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1.
JAMA Netw Open ; 5(3): e223245, 2022 03 01.
Artículo en Inglés | MEDLINE | ID: mdl-35311961

RESUMEN

Importance: Both major depression and firearm ownership are associated with an increased risk for death by suicide in the United States, but the extent of overlap among these major risk factors is not well characterized. Objective: To assess the prevalence of current and planned firearm ownership among individuals with depression. Design, Setting, and Participants: Cross-sectional survey study using data pooled from 2 waves of a 50-state nonprobability internet survey conducted between May and July 7, 2021. Internet survey respondents were 18 years of age or older and were sampled from all 50 US states and the District of Columbia. Main Outcomes and Measures: Self-reported firearm ownership; depressive symptoms as measured by the 9-item Patient Health Questionnaire. Results: Of 24 770 survey respondents (64.6% women and 35.4% men; 5.0% Asian, 10.8% Black, 7.5% Hispanic, and 74.0% White; mean [SD] age 45.8 [17.5]), 6929 (28.0%) reported moderate or greater depressive symptoms; this group had mean (SD) age of 38.18 (15.19) years, 4587 were female (66.2%), and 406 were Asian (5.9%), 725 were Black (10.5%), 652 were Hispanic (6.8%), and 4902 were White (70.7%). Of those with depression, 31.3% reported firearm ownership (n = 2167), of whom 35.9% (n = 777) reported purchasing a firearm within the past year. In regression models, the presence of moderate or greater depressive symptoms was not significantly associated with firearm ownership (adjusted odds ratio [OR], 1.07; 95% CI, 0.98-1.17) but was associated with greater likelihood of a first-time firearm purchase during the COVID-19 pandemic (adjusted OR, 1.77; 95% CI, 1.56-2.02) and greater likelihood of considering a future firearm purchase (adjusted OR, 1.53; 95% CI, 1.23-1.90). Conclusions and Relevance: In this study, current and planned firearm ownership was common among individuals with major depressive symptoms, suggesting a public health opportunity to address this conjunction of suicide risk factors.


Asunto(s)
COVID-19 , Trastorno Depresivo Mayor , Adolescente , Adulto , Estudios Transversales , Depresión/epidemiología , Trastorno Depresivo Mayor/epidemiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Propiedad , Pandemias , Prevalencia , Estados Unidos/epidemiología
2.
JAMA Netw Open ; 5(1): e2145697, 2022 01 04.
Artículo en Inglés | MEDLINE | ID: mdl-35061036

RESUMEN

Importance: Misinformation about COVID-19 vaccination may contribute substantially to vaccine hesitancy and resistance. Objective: To determine if depressive symptoms are associated with greater likelihood of believing vaccine-related misinformation. Design, Setting, and Participants: This survey study analyzed responses from 2 waves of a 50-state nonprobability internet survey conducted between May and July 2021, in which depressive symptoms were measured using the Patient Health Questionnaire 9-item (PHQ-9). Survey respondents were aged 18 and older. Population-reweighted multiple logistic regression was used to examine the association between moderate or greater depressive symptoms and endorsement of at least 1 item of vaccine misinformation, adjusted for sociodemographic features. The association between depressive symptoms in May and June, and new support for misinformation in the following wave was also examined. Exposures: Depressive symptoms. Main Outcomes and Measures: The main outcome was endorsing any of 4 common vaccine-related statements of misinformation. Results: Among 15 464 survey respondents (9834 [63.6%] women and 5630 [36.4%] men; 722 Asian respondents [4.7%], 1494 Black respondents [9.7%], 1015 Hispanic respondents [6.6%], and 11 863 White respondents [76.7%]; mean [SD] age, 47.9 [17.5] years), 4164 respondents (26.9%) identified moderate or greater depressive symptoms on the PHQ-9, and 2964 respondents (19.2%) endorsed at least 1 vaccine-related statement of misinformation. Presence of depression was associated with increased likelihood of endorsing misinformation (crude odds ratio [OR], 2.33; 95% CI, 2.09-2.61; adjusted OR, 2.15; 95% CI, 1.91-2.43). Respondents endorsing at least 1 misinformation item were significantly less likely to be vaccinated (crude OR, 0.40; 95% CI, 0.36-0.45; adjusted OR, 0.45; 95% CI, 0.40-0.51) and more likely to report vaccine resistance (crude OR, 2.54; 95% CI, 2.21-2.91; adjusted OR, 2.68; 95% CI, 2.89-3.13). Among 2809 respondents who answered a subsequent survey in July, presence of depression in the first survey was associated with greater likelihood of endorsing more misinformation compared with the prior survey (crude OR, 1.98; 95% CI, 1.42-2.75; adjusted OR, 1.63; 95% CI, 1.14-2.33). Conclusions and Relevance: This survey study found that individuals with moderate or greater depressive symptoms were more likely to endorse vaccine-related misinformation, cross-sectionally and at a subsequent survey wave. While this study design cannot address causation, the association between depression and spread and impact of misinformation merits further investigation.


