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Cross-sectional study to assess the association of color vision with mercury hair concentration in children from Brazilian Amazonian riverine communities.

Neurotoxicology; 65: 60-67, 2018 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-29428869


BACKGROUND: Mercury exposure in the Brazilian Amazon region has been an important concern since the 1980s, when gold mining activities contaminated many Amazonian river basins and the fish therein. Mercury exposure in humans can lead to changes in neural function. The visual system has been used as a functional indicator of methylmercury (organic) and mercury vapour (inorganic) toxicity. Children are particularly vulnerable to this metal exposure. OBJECTIVE: To compare the color vision of children from riverine communities of mercury-exposed (Tapajós basin) and non-exposed Amazonian rivers (Tocantins basin). METHODS: The study sample was 176 children, aged 7-14 years old. Children from two locations in the mercury-exposed Tapajós river basin, Barreiras (n = 71) and São Luiz do Tapajos (n = 41), were compared to children from Limoeiro do Ajuru (n = 64), a non-exposed area in the Tocantins river basin. No caregiver reported that any children had contact with mercury vapour during their lifetime, and probably most of the mercury in their bodies was obtained by fish consumption. Because of this, we decided to evaluate the mercury exposure by total mercury levels in hair samples, a good marker for organic mercury, and not in the urine, a marker for inorganic mercury. Color vision was assessed by the Lanthony Desaturated D-15 test. We used the Vingrys and King-Smith method (1988) to quantify the hue ordering test. The primary visual outcomes from this analysis were C-index (magnitude of the hue ordering error) and angle of the hue ordering. RESULTS: The Tapajós children had a higher mean hair mercury level (mean: 4.5 µg/g; range: 0.26-22.38 µg/g) than that of Tocantins children (mean: 0.49 µg/g; range: 0.03-1.91 µg/g) (p < 0.05). Mean difference was approximately 4.01 µg/g with a 95% confidence interval of 2.79-5.23. The results of the Lanthony D-15d test showed no significant difference between the C-index mean values of the Tapajós and Tocantins groups (p > 0.05). There was a weak linear correlation in the average C-index obtained from both eyes and the total mercury concentration. Multiple logistic regression analysis indicated that the location of the community and the age had a greater influence on the visual outcomes than the sex of the children and within-locale variation in mercury concentration. CONCLUSION: Our results suggest a difference in one aspect of vision, that is, color vision, between children living in two different river basins in the Brazilian Amazon. The association may be related to Hg exposure but also appeared related to the location of the community and age.

Freshwater shrimps (Macrobrachium depressimanum and Macrobrachium jelskii) as biomonitors of Hg availability in the Madeira River Basin, Western Amazon.

Environ Monit Assess; 190(2): 77, 2018 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-29322345


Total mercury (THg) concentrations measured in two freshwater shrimp species (Macrobrachium depressimanum and Macrobrachium jelskii) showed a relationship with the location of artisanal and small-scale gold mining (ASGM) from the Madeira River Basin, Western Amazon. Between August 2009 and May 2010, 212 shrimp samples were collected in the confluence of the Madeira River with three of its tributaries (Western Amazon). THg concentration was quantified in the exoskeleton, hepatopancreas and muscle tissue of the shrimps by cold vapor atomic absorption spectrophotometry. There were no significant differences between the two shrimp species when samples came from the Madeira River, but Hg concentrations were significantly lower in a tributary outside the influence of the gold mining area. Average THg concentrations were higher in the hepatopancreas (up to 160.0 ng g ) and lower in the exoskeleton and muscle tissue (10.0-35.0 ng g and < 0.9-42.0 ng g , respectively). Freshwater shrimps from the Madeira River respond to local environmental levels of Hg and can be considered as biomonitors for environmental Hg at this spatial scale. These organisms are important for moving Hg up food webs including those that harbor economic significant fish species and thus enhancing human exposure.

