Simultaneous detection of Plasmodium vivax dhfr, dhps, mdr1 and crt-o resistance-associated mutations in the Colombian Amazonian region.

BACKGROUND: Malaria continues being a public health problem worldwide. Plasmodium vivax is the species causing the largest number of cases of malaria in Asia and South America. Due to the lack of a completely effective anti-malarial vaccine, controlling this disease has been based on transmission vector management, rapid diagnosis and suitable treatment. However, parasite resistance to anti-malarial drugs has become a major yet-to-be-overcome challenge. This study was thus aimed at determining pvmdr1, pvdhfr, pvdhps and pvcrt-o gene mutations and haplotypes from field samples obtained from an endemic area in the Colombian Amazonian region. METHODS: Fifty samples of parasite DNA infected by a single P. vivax strain from symptomatic patients from the Amazonas department in Colombia were analysed by PCR and the pvdhfr, pvdhps, pvmdr1 and pvcrt-o genes were sequenced. Diversity estimators were calculated from the sequences and the haplotypes circulating in the Colombian Amazonian region were obtained. CONCLUSION: pvdhfr, pvdhps, pvmdr1 and pvcrt-o genes in the Colombian Amazonian region are characterized by low genetic diversity. Some resistance-associated mutations were found circulating in this population. New variants are also being reported. A selective sweep signal was located in pvdhfr and pvmdr1 genes, suggesting that these mutations (or some of them) could be providing an adaptive advantage.

Typology and characterization of the agricultural productive units in the NE Amazonian region of Ecuador.

Objective: Many studies have observed different characteristics among productive systems in the rural territories of Latin America. Therefore, understanding and characterizing them while they function plays an essential role in determining their relationship between development and environment. A study has been conducted in the Orellana province of NE Ecuador to determine their typology and then classify them according to the variables that describe their main traits or attributes using cluster analysis (CA). Materials and Methods: A survey was structured to investigate physical, productive, environmental, as well as socioeconomic character variables, which were subsequently applied to a random sample of the 5,963 agricultural productive units (APUs) through face-to-face contact with producers during an in situ visit to their farms. Result: The CA allowed us to identify three typologies of APUs in the Orellana Province. The first has been Type 1, which is denominated as the most conventional (40%), while Type 2 uses more efficient natural resources but represents an amount of only 9.4%. In contrast, type 3 (50.6%) depends on a significant part of local or national development programs. Conclusion: All groups indicated some peculiarities in common, as there were marked differences in the use and distribution of land as well as production methods among them. Consequently, this pioneering study allowed us to identify different production methods. Therefore, we encourage local and national governments to establish policies for natural resource conservation in such high-diversity zones.

Bioecological Aspects of Species of the Subgenus Mansonia (Mansonia) (Diptera: Culicidae) Prior to the Installation of Hydroelectric Dams on the Madeira River, Rondônia State, Brazil.

The objective of this study was to evaluate ecological aspects of Mansonia species before the construction of hydroelectric plants on the Madeira River, and thus enable the assessment of the impact of these projects on mosquitoes. A total of 199 samplings were carried out between November 2003 and August 2004, using the technique of attraction with protection. Temporal distribution was evaluated from monthly incidence values obtained from the bite index per man/hour. Relative abundance was subsequently calculated to evaluate the spatial distribution of species, according to land use and municipal districts; furthermore, the pattern of hematophagous activity was evaluated from 12-h and 4-h samplings. The data were analyzed according to the negative binomial distribution and generalized linear models to estimate the influence of environmental factors on the presence and abundance of Mansonia. A total of 1479 specimens were collected, distributed among four species-Mansonia titillans (87%), Mansonia humeralis (6.3%), Mansonia amazonensis (6%), and Mansonia indubitans (0.5%), and spatial distribution analysis showed Ma. titillans to be dominant. Hematophagous activity had peaks between 6:00 p.m. and 8:00 p.m. and species incidence was higher during the rainy season and in areas where domestic animals are raised. Therefore, the region studied presented characteristics favorable to the reproduction of Mansonia even before the construction of the hydroelectric plants and after construction, these conditions were enhanced, due to the increase in the availability of breeding sites for immatures and blood sources for females, as a consequence of changes in the environment.

A new species and distribution records of Dichotomius Hope, 1838 (Coleoptera: Scarabaeidae: Scarabaeinae) in Colombia.

Dichotomius (Dichotomius) quadrilobatus new species (Coleoptera: Scarabaeidae: Scarabaeinae: Dichotomiini), from western Amazonia (Brazil, Colombia, Ecuador and Peru) is described and its putative systematic position within the Dichotomius boreus species group is discussed. An updated identification key to the species of the Dichotomius boreus species group is provided. Additionally, Dichotomius (Selenocopris) fortepunctatus Luederwaldt, 1923 is recorded for the first time in Colombia.

