Northern Amazon Research Articles

A new madicolous species of Nilotanypus Kieffer (Diptera: Chironomidae) from Amazon region, northwestern Brazil.

A new species of Nilotanypus Kieffer is described and illustrated based on male, pupa and larva. Nilotanypus yanomami sp. n. was collected at madicolous system in a mountainous region of northern Amazonia. Additionally, the identification key for males is updated and a distribution map for the Neotropical species is provided.

Growth and survival over ten years of Brazil-nut trees planted in three anthropogenic habitats in northern Amazonia

ABSTRACT We examined the growth and survival of Brazil-nut trees, Bertholletia excelsa (Lecythidaceae) under different environmental conditions and levels of canopy openness within experimental plantations in the Trombetas River valley, in northern Brazil. We planted 144 seedlings in three anthropogenic habitats with different levels of sunlight exposition: crop field (100% canopy opening), shrub fallow (20-80% canopy opening) and Brazil-nut forest (< 10% canopy opening). We measured plant height and diameter annually and recorded mortality and resprouting over ten years. The performance of B. excelsa differed significantly among habitats, with the highest growth rate observed at the highest level of canopy openness (crop field). Survival was highest in crop field (85%) and shrub fallow (63%) and lowest in Brazil-nut forest (17%). Resprouting capacity was higher in the crop field, as Brazil-nut plants recovered after fire episodes, with most plants resprouting more than one shoot. Some trees in the crop field began to produce flowers and fruits at 9-10 years. We showed that B. excelsa juveniles are light-demanding, with higher survival and growth under conditions of high light exposure. We suggest the use of Brazil-nut trees for reforestation, restoration of degraded lands and enrichment of secondary vegetation, as long as an adequate management is adopted (e.g., maintaining plants exposed to direct sunlight and control of competing pioneer species).

Spatial pattern of COVID-19 deaths and infections in small areas of Brazil.

As of mid-August 2020, Brazil was the country with the second-highest number of cases and deaths by the COVID-19 pandemic, but with large regional and social differences. In this study, using data from the Brazilian Ministry of Health, we analyze the spatial patterns of infection and mortality from Covid-19 across small areas of Brazil. We apply spatial autoregressive Bayesian models and estimate the risks of infection and mortality, taking into account age, sex composition of the population and other variables that describe the health situation of the spatial units. We also perform a decomposition analysis to study how age composition impacts the differences in mortality and infection rates across regions. Our results indicate that death and infections are spatially distributed, forming clusters and hotspots, especially in the Northern Amazon, Northeast coast and Southeast of the country. The high mortality risk in the Southeast part of the country, where the major cities are located, can be explained by the high proportion of the elderly in the population. In the less developed areas of the North and Northeast, there are high rates of infection among young adults, people of lower socioeconomic status, and people without access to health care, resulting in more deaths.

Hydrological impacts of ethanol-driven sugarcane expansion in Brazil

Ethanol production in Brazil is projected to double between 2012 and 2030 in order to meet increased global demand, resulting in the expansion of sugarcane cultivation. Sugarcane expansion drives both direct and indirect land-use changes, and subsequent changes in hydrology may exacerbate problems of (local) water scarcity. This study assesses the impacts of projected ethanol-driven sugarcane expansion on agricultural and hydrological drought in Brazil. Drought due to sugarcane expansion is modelled using a spatial terrestrial hydrological model (PCR-GLOBWB) with spatiotemporally variable land-use change and climate change scenarios as input. We compare an ethanol scenario with increased ethanol demand to a reference situation in which ethanol demand does not increase.The results show that, on average, 29% of the Centre West Cerrado region is projected to experience agricultural drought between 2012 and 2030, and the drought deficit in this region is projected to be 7% higher in the ethanol scenario compared to the reference. The differences between the ethanol and the reference scenario are small when averaged over macro-regions, but can be considerable at a local scale. Differences in agricultural and hydrological drought between the ethanol and reference scenario are most notable in the Centre West Cerrado and Southeast regions. Locally, considerable changes may also occur in other regions, including the Northeast Coast and Northern Amazon region.Because the South East and Centre West Cerrado regions are responsible for a large proportion of agricultural production, increased agricultural drought may result in significant economic losses, while increased hydrological drought could exacerbate existing problems of water supply to large metropolitan areas in these regions. The identification of areas at risk of increased droughts can be important information for policy makers to take precautionary measures to avoid negative hydrological impacts of increased ethanol demand.

