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171.
Keith A. Cherkauer Stephen J. Burges Rebecca N. Handcock Jennifer E. Kay Stephanie K. Kampf Alan R. Gillespie 《Journal of the American Water Resources Association》2005,41(5):1149-1159
One central issue affecting the health of native fish species in the Pacific Northwest is water temperature. In situ observation methods monitor point temperatures, while thermal infrared (TIR) remote sensing captures spatial variations. Satellite‐based TIR sensors have the ability to view large regions in an instant. Four Pacific Northwest river reaches were selected to test the ability of both satellite‐based and moderate resolution aircraft‐based TIR remote sensing products to measure river temperatures. Images with resolutions of 5, 15, and 90 meters were compared with instream temperature observations to assess how along stream radiant temperatures are affected by resolution, reach width, and sensor platform. Where the stream reach can be resolved by the sensor, all sensors obtain water temperatures within ±2°C of instream observations. Along stream temperature variations of up to ±5°C were also observed. Trends were similar between two sets of TIR images taken several hours apart, indicating that the sensors are observing actual temperature patterns from the river surface. If sensor resolution is sufficient to obtain fully resolved water pixels in the river reach, accurate temperatures and spatial patterns can be observed. The current generation of satellite‐based TIR sensors is, however, only able to resolve about 6 percent of all Washington reaches listed as thermally impaired. 相似文献
172.
Macroalgal growth in nutrient-enriched estuaries: A biogeochemical and evolutionary perspective 总被引:1,自引:0,他引:1
Increased nutrient loading of a body of water leads to an increase in macroalgal growth. It is generally observed, however, that certain species thrive more than others, capitalising on the increased nutrient availability. These are usually small, fast-growing, ephemeral algae that often appear as nuisance blooms. This article discusses the correlation between nutrient increase and macroalgal bloom formation. From a historical perspective, the evolutionary history of nuisance macroalgae, and the habits available to them prior to anthropogenic influences on estuarine geochemistry are considered. The occurrence of macroalgal genera whose distribution is commonly related to estuaries with high nutrient loading is discussed, along with evidence suggesting that the ecophysiological traits of r-selected, ephemeral algae largely contribute to their ecological success and bloom-formation at nutrient-enriched sites. 相似文献
173.
Cross-Boundary Coordination on Forested Landscapes: Investigating Alternatives for Implementation 总被引:2,自引:0,他引:2
Cross-boundary coordination is a tool for ecosystem management whereby landowners voluntarily coordinate management practices
toward economic and/or ecological landscape-scale outcomes (e.g., fiber, invasive species control, habitat). Past research
indicates that it may be particularly applicable on landscapes that include small forest landholdings. To explore alternatives
by which coordination might occur, we conducted seven focus groups with landowners (n = 51) who actively manage their forests in southwest Wisconsin and northeast Iowa. Focus group participants were presented
with three hypothetical alternatives to coordinate with their neighbors; landowners could self-organize, work with a natural
resource professional (i.e., forester), or work with an organization to complete a cross-boundary practice. In this article,
we focus on the latter two alternatives and the role of two social theories—principal-agent and cooperation—in explaining
landowners’ evaluations of these alternatives. Key findings are that (1) cross-boundary coordination has the potential to
alleviate problems between landowners and resource professionals inherent to their typical working relationship, and (2) social
relationships are a major factor contributing to landowners’ willingness to participate. We posit that cross-boundary coordination
offers a non-economic incentive for landowners to work together as it may reduce the uncertainty associated with hiring a
resource professional. At the same time, professionals can provide a bridging function among landowners who are unacquainted.
To achieve these outcomes and expand the adoption of cross-boundary coordination, we suggest four guidelines. First, foster
dialogue among landowners toward shared cognition and oversight. Second, match landowners’ practices and objectives such that
there are clear benefits to all. Third, develop relationships through low risk activities where possible. Fourth, do not expect
on-going commitments.
相似文献
Mark RickenbachEmail: |
174.
