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1.
Oecologia ; 192(2): 553-564, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31932922

RESUMO

Trait variation among populations is important for shaping ecological dynamics. In marine intertidal systems, seawater temperature, low tide emersion temperature, and pH can drive variation in traits and affect species interactions. In western North America, Nucella dogwhelks are intertidal drilling predators of the habitat-forming mussel Mytilus californianus. Nucella exhibit local adaptation, but it is not known to what extent environmental factors and genetic structure contribute to variation in prey selectivity among populations. We surveyed drilled mussels at sites across Oregon and California, USA, and used multiple regression and Mantel tests to test the effects of abiotic factors and Nucella neutral genetic relatedness on the size of mussels drilled across sites. Our results show that Nucella at sites characterized by higher and less variable temperature and pH drilled larger mussels. Warmer temperatures appear to induce faster handling time, and more stable pH conditions may prolong opportunities for active foraging by reducing exposure to repeated stressful conditions. In contrast, there was no significant effect of genetic relatedness on prey size selectivity. Our results emphasize the role of climate in shaping marine predator selectivity on a foundation species. As coastal climates change, predator traits will respond to localized environmental conditions, changing ecological interactions.


Assuntos
Ecossistema , Comportamento Predatório , Animais , California , Clima , Oregon
3.
Oecologia ; 192(1): 79-90, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31768737

RESUMO

Plant reproduction is highly sensitive to stress from severe weather. While facilitation has been shown to buffer negative impacts along stress gradients, less is known about facilitating plant reproduction in drought periods. Because intensity and frequency of drought are predicted to increase, plant reproductive facilitation has important implications for a species ability to adapt to changes in climate. Our primary study objective is to test if nurse shrubs act as reproductive micro-refugia across soil types, by improving reproductive potential of perennial bunchgrass neighbors subjected to severe drought. To investigate this objective, we designed a fully factored study testing direct interaction between shrub and bunchgrasses in eastern Oregon sagebrush steppe, at two sites with different soil types. The study consisted of six simple effect treatments combining three moisture regimes (moist, ambient, and drought) with two shrub conditions (shrub intact or shrub removed). Our results indicate when facilitation of reproductive potential occurs, it occurs strongly and particularly in drought, consistent with the stress gradient hypothesis (SGH), where several species produced at least 54% more inflorescences in the presence of shrub neighbors. In addition, we found facilitation to be consistent with the SGH at the species level likely reflecting differences in plant strategy and perception of strain, but to follow alternative SGH models more closely at the site level where facilitation declined on the drier soil. Ultimately, our findings highlight the importance of facilitation in improving plant reproductive potential in drought, and support the role of nurse shrubs as micro-refugia in a changing climate.


Assuntos
Secas , Solo , Clima , Mudança Climática , Ecossistema , Oregon
4.
J Dent Hyg ; 93(6): 13-20, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31882557

RESUMO

Purpose: Higher education teaching has been traditionally delivered through a lecture format, limiting the opportunities for interpersonal communication between faculty and students. The purpose of this study was to determine whether entry-level dental hygiene (DH) students and faculty perceive social media (SM) applications as an effective out-of-class communication (OCC) tool for enhancing learning in a dental hygiene program.Methods: A cross-sectional, comparative research design was used for this pilot study. An investigator-designed, paper survey was administered to a convenience sample of entry-level DH students and faculty from nine dental hygiene programs in Utah, Idaho, Oregon, Washington, and California. Data were analyzed using descriptive and inferential statistics (p=0.05).Results: A total of 418 students and 149 faculty members met the eligibility criteria; 325 DH students (n=325) and 77 faculty completed the surveys (n=77) for a combined response rate of 70.9%. While most faculty and DH students agreed SM could enhance learning for OCC, their level of comfort using these applications varied. Both faculty and DH students use SM applications for questions about assignments, clarification on lecture topics, and feedback on assignments. Statistical significance was found for the frequency of using SM applications for OCC (X2 =16.92; df =4; p =.002). Learning management systems were used and preferred most by both groups followed by Facebook. Statistical significance was found between both groups when ranking electronic devices for OCC.Conclusion: Dental hygiene students and faculty differ in their frequency and levels of comfort in using SM for out-of-class communication. Additional research related to the phenomenon of social media and communication to enhance learning in dental hygiene should be explored.