Effect of using isolated interannual and decadal time scales on the water balance of the Amazon basin

In this study, we evaluated the isolated effects of interannual and decadal time scales on the water balance of the Amazon basin. This research is interesting because it brings the dynamical response of water balance components to a particular ocean-scale variability. For this, we used the Brazilian Global Atmospheric Model (BAM) and SST filtering techniques. The impact of isolated interannual and decadal time scales was quantified for episodes of ENSO and the Atlantic dipole (AD). The results show that isolated interannual scales weaken the impacts of El Niño and La Niña on water balance components in the northern Amazon and northeastern Brazil. Such weakening is more evident in episodes of El Niño than in those of La Niña. This indicates that El Niño is more dependent on other time scales (in addition to interannual) than is La Niña. In relation to the Atlantic, a positive AD increases (decreases) precipitation in the northern (southern) Amazon basin in the experiment with all SST time scale variabilities. On the other hand, when the decadal scale is isolated, an increase in precipitation in the northern basin is not observed, losing the dipole pattern in the precipitation anomaly between the northern and southern Amazon basin. BAM is not sensitive to a negative AD when SST is isolated in the decadal scale. These results are important for monitoring the climate of humid tropical regions, mainly for the study of ENSO, since, according to recent research, these extreme events will be increasingly frequent and intense.

L’açaí en France d'Outre-Mer : La Guyane française vers une nouvelle frontière agricole de l'Euterpe oleracea dans l'Amazonie septentrionale

Originaire du palmier Euterpe oleracea, l'açaí est un fruit endémique de la forêt amazonienne, dont la consommation s’est fortement développée au Brésil depuis les années 1990 et est émergente dans d'autres régions du monde. Consommé surtout sous forme de pulpe et érigé en « superfruit » par des acteurs du marketing pour son potentiel antioxydant et nutritionnel, la baie d'açaí traverse un processus dynamique englobant à la fois son circuit spatial de production et de distribution internationale ainsi que sa composition de produits dérivés. Avec plus de 85 % de son territoire inséré dans la forêt amazonienne, la Guyane française a toutes les exigences environnementales nécessaires pour le développement et la production de baies d'açaí. Actuellement dans ce territoire, la plus forte concentration de la production extractive d’Euterpe oleracea se trouve dans la région du bas Oyapock, à la frontière avec le Brésil. Malgré le peu d'intérêt gouvernemental derrière le fruit, il y a un peu plus de six ans, les producteurs agricoles de la région métropolitaine de Cayenne ont analysé de près la dynamique et la consommation des produits dérivés de l’açaí en Europe et sur d'autres continents. A partir des résultats favorables de l'analyse du marché international, ces agriculteurs ont créé la société Yana Wassaï dont l'objectif principal est de développer le processus de production local ciblant le marché extérieur. L'un des objectifs de ce groupe est de transformer la baie d'açaí en un produit « européen ». Avec une grande partie du projet déjà en cours, le groupe prévoit d'augmenter la superficie cultivée d'environ 300 hectares dans les trois prochaines années pour atteindre un total de plus de 1 000 hectares de cultures en les huit prochaines années. Lors de notre séjour à Guyane française, il a été possible de discuter de plus près avec les principaux acteurs de ce projet, en plus de visiter et de connaître les premières plantations irriguées du palmier Euterpe oleracea appartenance au groupe.