Rebecca Efroymson Henriette Jager Virginia Dale James Westervelt 《Environmental management》2009,44(6):1163-1179
A decision framework for setting management goals for species at risk is presented. Species at risk are those whose potential
future rarity is of concern. Listing these species as threatened or endangered could potentially result in significant restrictions
to activities in resource management areas in order to maintain those species. The decision framework, designed to foster
proactive management, has nine steps: identify species at risk on and near the management area, describe available information
and potential information gaps for each species, determine the potential distribution of species and their habitat, select
metrics for describing species status, assess the status of local population or metapopulation, conduct threat assessment,
set and prioritize management goals, develop species management plans, and develop criteria for ending special species management
where possible. This framework will aid resource managers in setting management goals that minimally impact human activities
while reducing the likelihood that species at risk will become rare in the near future. The management areas in many of the
examples are United States (US) military installations, which are concerned about potential restrictions to military training
capacity if species at risk become regulated under the US Endangered Species Act. The benefits of the proactive management
set forth in this formal decision framework are that it is impartial, provides a clear procedure, calls for identification
of causal relationships that may not be obvious, provides a way to target the most urgent needs, reduces costs, enhances public
confidence, and, most importantly, decreases the chance of species becoming more rare. 相似文献
175.
Team trust is gaining attention in research and practice due to its benefits for team performance, yet clarity about the intricacies of its measurement is needed. Therefore, we meta-analyzed 118 studies (N = 7,738) to untangle the role of measurement features by investigating the degree to which they influence the trust–performance relationship. Results showed that the trust–performance relationship is contingent upon time lag and source of measurement. Specifically, cross-sectional and single-source studies produced higher effect sizes than time-lagged and different-source studies. In contrast, the moderating roles of conceptualization–operationalization alignment and referent of trust measures were not supported. Post hoc analyses revealed that affective trust is more strongly related to global, versus specific team outcomes, and that mixed-referent items are particularly effective within intact teams, whereas the trust–performance relationship is constrained when direct consensus items are used within ad hoc teams. Furthermore, we provided a critical review that highlights the importance of composites, multilevel forces, and item content and wording. Finally, we clarified key gaps in the literature, calling for research where needed. This review serves as a bridge between conceptualization and measurement and lays the groundwork for advancing knowledge of team trust. 相似文献
176.
Rebecca L. Greenbaum Julena M. Bonner Mary B. Mawritz Marcus M. Butts Mickey B. Smith 《组织行为杂志》2020,41(6):503-517
We examine bottom-line mentality (BLM) at the group level and examine the effect of group BLM on group psychological safety and subsequent group creativity. We draw on goal shielding theory to suggest that groups high in BLM narrowly focus on bottom-line outcomes, which encourages them to eliminate distracting considerations from their work processes. Because the group's high BLM encapsulates goal shielding, these groups are deficient in fostering psychological safety as an important interpersonal process that facilitates group creativity. We also couple goal shielding theory with arguments related to situational strength to examine group BLM agreement (i.e., the standard deviation of the mean of group BLM) as a first stage moderator. We contend that high-BLM agreement (vs. low agreement) strengthens the goal shielding effect of group BLM, which is reflected by a stronger detrimental effect on group psychological safety that then reduces group creativity. We found support for our theoretical model using multisource, multiwave field data from a diverse sample of workgroups and their supervisors. We discuss the theoretical implications of our research and provide practical suggestions for limiting the deleterious consequences of group BLMs in the workplace. 相似文献
177.
178.
Pharmaceuticals and personal care products found in the Great Lakes above concentrations of environmental concern 总被引:2,自引:0,他引:2
The monitoring of pharmaceuticals and personal care products (PPCPs) has focused on the distribution in rivers and small lakes, but data regarding their occurrence and effects in large lake systems, such as the Great Lakes, are sparse. Wastewater treatment processes have not been optimized to remove influent PPCPs and are a major source of PPCPs in the environment. Furthermore, PPCPs are not currently regulated in wastewater effluent. In this experiment we evaluated the concentration, and corresponding risk, of PPCPs from a wastewater effluent source at varying distances in Lake Michigan. Fifty-four PPCPs and hormones were assessed on six different dates over a two-year period from surface water and sediment samples up to 3.2 km from a wastewater treatment plant and at two sites within a harbor. Thirty-two PPCPs were detected in Lake Michigan and 30 were detected in the sediment, with numerous PPCPs being detected up to 3.2 km away from the shoreline. The most frequently detected PPCPs in Lake Michigan were metformin, caffeine, sulfamethoxazole, and triclosan. To determine the ecological risk, the maximum measured environmental concentrations were compared to the predicted no-effect concentration and 14 PPCPs were found to be of medium or high ecological risk. The environmental risk of PPCPs in large lake systems, such as the Great Lakes, has been questioned due to high dilution; however, the concentrations found in this study, and their corresponding risk quotient, indicate a significant threat by PPCPs to the health of the Great Lakes, particularly near shore organisms. 相似文献
179.