Asunto(s)
Vacunas contra la COVID-19 , COVID-19 , Comunicación , Trastorno Depresivo Mayor , Conocimientos, Actitudes y Práctica en Salud , Vacilación a la Vacunación , Vacunación , Adulto , Anciano , Anciano de 80 o más Años , Depresión , Femenino , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Pandemias , SARS-CoV-2 , Encuestas y Cuestionarios , Estados Unidos , Adulto Joven
3.
Sci Rep ; 12(1): 1072, 2022 01 20.
Artículo en Inglés | MEDLINE | ID: mdl-35058533

RESUMEN

Land modified for human use alters matrix shape and composition and is a leading contributor to global biodiversity loss. It can also play a key role in facilitating range expansion and ecosystem invasion by anthrophilic species, as it can alter food abundance and distribution while also influencing predation risk; the relative roles of these processes are key to habitat selection theory. We researched these relative influences by examining human footprint, natural habitat, and predator occurrence on seasonal habitat selection by range-expanding boreal white-tailed deer (Odocoileus virginianus) in the oil sands of western Canada. We hypothesized that polygonal industrial features (e.g. cutblocks, well sites) drive deer distributions as sources of early seral forage, while linear features (e.g. roads, trails, and seismic lines) and habitat associated with predators are avoided by deer. We developed seasonal 2nd -order resource selection models from three years of deer GPS-telemetry data, a camera-trap-based model of predator occurrence, and landscape spatial data to weigh evidence for six competing hypotheses. Deer habitat selection was best explained by the combination of polygonal and linear features, intact deciduous forest, and wolf (Canis lupus) occurrence. Deer strongly selected for linear features such as roads and trails, despite a potential increased risk of wolf encounters. Linear features may attract deer by providing high density forage opportunity in heavily exploited landscapes, facilitating expansion into the boreal north.


Asunto(s)
Conservación de los Recursos Naturales/métodos , Caza/tendencias , Alberta , Animales , Biodiversidad , Canadá , Conservación de los Recursos Naturales/estadística & datos numéricos , Ciervos/fisiología , Ecología/métodos , Ecosistema , Bosques , Humanos , Modelos Estadísticos , Conducta Predatoria/fisiología , Estaciones del Año
4.
JAMA Netw Open ; 4(11): e2136113, 2021 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-34812844

RESUMEN

Importance: Some studies suggest that social media use is associated with risk for depression, particularly among children and young adults. Objective: To characterize the association between self-reported use of individual social media platforms and worsening of depressive symptoms among adults. Design, Setting, and Participants: This survey study included data from 13 waves of a nonprobability internet survey conducted approximately monthly between May 2020 and May 2021 among individuals aged 18 years and older in the US. Data were analyzed in July and August 2021. Main Outcomes and Measures: Logistic regression was applied without reweighting, with a 5 point or greater increase in 9-item Patient Health Questionnaire (PHQ-9) score as outcome and participant sociodemographic features, baseline PHQ-9, and use of each social media platform as independent variables. Results: In total, 5395 of 8045 individuals (67.1%) with a PHQ-9 score below 5 on initial survey completed a second PHQ-9. These respondents had a mean (SD) age of 55.8 (15.2) years; 3546 respondents (65.7%) identified as female; 329 respondents (6.1%) were Asian, 570 (10.6%) Black, 256 (4.7%) Hispanic, 4118 (76.3%) White, and 122 (2.3%) American Indian or Alaska Native, Pacific Islander or Native Hawaiian, or other. Among eligible respondents, 482 (8.9%) reported 5 points or greater worsening of PHQ-9 score at second survey. In fully adjusted models for increase in symptoms, the largest adjusted odds ratio (aOR) associated with social media use was observed for Snapchat (aOR, 1.53; 95% CI, 1.19-1.96), Facebook (aOR, 1.42; 95% CI, 1.10-1.81), and TikTok (aOR, 1.39; 95% CI, 1.03-1.87). Conclusions and Relevance: Among survey respondents who did not report depressive symptoms initially, social media use was associated with greater likelihood of subsequent increase in depressive symptoms after adjustment for sociodemographic features and news sources. These data cannot elucidate the nature of this association, but suggest the need for further study to understand how social media use may factor into depression among adults.