Nutritional status and biomass of african mahogany seedlings grown with nutrient solution in the Northern Amazon

O objetivo neste trabalho foi determinar aspectos sobre variáveis de crescimento e partição de massa seca das mudas de Khaya senegalensis, bem como a marcha de absorção de nutrientes, em função das épocas e adubação mineral. O delineamento experimental utilizado foi inteiramente casualizado, em esquema fatorial 2 x 6. Dois níveis do fator solução nutritiva (sem e com adição) e seis níveis para o fator período (0; 60; 80; 100; 120 e 140 dias). Foram utilizadas 4 repetições, sendo cada uma delas composta de 10 mudas. Para avaliação da qualidade das mudas, consideraram-se os parâmetros morfológicos, relações e índices de qualidade: altura da parte aérea (H; cm); diâmetro do coleto (DC; mm); massa seca da parte aérea (MSPA; g planta-1); massa seca da raiz (MSR; g planta-1); massa seca total (MST = MSPA + MSR; g planta-1); relação massa seca da parte aérea e massa seca da raiz (MSPA/MSR); índice de robustez (IR= H/DC; cm mm-1); e índice de qualidade de Dickson (IQD) e o acúmulo de macronutrientes na parte aérea e sistemaradicular. A adição de solução é recomendada para mudas de Khaya senegalensis a partir da época 100 dias após o transplantio em viveiro de telado na Amazônia setentrional. A manutenção das mudas de Khaya senegalensis com uso de solução nutritiva proporciona as melhores condições para o aproveitamento dos macronutrientes e permite obter mudas aptas para campo em 140 dias após o transplantio em viveiro de telado em Roraima.

Molecular surveillance of the Plasmodium vivax multidrug resistance 1 gene in Peru between 2006 and 2015

BackgroundThe high incidence of Plasmodium vivax infections associated with clinical severity and the emergence of chloroquine (CQ) resistance has posed a challenge to control efforts aimed at eliminating this disease. Despite conflicting evidence regarding the role of mutations of P. vivax multidrug resistance 1 gene (pvmdr1) in drug resistance, this gene can be a tool for molecular surveillance due to its variability and spatial patterns.MethodsBlood samples were collected from studies conducted between 2006 and 2015 in the Northern and Southern Amazon Basin and the North Coast of Peru. Thick and thin blood smears were prepared for malaria diagnosis by microscopy and PCR was performed for detection of P. vivax monoinfections. The pvmdr1 gene was subsequently sequenced and the genetic data was used for haplotype and diversity analysis.ResultsA total of 550 positive P. vivax samples were sequenced; 445 from the Northern Amazon Basin, 48 from the Southern Amazon Basin and 57 from the North Coast. Eight non-synonymous mutations and three synonymous mutations were analysed in 4,395 bp of pvmdr1. Amino acid changes at positions 976F and 1076L were detected in the Northern Amazon Basin (12.8%) and the Southern Amazon Basin (4.2%) with fluctuations in the prevalence of both mutations in the Northern Amazon Basin during the course of the study that seemed to correspond with a malaria control programme implemented in the region. A total of 13 pvmdr1 haplotypes with non-synonymous mutations were estimated in Peru and an overall nucleotide diversity of π = 0.00054. The Northern Amazon Basin was the most diverse region (π = 0.00055) followed by the Southern Amazon and the North Coast (π = 0.00035 and π = 0.00014, respectively).ConclusionThis study showed a high variability in the frequencies of the 976F and 1076L polymorphisms in the Northern Amazon Basin between 2006 and 2015. The low and heterogeneous diversity of pvmdr1 found in this study underscores the need for additional research that can elucidate the role of this gene on P. vivax drug resistance as well as in vitro and clinical data that can clarify the extend of CQ resistance in Peru.

