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31.
Traditional bacterial indicators used in public health to assess water quality and the Biolog system were evaluated to compare their response to biological, chemical, and physical habitat indicators of stream condition both within the state of Oregon and among ecoregion aggregates (Coast Range, Willamette Valley, Cascades, and eastern Oregon). Forty-three randomly selected Oregon river sites were sampled during the summer in 1997 and 1998. The public health indicators included heterotrophic plate counts (HPC), total coliforms (TC), fecal coliforms (FC) and Escherichia coli (EC). Statewide, HPC correlated strongly with physical habitat (elevation, riparian complexity, % canopy presence, and indices of agriculture, pavement, road, pasture, and total disturbance) and chemistry (pH, dissolved O2, specific conductance, acid-neutralizing capacity, dissolved organic carbon, total N, total P, SiO2, and SO4). FC and EC were significantly correlated generally with the river chemistry indicators. TC bacteria significantly correlated with riparian complexity, road disturbance, dissolved O2, and SiO2 and FC. Analyzing the sites by ecoregion, eastern Oregon was characterized by high HPC, FC, EC, nutrient loads, and indices of human disturbance, whereas the Cascades ecoregion had correspondingly low counts of these indicators. The Coast Range and Willamette Valley presented inconsistent indicator patterns that are more difficult to characterize. Attempts to distinguish between ecoregions with the Biolog system were not successful, nor did a statistical pattern emerge between the first five principle components and the other environmental indicators. Our research suggests that some traditional public health microbial indicators may be useful in measuring the environmental condition of lotic systems. 相似文献
32.
Burger J Gochfeld M Powers CW Waishwell L Warren C Goldstein BD 《Environmental management》2001,27(4):501-514
In recent years there has been a startling rise in the issuance of fish consumption advisories. Unfortunately, compliance
by the public is often low. Low compliance can be due to a number of factors, including confusion over the meaning of advisories,
conflicting advisories issued by different agencies, controversies involving health benefits versus the risks from consuming
fish, and an unwillingness to act on the advisories because of personal beliefs. In some places, such as along the Savannah
River, one state (South Carolina) had issued a consumption advisory while the other (Georgia) had not, although at present,
both states now issue consumption advisories for the Savannah River. Herein we report on the development of a fish fact sheet
to address the confusing and conflicting information available to the public about consuming fish from the Savannah River.
The process involved interviewing fishers to ascertain fishing and consumption patterns, evaluating contaminant levels and
exposure pathways, discussing common grounds for the provision of information, and consensus-building among different regulatory
agencies (US Environmental Protection Agency, South Carolina Department of Health and Environmental Control, Georgia Department
of Natural Resources) and the Department of Energy. Consensus, a key ingredient in solving many different types of “commons”
problems, was aided by an outside organization, the Consortium for Risk Evaluation with Stakeholder Participation (CRESP).
The initial role for CRESP was to offer scientific data as a basis for groups with different assumptions about risks to reach
agreement on a regulatory response action. The process was an example of how credible science can be used to implement management
and policies and provide a basis for consensus-building on difficult risk communication issues. The paper provides several
lessons for improving the risk process from stakeholder conflicts, through risk assessment, to risk management. It also suggests
that consensus-building and risk communication are continuing processes that involve assimilation of new information on contaminants
and food-chain processes, state and federal law, public policy, and public response. 相似文献
33.
The Long-Term Effects of Tiger Poaching on Population Viability 总被引:4,自引:0,他引:4
JOHN S. KENNEY JAMES L. D. SMITH ANTHONY M. STARFIELD CHARLES W. MCDOUGAL 《Conservation biology》1995,9(5):1127-1133
Poaching tigers, primarily for their bones, has become the latest threat to the persistence of wild tiger populations throughout the world. Anecdotal information indicates the seriousness of this new threat. It is important, however, to provide a quantitative analysis of poaching as a basis for strong policy action. We therefore created a tiger simulation model to explore the effects of realistic levels of poaching on population viability. The model is an individually based, stochastic spatial model that is based on the extensive data set from Royal Chitwan National Park, Nepal. We found that as poaching continues over time, the probability of population extinction increases sigmoidally; a critical zone exists in which a small, incremental increase in poaching greatly increases the probability of extinction. The implication is that poaching may not at first be seen as a threat but could suddenly become one. Moreover, even if poaching is effectively stopped, tiger populations will still be vulnerable and could go extinct due to demographic and environmental stochasticity. Our model also shows that poaching reduces genetic variability, which could further reduce population viability due to inbreeding depression. The longer poaching is allowed to continue, the more vulnerable a population will be to these stochastic events. At currently reported rates of poaching our analysis indicates that many wild tiger populations will be extirpated during the latter half of the 1990s. 相似文献
34.