When roads appear jaguars decline: Increased access to an Amazonian wilderness area reduces potential for jaguar conservation.

PLoS One; 13(1): e0189740, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29298311


Roads are a main threat to biodiversity conservation in the Amazon, in part, because roads increase access for hunters. We examine how increased landscape access by hunters may lead to cascading effects that influence the prey community and abundance of the jaguar (Panthera onca), the top Amazonian terrestrial predator. Understanding such ecological effects originating from anthropogenic actions is essential for conservation and management of wildlife populations in areas undergoing infrastructure development. Our study was conducted in Yasuní Biosphere Reserve, the protected area with highest potential for jaguar conservation in Ecuador, and an area both threatened by road development and inhabited by indigenous groups dependent upon bushmeat. We surveyed prey and jaguar abundance with camera traps in four sites that differed in accessibility to hunters and used site occupancy and spatially explicit capture-recapture analyses to evaluate prey occurrence and estimate jaguar density, respectively. Higher landscape accessibility to hunters was linked with lower occurrence and biomass of game, particularly white-lipped peccary (Tayassu pecari) and collared peccary (Pecari tajacu), the primary game for hunters and prey for jaguars. Jaguar density was up to 18 times higher in the most remote site compared to the most accessible site. Our results provide a strong case for the need to: 1) consider conservation of large carnivores and other wildlife in policies about road construction in protected areas, 2) coordinate conservation initiatives with local governments so that development activities do not conflict with conservation objectives, and 3) promote development of community-based strategies for wildlife management that account for the needs of large carnivores.

Surveillance of seroepidemiology and morbidity of Chagas disease in the Negro River, Brazilian Amazon.

Mem Inst Oswaldo Cruz; 113(1): 17-23, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29211104


BACKGROUND: Chagas disease in the Brazilian Amazon Region was previously regarded as an enzootic disease of wild animals. More recently, in situations where humans have penetrated the wild ecotope or where triatomines and/or wild animals (marsupials) have invaded human homes resulting in disease transmission, Chagas disease has come to be regarded as an anthropozoonosis. We found that the highest incidence of infection due to Trypanosoma cruzi and Chagas disease occurred among piassaba fibre gatherers and their families. OBJECTIVES: Considering the results of previous surveys, we conducted a new survey of piassaba gatherers and their families in the creeks of the Aracá, Curuduri, Demini, Ererê and Padauiri rivers, which are tributaries on the left bank of the Negro River, in the municipality of Barcelos; Barcelos-Caurés highway; Negro River in Santa Isabel of the Negro River; and Marié River, on the right bank of the Negro River. METHODS: A questionnaire was applied to 482 piassaba gatherers and their families who accompanied them. We collected 5-mL blood samples (with permission from each subject), separated the serum, and performed serological tests using indirect immunofluorescence and conventional and recombinant enzyme-linked immunosorbent assays (ELISA). We performed brief clinical examination and electrocardiograms. Only 273 subjects attended our field base for detailed clinical examination and electrocardiogram. FINDINGS AND MAIN CONCLUSIONS: The questionnaire revealed that 100% of the 482 patients recognised the triatomine Rhodnius brethesi, which they had seen in the piassaba plantation and 81% in their field huts. A total of 79% of subjects had previously been bitten by this vector and 21% did not know. The 25 subjects seropositive for T. cruzi infection (5.2%) stated that they had been bitten more than 10 times by this insect. Of the 273 subjects who underwent electrocardiogram, 22% showed conditions that were possibly attributable to Chagas disease or other cardiovascular disease.

The invisibility of fisheries in the process of hydropower development across the Amazon.

