2,792 research outputs found
Evidence of Climate-Induced Range Contractions in Bull Trout \u3ci\u3eSalvelinus confluentus\u3c/i\u3e in a Rocky Mountain Watersehd, U.S.A.
Many freshwater fish species are considered vulnerable to stream temperature warming associated with climate change because they are ectothermic, yet there are surprisingly few studies documenting changes in distributions. Streams and rivers in the U.S. Rocky Mountains have been warming for several decades. At the same time these systems have been experiencing an increase in the severity and frequency of wildfires, which often results in habitat changes including increased water temperatures. We resampled 74 sites across a Rocky Mountain watershed 17 to 20 years after initial samples to determine whether there were trends in bull trout occurrence associated with temperature, wildfire, or other habitat variables. We found that site abandonment probabilities (0.36) were significantly higher than colonization probabilities (0.13), which indicated a reduction in the number of occupied sites. Site abandonment probabilities were greater at low elevations with warm temperatures. Other covariates, such as the presence of wildfire, nonnative brook trout, proximity to areas with many adults, and various stream habitat descriptors, were not associated with changes in probability of occupancy. Higher abandonment probabilities at low elevation for bull trout provide initial evidence validating the predictions made by bioclimatic models that bull trout populations will retreat to higher, cooler thermal refuges as water temperatures increase. The geographic breadth of these declines across the region is unknown but the approach of revisiting historical sites using an occupancy framework provides a useful template for additional assessments
Fire and Fish Dynamics in a Changing Climate: Broad- and Local-Scale Effects of Fire-Induced Water Temperature Changes on Native and Nonnative Fish Communities
Fire is a key natural disturbance that affects the distribution and abundance of native fishes in the Rocky Mountain West. In the absence of migratory individuals from undisturbed portions of a watershed, persistence of native fish populations depends on the conditions of the post-fire stream environment. Stream temperatures typically warm after fire, and remain elevated until riparian vegetation recovers. An additional threat to native species is that nonnative fishes have invaded many waters, and these species tolerate or prefer warmer water temperatures. Thus, forecasting the long-term effects of fire on native fish populations requires an understanding of fire dynamics (size, distribution, frequency, and severity), the extent and location of changes in riparian forest structure and time to recovery, changes in stream temperatures associated with these forest changes, and how native and nonnative fish respond to changes in water temperature. To perform spatially explicit simulation modeling that examined the relations among fire disturbance, stream temperature, and fish communities, we upgraded and then linked the fire-forest succession model FireBGCv2 to a stream temperature model to project changes in water temperature in the East Fork Bitterroot River basin in Montana under an array of climate and fire management scenarios. Model projections indicated that although climate led to increases in fire severity, frequency, or size, water temperature increases at the basin scale were primarily a consequence of climate-driven atmospheric warming rather than changes in fire regime. Consequently, variation in fire management—fuel treatment or fire suppression—had little effect at this scale, but assumed greater importance at the scale of riparian stands. By revisiting a large number of previously sampled sites in the East Fork Bitterroot River basin in Montana, we evaluated whether bull trout persistence and other native and nonnative fish distributions were related to temperature changes associated with fire and recent climatic trends. Although fires were related to marked increases in summer water temperatures, these changes had a positive effect (westslope cutthroat trout) or a negligible effect (bull trout) on the abundance and distribution of native fish species, whereas the abundance of nonnative brook trout markedly declined in some instances. Fire-related changes in factors other than the thermal regime may have contributed to these patterns. In contrast, at the scale of the entire basin we observed an upward-directed contraction in the distribution of bull trout that was unrelated to fire. We concluded that this may be a response to temperature increases related to climate change
Fire and Fish Dynamics in a Changing Climate: Broad- and Local-Scale Effects of Fire-Induced Water Temperature Changes on Native and Nonnative Fish Communities
Fire is a key natural disturbance that affects the distribution and abundance of native fishes in the Rocky Mountain West. In the absence of migratory individuals from undisturbed portions of a watershed, persistence of native fish populations depends on the conditions of the post-fire stream environment. Stream temperatures typically warm after fire, and remain elevated until riparian vegetation recovers. An additional threat to native species is that nonnative fishes have invaded many waters, and these species tolerate or prefer warmer water temperatures. Thus, forecasting the long-term effects of fire on native fish populations requires an understanding of fire dynamics (size, distribution, frequency, and severity), the extent and location of changes in riparian forest structure and time to recovery, changes in stream temperatures associated with these forest changes, and how native and nonnative fish respond to changes in water temperature. To