Assuntos
Mídias Sociais , California , Comunicação , Estudos Transversais , Higienistas Dentários , Humanos , Idaho , Oregon , Projetos Piloto , Utah , Washington
5.
Zootaxa ; 4674(5): zootaxa.4674.5.6, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31715988

RESUMO

Two new species of millipedes are described from Oregon Caves National Monument, Josephine County, Oregon, USA: Taiyutyla caseophila, n. sp. (Conotylidae), a troglophile; and Opiona catorycha, n. sp. (Caseyidae), a troglobiont found in at least one other cave in the region. We also provide a brief discussion of the invertebrate biodiversity of Oregon Cave.


Assuntos
Artrópodes , Animais , Biodiversidade , Oregon , Estados Unidos
6.
Health Serv Res ; 54(6): 1193-1202, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31657003

RESUMO

OBJECTIVE: To examine the impact of Oregon's Coordinated Care Organizations (CCOs), an accountable care model for Oregon Medicaid enrollees implemented in 2012, on neonatal and infant mortality. DATA SOURCES: Oregon birth certificates linked with death certificates, and Medicaid/CCO enrollment files for years 2008-2016. STUDY DESIGN: The sample consisted of the pre-CCO birth cohort of 135 753 infants (August 2008-July 2011) and the post-CCO birth cohort of 148 650 infants (August 2012-December 2015). We used a difference-in-differences probit model to estimate the difference in mortality between infants enrolled in Medicaid and infants who were not enrolled. We examined heterogeneous effects of CCOs for preterm and full-term infants and the impact of CCOs over the implementation timeline. All models were adjusted for maternal and infant characteristics and secular time trends. PRINCIPAL FINDINGS: The CCO model was associated with a 56 percent reduction in infant mortality compared to the pre-CCO level (-0.20 percentage points [95% CI: -0.35; -0.05]), and also with a greater reduction in infant mortality among preterm infants compared to full-term infants. The impact on mortality grew in magnitude over the postimplementation timeline. CONCLUSIONS: The CCO model contributed to a reduction in mortality within the first year of birth among infants enrolled in Medicaid.


Assuntos
Organizações de Assistência Responsáveis/estatística & dados numéricos , Mortalidade Infantil , Cobertura do Seguro/estatística & dados numéricos , Programas de Assistência Gerenciada/estatística & dados numéricos , Medicaid/estatística & dados numéricos , Pobreza , Adulto , Estudos de Coortes , Feminino , Humanos , Lactente , Recém-Nascido , Recém-Nascido Prematuro , Masculino , Oregon , Estados Unidos
7.
Ying Yong Sheng Tai Xue Bao ; 30(10): 3579-3588, 2019 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-31621246