Ambio; 2017 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-29210012


We analyze the invisibility of fisheries and inadequacy of fishers' participation in the process of hydropower development in the Amazon, focusing on gaps between legally mandated and actual outcomes. Using Ostrom's institutional design principles for assessing common-pool resource management, we selected five case studies from Brazilian Amazonian watersheds to conduct an exploratory comparative case-study analysis. We identify similar problems across basins, including deficiencies in the dam licensing process; critical data gaps; inadequate stakeholder participation; violation of human rights; neglect of fishers' knowledge; lack of organization and representation by fishers' groups; and lack of governmental structure and capacity to manage dam construction activities or support fishers after dam construction. Fishers have generally been marginalized or excluded from decision-making regarding planning, construction, mitigation, compensation, and monitoring of the social-ecological impacts of hydroelectric dams. Addressing these deficiencies will require concerted investments and efforts by dam developers, government agencies and civil society, and the promotion of inter-sectorial dialogue and cross-scale participatory planning and decision-making that includes fishers and their associations.

Production and characterization of a biosurfactant produced by Streptomyces sp. DPUA 1559 isolated from lichens of the Amazon region.

Braz J Med Biol Res; 51(2): e6657, 2017 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-29267499


Surfactants are amphipathic compounds containing both hydrophilic and hydrophobic groups, capable to lower the surface or interfacial tension. Considering the advantages of the use of biosurfactants produced by microorganisms, the aim of this paper was to develop and characterize a biosurfactant produced by Streptomyces sp. DPUA1559 isolated from lichens of the Amazon region. The microorganism was cultured in a mineral medium containing 1% residual frying soybean oil as the carbon source. The kinetics of biosurfactant production was accompanied by reducing the surface tension of the culture medium from 60 to values around 27.14 mN/m, and by the emulsification index, which showed the efficiency of the biosurfactant as an emulsifier of hydrophobic compounds. The yield of the isolated biosurfactant was 1.74 g/L, in addition to the excellent capability of reducing the surface tension (25.34 mN/m), as observed from the central composite rotational design when the biosurfactant was produced at pH 8.5 at 28°C. The critical micelle concentration of the biosurfactant was determined as 0.01 g/mL. The biosurfactant showed thermal and pH stability regarding the surface tension reduction, and tolerance under high salt concentrations. The isolated biosurfactant showed no toxicity to the micro-crustacean Artemia salina, and to the seeds of lettuce (Lactuca sativa L.) and cabbage (Brassica oleracea L.). The biochemistry characterization of the biosurfactant showed a single protein band, an acid character and a molecular weight around 14.3 kDa, suggesting its glycoproteic nature. The results are promising for the industrial application of this new biosurfactant.

Effects of increasing temperature and, CO2 on quality of litter, shredders, and microorganisms in Amazonian aquatic systems.

PLoS One; 12(11): e0188791, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29190723


Climate change may affect the chemical composition of riparian leaf litter and, aquatic organisms and, consequently, leaf breakdown. We evaluated the effects of different scenarios combining increased temperature and carbon dioxide (CO2) on leaf detritus of Hevea spruceana (Benth) Müll. and decomposers (insect shredders and microorganisms). We hypothesized that simulated climate change (warming and elevated CO2) would: i) decrease leaf-litter quality, ii) decrease survival and leaf breakdown by shredders, and iii) increase microbial leaf breakdown and fungal biomass. We performed the experiment in four microcosm chambers that simulated air temperature and CO2 changes in relation to a real-time control tracking current conditions in Manaus, Amazonas, Brazil. The experiment lasted seven days. During the experiment mean air temperature and CO2 concentration ranged from 26.96 ± 0.98ºC and 537.86 ± 18.36 ppmv in the control to 31.75 ± 0.50ºC and 1636.96 ± 17.99 ppmv in the extreme chamber, respectively. However, phosphorus concentration in the leaf litter decreased with warming and elevated CO2. Leaf quality (percentage of carbon, nitrogen, phosphorus, cellulose and lignin) was not influenced by soil flooding. Fungal biomass and microbial leaf breakdown were positively influenced by temperature and CO2 increase and reached their highest values in the intermediate condition. Both total and shredder leaf breakdown, and shredder survival rate were similar among all climatic conditions. Thus, low leaf-litter quality due to climate change and higher leaf breakdown under intermediate conditions may indicate an increase of riparian metabolism due to temperature and CO2 increase, highlighting the risk (e.g., decreased productivity) of global warming for tropical streams.

