Cities can have profound impacts on ecosystems, yet our understanding of these impacts is currently limited. First, the effects of the socioeconomic dimensions of human society are often overlooked. ...Second, correlative analyses are common, limiting our causal understanding of mechanisms. Third, most research has focused on terrestrial systems, ignoring aquatic systems that also provide important ecosystem services. Here we compare the effects of human population density and low‐income prevalence on the macroinvertebrate communities and ecosystem processes within water‐filled artificial tree holes. We hypothesized that these human demographic variables would affect tree holes in different ways via changes in temperature, water nutrients, and the local tree hole environment. We recruited community scientists across Greater Vancouver (Canada) to provide host trees and tend 50 tree holes over 14 weeks of colonization. We quantified tree hole ecosystems in terms of aquatic invertebrates, litter decomposition, and chlorophyll a (chl a). We compiled potential explanatory variables from field measurements, satellite images, or census databases. Using structural equation models, we showed that invertebrate abundance was affected by low‐income prevalence but not human population density. This was driven by cosmopolitan species of Ceratopogonidae (Diptera) with known associations to anthropogenic containers. Invertebrate diversity and abundance were also affected by environmental factors, such as temperature, elevation, water nutrients, litter quantity, and exposure. By contrast, invertebrate biomass, chl a, and litter decomposition were not affected by any measured variables. In summary, this study shows that some urban ecosystems can be largely unaffected by human population density. Our study also demonstrates the potential of using artificial tree holes as a standardized, replicated habitat for studying urbanization. Finally, by combining community science and urban ecology, we were able to involve our local community in this pandemic research pivot.
REPLY TO SKLENÁR Morueta-Holme, Naia; Engemann, Kristine; Sandoval-Acuña, Pablo ...
Proceedings of the National Academy of Sciences - PNAS,
2016-Jan-26, Letnik:
113, Številka:
4
Journal Article
Reply to Feeley and Rehm Morueta-Holme, Naia; Engemann, Kristine; Sandoval-Acuña, Pablo ...
Proceedings of the National Academy of Sciences - PNAS,
11/2015, Letnik:
112, Številka:
45
Journal Article
•Spatial and field analyses were done to studylong-termspecies recovery after fire.•Vegetation and species composition recovered after low and medium–high fire severity.•10–20 years after fire cover ...and spp composition tend to be similar to unburned sites.•Years after fire, pre-fire vegetation, altitude, latitude were recovery descriptors.
It has been debated if Chilean sclerophyllous vegetation can recover after fire of different severity and short and long term. We evaluated the resiliency of this vegetation type after single-occurrence fires of different severities that occurred 30, 20 and 10 years in Central Chile before the study. Two approaches were followed: satellite image analysis and vegetation sampling. Wildfires that occurred between 1985 and 2015 were identified based on Landsat images. We selected 30 sites burned by a single fire in either 1985, 1995 or 2005, and that was not converted to another land use by 2015, then determined the percentage cover by vegetation type. We recorded or estimated the independent variables of burn severity, slope, altitude, pre-fire vegetation type and latitude of the sites. Composition, richness, and abundance of adult and regeneration of woody vegetation and herbaceous cover were sampled. Generalized linear models were used to evaluate the effect of the independent variables and the time elapsed since the fire on vegetation recovery. The proportion of dense vegetation forest cover was significantly higher with more time elapsed since the fire, while semi-dense forest/shrubland and open shrubland vegetation cover returned to pre-fire levels more quickly. The richness and abundance of regenerated woody species was significantly greater with more time elapsed since the fire. However, no relationship was found between species richness and abundance of adult woody species and time elapsed post-fire. We found that vegetative recovery over time was not related to burn severity. Forested and mixed forest/shrubland cover is reached 10–20 years after the fire, if no further intervention occurs. Richness and species abundance was similar to that of unburned sites after 20 or more years post-fire. This study provided evidence thatforestvegetation in the Chilean Mediterranean ecosystem is resilient to fires of at least low and medium intensities.
Myiopsitta monachus is an invasive psittacine with wide distribution due to the pet trade. Its large communal nests and synanthropic nature contribute to its successful colonization of cities, from ...where it seems to be expanding in range and numbers. This is relevant with regard to pathogens that invasive species may harbor, especially when host populations thrive. We aimed to identify an abundant mite found in invasive monk parakeet chicks that had been collected in Santiago during 2017 and 2018. Through morphological and molecular identification of the 18S ribosomal RNA gene, we confirmed the presence of Ornithonyssus bursa. This was the first report of this mite in Chile. This mite is common in native and invasive monk parakeet populations and may affect other birds, including domestic fowl. Further, this mite bites people and can be a potential vector of pathogens such as bacteria or viruses. We conclude that this parasite was likely introduced with the parakeet and discuss possible ecological, health and economic consequences of this new potential pest.