Asunto(s)
Depresión/epidemiología , Autoinforme/estadística & datos numéricos , Medios de Comunicación Sociales/estadística & datos numéricos , Adolescente , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Factores Sexuales , Encuestas y Cuestionarios , Estados Unidos/epidemiología , Adulto Joven
5.
medRxiv ; 2021 Mar 08.
Artículo en Inglés | MEDLINE | ID: mdl-33758896

RESUMEN

IMPORTANCE: COVID-19 symptoms are increasingly recognized to persist among a subset of individual following acute infection, but features associated with this persistence are not well-understood. OBJECTIVE: We aimed to identify individual features that predicted persistence of symptoms over at least 2 months at the time of survey completion.Design: Non-probability internet survey. Participants were asked to identify features of acute illness as well as persistence of symptoms at time of study completion. We used logistic regression models to examine association between sociodemographic and clinical features and persistence of symptoms at or beyond 2 months. SETTING: Ten waves of a fifty-state survey between June 13, 2020 and January 13, 2021. PARTICIPANTS: 6,211 individuals who reported symptomatic COVID-19 illness confirmed by positive test or clinician diagnosis. EXPOSURE: symptomatic COVID-19 illness. RESULTS: Among 6,211 survey respondents reporting COVID-19 illness, with a mean age of 37.8 (SD 12.2) years and 45.1% female, 73.9% white, 10.0% Black, 9.9% Hispanic, and 3.1% Asian, a total of 4946 (79.6%) had recovered within less than 2 months, while 491 (7.9%) experienced symptoms for 2 months or more. Of the full cohort, 3.4% were symptomatic for 4 months or more and 2.2% for 6 months or more. In univariate analyses, individuals with persistent symptoms on average reported greater initial severity. In logistic regression models, older age was associated with greater risk of persistence (OR 1.10, 95% CI 1.01-1.19 for each decade beyond 40); otherwise, no significant associations with persistence were identified for gender, race/ethnicity, or income. Presence of headache was significantly associated with greater likelihood of persistence (OR 1.44, 95% CI 1.11-1.86), while fever was associated with diminished likelihood of persistence (OR 0.66, 95% CI 0.53-0.83). CONCLUSION AND RELEVANCE: A subset of individuals experience persistent symptoms from 2 to more than 10 months after acute COVID-19 illness, particularly those who recall headache and absence of fever. In light of this prevalence, strategies for predicting and managing such sequelae are needed. TRIAL REGISTRATION: NA. KEY POINTS: Question: Which individuals are at greatest risk for post-acute sequelae of COVID-19?Findings: In this non-probability internet survey, among 6,211 individuals with symptomatic COVID-19 illness, 7.9% experienced persistence of symptoms lasting 2 months or longer. Older age, but not other sociodemographic features, was associated with risk for persistence, as was headache.Meaning: Identifying individuals at greater risk for symptomatic persistence may facilitate development of targeted interventions.

7.
Proc Biol Sci ; 287(1937): 20202010, 2020 10 28.
Artículo en Inglés | MEDLINE | ID: mdl-33081614

RESUMEN

The spread of infection from reservoir host populations is a key mechanism for disease emergence and extinction risk and is a management concern for salmon aquaculture and fisheries. Using a quantitative environmental DNA methodology, we assessed pathogen environmental DNA in relation to salmon farms in coastal British Columbia, Canada, by testing for 39 species of salmon pathogens (viral, bacterial, and eukaryotic) in 134 marine environmental samples at 58 salmon farm sites (both active and inactive) over 3 years. Environmental DNA from 22 pathogen species was detected 496 times and species varied in their occurrence among years and sites, likely reflecting variation in environmental factors, other native host species, and strength of association with domesticated Atlantic salmon. Overall, we found that the probability of detecting pathogen environmental DNA (eDNA) was 2.72 (95% CI: 1.48, 5.02) times higher at active versus inactive salmon farm sites and 1.76 (95% CI: 1.28, 2.42) times higher per standard deviation increase in domesticated Atlantic salmon eDNA concentration at a site. If the distribution of pathogen eDNA accurately reflects the distribution of viable pathogens, our findings suggest that salmon farms serve as a potential reservoir for a number of infectious agents; thereby elevating the risk of exposure for wild salmon and other fish species that share the marine environment.