Housing conditions and the degree of home satisfaction of elderly riverside residents of the Amazon region / Condições de habitação e grau de satisfação domiciliar entre idosos ribeirinhos amazônicos / Las condiciones de vivienda y el grado de satisfacción del hogar entre ribereños amazónicos ancianos

Psico USF; 22(3): 389-399, set.-dez. 2017. tab, ilus
Artigo em Inglês | LILACS | ID: biblio-878067


At the crossroads of environmental psychology and social gerontology, this descriptive and exploratory study investigates the housing conditions of the elderly who live close to an Amazonian river and assesses their degree of satisfaction with their housing. Using four instruments, we study 23 elderly residents of the river islands of the municipality of Cametá, Pará, Brazil. Despite high territorial isolation, low socioeconomic status, and largely inappropriate housing conditions, the results reveal the elderly's overall satisfaction with their home environment, except in relation to accessibility and safety. The data of this study give larger visibility to people's main needs in this context and provide relevant information for the planning of social and health policies aimed at bettering the quality of this stage of the life span.(AU)
Condições de habitação e grau de satisfação domiciliar entre idosos ribeirinhos amazônicos Resumo: À perspectiva da Psicologia Ambiental e da Gerontologia Social, este estudo de caráter descritivo e exploratório objetivou investigar as condições habitacionais de idosos ribeirinhos amazônicos, assim como, descrever o grau de satisfação dos mesmos quanto ao ambiente de moradia onde vivem. Utilizando-se de quatro instrumentos metodológicos, foram investigados 23 idosos residentes das ilhas fluviais do município de Cametá, Pará, Brasil. Os resultados revelaram que apesar do grande isolamento territorial, do baixo nível socioeconômico e das condições pouco adequadas de habitação dos idosos ribeirinhos amazônicos inqueridos, os mesmos denotam bom grau de satisfação em relação ao ambiente domiciliar, exceto em relação à acessibilidade e segurança. Os dados apresentados neste estudo dão maior visibilidade às principais carências desse contexto e fornece subsídios para o planejamento de políticas sociais e de saúde que visem melhor qualidade nesta etapa da vida e neste contexto.(AU)
Desde la perspectiva de la Psicología Ambiental y Gerontología Social, este estudio de carácter descriptivo y exploratorio tuvo como objetivo investigar las condiciones habitacionales entre ancianos ribereños amazónicos, así como describir el grado de satisfacción de los mismos, con relación al ambiente de la vivienda donde habitan.Usando cuatro instrumentos metodológicos se investigaron 23 ancianos residentes en las islas fluviales del municipio de Cametá, Pará, Brasil. Los resultados revelaron que a pesar del gran aislamiento territorial, del bajo nivel socio-económico y de las condiciones poco adecuadas de habitación, los ancianos demuestran buen grado de satisfacción con el ambiente domiciliar, excepto en lo que se refiere a accesibilidad y seguridad. Los datos presentados en este estudio dan mayor visibilidad a las principales carencias de este contexto y proporcionan subsidios para la planificación de políticas sociales y de salud, dirigidas a una mejor calidad de vida en esta etapa y en este contexto.(AU)
Biblioteca responsável: BR1249.1

Mercury concentrations in bats (Chiroptera) from a gold mining area in the Peruvian Amazon.