Abstract The biomass content and carbon captured by forest plantations is of interest, for example in the context of climate change and carbon budgets.The main objective of our study was to develop ...functions to estimate the total biomass and its components (stem, branches, bark and leaves) of Pinus radiata D. Don trees in Chile. The methodology proposed for the model fitting uses the maximum likelihood method in a multivariate equation system fitting simultaneously. The fit strategy incorporates additivity restrictions in the estimation functions and in the variance functions to incorporate the heteroskedasticity of biomass, and three structures of the variance–covariance matrix were evaluated to assess the dependence of the different components of tree biomass. Non-linear biomass functions that used the variable $D^2H$ performed best according to several indicators of goodness-of-fit (log-likelihood, Akaike Information Criterion and Bayesian Information Criterion) and estimation precision (root mean square error (RMSE), Bias and EI). The simple structure of both biomass and variance estimation functions was $\beta _1 (D^2H)^{\beta _2}$, and in the modelling system for total tree biomass RMSE between 54.1-54.4 kg (28-36%) were obtained. The three variance–covariance matrix structures evaluated did not generate clear differences in relation to the RMSE, bias and Error Index indicators. The structure of the variance–covariance matrix that incorporated explicitly in the system equations allowed modelling of the relationship between biomass components.
Background. Andes virus (ANDV)—related hantavirus cardiopulmonary syndrome (HCPS) has a 35% case fatality rate in Chile and no specific treatment. In an immunomodulatory approach, we evaluated the ...efficacy of intravenous methylprednisolone for HCPS treatment, through a parallel-group, placebo-controlled clinical trial. Methods. Patients aged >2 years, with confirmed or suspected HCPS in cardiopulmonary stage, admitted to any of 13 study sites in Chile, were randomized by study center in blocks of 4 with a 1:1 allocation and assigned through sequentially numbered envelopes to receive placebo or methylprednisolone 16 mg/kg/day (≤1000 mg) for 3 days. All personnel remained blinded except the local pharmacist. Infection was confirmed by immunoglobulin M antibodies or ANDV RNA in blood. The composite primary endpoint was death, partial pressure of arterial oxygen/fraction of inspired oxygen ratio ≤55, cardiac index ≤2.2, or ventricular tachycardia or fibrillation within 28 days. Safety endpoints included the number of serious adverse events (SAEs) and quantification of viral RNA in blood. Analysis was by intention to treat. Results. Infection was confirmed in 60 of 66 (91%) enrollees. Fifteen of 30 placebo-treated patients and 11 of 30 methylprednisolone-treated patients progressed to the primary endpoint (P = .43). We observed no significant difference in mortality between treatment groups (P = .41). There was a trend toward more severe disease in placebo recipients at entry. More subjects in the placebo group experienced SAEs (P = .02). There were no SAEs clearly related to methylprednisolone administration, and methylprednisolone did not increase viral load. Conclusions. Although methylprednisolone appears to be safe, it did not provide significant clinical benefit to patients. Our results do not support the use of methylprednisolone for HCPS. Clinical Trials Registration. NCT00128180.
Arsenic has been associated with multiple harmful effects at the cellular level. Indirectly these defects could be related to impairment of the integrity of the immune system, in particular in ...lymphoid population. To characterize the effect of Arsenic on redox status on this population, copper smelter workers and arsenic unexposed donors were recruited for this study. We analyzed urine samples and lymphocyte enriched fractions from donors to determinate arsenic levels and lymphocyte proliferation. Moreover, we studied the presence of oxidative markers MDA, vitamin E and SOD activity in donor plasma. Here we demonstrated that in human beings exposed to high arsenic concentrations, lymphocyte MDA and arsenic urinary levels showed a positive correlation with SOD activity, and a negative correlation with vitamin E serum levels. Strikingly, lymphocytes from the arsenic exposed population respond to a polyclonal stimulator, phytohemaglutinin, with higher rates of thymidine incorporation than lymphocytes of a control population. As well, similar in vitro responses to arsenic were observed using a T cell line. Our results suggest that chronic human exposure to arsenic induces oxidative damage in lymphocytes and could be considered more relevant than evaluation of T cell surveillance.
The disco-malleolar and anterior malleolar ligaments are common to the middle ear, the temporomandibular joint and the jaw, all of them sharing a common embryological origin; these ligaments' ...morphometric and functional aspects were studied in 23 temporal bones. Experimental design: The epitympanum roof and the temporomandibular joint roof were elevated by micro-dissection of the middle cranial fossa, exposing both disco-malleolar and anterior malleolar ligaments and their association with the malleus, the temporomandibular joint disc and the mandibular lingula. Principal observations: Both ligaments start in the malleus and take anterior and divergent routes towards the temporomandibular joint and lingula, passing through Huguier's canal. The disco-malleolar and anterior malleolar ligaments' mean lengths were 6.88 mm (SD 0.81) and 4.22mm (SD 1.17), respectively, no statistically significant difference being revealed between the sides. Temporomandibular joint disc traction was applied for verifying malleus mobility; malleus movement was observed when applying disco-malleolar traction in 30.5% of the samples. Correlation was observed between malleus movement and disco-malleolar length (R2=-0.499, p<0.05). Both ligaments common to the stomatognathic system and middle ear were present in all specimens. Conclusions: There was an anatomical and functional relationship between human TMJ and the middle ear.
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