RESUMO

Silver nanoparticle is widely used in the field of medicine because of its strong and effective antibacterial action. However, it has potential biological toxicity. In this study, the classical model organism, Drosophila melanogaster, was used to explore underlying mechanism for the toxic effects of silver nanoparticle. The pupation rate, eclosion time, eclosion rate and lifespan of Oregon R, w1118, and MTF mutants under different concentrations of silver nanoparticle were measured. The lacZ activity of rpr-lacZ strain was used to determine apoptosis of imaginal disc after treated with different concentrations of silver nanoparticle. The difference of intestinal protein expression in MTF mutants treated with different concentrations of silver nanoparticle was studied by SDS-PAGE. The amino acid sequence of differential proteins was further analyzed by mass spectrometry. The results showed that pupation rate and eclosion rate of MTF mutants significantly decreased when the concentration of silver nanoparticle increased to 200 µg·mL-1 and above. When the concentration of silver nanoparticle increased to 800 µg·mL-1, the rate of pupation and eclosion was significantly reduced, with the time of pupation and eclosion being not correlated to the concentration of silver nanoparticle. The concentrations of silver nanoparticle had no effect on the lifespan of Oregon R and w1118, while 200 µg·mL-1 silver nanoparticle significantly reduced the average lifespan of MTF mutant. Apoptosis increased with increasing concentration of silver nanoparticle. Results from SDS-PAGE and mass spectrometry analysis showed that the expression levels of proteins such as ATP kinase, heat shock protein and glucose metabolism related enzymes increased with increasing concentration of silver nanoparticle. Our results showed that high concentration of silver nanoparticle would reduce the survival rate of Drosophila, promote apoptosis and the expression of some proteins, which provided a theoretical basis for further understanding of the toxic mechanism of silver nanoparticle.


Assuntos
Drosophila melanogaster , Nanopartículas Metálicas , Animais , Apoptose , Longevidade , Oregon , Prata
8.
J Low Genit Tract Dis ; 23(4): 272-278, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31592975

RESUMO

OBJECTIVE: The aim of the study was to document treatment-seeking experiences of women with chronic vulvar pain, comfort communicating about pain, and test the clinical utility of the screening version of the Vulvar Pain Assessment Questionnaire, screening version (VPAQscreen). MATERIALS AND METHODS: Patients scheduled for an appointment with the Program in Vulvar Health at Oregon Health and Science University were invited to complete the VPAQscreen and answer descriptive questions about previous treatment-seeking experiences and communication with health care providers. Clinicians provided provisional diagnoses based on VPAQscreen summaries, final diagnoses based on gynecological examination, and commented on alignment with clinical observations. Patients gave feedback on the accuracy and helpfulness of the VPAQscreen summary, characteristics of the questions asked, and whether their comfort communicating increased. RESULTS: Participants reported previously seeing approximately 5 medical doctors and 2 other health care providers and perceived them as lacking knowledge of vulvar pain syndromes. Providers indicated that VPAQscreen summaries aligned with clinical presentations and suggested provisional diagnoses with more than 80% accuracy. Participants reported that VPAQscreen summaries were helpful and accurate in summarizing symptoms. Most reported that the number, range, and readability of VPAQscreen questions were good or excellent. More than half reported that completing the VPAQscreen increased comfort when speaking with their Oregon Health and Science University physician. CONCLUSIONS: Patients with vulvar pain often endure a lengthy process of consulting multiple clinicians before securing care. The VPAQscreen was more than 80% accurate in predicting diagnosis at this specialty clinic and was useful in assisting patients with expressing symptoms. The applicability of the VPAQscreen in general practice is unknown, although it shows promise.


Assuntos
Dor Crônica/diagnóstico , Medição da Dor , Inquéritos e Questionários , Doenças da Vulva/diagnóstico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Pessoa de Meia-Idade , Oregon , Projetos Piloto , Adulto Jovem
9.
J Agric Food Chem ; 67(46): 12780-12785, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31647652

RESUMO

Aphanizomenon flos-aquae (AFA) cyanobacteria from Klamath Lake (Oregon) are considered a "superfood" due to their broad nutritional profile that has proved to have health-enhancing properties. The AFA metabolome is quite complex. Here, we present a study that, combining multinuclear 1H, 31P, and 13C Nuclear Magnetic Resonance (NMR) spectroscopy and high-resolution mass spectrometry, led to the detection of uncommon phosphorylated metabolites in AFA. We focused our attention on 31P NMR signals at 20 ppm, a chemical shift that usually points to the presence of phosphonates. The molecules contributing to 20 ppm 31P NMR signals revealed, instead, to be nucleoside 2',3'-cyclic monophosphates. These metabolites were fully characterized by multinuclear 1H, 31P, and 13C NMR spectroscopy and high-resolution mass spectrometry.