Ecotoxicology; 2017 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-29101638


In the southeastern Peruvian Amazon, artisanal and small-scale gold mining (ASGM) is estimated to have released up to 300 tonnes of mercury (Hg) to the environment between 1995 and 2007 alone, and is claimed to be responsible for Hg concentrations above international thresholds for aquatic wildlife species. Here, we examined whether Hg concentrations in bat populations are potentially related to regional ASGM-Hg releases. We determined Hg concentrations in the fur of bats collected at three different distances from the major ASGM areas in Peru. Our findings from 204 individuals of 32 species indicate that Hg concentrations in bat fur mainly resulted from differences in feeding habits, because Hg concentrations were significantly higher in omnivorous bats than in frugivorous bats. At least in two species, populations living in ASGM-affected sites harbored higher Hg concentrations than did populations in unaffected sites. Because Hg concentrations reflect Hg dietary exposure, Hg emissions from amalgam roasting sites appear to deposit locally and enter the terrestrial food web. Although our study demonstrates that ASGM activities (and Hg point sources) increase Hg exposure in wildlife, the overall Hg concentrations reported here are relatively low. The measured Hg concentrations were below the toxicity threshold at which adverse neurological effects have been reported in rodents and mink (>10 µg g ), and were in the range of Hg concentrations in the fur of bats from nonpoint source affected sites in other latitudes. This study emphasizes the importance of considering feeding habits when evaluating Hg concentrations in bats and other vertebrates.

The effect of dam construction on the movement of dwarf caimans, Paleosuchus trigonatus and Paleosuchus palpebrosus, in Brazilian Amazonia.

PLoS One; 12(11): e0188508, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29176830


Run-of-the-river hydroelectric dams cause changes in seasonal inundation of the floodplains, and this may cause displacement of semi-aquatic vertebrates present before dam construction. This study evaluated the movement of crocodilians before and after the filling of the Santo Antônio hydroelectric reservoir on the Madeira River in the Brazilian Amazon, which occurred in November 2011. We radio-tracked four adult male Paleosuchus palpebrosus and four adult male Paleosuchus trigonatus before and after the formation of the reservoir between 2011 and 2013. The home ranges of the P. palpebrosus varied from < 1 km2 to 91 km2 and the home ranges of the P. trigonatus varied from < 1km2 to 5 km2. The species responded differently to time since filling and water level in weekly movement and home range. However, overall the dam appears to have had little effect on the use of space by the individuals that were present before dam construction.

Quantitative proteomic analysis of amastigotes from Leishmania (L.) amazonensis LV79 and PH8 strains reveals molecular traits associated with the virulence phenotype.

PLoS Negl Trop Dis; 11(11): e0006090, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29176891


BACKGROUND: Leishmaniasis is an antropozoonosis caused by Leishmania parasites that affects around 12 million people in 98 different countries. The disease has different clinical forms, which depend mainly on the parasite genetics and on the immunologic status of the host. The promastigote form of the parasite is transmitted by an infected female phlebotomine sand fly, is internalized by phagocytic cells, mainly macrophages, and converts into amastigotes which replicate inside these cells. Macrophages are important cells of the immune system, capable of efficiently killing intracellular pathogens. However, Leishmania can evade these mechanisms due to expression of virulence factors. Different strains of the same Leishmania species may have different infectivity and metastatic phenotypes in vivo, and we have previously shown that analysis of amastigote proteome can give important information on parasite infectivity. Differential abundance of virulence factors probably accounts for the higher virulence of PH8 strain parasites shown in this work. In order to test this hypothesis, we have quantitatively compared the proteomes of PH8 and LV79 lesion-derived amastigotes using a label-free proteomic approach. METHODOLOGY/PRINCIPAL FINDINGS: In the present work, we have compared lesion development by L. (L.) amazonensis PH8 and LV79 strains in mice, showing that they have different virulence in vivo. Viability and numbers of lesion-derived amastigotes were accordingly significantly different. Proteome profiles can discriminate parasites from the two strains and several proteins were differentially expressed. CONCLUSIONS/SIGNIFICANCE: This work shows that PH8 strain is more virulent in mice, and that lesion-derived parasites from this strain are more viable and more infective in vitro. Amastigote proteome comparison identified GP63 as highly expressed in PH8 strain, and Superoxide Dismutase, Tryparedoxin Peroxidase and Heat Shock Protein 70 as more abundant in LV79 strain. The expression profile of all proteins and of the differential ones precisely classified PH8 and LV79 samples, indicating that the two strains have proteins with different abundances and that proteome profiles correlate with their phenotypes.