perform spatially explicit simulation modeling that examined the relations among fire disturbance, stream temperature, and fish communities, we upgraded and then linked the fire-forest succession model FireBGCv2 to a stream temperature model to project changes in water temperature in the East Fork Bitterroot River basin in Montana under an array of climate and fire management scenarios. Model projections indicated that although climate led to increases in fire severity, frequency, or size, water temperature increases at the basin scale were primarily a consequence of climate-driven atmospheric warming rather than changes in fire regime. Consequently, variation in fire management—fuel treatment or fire suppression—had little effect at this scale, but assumed greater importance at the scale of riparian stands. By revisiting a large number of previously sampled sites in the East Fork Bitterroot River basin in Montana, we evaluated whether bull trout persistence and other native and nonnative fish distributions were related to temperature changes associated with fire and recent climatic trends. Although fires were related to marked increases in summer water temperatures, these changes had a positive effect (westslope cutthroat trout) or a negligible effect (bull trout) on the abundance and distribution of native fish species, whereas the abundance of nonnative brook trout markedly declined in some instances. Fire-related changes in factors other than the thermal regime may have contributed to these patterns. In contrast, at the scale of the entire basin we observed an upward-directed contraction in the distribution of bull trout that was unrelated to fire. We concluded that this may be a response to temperature increases related to climate change
The Discovery of a Giant H-alpha Filament in NGC 7213
The nearby Seyfert galaxy NGC 7213 has been imaged in H-alpha and HI with the
CTIO 1.5 m telescope and with the Australia Telescope Compact Array (ATCA),
respectively. Optically NGC 7213 looks undisturbed and relatively featureless
but the continuum-subtracted H-alpha image shows a 19 kpc long filament located
approximately 18.6 kpc from the nucleus. The H-alpha filament could be neutral
gas photo-ionized by the active nucleus, as has been suggested for the Seyfert
galaxy NGC 5252, or shock-ionized by a jet interacting with the surrounding HI,
as has been suggested for the radio galaxy PKS 2240-41. The HI map reveals NGC
7213 to be a highly disturbed system suggesting a past merging event.Comment: 14 pages including 4 figures and 1 table. Figures 1-4 are in jpeg
format; Better quality images can be retrieved in postscript format at
ftp://charon.nmsu.edu/pub/shameed/ ; Accepted for publication in ApJ Letter
Agricultural Scientists’ Perceptions of Working with Reporters
Mass media is the main source of scientific information for most Americans, but inaccuracy of reporting has threatened the public’s understanding of science. Perceived media bias and fake news has also made the public skeptical of the media, and scientists’ perceptions are no different. Because scientists are the most trusted source for scientific information in America, it is important they remain willing to work with the media. This study used the Theory of Planned Behavior (TPB) to explore scientists’ perceptions of working with reporters, including their attitude, subjective norms, behavioral control, and intent to engage with the media in the future. In-depth interviews were conducted with 13 tenure-track faculty at the University of Florida’s Institute of Food and Agricultural Sciences (UF/IFAS) in spring 2018. These participants represented low, moderate, and high communicators. The findings from this study indicated mostly negative attitudes toward reporters due to skepticism in their ability to accurately report science. Behavioral control was also limited due to time and ability constraints, but participants recommended trainings as ways to increase behavioral control. Subjective norms were somewhat mixed, with some positive norms from mentors but perceived negative norms from the public. Despite negative attitudes toward reporters, intent to engage with the media was mixed. However, subjective norms and behavioral control were often discussed as reasons to not engage with reporters. The findings from this study offered recommendations for both practice and research to help foster positive relationships between scientists and reporters
Who stands in the way of women? Open vs. closed lists and candidate gender in Estonia
The literature on women's descriptive representation has looked at the debate on open and closed lists as a choice between electoral systems. This article instead focuses on whether voters or the parties are biased against female candidates. Using data from six Estonian elections, the article finds that voters are not consistently biased against female candidates and open lists do not necessarily decrease women's representation. However, unknown and non-incumbent female candidates fare significantly worse than similar men. The analysis also shows that parties do not place women in electable positions on closed lists, and closed lists do not improve women's representation
Compound heterozygote myocilin mutations in a pedigree with high prevalence of primary open-angle glaucoma
This article is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License 3.0, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license.Purpose: To describe the phenotype of ocular hypertension and primary open-angle glaucoma in a family with individuals compound heterozygote for Gln368STOP and Thr377Met myocilin (MYOC) mutations.
Methods: Family members of the proband underwent comprehensive ocular clinical examination and DNA sequencing for MYOC mutations.