A Simple Conceptual Model for the Heat Induced Circulation over Northern South America and Meso-America

The physical description of the atmosphere’s general circulation over Northern South America and Meso-America deserves a more comprehensive explanation. This work presents the Pacific coast of Colombia as the rainiest place on Earth, with annual rainfall averaging 5000 to 13,000 mm, and record values as high as 13,159 mm for the location of Puerto López (77∘14′ W, 2∘50′ N). Using information from the ECMWF ERA-40 Atlas and ERA-Interim Reanalysis, we describe the existence of a concentrated diabatic heating source due to condensation and the main features of its related circulation over Northern South America and Meso-America. For simplicity, we used the analytical solution of the Phlips-Gill Model to diagnose the main flow patterns. Results show that the diabatic source over western Colombia generates equatorial trapped Rossby-Kelvin waves, which dominate the low-level circulation. A Kelvin wave explains the low-level easterly flows over the Tropical Atlantic Ocean, the Caribbean Sea, the Venezuelan-Colombian Llanos, and the Northern Amazon Basin. This circulation is analogous to a Walker cell. To the west, two cyclonic flows and strong westerly winds are present in Meso-America and the far eastern Pacific because planetary waves propagate there. A slight asymmetry in the equator’s diabatic heating location is responsible for the intense low-level pressure over Panama. The vertical velocity over the source area induces vortex tube stretching, and zonal mean flow excites a mixed wave and a northward flow.

Soil bacterial diversities and response to deforestation, land use and burning in North Amazon, Brazil

The biodiversity in Amazon forest soils is continuously challenged by anthropogenic activities or disturbances, impacting the quantity and quality of its natural resources and a wide range of ecosystem services. Understanding microbial processes and response to various soil management practices provide valuable information to maintain sustainable ecological environments. We hypothesized that microbial assemblages (several not yet identified) and activities are continuously changing in forest ecosystems, mostly due to management selections. Therefore, our work's objective was to assess bacteria communities' changes via next-generation sequencing techniques and bridge knowledge gaps in our understanding of their responses to deforestations, intensive agriculture, and repeated forest burning activities in altered and native forest locations in the Northern Amazon Rainforest, Brazil. We evaluated soils during different climatic periods (dry and rainy) collected at selected sites for pasture, conventional agriculture, and forestry. Intensive conversion to pasture and conventional plantations seriously impacted the bacterial diversities and species richness. The forest area presented the greatest bacterial diversities and species richness, followed by the pasture areas, especially in the 0–5 cm soil layer. Conventional plantations showed the lowest diversities and species richness. There was no change in species richness between the dry and rainy periods; however, the wet period showed lesser species diversities. Based on the analyses, the bacterial communities comprised of the phyla: Acidobacteria, Firmicutes, Verrucomicrobia, Actinobacteria, Proteobacteria, Planctomycetes, and Cyanobacteria. Bacteria trends identified are being considered in future management decisions to preserve biodiversities and the region's forest ecosystems' functioning.

On the general circulation of the atmosphere around Colombia

The average annual precipitation in the Pacific coast of Colombia ranges from 8,000 to 13,000 mm. The annual average (1960-2018) in Puerto López (Cauca) rain gauge (77°14’56.3”W, 2°50’43.0”N) is 13.159 mm making it, probably, the rainiest place on the Earth. Such a large amount of precipitation also means a sizeable diabatic heating source over western Colombia, which is responsible for driving the circulation in northern South America and Mesoamerica from mid-March to the end of November. We applied a simple conceptual model to study the heat-induced circulation. Our results indicated that the heating source over western Colombia produces a steady, low-level westerly inflow as a result of a half planetary wave propagating over Mesoamerica and the far eastern Pacific that generates two cyclonical flows. On the east side of the heating source, a Kelvin wave generates a low-level easterly flow from the tropical Atlantic Ocean and the Northern Amazon and Orinoco basins in a Walker-type circulation. This Rossby and Kelvin patterns create information pathways, which, in their turn, dominate the low- and upper-level wind fields. Documented observations about the atmosphere’s general circulation over northern South America and Mesoamérica are consistent enough to support the assertion that a set of waves trapped in the tropics induced by a heating source explains the circulation over Colombia and its surroundings.