Characterization of hepatitis B virus in Amerindian children and mothers from Amazonas State, Colombia.

PLoS One; 12(10): e0181643, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29016603


BACKGROUND: Hepatitis B Virus (HBV) infection is a worldwide public health problem. In the 1980's a highly effective and safe vaccine against HBV was developed, although breakthrough infection still occasionally occurs because of the emergence of escape mutants. The aim of this study was to identify HBV genotypes and escape mutants in children and their mothers in Amerindian communities of the Amazonas State, Southern Colombia. METHODS: Blood specimens collected from children and mothers belonging to 37 Amerindian communities in Amazonas state, were screened for HBsAg and anti-HBc using ELISA. The partial region containing the S ORF was amplified by nested PCR, and amplicons were sequenced. The phylogenetic analysis was performed using the MEGA 5.05 software. RESULTS: Forty-six children (46/1275, 3.6%) and one hundred and seventy-seven mothers (177/572, 30.9%) were tested positive for the anti-HBc serological marker. Among them, 190 samples were tested for viral genome detection; 8.3% (2/31) serum samples obtained from children and 3.1% (5/159) from mothers were positive for the ORF S PCR. The predominant HBV genotype in the study population was F, subgenotype F1b; in addition, subgenotype F1a and genotype A were also characterized. Two HBV escape mutants were identified, G145R, reported worldwide, and W156*; this stop codon was identified in a child with occult HBV infection. Other mutations were found, L109R and G130E, located in critical positions of the HBsAg sequence. CONCLUSIONS: This study aimed to characterize the HBV genotype F, subgenotypes F1b and F1a, and genotype A in Amerindian communities and for the first time escape mutants in Colombia. Further investigations are necessary to elucidate the frequency and the epidemiological impact of the escape mutants in the country.

Model uncertainties do not affect observed patterns of species richness in the Amazon.

PLoS One; 12(10): e0183785, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29023503


BACKGROUND: Climate change is arguably a major threat to biodiversity conservation and there are several methods to assess its impacts on species potential distribution. Yet the extent to which different approaches on species distribution modeling affect species richness patterns at biogeographical scale is however unaddressed in literature. In this paper, we verified if the expected responses to climate change in biogeographical scale-patterns of species richness and species vulnerability to climate change-are affected by the inputs used to model and project species distribution. METHODS: We modeled the distribution of 288 vertebrate species (amphibians, birds and mammals), all endemic to the Amazon basin, using different combinations of the following inputs known to affect the outcome of species distribution models (SDMs): 1) biological data type, 2) modeling methods, 3) greenhouse gas emission scenarios and 4) climate forecasts. We calculated uncertainty with a hierarchical ANOVA in which those different inputs were considered factors. RESULTS: The greatest source of variation was the modeling method. Model performance interacted with data type and modeling method. Absolute values of variation on suitable climate area were not equal among predictions, but some biological patterns were still consistent. All models predicted losses on the area that is climatically suitable for species, especially for amphibians and primates. All models also indicated a current East-western gradient on endemic species richness, from the Andes foot downstream the Amazon river. Again, all models predicted future movements of species upwards the Andes mountains and overall species richness losses. CONCLUSIONS: From a methodological perspective, our work highlights that SDMs are a useful tool for assessing impacts of climate change on biodiversity. Uncertainty exists but biological patterns are still evident at large spatial scales. As modeling methods are the greatest source of variation, choosing the appropriate statistics according to the study objective is also essential for estimating the impacts of climate change on species distribution. Yet from a conservation perspective, we show that Amazon endemic fauna is potentially vulnerable to climate change, due to expected reductions on suitable climate area. Climate-driven faunal movements are predicted towards the Andes mountains, which might work as climate refugia for migrating species.