Asunto(s)
Acuicultura , ADN Ambiental , Animales , Colombia Británica , Monitoreo del Ambiente , Granjas , Enfermedades de los Peces , Explotaciones Pesqueras , Salmo salar , Microbiología del Agua
8.
Sci Rep ; 9(1): 10852, 2019 07 26.
Artículo en Inglés | MEDLINE | ID: mdl-31350429

RESUMEN

Biologging data allow animal ecologists to directly measure species' fine-scale spatiotemporal responses to environments, such as movement - critical for our understanding of biodiversity declines in the Anthropocene. Animal movement between resource patches is a behavioral expression of multiple ecological processes that affect individual fitness. Protected area (PA) networks are a tool used to conserve biodiversity by sustaining habitat patches across vast heterogeneous landscapes. However, our ability to design PA networks that conserve biodiversity relies on our accurate understanding of animal movement and functional connectivity; this understanding is rarely tested in real-world situations due to the large geographic expanse of most PA networks. Using a tractable PA network mesocosm, we employ cutting-edge biologging technology to analyze animal movement decisions in response to a highly heterogeneous landscape. We analyze these data to test, in a novel way, three common hypotheses about functional connectivity - structural corridors, least cost paths, and stepping stones. Consistently, animals moved along structurally self-similar corridors. In reference to the Aichi 2020 Biodiversity Targets, relying on species to "stepping stone" across habitat remnants may not achieve protected area network conservation objectives.


Asunto(s)
Migración Animal , Conservación de los Recursos Naturales/métodos , Ecosistema , Mustelidae/fisiología , Recursos Naturales , Animales , Biodiversidad , Canadá , Ecología/métodos , Sistemas de Información Geográfica , Locomoción
9.
J Cyst Fibros ; 17(1): 71-77, 2018 01.
Artículo en Inglés | MEDLINE | ID: mdl-28302366

RESUMEN

BACKGROUND: Current palliative care tools do not address distressing chronic symptoms that are most relevant to cystic fibrosis. METHODS: A CF-specific structured assessment based on a primary palliative care framework was administered to 41 adolescents and adults with CF. Descriptive and correlational analyses were conducted. RESULTS: Patients reported numerous physical and psychological symptoms (mean of 10 per patient), with psychological symptoms rated as more distressing. Anxiety (34%) and depression (44%) were prevalent and correlated with distress attributable to physical symptoms and difficulty with CF self-management, but did not correlate with disease severity. CONCLUSIONS: Individuals with CF, regardless of disease severity, face challenges managing symptom burden. Frequently reported symptoms are not consistently associated with distress, suggesting the importance of individualized evaluation. The CF-CARES (Coping, goal Assessment, and Relief from Evolving CF Symptoms) primary palliative care assessment model provides a framework for patients experiencing chronic symptoms to explore interventional options with their clinicians.


Asunto(s)
Ansiedad , Costo de Enfermedad , Fibrosis Quística , Depresión , Cuidados Paliativos , Automanejo/psicología , Adaptación Psicológica , Adolescente , Adulto , Ansiedad/diagnóstico , Ansiedad/fisiopatología , Fibrosis Quística/psicología , Fibrosis Quística/terapia , Depresión/diagnóstico , Depresión/fisiopatología , Femenino , Humanos , Masculino , Modelos Organizacionales , Cuidados Paliativos/métodos , Cuidados Paliativos/psicología , Manejo de Atención al Paciente/organización & administración , Evaluación de Síntomas/psicología
10.
Ecol Evol ; 7(21): 8903-8914, 2017 11.
Artículo en Inglés | MEDLINE | ID: mdl-29152186