Thought self-leadership involves employee self-influence through cognitive strategies that focus on individual self-dialogue, mental imagery, beliefs and assumptions, and thought patterns. A training intervention-based field study with a control group was undertaken to empirically examine the applicability of thought self-leadership in an organizational setting (of bankruptcy financial status), and the potential for cognitions to be self-controlled. Results suggested that individuals who received the thought self-leadership training experienced increased mental performance, positive affect (enthusiasm), job satisfaction, and decreased negative affect (nervousness) relative to those not receiving the training. Additionally, the trainees reported a strong and positive reaction to the training. Finally, those who received the training experienced enhanced perceptions of self-efficacy and more optimistic perceptions of the organization's bankruptcy condition than those not receiving the training. 相似文献
35.
Regeneration of Native Trees in the Presence of Invasive Saltcedar in the Colorado River Delta, Mexico 总被引:3,自引:0,他引:3
PAMELA L. NAGLER†† OSVEL HINOJOSA-HUERTA† EDWARD P. GLENN JAQUELINE GARCIA-HERNANDEZ‡ REGGIE ROMO CHARLES CURTIS§ ALFREDO R. HUETE STEPHEN G. NELSON 《Conservation biology》2005,19(6):1842-1852
Abstract: Many riparian zones in the Sonoran Desert have been altered by elimination of the normal flood regime; such changes to the flow regime have contributed to the spread of saltcedar ( Tamarix ramosissma Ledeb.), an exotic, salt-tolerant shrub. It has been proposed that reestablishment of a natural flow regime on these rivers might permit passive restoration of native trees, without the need for aggressive saltcedar clearing programs. We tested this proposition in the Colorado River delta in Mexico, which has received a series of large-volume water releases from U.S. dams over the past 20 years. We mapped the vegetation of the delta riparian corridor through ground and aerial surveys (1999–2002) and satellite imagery (1992–2002) and related vegetation changes to river flood flows and fire events. Although saltcedar is still the dominant plant in the delta, native cottonwood ( Populus fremontii S. Wats.) and willow ( Salix gooddingii C. Ball) trees have regenerated multiple times because of frequent flood releases from U.S. dams since 1981. Tree populations are young and dynamic (ages 5–10 years). The primary cause of tree mortality between floods is fire. Biomass in the floodplain, as measured by the normalized difference vegetation index on satellite images, responds positively even to low-volume (but long-duration) flood events. Our results support the hypothesis that restoration of a pulse flood regime will regenerate native riparian vegetation despite the presence of a dominant invasive species, but fire management will be necessary to allow mature tree stands to develop. 相似文献
36.
Abstract: The last century has seen the ascendance of a core economic model, which we will refer to as Walrasian economics. This model is driven by the psychological assumptions that humans act only in a self‐referential and narrowly rational way and that production can be described as a self‐contained circular flow between firms and households. These assumptions have critical implications for the way economics is used to inform conservation biology. Yet the Walrasian model is inconsistent with a large body of empirical evidence about actual human behavior, and it violates a number of basic physical laws. Research in behavioral science and neuroscience shows that humans are uniquely social animals and not self‐centered rational economic beings. Economic production is subject to physical laws including the laws of thermodynamics and mass balance. In addition, some contemporary economic theory, spurred by exciting new research in human behavior and a wealth of data about the negative global impact of the human economy on natural systems, is moving toward a world view that places consumption and production squarely in its behavioral and biophysical context. We argue that abandoning the straightjacket of the Walrasian core is essential to further progress in understanding the complex, coupled interactions between the human economy and the natural world. We call for a new framework for economic theory and policy that is consistent with observed human behavior, recognizes the complex and frequently irreversible interaction between human and natural systems, and directly confronts the cumulative negative effects of the human economy on the Earth's life support systems. Biophysical economics and ecological economics are two emerging economic frameworks in this movement. 相似文献
37.
JAMES R. FARMER DOUG KNAPP VICKY J. MERETSKY CHARLES CHANCELLOR BURNELL C. FISCHER 《Conservation biology》2011,25(4):827-834
Abstract: The use of conservation easements as a conservation mechanism for private land has increased greatly in the past decade; conservation easements now protect over 15 million ha across the United States from residential and commercial development. We used a mailed survey and in‐depth telephone interviews to determine factors that motivate private landowners in Iowa, Illinois, Michigan, Ohio, and Wisconsin (U.S.A.) to place conservation easements on their properties. The mailed survey asked about characteristics of landowners, their properties, and their opinions on 9 factors related to the decision to place an easement. A follow‐up telephone interview was completed with 19 mail‐survey participants to gain an in‐depth understanding of the action and to triangulate the results with the questionnaire. Place attachment, which is a measure of personal connection to a location or property, was the greatest motivation for implementation of an easement. Results of a principal components analysis suggested contributing to the public good underlaid several of the strong motivational factors for participation. Financial reasons were the lowest ranked motivational factor; however, financial concerns may facilitate placement of an easement that would otherwise not be realized. We believe that our results may be transferable to places where land protected by easements is not dominated by traditional farming (row crops, pastures, and hay), timber harvesting, or nonextractive uses (e.g., habitat for wild animals, recreation, and protection of ecosystem services). 相似文献
38.