Woody lianas increase in dominance and maintain compositional integrity across an Amazonian dam-induced fragmented landscape.

PLoS One; 12(10): e0185527, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29040272


Tropical forest fragmentation creates insular biological communities that undergo species loss and changes in community composition over time, due to area- and edge-effects. Woody lianas thrive in degraded and secondary forests, due to their competitive advantage over trees in these habitats. Lianas compete both directly and indirectly with trees, increasing tree mortality and turnover. Despite our growing understanding of liana-tree dynamics, we lack detailed knowledge of the assemblage-level responses of lianas themselves to fragmentation, particularly in evergreen tropical forests. We examine the responses of both sapling and mature liana communities to landscape-scale forest insularization induced by a mega hydroelectric dam in the Brazilian Amazon. Detailed field inventories were conducted on islands created during reservoir filling, and in nearby mainland continuous forest. We assess the relative importance of variables associated with habitat fragmentation such as area, isolation, surrounding forest cover, fire and wind disturbance, on liana community attributes including abundance, basal area, diversity, and composition. We also explore patterns of liana dominance relative to tree saplings and adults ≥10 cm diameter at breast height. We find that 1) liana community composition remains remarkably similar across mainland continuous forest and islands, regardless of extreme area- and edge- effects and the loss of vertebrate dispersers in the latter; and 2) lianas are increasing in dominance relative to trees in the sapling layer in the most degraded islands, with both the amount of forest cover surrounding islands and fire disturbance history predicting liana dominance. Our data suggest that liana communities persist intact in isolated forests, regardless of extreme area- and edge-effects; while in contrast, tree communities simultaneously show evidence of increased turnover and supressed recruitment. These processes may lead to lianas becoming a dominant component of this dam-induced fragmented landscape in the future, due to their competitive advantage over trees in degraded forest habitats. Additional loss of tree biomass and diversity brought about through competition with lianas, and the concurrent loss of carbon storage, should be accounted for in impact assessments of future dam development.

Constructing regional climate networks in the Amazonia during recent drought events.

PLoS One; 12(10): e0186145, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29040296


Climate networks are powerful approaches to disclose tele-connections in climate systems and to predict severe climate events. Here we construct regional climate networks from precipitation data in the Amazonian region and focus on network properties under the recent drought events in 2005 and 2010. Both the networks of the entire Amazon region and the extreme networks resulted from locations severely affected by drought events suggest that network characteristics show slight difference between the two drought events. Based on network degrees of extreme drought events and that without drought conditions, we identify regions of interest that are correlated to longer expected drought period length. Moreover, we show that the spatial correlation length to the regions of interest decayed much faster in 2010 than in 2005, which is because of the dual roles played by both the Pacific and Atlantic oceans. The results suggest that hub nodes in the regional climate network of Amazonia have fewer long-range connections when more severe drought conditions appeared in 2010 than that in 2005.

Measuring local depletion of terrestrial game vertebrates by central-place hunters in rural Amazonia.

PLoS One; 12(10): e0186653, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29040340