Regional development in Amazonas, Peru: science-society interactions for sustainability

Scientific-technological knowledge maintains the anthropocentric power-pattern and exploitive attitude with regard to nature, but sustainability science asks for an integration of territorial and decontextualized knowledge systems. Visual participatory methodologies involving diverse local stakeholder facilitate dialogue on environmental and sustainability issues. Inspired by visual ethnography and mediated discourse analysis, the present article uses semiological analysis to reconstruct the depicted narratives on the nature-society system in drawings representing “regional development”. The drawings were elaborated in a series of participatory workshops involving university faculty and students, regional government and non-governmental organizations and farmers from local communities in the northern Amazonian region of Peru. The analysis reveals a prevailing anthropo and technology centered, “colonial” conception of the nature-society system, and a marginalization of alternative narratives. Beyond confirming the potential for visual participatory methods to enhance multi-stakeholder dialogue, it demonstrates how semiological analysis can be used to deepen an understanding of the cultural, organizational and technological constraints facing critical, trans-disciplinary efforts to decolonize the technology-centered, anthropocentric mainstream worldview of nature and society.

Universidade, desenvolvimento e modernização no Mato Grosso

As universidades públicas do estado Mato Grosso são o objeto deste trabalho. Elaborou-se uma narrativa cronológica linear das primeiras iniciativas de criação de escolas de ensino superior, contemplando-se as que ocorreram no atual Mato Grosso do Sul, para, em seguida, centrar as atenções sobre Mato Grosso no o período da divisão do Estado, de 1977. No decorrer do trabalho, opera-se uma análise dos discursos que associam às universidades um papel de promoção do desenvolvimento e modernização regional nas esferas econômicas e sociais, na intenção de demonstrar os limites desse tipo de discurso ideológico. Este trabalho é um recorte da tese de doutorado da autoria, intitulada História e Universidade, e, ainda neste trabalho, são contempladas reflexões dirigidas à expansão da UFMT e da UNEMAT rumo o interior do Estado, sobretudo, o espaço que diz respeito à Amazônia norte-mato-grossense.

Simulated deforestation versus satellite data in Roraima, Northern Amazonia, Brazil

Cenários de mudança de uso e cobertura da terra na Amazônia são necessários para subsidiar decisões que podem evitar a emissão de milhões de toneladas de CO2 para a atmosfera. Portanto, é importante avaliar modelos que visam a geração de cenários futuros. O atual estudo avaliou cenários gerados para o período 2011-2017 em Roraima, norte da Amazônia. Comparou-se o desmatamento simulado com os dados de satélite do PRODES. O mapeamento compreendeu (i) uma Área de Uso Silvo-pastoril – AUS (excluindo terras indígenas, unidades de conservação e não-floresta) intersectada com (ii) uma grade de nove (9) células de 10.000 km2 (100 × 100 km) para avaliações. O cenário de 2013 apresentou a maior similaridade (55,2%) com o mapa correspondente do PRODES. Apesar das divergências entre o desmatamento simulado nos cenários e o desmatamento oficial, no geral, as avaliações demonstraram a validade do modelo e a sua habilidade para gerar cenários que representam, de forma realística, o desmatamento ocorrido em Roraima no período analisado.

The expansion of the agricultural frontier in the northern Amazon region of Ecuador, 2000–2011: Process, causes, and impact

The Amazon forest has been characterized as one of the areas with the most extraordinary biodiversity in the world. However, the implementation of public policies throughout history has been one cause of an increasing presence of farmers who exert pressure on resources. The need to determine agricultural frontier growth and document the problem has been addressed by many authors who have focused their research on methodologies based on the use of geographic information systems. However, an approach based on quantitative and qualitative data could be constructive in validating and/or complementing such studies. In our case, from a historical contextualization, we identify the main causes of agricultural frontier expansion and, by analyzing information compiled from surveys and interviews, attempt to establish its main impacts. We found that the rate of deforestation for the period under review is at odds with rates determined by other methodologies. We also conclude that rapid population growth and the implementation of government projects in the area have led, first, to a division of land (farms) and a change in land use and, second, to a significant reduction in the forest cover.