The first two blind troglobitic spiders of the genus Ochyrocera from caves in Floresta Nacional de Carajás, state of Pará, Brazil (Araneae, Ochyroceratidae).

The first two anophthalmic species of spiders of the genus Ochyrocera Simon, 1892, are described for caves located in the iron formation of Floresta Nacional (FLONA) de Carajás in southeastern Pará State, Brazil. The caves are located in the municipalities of Parauapebas and Canaã dos Carajás, in the eastern portion of the Amazon Forest domain. Ochyrocera ritxoco sp. nov. and O. ritxoo sp. nov. are described based on males and females. The species have similar body characteristics with the total absence of eyes and complete depigmentation, characteristics that indicate possible evolution in subterranean environments , and thus are classified as troglobites. Each species is associated with a single geomorphological unit (mountain range), with Ochyrocera ritxoco sp. nov. being restricted to caves of Serra Norte (North Mountain) and O. ritxoo sp. nov. to caves of Serra Sul (South Mountain). Both species were collected in aphotic zones of the caves. Small and tangled webs of O. ritxoco sp. nov. were observed under blocks of stone in the soil or in cracks of the walls.

Proteomic and toxinological characterization of Peruvian pitviper Bothrops brazili ("jergón shushupe"), venom.

Bothrops brazili is a pitviper from Amazonian region, responsible for many accidents in Peru. Despite its relevance, its venom has not been extensively characterized. In the present work, Bothrops brazili venom (BbV) components were analyzed by RP-HPLC, SDS-PAGE and MALDI-TOF/TOF. Approximately 37 proteins were identified, belonging to 7 families. Snake venom metalloproteinases (SVMPs) were the most abundant proteins of the venom (33.05%), followed by snake venom serine proteinases (SVSPs, 26.11%), phospholipases A2 (PLA2, 25.57%), snake C-type lectins (CTLs, 9.61%), L-aminoacid oxidase (LAAO, 3.80%), cystein-rich secretory proteins (CRISP, 1.67%) and Bradykinin-potentiating peptide (BPP, 0.20%). In vitro enzymatic activities of BbV showed high levels of SVMP activity and reduced Hyal activity in comparison with other bothropic venoms. Furthermore, BbV reduced VERO cells viability. ELISA and Western Blotting showed that both Peruvian and Brazilian bothropic antivenoms were able to recognize BbV components. This work provides an overview of BbV venom content and indicates a potential efficiency of Peruvian and Brazilian antivenoms to treat accidents with this species.

Zika Virus Infection in a Cohort of Pregnant Women with Exanthematic Disease in Manaus, Brazilian Amazon.

The epidemic transmission of Zika virus (ZIKV) in Brazil has been identified as a cause of microcephaly and other neurological malformations in the babies of ZIKV-infected women. The frequency of adverse outcomes of Zika virus infection (ZIKVi) in pregnancy differs depending on the characteristics of exposure to infection, the time of recruitment of research participants, and the outcomes to be observed. This study provides a descriptive analysis-from the onset of symptoms to delivery-of a cohort registered as having maternal ZIKVi in pregnancy, from November 2015 to December 2016. Suspected cases were registered at a referral center for infectious and tropical diseases in Manaus, in the Amazonian region of Brazil. Of 834 women notified, 762 women with confirmed pregnancies were enrolled. Reverse-transcriptase polymerase chain reaction (RT-PCR) confirmed ZIKVi in 42.3% of the cohort. In 35.2% of the cohort, ZIKV was the sole infection identified. Severe adverse pregnancy outcomes (miscarriage, stillbirth, or microcephaly) were observed in both RT-PCR ZIKV-positive (5.0%) and ZIKV-negative (1.8%) cases (RR 3.1; 95% IC 1.4-7.3; p < 0.05), especially during the first trimester of pregnancy (RR 6.2, 95% IC 2.3-16.5; p < 0.001). Although other infectious rash diseases were observed in the pregnant women in the study, having confirmed maternal ZIKVi was the most important risk factor for serious adverse pregnancy events.

Seven new species of the spider genus Ochyrocera from caves in Floresta Nacional de Carajás, PA, Brazil (Araneae, Ochyroceratidae).