RESUMEN

Contemporary landscapes are subject to a multitude of human-derived stressors. Effects of such stressors are increasingly realized by population declines and large-scale extirpation of taxa worldwide. Most notably, cumulative effects of climate and landscape change can limit species' local adaptation and dispersal capabilities, thereby reducing realized niche space and range extent. Resolving the cumulative effects of multiple stressors on species persistence is a pressing challenge in ecology, especially for declining species. For example, wolverines (Gulo gulo L.) persist on only 40% of their historic North American range. While climate change has been shown to be a mechanism of range retractions, anthropogenic landscape disturbance has been recently implicated. We hypothesized these two interact to effect declines. We surveyed wolverine occurrence using camera trapping and genetic tagging at 104 sites at the wolverine range edge, spanning a 15,000 km2 gradient of climate, topographic, anthropogenic, and biotic variables. We used occupancy and generalized linear models to disentangle the factors explaining wolverine distribution. Persistent spring snow pack-expected to decrease with climate change-was a significant predictor, but so was anthropogenic landscape change. Canid mesocarnivores, which we hypothesize are competitors supported by anthropogenic landscape change, had comparatively weaker effect. Wolverine population declines and range shifts likely result from climate change and landscape change operating in tandem. We contend that similar results are likely for many species and that research that simultaneously examines climate change, landscape change, and the biotic landscape is warranted. Ecology research and species conservation plans that address these interactions are more likely to meet their objectives.

11.
Ecol Evol ; 6(5): 1493-503, 2016 03.
Artículo en Inglés | MEDLINE | ID: mdl-26900450

RESUMEN

Understanding a species' behavioral response to rapid environmental change is an ongoing challenge in modern conservation. Anthropogenic landscape modification, or "human footprint," is well documented as a central cause of large mammal decline and range contractions where the proximal mechanisms of decline are often contentious. Direct mortality is an obvious cause; alternatively, human-modified landscapes perceived as unsuitable by some species may contribute to shifts in space use through preferential habitat selection. A useful approach to tease these effects apart is to determine whether behaviors potentially associated with risk vary with human footprint. We hypothesized wolverine (Gulo gulo) behaviors vary with different degrees of human footprint. We quantified metrics of behavior, which we assumed to indicate risk perception, from photographic images from a large existing camera-trapping dataset collected to understand wolverine distribution in the Rocky Mountains of Alberta, Canada. We systematically deployed 164 camera sites across three study areas covering approximately 24,000 km(2), sampled monthly between December and April (2007-2013). Wolverine behavior varied markedly across the study areas. Variation in behavior decreased with increasing human footprint. Increasing human footprint may constrain potential variation in behavior, through either restricting behavioral plasticity or individual variation in areas of high human impact. We hypothesize that behavioral constraints may indicate an increase in perceived risk in human-modified landscapes. Although survival is obviously a key contributor to species population decline and range loss, behavior may also make a significant contribution.

12.
Conn Med ; 79(2): 87-91, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26244206

RESUMEN

Arteriovenous malformation (AVM) and synovial sarcomas are both rare lesions in the mediastinum. Rarer still is a collision tumor in that region. Herein we present a case of a collision tumor comprised of AVM and synovial sarcoma in a 76-year-old man, presenting with pneumonia. Imaging showed a vascular lesion that spontaneously ruptured, causing enlargement of the mass and hemothorax. The resected specimen revealed the malignant second component. This report is a discussion of the never-before reported lesion.


Asunto(s)
Malformaciones Arteriovenosas/complicaciones , Arterias Bronquiales/anomalías , Arterias Mamarias/anomalías , Neoplasias del Mediastino/complicaciones , Sarcoma Sinovial/complicaciones , Anciano , Hemotórax/etiología , Humanos , Masculino , Rotura Espontánea
13.
Arch Pathol Lab Med ; 137(11): 1684-7, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-24168511

RESUMEN

Immunosuppressive drugs are an integral part of therapy in organ transplantation. However, they are not without side effects, and although rare, these agents should be considered in the differential diagnosis of pulmonary complications in patients receiving transplants. We present a case of a patient who developed acute respiratory failure 7 days after orthotopic heart transplantation and who had been on both mycophenolate mofetil (MMF) and tacrolimus agents. Lung biopsy revealed features of pulmonary hemorrhage with capillaritis. Considered as a possible etiology, MMF was withdrawn. There was immediate improvement of the patient's symptoms. The temporal relationship between MMF exposure and onset of pulmonary symptoms in the absence of other possible etiologies strongly suggests a causal relationship. Previously published reports of pulmonary toxicity from MMF included interstitial fibrosis. To the best of our knowledge, this is the first reported case of pulmonary hemorrhage with capillaritis because of administration of MMF.