MARISKA WEIJERMAN C. MARK EAKIN PAUL MCELHANY MARGARET W. MILLER MATT PATTERSON GREGORY A. PINIAK MATTHEW J. DUNLAP CHARLES BIRKELAND 《Conservation biology》2013,27(6):1169-1178
Many marine invertebrate species facing potential extinction have uncertain taxonomies and poorly known demographic and ecological traits. Uncertainties are compounded when potential extinction drivers are climate and ocean changes whose effects on even widespread and abundant species are only partially understood. The U.S. Endangered Species Act mandates conservation management decisions founded on the extinction risk to species based on the best available science at the time of consideration—requiring prompt action rather than awaiting better information. We developed an expert‐opinion threat‐based approach that entails a structured voting system to assess extinction risk from climate and ocean changes and other threats to 82 coral species for which population status and threat response information was limited. Such methods are urgently needed because constrained budgets and manpower will continue to hinder the availability of desired data for many potentially vulnerable marine species. Significant species‐specific information gaps and uncertainties precluded quantitative assessments of habitat loss or population declines and necessitated increased reliance on demographic characteristics and threat vulnerabilities at genus or family levels. Adapting some methods (e.g., a structured voting system) used during other assessments and developing some new approaches (e.g., integrated assessment of threats and demographic characteristics), we rated the importance of threats contributing to coral extinction risk and assessed those threats against population status and trend information to evaluate each species’ extinction risk over the 21st century. This qualitative assessment resulted in a ranking with an uncertainty range for each species according to their estimated likelihood of extinction. We offer guidance on approaches for future biological extinction risk assessments, especially in cases of data‐limited species likely to be affected by global‐scale threats. Incorporación del Cambio Climático y Oceánico en Estudios de Riesgo de Extinción para 82 Especies de Coral 相似文献
39.
The high degree of physical disturbance associated with conventional response options to oil spills in wetlands is driving
the investigation of alternative cleanup methodologies. In March 1995, a spill of gas condensate in a brackish marsh at Rockefeller
Wildlife Refuge in southwestern Louisiana was remediated through the use of in situ burning. An assessment of vegetation recovery
was initiated in three treatment marshes: (1) oil-impacted and burned, (2) oil impacted and unburned, and (3) a nonoiled unburned
reference. We compared percent cover, stem density, and biomass in the treatment marshes to define ecological recovery of
the marsh vegetation and soil hydrocarbon content to determine the efficacy of in situ burning as a cleanup technique. Burning
led to a rapid decrease in soil hydrocarbon concentrations in the impacted-and-burned marsh to background levels by the end
of the first growing season. Although a management fire accidentally burned the oil-impacted-and-unburned and reference marshes
in December 1995, stem density, live biomass, and total percent cover values in the oil-impacted-and-burned marsh were equivalent
to those in the other treatment marshes after three years. In addition, plant community composition within the oil-impacted-and-burned
marsh was similar to the codominant mix of the grasses Distichlis spicata (salt grass) and Spartina patens (wire grass) characteristic of the surrounding marsh after the same time period. Rapid recovery of the oil-impacted-and-unburned
marsh was likely due to lower initial hydrocarbon exposure. Water levels inundating the soil surface of this grass-dominated
marsh and the timing of the in situ burn early in the growing season were important factors contributing to the rapid recovery
of this wetland. The results of this in situ burn evaluation support the conclusion that burning, under the proper conditions,
can be relied upon as an effective cleanup response to hydrocarbon spills in herbaceous wetlands. 相似文献
40.
Burger J Leschine TM Greenberg M Karr JR Gochfeld M Powers CW 《Environmental management》2003,31(2):0157-0167
More than 50 years of research, development, manufacture, and testing of nuclear weapons at Department of Energy (DOE) sites
has left a legacy of on-site contamination that often spreads to surrounding areas. Despite substantial cleanup budgets in
the last decade, the DOE's top-to-bottom review team concluded that relatively little actual cleanup has been accomplished,
although milestones have been met and work packages completed. Rather than solely use regulatory constraints to direct cleanup,
many people have suggested that human and ecological health should guide long-term stewardship goals of DOE-managed sites.
The main questions are how ecological and human health considerations should be applied in deciding the extent of cleanup
that contaminated sites should receive and how near-term and longer run considerations of costs and benefits should be balanced
as cleanup decisions are made. One effort to protect ecological integrity is the designation of the largest sites as National
Environmental Research Parks (NERPs). Recently, the Competitive Enterprise Institute (CEI) suggested isolating and conserving
DOE sites as a policy priority because of their rich ecological diversity. A more effective long-term stewardship approach
for former nuclear weapons complex sites may emerge if the guiding principles are to (1) reduce risks to human and ecological
health, (2) protect cultural traditions, and (3) lower short- and long-term cleanup and remediation costs. A “net benefits”
perspective that takes both near- and longer-term costs and consequences into account can help illuminate the trade-offs between
expensive cleanup in the near term and the need to assure long-term protection of human health, cultural values, and high
levels of biodiversity and ecological integrity that currently exist at many DOE sites. 相似文献