Results: A 34-year-old woman with marked ocular hypertension was found to carry Gln368STOP and Thr377Met MYOC mutations. Three other siblings carried both mutations, while one carried Gln368STOP alone. Three of five siblings had received treatment for ocular hypertension or early glaucoma, with the average age of diagnosis 28 years; one required trabeculectomy at age 27. The mother of the proband was found to be a carrier for Gln368STOP alone, which indicates that her offspring with both Gln368STOP and Thr377Met carry variants on opposing alleles.
Conclusions: This pedigree is the first report with individuals compound heterozygote for the two most common glaucoma-causing MYOC variants. The combination of mutations manifests a more severe phenotype than either alone. Identification of gene changes associated with glaucoma within the family has enabled unaffected members to stratify their risk of future disease and institute closer monitoring and early treatment.CERA receives Operational Infrastructure Support from the Victorian Government. The Australian and New Zealand Registry of Advanced Glaucoma is funded by the RANZCO Eye Foundation. KPB and JEC are funded by a Career Development Award and Practitioner Fellowship from the National Health and Medical Research Council of Australia, respectively
Comparison of bird community indices for riparian restoration planning and monitoring
The use of a bird community index that characterizes ecosystem integrity is very attractive to conservation planners and habitat managers, particularly in the absence of any single focal species. In riparian areas of the western USA, several attempts at arriving at a community index signifying a functioning riparian bird community have been made previously, mostly resorting to expert opinions or national conservation rankings for species weights. Because extensive local and regional bird monitoring data were available for Nevada, we were able to develop three different indices that were derived empirically, rather than from expert opinion. We formally examined the use of three species weighting schemes in comparison with simple species richness, using different definitions of riparian species assemblage size, for the purpose of predicting community response to changes in vegetation structure from riparian restoration. For the three indices, species were weighted according to the following criteria: (1) the degree of riparian habitat specialization based on regional data, (2) the relative conservation ranking of landbird species, and (3) the degree to which a species is under-represented compared to the regional species pool for riparian areas. To evaluate the usefulness of these indices for habitat restoration planning and monitoring, we modeled them using habitat variables that are expected to respond to riparian restoration efforts, using data from 64 sampling sites in the Walker River Basin in Nevada and California. We found that none of the species-weighting schemes performed any better as an index for evaluating overall habitat condition than using species richness alone as a community index. Based on our findings, the use of a fairly complete list of 30–35 riparian specialists appears to be the best indicator group for predicting the response of bird communities to the restoration of riparian vegetation
Comparison of bird community indices for riparian restoration planning and monitoring
The use of a bird community index that characterizes ecosystem integrity is very attractive to conservation planners and habitat managers, particularly in the absence of any single focal species. In riparian areas of the western USA, several attempts at arriving at a community index signifying a functioning riparian bird community have been made previously, mostly resorting to expert opinions or national conservation rankings for species weights. Because extensive local and regional bird monitoring data were available for Nevada, we were able to develop three different indices that were derived empirically, rather than from expert opinion. We formally examined the use of three species weighting schemes in comparison with simple species richness, using different definitions of riparian species assemblage size, for the purpose of predicting community response to changes in vegetation structure from riparian restoration. For the three indices, species were weighted according to the following criteria: (1) the degree of riparian habitat specialization based on regional data, (2) the relative conservation ranking of landbird species, and (3) the degree to which a species is under-represented compared to the regional species pool for riparian areas. To evaluate the usefulness of these indices for habitat restoration planning and monitoring, we modeled them using habitat variables that are expected to respond to riparian restoration efforts, using data from 64 sampling sites in the Walker River Basin in Nevada and California. We found that none of the species-weighting schemes performed any better as an index for evaluating overall habitat condition than using species richness alone as a community index. Based on our findings, the use of a fairly complete list of 30–35 riparian specialists appears to be the best indicator group for predicting the response of bird communities to the restoration of riparian vegetation
Inflammatory biomarker changes and their correlation with Framingham cardiovascular risk and lipid changes in antiretroviral-naive HIV-infected patients treated for 144 weeks with abacavir/lamivudine/atazanavir with or without ritonavir in ARIES.
Propensity for developing coronary heart disease (CHD) is linked with Framingham-defined cardiovascular risk factors and elevated inflammatory biomarkers. Cardiovascular risk and inflammatory biomarkers were evaluated in ARIES, a Phase IIIb/IV clinical trial in which 515 antiretroviral-naive HIV-infected subjects initially received abacavir/lamivudine + atazanavir/ritonavir for 36 weeks. Subjects who were virologically suppressed by week 30 were randomized 1:1 at week 36 to either maintain or discontinue ritonavir for an additional 108 weeks. Framingham 10-year CHD risk scores (FRS) and risk category o
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