Efroymson RA Peterson MJ Giffen NR Ryon MG Smith JG Hargrove WW Roy WK Welsh CJ Druckenbrod DL Quarles HD 《Journal of environmental management》2008,88(4):1452-1470
Habitat valuation methods were implemented to support remedial decisions for aquatic and terrestrial contaminated sites at the East Tennessee Technology Park (ETTP) on the US Department of Energy (DOE) Oak Ridge Reservation in Oak Ridge, TN, USA. The habitat valuation was undertaken for six contaminated sites: Contractor's Spoil Area, K-901-N Disposal Area, K-770 Scrapyard, K-1007-P1 pond, K-901 pond, and the Mitchell Branch stream. Four of these sites are within the industrial use area of ETTP and two are in the Black Oak Ridge Conservation Easement. These sites represent terrestrial and aquatic habitat for vertebrates, terrestrial habitat for plants, and aquatic habitat for benthic invertebrates. Current and potential future, no-action (no remediation) scenarios were evaluated primarily using existing information. Valuation metrics and scoring criteria were developed in a companion paper, this volume. The habitat valuation consists of extensive narratives, as well as scores for aspects of site use value, site rarity, and use value added from spatial context. Metrics for habitat value were expressed with respect to different spatial scales, depending on data availability. There was significant variation in habitat value among the six sites, among measures for different taxa at a single site, between measures of use and rarity at a single site, and among measures for particular taxa at a single site with respect to different spatial scales. Most sites had aspects of low, medium, and high habitat value. Few high scores for current use value were given. These include: wetland plant communities at all aquatic sites, Lepomid sunfish and waterbirds at 1007-P1 pond, and Lepomid sunfish and amphibians at K-901 pond. Aquatic sites create a high-value ecological corridor for waterbirds, and the Contractor's Spoil Area and possibly the K-901-N Disposal Site have areas that are part of a strong terrestrial ecological corridor. The only example of recent observations of rare species at these sites is the gray bat observed at the K-1007-P1 pond. Some aspects of habitat value are expected to improve under no-action scenarios at a few of the sites. Methods are applicable to other contaminated sites where sufficient ecological data are available for the site and region. 相似文献
180.
Worldwide, the ecological condition of streams and rivers has been impaired by agricultural practices such as broadscale modification of catchments, high nutrient and sediment inputs, loss of riparian vegetation, and altered hydrology. Typical responses include channel incision, excessive sedimentation, declining water quality, and loss of in-stream habitat complexity and biodiversity. We review these impacts, focusing on the potential benefits and limitations of wood reintroduction as a transitional rehabilitation technique in these agricultural landscapes using Australian examples. In streams, wood plays key roles in shaping velocity and sedimentation profiles, forming pools, and strengthening banks. In the simplified channels typical of many agricultural streams, wood provides habitat for fauna, substrate for biofilms, and refuge from predators and flow extremes, and enhances in-stream diversity of fish and macroinvertebrates.Most previous restoration studies involving wood reintroduction have been in forested landscapes, but some results might be extrapolated to agricultural streams. In these studies, wood enhanced diversity of fish and macroinvertebrates, increased storage of organic material and sediment, and improved bed and bank stability. Failure to meet restoration objectives appeared most likely where channel incision was severe and in highly degraded environments. Methods for wood reintroduction have logistical advantages over many other restoration techniques, being relatively low cost and low maintenance. Wood reintroduction is a viable transitional restoration technique for agricultural landscapes likely to rapidly improve stream condition if sources of colonists are viable and water quality is suitable. 相似文献