargic, and responded little when touched. Eight of 74 other radiomarked hatchlings monitored at Yucca Mountain during 1992-1994 were found dead with fire ants on their carcass 3-7 days after the hatchlings emerged from their nests. It is not known whether those tortoises were killed by ants or were being scavenged when found. While imported fire ants (S. invicta) have long been known to kill hatchling gopher tortoises (G. polyphemus; Mount 1981. J. Alabama Acad. Sci. 52: 71-78), native fire ants have previously not been implicated as predators of desert tortoises. However, only 1 of 75 (or at worst 9 of 75) was killed by fire ants, suggesting that although fire ants do kill hatchlings, they were not important predators on desert tortoises during this study. Tortoise specimens were deposited at the University of California at Berkeley.
Date: December 16, 1997
Partner: UNT Libraries Government Documents Department