Assuntos
Aphanizomenon/química , Nucleosídeos/química , Aphanizomenon/metabolismo , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Estrutura Molecular , Nucleosídeos/metabolismo , Oregon
10.
Plant Dis ; 103(12): 3154-3160, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31560616

RESUMO

Phytophthora ramorum, the cause of sudden oak death (SOD), kills tanoak (Notholithocarpus densiflorus) trees in southwestern Oregon and California. Two lineages of P. ramorum are now found in wildland forests of Oregon (NA1 and EU1). In addition to the management of SOD in forest ecosystems, disease resistance could be used as a way to mitigate the impact of P. ramorum. The objectives of this study were to (i) characterize the variability in resistance of N. densiflorus among families using lesion length; (ii) determine whether lineage, isolate, family, or their interactions significantly affect variation in lesion length; and (iii) determine whether there are differences among isolates and among families in terms of lesion length. The parameters isolate nested within lineage (isolate[lineage]) and family × isolate(lineage) interaction explained the majority of the variation in lesion length. There was no significant difference between the NA1 and EU1 lineages in terms of mean lesion length; however, there were differences among the six isolates. Lesions on seedlings collected from surviving trees at infested sites were smaller, on average, than lesions of seedlings collected from trees at noninfested sites (P = 0.0064). The results indicate that there is potential to establish a breeding program for tanoak resistance to SOD and that several isolates of P. ramorum should be used in an artificial inoculation assay.


Assuntos
Phytophthora , Quercus , California , Resistência à Doença , Oregon , Phytophthora/classificação , Phytophthora/fisiologia , Doenças das Plantas/parasitologia , Quercus/parasitologia
11.
Med Care ; 57(10): 788-794, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31513138

RESUMO

BACKGROUND: Previous studies suggest the newly Medicaid insured are more likely to use the emergency department (ED) however they did not differentiate between patients established or not established with primary care. OBJECTIVES: To understand where Oregon Medicaid beneficiaries sought care after the Patient Protection and Affordable Care Act (PPACA) Medicaid expansion (ED, primary care, or specialist) and the interaction between primary care establishment and outpatient care utilization. RESEARCH DESIGN: A retrospective cohort study. SUBJECTS: Adults continuously insured from 2014 through 2015 who were either newly, returning, or continuously insured post-PPACA. MEASURES: Site of first and last outpatient visit, established with primary care status, and outpatient care utilization. RESULTS: The odds of being established with primary care at their first visit were lower among newly [odds ratio (OR), 0.18; 95% confidence interval (CI), 0.18-0.19] and returning insured (OR, 0.22; 95% CI, 0.22-0.23) than the continuously insured. Continuously insured, new patients with primary care had higher odds of visiting the ED (OR, 2.15; 95% CI, 2.01-2.30) at their first visit than newly or returning insured. Patients established with a single primary care provider in all insurance groups had lower rates of ED visit, whereas those established with multiple primary care providers had the highest ED visit rates. CONCLUSIONS: Most newly and returning insured Medicaid enrollees sought primary care rather than ED services and most became established with primary care. Our findings suggest that both insurance and primary care continuity play a role in where patients seek health care services.


Assuntos
Assistência Ambulatorial/estatística & dados numéricos , Serviço Hospitalar de Emergência/estatística & dados numéricos , Utilização de Instalações e Serviços/estatística & dados numéricos , Patient Protection and Affordable Care Act/estatística & dados numéricos , Atenção Primária à Saúde/estatística & dados numéricos , Adulto , Continuidade da Assistência ao Paciente , Feminino , Humanos , Cobertura do Seguro/economia , Cobertura do Seguro/legislação & jurisprudência , Masculino , Medicaid/legislação & jurisprudência , Pessoa de Meia-Idade , Oregon , Estudos Retrospectivos , Estados Unidos
12.
J Agric Food Chem ; 67(46): 12670-12674, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31398037