Asunto(s)
Trasplante de Corazón/efectos adversos , Hemorragia/inducido químicamente , Inmunosupresores/efectos adversos , Enfermedades Pulmonares/inducido químicamente , Ácido Micofenólico/análogos & derivados , Vasculitis/inducido químicamente , Hemorragia/patología , Humanos , Inmunosupresores/administración & dosificación , Enfermedades Pulmonares/patología , Masculino , Persona de Mediana Edad , Ácido Micofenólico/administración & dosificación , Ácido Micofenólico/efectos adversos , Tacrolimus/administración & dosificación , Vasculitis/patología
14.
Ecol Appl ; 21(3): 897-914, 2011 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-21639053

RESUMEN

For some salmon populations, the individual and population effects of sea lice (Lepeophtheirus salmonis) transmission from sea cage salmon farms is probably mediated by predation, which is a primary natural source of mortality of juvenile salmon. We examined how sea lice infestation affects predation risk and mortality of juvenile pink (Oncorhynchus gorbuscha) and chum (O. keta) salmon, and developed a mathematical model to assess the implications for population dynamics and conservation. A risk-taking experiment indicated that infected juvenile pink salmon accept a higher predation risk in order to obtain foraging opportunities. In a schooling experiment with juvenile chum salmon, infected individuals had increased nearest-neighbor distances and occupied peripheral positions in the school. Prey selection experiments with cutthroat trout (O. clarkii) predators indicated that infection reduces the ability of juvenile pink salmon to evade a predatory strike. Group predation experiments with coho salmon (O. kisutch) feeding on juvenile pink or chum salmon indicated that predators selectively consume infected prey. The experimental results indicate that lice may increase the rate of prey capture but not the handling time of a predator. Based on this result, we developed a mathematical model of sea lice and salmon population dynamics in which parasitism affects the attack rate in a type II functional response. Analysis of the model indicates that: (1) the estimated mortality of wild juvenile salmon due to sea lice infestation is probably higher than previously thought; (2) predation can cause a simultaneous decline in sea louse abundance on wild fish and salmon productivity that could mislead managers and regulators; and (3) compensatory mortality occurs in the saturation region of the type II functional response where prey are abundant because predators increase mortality of parasites but not overall predation rates. These findings indicate that predation is an important component of salmon-louse dynamics and has implications for estimating mortality, reducing infection, and developing conservation policy.


Asunto(s)
Acuicultura , Arguloida/fisiología , Enfermedades de los Peces/parasitología , Conducta Predatoria , Salmón/fisiología , Animales , Enfermedades Parasitarias en Animales/patología , Dinámica Poblacional , Factores de Riesgo
15.
Ecol Evol ; 1(4): 517-28, 2011 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-22393519

RESUMEN

Niche theory in its various forms is based on those environmental factors that permit species persistence, but less work has focused on defining the extent, or size, of a species' environment: the area that explains a species' presence at a point in space. We proposed that this habitat extent is identifiable from a characteristic scale of habitat selection, the spatial scale at which habitat best explains species' occurrence. We hypothesized that this scale is predicted by body size. We tested this hypothesis on 12 sympatric terrestrial mammal species in the Canadian Rocky Mountains. For each species, habitat models varied across the 20 spatial scales tested. For six species, we found a characteristic scale; this scale was explained by species' body mass in a quadratic relationship. Habitat measured at large scales best-predicted habitat selection in both large and small species, and small scales predict habitat extent in medium-sized species. The relationship between body size and habitat selection scale implies evolutionary adaptation to landscape heterogeneity as the driver of scale-dependent habitat selection.

16.
Proc Biol Sci ; 276(1668): 2819-28, 2009 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-19419983

RESUMEN

The ecological impact of parasite transmission from fish farms is probably mediated by the migration of wild fishes, which determines the period of exposure to parasites. For Pacific salmon and the parasitic sea louse, Lepeophtheirus salmonis, analysis of the exposure period may resolve conflicting observations of epizootic mortality in field studies and parasite rejection in experiments. This is because exposure periods can differ by 2-3 orders of magnitude, ranging from months in the field to hours in experiments. We developed a mathematical model of salmon-louse population dynamics, parametrized by a study that monitored naturally infected juvenile salmon held in ocean enclosures. Analysis of replicated trials indicates that lice suffer high mortality, particularly during pre-adult stages. The model suggests louse populations rapidly decline following brief exposure of juvenile salmon, similar to laboratory study designs and data. However, when the exposure period lasts for several weeks, as occurs when juvenile salmon migrate past salmon farms, the model predicts that lice accumulate to abundances that can elevate salmon mortality and depress salmon populations. The duration of parasite exposure is probably critical to salmon-louse population dynamics, and should therefore be accommodated in coastal planning and management where fish farms are situated on wild fish migration routes.