Projected End-of-Century Changes in the South American Monsoon in the CESM Large Ensemble

AbstractProjected changes in the South American monsoon system by the end of the twenty-first century are analyzed using the Community Earth System Model Large Ensemble (CESM-LENS). The wet season is shorter in LENS when compared to observations, with the mean onset occurring 19 days later and the mean retreat date 21 days earlier in the season. Despite a precipitation bias, the seasonality of rainfall over South America is reproduced in LENS, as well as the main circulation features associated with the development of the South American monsoon. Both the onset and retreat of the wet season over South America are delayed in the future compared to current climate by 3 and 7 days, respectively, with a slightly longer wet season. Central and southeastern Brazil are projected to get wetter as a result of moisture convergence from the strengthening of the South Atlantic low-level jet and a weaker South Atlantic subtropical high. The Amazon is projected to get drier by the end of the century, negatively affecting rain forest productivity. During the wet season, an increase in the frequency and intensity of extreme precipitation events is found over most of South America, and especially over northeastern and southern Brazil and La Plata. Meanwhile, during the dry season an increase in the maximum number of consecutive dry days is found over northeastern Brazil and the northern Amazon.

Knowledge status and trends in description of amphibian species in Brazil

Overcoming the Linnaean and Wallacean shortfalls is an urgent task for biologists. It has been estimated that only a small fraction of the biodiversity on Earth is known, while geographic ranges of already described species are poorly documented. We performed a systematic review and modeling on species descriptions of Brazilian amphibians to evaluate the taxonomic knowledge on this group, to estimate the number of new species that remain to be described, and to identify description trends and relevant information for guiding future studies. All descriptions made between 1758 and 2017 of amphibian species and anuran tadpoles in Brazil, the country with the richest amphibian fauna, were gathered and characterized (species, year of description, number of authors per article, and coordinates of the collecting site). We found 1,119 amphibian species reported occurring in Brazil. The number of descriptions of both amphibian species and anuran tadpoles, as well as the number of authors per article, has exponentially increased over time. Phylogenetic regression analysis revealed that species with smaller body length and distribution area were described later, and that these two species traits are also correlated. According to two predictive models and several scenarios, we estimated that at least 25% of the Brazilian amphibian species have not yet been described. Our findings highlight the maintenance of significant Linnaean and Wallacean shortfalls in the knowledge of Brazilian amphibian species, despite of the increasing research efforts. The northern (Amazon) and central region (Cerrado) of Brazil should be priority areas for herpetological research. Society and the scientific community must commit to a greater investment in biodiversity knowledge to improve conservation strategies before the described and undescribed species become extinct.

Crustal growth and reworking of Archean crust within the Rhyacian domains of the southeastern Guiana Shield, Brazil: Evidence from zircon U–Pb–Hf and whole-rock Sm–Nd geochronology