RESUMO

A comprehensive multiresidue pesticide analysis for Cannabis flower matrices using quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample preparation, liquid chromatography paired with triple quadrupole mass spectrometry (LC-MS/MS), and gas chromatography paired with triple quadrupole mass spectrometry (GC-MS/MS) was established and validated for 367 pesticides with excellent recoveries (70-120%) for over 99% of analytes included. This research demonstrates the viability of pesticide testing in Cannabis, with a wide scope of analysis mirroring the methodology used in food and crop analyses of pesticides worldwide, with tools most analytical laboratories possess. The method developed here was then applied to Cannabis flower samples from Oregon, and results were compared to existing state pesticide regulations. A total of 4 of these 100 samples analyzed contained pesticides unregulated in Oregon, while 3 samples contained regulated pesticides significantly above the regulated action levels of Oregon. These results suggest a need for more complete testing regulations surrounding Cannabis and highlight possible deficiencies in quality control and oversight among independent testing laboratories in states with mandatory Cannabis testing.


Assuntos
Cannabis/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Espectrometria de Massas/métodos , Resíduos de Praguicidas/análise , Flores/química , Contaminação de Alimentos/análise , Oregon
14.
Plant Dis ; 103(9): 2171-2178, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31298991

RESUMO

Cereal cyst nematodes (CCN; Heterodera avenae and H. filipjevi), cause substantial worldwide yield loss in small grain cereals such as wheat, barley, and oat. H. avenae was first detected in the United States in western Oregon in 1974 and had spread to northeast Oregon by the mid-1980s. Although H. avenae was detected in eastern Washington in 1984, extensive infestations were not recognized until 2010. H. filipjevi, first detected in Oregon in 2008, was found in eastern Washington in 2014. To gain more information about the distribution of these two species, an extensive survey was undertaken in eastern Washington, and methods were developed to distinguish species using DNA sequencing of single cysts. In this study, we surveyed 356 wheat and barley fields in eastern Washington from 2007 to 2017. CCN from the infested locations were identified to species level by sequencing the ribosomal internal transcribed spacers (ITS) and/or 28S ribosomal RNA (rRNA) genes. The sequences were compared in the GenBank database in the National Center for Biotechnology Information (NCBI) to identify species. The results show that H. filipjevi is primarily confined to southern Whitman County, WA; and H. avenae has a wider distribution across the higher precipitation annual cropping area of eastern Whitman County. Knowledge of species identification is critical for deployment of host resistance as an effective means of management, since resistance genes for one species of CCN may not be effective against the other.


Assuntos
Distribuição Animal , Grão Comestível , Tylenchoidea , Animais , Grão Comestível/parasitologia , Interações Hospedeiro-Parasita , Oregon , Washington
15.
Medicine (Baltimore) ; 98(28): e16169, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31305399

RESUMO

We aim to examine temporal trends of orthopedic operations and opioid-related hospital stays among seniors in the nation and states of Oregon and Washington where marijuana legalization was accepted earlier than any others.As aging society advances in the United States (U.S.), orthopedic operations and opioid-related hospital stays among seniors increase in the nation.A serial cross-sectional cohort study using the healthcare cost and utilization project fast stats from 2006 through 2015 measured annual rate per 100,000 populations of orthopedic operations by age groups (45-64 vs 65 and older) as well as annual rate per 100,000 populations of opioid-related hospital stays among 65 and older in the nation, Oregon and Washington states from 2008 through 2017. Orthopedic operations (knee arthroplasty, total or partial hip replacement, spinal fusion or laminectomy) and opioid-related hospital stays were measured. The compound annual growth rate (CAGR) was used to quantify temporal trends of orthopedic operations by age groups as well as opioid-related hospital stays and was tested by Rao-Scott correction of χ for categorical variables.The CAGR (4.06%) of orthopedic operations among age 65 and older increased (P < .001) unlike the unchanged rate among age 45 to 64. The CAGRs of opioid-related hospital stays among age 65 and older were upward trends among seniors in general (6.79%) and in Oregon (10.32%) and Washington (15.48%) in particular (all P < .001).Orthopedic operations and opioid-related hospital stays among seniors increased over time in the U.S. Marijuana legalization might have played a role of gateway drug to opioid among seniors.