Asunto(s)
Migración Animal/fisiología , Copépodos/fisiología , Enfermedades de los Peces/parasitología , Enfermedades Parasitarias en Animales/parasitología , Salmón/parasitología , Animales , Océano Pacífico , Factores de Tiempo
17.
Proc Natl Acad Sci U S A ; 103(42): 15506-10, 2006 Oct 17.
Artículo en Inglés | MEDLINE | ID: mdl-17021017

RESUMEN

The continuing decline of ocean fisheries and rise of global fish consumption has driven aquaculture growth by 10% annually over the last decade. The association of fish farms with disease emergence in sympatric wild fish stocks remains one of the most controversial and unresolved threats aquaculture poses to coastal ecosystems and fisheries. We report a comprehensive analysis of the spread and impact of farm-origin parasites on the survival of wild fish populations. We mathematically coupled extensive data sets of native parasitic sea lice (Lepeophtheirus salmonis) transmission and pathogenicity on migratory wild juvenile pink (Oncorhynchus gorbuscha) and chum (Oncorhynchus keta) salmon. Farm-origin lice induced 9-95% mortality in several sympatric wild juvenile pink and chum salmon populations. The epizootics arise through a mechanism that is new to our understanding of emerging infectious diseases: fish farms undermine a functional role of host migration in protecting juvenile hosts from parasites associated with adult hosts. Although the migratory life cycles of Pacific salmon naturally separate adults from juveniles, fish farms provide L. salmonis novel access to juvenile hosts, in this case raising infection rates for at least the first approximately 2.5 months of the salmon's marine life (approximately 80 km of the migration route). Spatial segregation between juveniles and adults is common among temperate marine fishes, and as aquaculture continues its rapid growth, this disease mechanism may challenge the sustainability of coastal ecosystems and economies.


Asunto(s)
Acuicultura , Enfermedades de los Peces , Enfermedades Parasitarias en Animales , Salmón/parasitología , Animales , Ecosistema , Enfermedades de los Peces/epidemiología , Enfermedades de los Peces/parasitología , Enfermedades de los Peces/transmisión , Explotaciones Pesqueras , Estadios del Ciclo de Vida , Matemática , Modelos Teóricos , Enfermedades Parasitarias en Animales/epidemiología , Enfermedades Parasitarias en Animales/parasitología , Enfermedades Parasitarias en Animales/transmisión , Agua de Mar , Tasa de Supervivencia
18.
Proc Biol Sci ; 272(1564): 689-96, 2005 Apr 07.
Artículo en Inglés | MEDLINE | ID: mdl-15870031

RESUMEN

Marine salmon farming has been correlated with parasitic sea lice infestations and concurrent declines of wild salmonids. Here, we report a quantitative analysis of how a single salmon farm altered the natural transmission dynamics of sea lice to juvenile Pacific salmon. We studied infections of sea lice (Lepeophtheirus salmonis and Caligus clemensi) on juvenile pink salmon (Oncorhynchus gorbuscha) and chum salmon (Oncorhynchus keta) as they passed an isolated salmon farm during their seaward migration down two long and narrow corridors. Our calculations suggest the infection pressure imposed by the farm was four orders of magnitude greater than ambient levels, resulting in a maximum infection pressure near the farm that was 73 times greater than ambient levels and exceeded ambient levels for 30 km along the two wild salmon migration corridors. The farm-produced cohort of lice parasitizing the wild juvenile hosts reached reproductive maturity and produced a second generation of lice that re-infected the juvenile salmon. This raises the infection pressure from the farm by an additional order of magnitude, with a composite infection pressure that exceeds ambient levels for 75 km of the two migration routes. Amplified sea lice infestations due to salmon farms are a potential limiting factor to wild salmonid conservation.


Asunto(s)
Animales Domésticos/parasitología , Animales Salvajes/parasitología , Copépodos , Enfermedades de los Peces/parasitología , Enfermedades de los Peces/transmisión , Infestaciones por Piojos/veterinaria , Oncorhynchus , Migración Animal , Animales , Acuicultura , Colombia Británica , Infestaciones por Piojos/transmisión , Modelos Biológicos , Ríos
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