The degree to which terrestrial vertebrate populations are depleted in tropical forests occupied by human communities has been the subject of an intense polarising debate that has important conservation implications. Conservation ecologists and practitioners are divided over the extent to which community-based subsistence offtake is compatible with ecologically functional populations of tropical forest game species. To quantify depletion envelopes of forest vertebrates around human communities, we deployed a total of 383 camera trap stations and 78 quantitative interviews to survey the peri-community areas controlled by 60 semi-subsistence communities over a combined area of over 3.2 million hectares in the Médio Juruá and Uatumã regions of Central-Western Brazilian Amazonia. Our results largely conform with prior evidence that hunting large-bodied vertebrates reduces wildlife populations near settlements, such that they are only found at a distance to settlements where they are hunted less frequently. Camera trap data suggest that a select few harvest-sensitive species, including lowland tapir, are either repelled or depleted by human communities. Nocturnal and cathemeral species were detected relatively more frequently in disturbed areas close to communities, but individual species did not necessarily shift their activity patterns. Group biomass of all species was depressed in the wider neighbourhood of urban areas rather than communities. Interview data suggest that species traits, especially group size and body mass, mediate these relationships. Large-bodied, large-group-living species are detected farther from communities as reported by experienced informants. Long-established communities in our study regions have not "emptied" the surrounding forest. Low human population density and low hunting offtake due to abundant sources of alternative aquatic protein, suggest that these communities represent a best-case scenario for sustainable hunting of wildlife for food, thereby providing a conservative assessment of game depletion. Given this 'best-case' camera trap and interview-based evidence for hunting depletion, regions with higher human population densities, external trade in wildlife and limited access to alternative protein will likely exhibit more severe depletion.

Loop-mediated isothermal DNA amplification for asymptomatic malaria detection in challenging field settings: Technical performance and pilot implementation in the Peruvian Amazon.

PLoS One; 12(10): e0185742, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28982155


BACKGROUND: Loop-mediated isothermal DNA amplification (LAMP) methodology offers an opportunity for point-of-care (POC) molecular detection of asymptomatic malaria infections. However, there is still little evidence on the feasibility of implementing this technique for population screenings in isolated field settings. METHODS: Overall, we recruited 1167 individuals from terrestrial ('road') and hydric ('riverine') communities of the Peruvian Amazon for a cross-sectional survey to detect asymptomatic malaria infections. The technical performance of LAMP was evaluated in a subgroup of 503 samples, using real-time Polymerase Chain Reaction (qPCR) as reference standard. The operational feasibility of introducing LAMP testing in the mobile screening campaigns was assessed based on field-suitability parameters, along with a pilot POC-LAMP assay in a riverine community without laboratory infrastructure. RESULTS: LAMP had a sensitivity of 91.8% (87.7-94.9) and specificity of 91.9% (87.8-95.0), and the overall accuracy was significantly better among samples collected during road screenings than riverine communities (p≤0.004). LAMP-based diagnostic strategy was successfully implemented within the field-team logistics and the POC-LAMP pilot in the riverine community allowed for a reduction in the turnaround time for case management, from 12-24 hours to less than 5 hours. Specimens with haemolytic appearance were regularly observed in riverine screenings and could help explaining the hindered performance/interpretation of the LAMP reaction in these communities. CONCLUSIONS: LAMP-based molecular malaria diagnosis can be deployed outside of reference laboratories, providing similar performance as qPCR. However, scale-up in remote field settings such as riverine communities needs to consider a number of logistical challenges (e.g. environmental conditions, labour-intensiveness in large population screenings) that can influence its optimal implementation.

Comment on "Persistent effects of pre-Columbian plant domestication on Amazonian forest composition".

Science; 358(6361)2017 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-29051349


Levis (Research Articles, 3 March 2017, p. 925) concluded that pre-Columbian tree domestication has shaped present-day Amazonian forest composition. The study, however, downplays five centuries of human influence following European arrival to the Americas. We show that the effects of post-Columbian activities in Amazonia are likely to have played a larger role than pre-Columbian ones in shaping the observed floristic patterns.

Response to Comment on "Persistent effects of pre-Columbian plant domestication on Amazonian forest composition".

Science; 358(6361)2017 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-29051350


McMichael state that we overlooked the effects of post-Columbian human activities in shaping current floristic patterns in Amazonian forests. We formally show that post-Columbian human influences on Amazonian forests are indeed important, but they have played a smaller role when compared to the persistent effects of pre-Columbian human activities on current forest composition.
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