Assuntos
Analgésicos Opioides/uso terapêutico , Controle de Medicamentos e Entorpecentes , Artropatias/tratamento farmacológico , Idoso , Estudos Transversais , Custos de Cuidados de Saúde , Hospitalização/tendências , Humanos , Artropatias/economia , Artropatias/cirurgia , Uso da Maconha/legislação & jurisprudência , Pessoa de Meia-Idade , Oregon , Procedimentos Ortopédicos , Aceitação pelo Paciente de Cuidados de Saúde , Estudos Retrospectivos , Washington
17.
J Vet Diagn Invest ; 31(5): 747-751, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31272304

RESUMO

We report herein Rhodococcus equi infection in an 11-y-old, male llama with a history of diarrhea and endoparasitism. Postmortem examination revealed granulomatous and ulcerative enteritis, pyogranulomatous mesenteric lymphadenitis, fibrinosuppurative peritonitis, and granulomatous hepatitis. Intralesional macrophages were laden with gram-positive cocci. Bacteriology identified R. equi, and cultures tested positive for R. equi choE and vapA genes by PCR. This case expands the reported spectrum of lesions associated with R. equi infections in llamas from pyogranulomatous bronchopneumonia and peripheral lymphadenitis to pyogranulomatous mesenteric lymphadenitis and enteritis. We also link a R. equi that is carrying the virulent-associated protein gene VapA to clinical disease in New World camelids.


Assuntos
Infecções por Actinomycetales/veterinária , Camelídeos Americanos , Enterite/veterinária , Linfadenite Mesentérica/veterinária , Rhodococcus equi/isolamento & purificação , Infecções por Actinomycetales/microbiologia , Animais , Animais Domésticos , Proteínas de Bactérias/análise , Enterite/microbiologia , Masculino , Linfadenite Mesentérica/microbiologia , Oregon , Rhodococcus equi/genética , Rhodococcus equi/patogenicidade , Fatores de Virulência
18.
Environ Sci Technol ; 53(15): 9203-9213, 2019 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-31290326

RESUMO

Feline hyperthyroidism is the most commonly diagnosed endocrine-related disease among senior and geriatric housecats, but the causes remain unknown. Exposure to endocrine-disrupting compounds with thyroid targets, such as flame retardants (FRs), may contribute to disease development. Silicone passive sampling devices, or pet tags, quantitatively assessed the bioavailable FR exposures of 78 cats (≥7 y) in New York and Oregon using gas chromatography-mass spectrometry. Pet tags were analyzed for 36 polybrominated diphenyl ethers, six organophosphate esters (OPEs), and two alternative brominated FRs. In nonhyperthyroid cats, serum free thyroxine (fT4), total T4 (TT4), total triiodothyronine, and thyroid-stimulating hormone concentrations were compared with FR concentrations. Tris(1,3-dichloro-2-isopropyl) phosphate (TDCIPP) concentrations were higher in hyperthyroid pet tags in comparison to nonhyperthyroid pet tags (adjusted odds ratio, p < 0.07; Mantel-Cox, p < 0.02). Higher TDCIPP concentrations were associated with air freshener use in comparison to no use (p < 0.01), residences built since 2005 compared to those pre-1989 (p < 0.002), and cats preferring to spend time on upholstered furniture in comparison to no preference (p < 0.05). Higher TDCIPP concentrations were associated with higher fT4 and TT4 concentrations (p < 0.05). This study provides proof-of-concept data for the use of silicone pet tags with companion animals and further indicates that bioavailable TDCIPP exposures are associated with feline hyperthyroidism.