The southeastern Guiana Shield, northern Amazonian Craton, is part of a Paleoproterozoic orogenic belt that was built up during the Transamazonian orogenic cycle (2.26–1.95 Ga). This cycle includes large segments of Rhyacian juvenile crust and some reworked Archean terranes. The geology in this region consists mainly of Paleoproterozoic granulitic-migmatitic-gneissic complexes, deformed and metamorphosed metavolcanic and metasedimentary rocks, and granitoids (granitic and TTG magmatism). Three tectonic domains are distinguished in the Brazilian territory of the southeastern Guiana Shield. They are known as the Amapá Block, Lourenço Domain, and Carecuru Domain. The Amapá Block is a Meso–Neoarchean continental block that was intensely reworked during the Transamazonian orogeny. The other two domains represent Rhyacian landmasses, the evolution of which involved several stages of subduction of oceanic lithosphere in magmatic arc environments. There are also relics of reworked Archean continental crust, the formation of which was followed by a collisional stage of tectonic accretion of the magmatic arcs. Whole-rock Sm–Nd and U–Pb zircon geochronology have confirmed the juvenile character of much of this Transamazonian orogenic belt. However, for the Lourenço and Carecuru domains, Nd isotopic signatures indicate the participation of Meso–Neoarchean crustal material in the sources of the magmatic rocks. Combined zircon U–Pb and Lu–Hf isotopic analyses by LA-ICP-MS were performed on eleven Rhyacian granitoids and orthogneisses from the Lourenço and Carecuru domains. The aim was to verify the extension of the influence of the Archean continental crust in the adjacent Paleoproterozoic domains. The main magmatic episodes were identified in the Lourenço Domain (~2.17–2.18, 2.14 and 2.12–2.09 Ga) and Carecuru Domain (2.14 Ga) by U–Pb zircon geochronology. The Lu–Hf isotope data point to the predominance of crustal reworking processes (ƐHf(2.2–2.1 Ga) < 0; 67% of zircon crystals) during the formation of Lourenço and Carecuru domains. Hf model ages were found to be mostly Archean (98.4%), even for zircon grains that have positive ƐHf(2.2–2.1 Ga) values. For the terrane at the border of the Lourenço and Carecuru domains with the Amapá Block, assimilation of Archean crust of different ages and proportions in a magmatic arc environment accounts for the Hf–Nd isotopic signatures and Hf model ages of Rhyacian magmatism. In the northwestern part of the Lourenço Domain, more than 100 km north of the Amapá Block, the Hf–Nd isotopic signatures and Hf model ages indicate the participation of Archean crustal material, either as continental fragments and/or through incorporation of continental sediments in island arc environments, similar to what has been recorded for some Birimian terranes of the West African Craton in Ghana.

Mercury Exposure through Fish Consumption in Traditional Communities in the Brazilian Northern Amazon.

Artisanal small-scale gold mining (ASGM) is the main source of anthropogenic mercury emissions and contamination in Latin America. In the Brazilian northern Amazon, ASGM has contaminated the environment and people over the past century. The main contamination route is through fish consumption, which endangers the food security and livelihoods of traditional communities. Our study aims to assess the potential toxicological health risks caused by the consumption of Hg-contaminated fish across five regions in Amapá State. We sampled 428 fish from 18 sites across inland and coastal aquatic systems. We measured the total mercury content in fish samples, and the results were applied to a mercury exposure risk assessment targeting three distinct groups (adults, women of childbearing age, and children). Mercury contamination was found to exceed the World Health Organization’s safe limit in 28.7% of all fish samples, with higher prevalence in inland zones. Moreover, the local preference for carnivorous fish species presents a serious health risk, particularly for communities near inland rivers in the region. This is the first study to provide clear recommendations for reducing the mercury exposure through fish consumption in Amapá State. It builds scientific evidence that helps decision-makers to implement effective policies for protecting the health of riverine communities.

TERRITÓRIO, PODERES TUTELARES E AGÊNCIAS INDÍGENAS: ANÁLISES PRELIMINARES SOBRE TRÂNSITOS, TROCAS E R-EXISTÊNCIAS NA FRONTEIRA BRASIL-GUIANA FRANCESA (1930-1945)

O artigo analisa as dinâmicas indígenas na região de fronteira entre Brasil e Guiana Francesa, no contexto da Era Vargas (1930-1945). Visa entender suas configurações territoriais e agenciamentos em face às políticas estatais de ocupação dos sertões fronteiriços, no norte amazônico. Utilizando as fontes do Serviço de Proteção aos Índios, dimensiona as vivências e estratégias adotadas pelos povos indígenas da região para reinterpretar, e ressignificar, as ações tutelares que visavam disciplinarizar e dominar seus corpos, mentes e culturas. Isso engendrou outras formas de existência grupal entre os indígenas, que atendiam as pressões da sociedade envolvente sem ocasionar, no entanto, a perda de suas complexidades sociopolíticas e cosmológicas. Logo, a pesquisa revela, ainda de forma preliminar, o dinamismo desse quadro de relações interétnicas na Guiana indígena.Palavras-chave: Amazônia; fronteiras; territórios; relações interétnicas; r-existências indígenas.