Assuntos
Retardadores de Chama , Hipertireoidismo , Animais , Gatos , Éteres Difenil Halogenados , New York , Oregon , Organofosfatos , Fosfatos , Silicones
19.
Ecology ; 100(10): e02816, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31287561

RESUMO

Species interactions in food webs are usually recognized as dynamic, varying across species, space, and time because of biotic and abiotic drivers. Yet food webs also show emergent properties that appear consistent, such as a skewed frequency distribution of interaction strengths (many weak, few strong). Reconciling these two properties requires an understanding of the variation in pairwise interaction strengths and its underlying mechanisms. We estimated stream sculpin feeding rates in three seasons at nine sites in Oregon to examine variation in trophic interaction strengths both across and within predator-prey pairs. Predator and prey densities, prey body mass, and abiotic factors were considered as putative drivers of within-pair variation over space and time. We hypothesized that consistently skewed interaction strength distributions could result if individual interaction strengths show relatively little variation, or alternatively, if interaction strengths vary but shift in ways that conserve their overall frequency distribution. Feeding rate distributions remained consistently and positively skewed across all sites and seasons. The mean coefficient of variation in feeding rates within each of 25 focal species pairs across surveys was less than half the mean coefficient of variation seen across species pairs within a survey. The rank order of feeding rates also remained conserved across streams, seasons and individual surveys. On average, feeding rates on each prey taxon nonetheless varied by a hundredfold, with some feeding rates showing more variation in space and others in time. In general, feeding rates increased with prey density and decreased with high stream flows and low water temperatures, although for nearly half of all species pairs, factors other than prey density explained the most variation. Our findings show that although individual interaction strengths exhibit considerable variation in space and time, they can nonetheless remain relatively consistent, and thus predictable, compared to the even larger variation that occurs across species pairs. These results highlight how the ecological scale of inference can strongly shape conclusions about interaction strength consistency and help reconcile how the skewed nature of interaction strength distributions can persist in highly dynamic food webs.


Assuntos
Cadeia Alimentar , Comportamento Predatório , Animais , Oregon , Rios , Estações do Ano
20.
Sci Total Environ ; 691: 112-123, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31319249

RESUMO

Natural disturbances help maintain healthy forested and aquatic ecosystems. However, biotic and abiotic disturbance regimes are changing rapidly. For example, the Swiss needle cast (SNC) epidemic in the Coast Range of Oregon in the U.S. Pacific Northwest has increased in area from 53,050 to 238,705ha over the 1996-2015 period. We investigated whether the hydrologic regime (i.e., annual streamflow, runoff ratio, and magnitude and timing of peak flows and low flows) was affected by SNC in 12 catchments in western Oregon. The catchments ranged in size from 183 to 1834km2 and area affected by SNC from 0 to 90.5%. To maximize the number of catchments included in the study, we analyzed 20years of SNC aerial survey data and 15-26years of stream discharge (Q) and PRISM precipitation (P) and air temperature (Tair) data to test for trends in hydrologic variables for each catchment. As expected, we found that runoff ratios (Q/P) increased in five catchments, all with an area impacted by SNC >10%. This was likely due to the effects of SNC on the hydraulic architecture (i.e., needle retention, sapwood area, sapwood permeability) of affected trees, leading to decreased canopy interception and transpiration losses. Interestingly, two catchments with the greatest area affected by SNC showed no changes in hydrologic regime. The lack of hydrologic response could either be due to compensatory transpiration by vegetation unaffected by the disease or sub-canopy abiotic evaporation, which counteracted reductions in transpiration. This study is the first to illustrate that chronic canopy disturbance from a foliage pathogen can influence catchment scale hydrology.


Assuntos
Monitoramento Ambiental , Florestas , Doenças das Plantas , Rios/química , Movimentos da Água , Ecossistema , Hidrologia , Oregon , Árvores
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