Seven new species of the spider genus Ochyrocera from cave areas in Floresta Nacional de Carajás (state of Pará, northern Brazil) are described: Ochyrocera varyssp. n., Ochyrocera atlachnachasp. n., Ochyrocera laracnasp. n., Ochyrocera aragoguesp. n., Ochyrocera misspidersp. n., Ochyrocera charlottesp. n., and Ochyrocera ungoliantsp. n. Two groups of the species are discussed, the quinquivittata group that include specimens with an apparently bifid retrolateral apophysis in the cymbium of the male palp and the arietina group, here proposed, that include those specimens with an entire cymbium, with no retrolateral apophysis, in the male palp. Although these species were abundant inside caves, the examined specimens do not have troglomorphic characteristics and can be classified as edaphic troglophile species, capable of completing its life cycle in soil, shallow subterranean habitats, or caves.

Bacterial diversity of artisanal cheese from the Amazonian region of Brazil during the dry and rainy seasons.

The microbiota from artisanal cheeses produced in the Amazonian region is evaluated. Samples of artisanal cheeses were obtained from markets in Conceição do Araguaia and Redenção (Pará, Brazil) over rainy and dry seasons, and their biodiversity was assessed by culture-dependent and culture-independent methods. Mean counts of lactic acid bacteria (LAB) in cheeses ranged from 7.32 to 8.84 log CFU/g, for both seasons. Members of genera Lactobacillus, Lactococcus, Weissella, Enterococcus, Pediococcus, and Leuconostoc were predominant. The amplification of the 16S rRNA V6-V9 region, followed by a temporal temperature-gradient gel electrophoresis (TTGE) and sequencing of the TTGE bands revealed important differences in the microbial composition variability between samples from the two seasons and among cheese samples analyzed. TTGE showed the presence of microorganisms that are frequently found in cheese, such as L. lactis subsp. lactis, as well as other non-usual species, such as Macrococcus caseolyticus and Corynebacterium variabile. Moreover, TTGE analysis revealed the presence of microorganisms that have been isolated from other types of foods (Paralactobacillus selangorenses) along with some not usually found in foods, such as Exiguobacterium acetylicum, plus the presence of pathogenic microorganisms (Granulicatella elegans and Aerococcus sanguinicola). The present molecular approaches combined with culture-dependent methods provided a more detailed description of the microbial ecology of traditional cheeses from the Amazonian region in northern Brazil.

A new species of Notodiaptomus from the Amazon basin (Crustacea, Copepoda, Calanoida, Diaptomidae).

A new Diaptomidae species is presented from the Neotropical region. It was found in two Amazonian lakes, Ressaca and Arapujá, both in Pará State, Brazil. The lakes are 400 km apart and threatened by the building of reservoirs for hydropower generation and pollution by human settlements. The new species resembles N. paraensis Dussart & Robertson, 1984, but it can be distinguished from this species and other congeners in having a special process on the fifth leg basis of the male, by the place of insertion of lateral spine in the last segment of right P5 of male, the shape and relationship between length and width of segments of male and female P5 exopodite 2 with stout inner process bearing short setules and outer small spine, exopodite 3, with two terminal setae, outer smaller; endopodite 1-segmented with one subterminal seta and oblique comb of spinules, the presence of a line of dorsal spinules at the distal margin of thoracic somites in both sexes. A brief comparison with other Notodiaptomus species is presented in the discussion.

Two new species of Coleoxestia Aurivillius, 1912 from Brazil (Coleoptera, Cerambycidae, Cerambycinae, Cerambycini).

Two new species of Coleoxestia Aurivillius, 1912 are described from Brazil: Coleoxestia apeara, and Coleoxestia moromokoi. Both are included in a previous key.

A Retrospective Survey of Rodent-borne Viruses in Rural Populations of Brazilian Amazon

Abstract INTRODUCTION: The Amazon tropical rainforest has the most dense and diverse ecosystem worldwide. A few studies have addressed rodent-borne diseases as potential hazards to humans in this region. METHODS: A retrospective survey was conducted using enzyme-linked immunosorbent assay for detecting mammarenavirus and orthohantavirus antibodies in 206 samples collected from rural settlers of the Brazilian Western Amazonian region. RESULTS: Six (2.91%) individuals in the age group of 16 to 36 years were found to possess antibodies against mammarenavirus. CONCLUSION: Evidence of previous exposure to mammarenavirus in the rural population points to its silent circulation in this region.

Giant rhinoceros beetle Golofa claviger (Linnaeus) (Coleoptera: Melolonthidae: Dynastini) is damaging North Brazilian oil palm plantations

ABSTRACT The oil palm is an economically important crop cultivated in the North of Brazil. Damage caused by insects is one of the main causes of reduced productivity for the oil palm. Before this research, only the beetles of the family Curculionidae were considered to be oil palm pests in Brazil. However, for the first time, we report on the damage caused by a giant rhinoceros beetle to oil palm plantations in Pará, Brazil. The beetle was identified as Golofa claviger (Linnaeus, 1771), which has a single record in Brazil (Pará) but is widely distributed in South America. The species occurs in an unprecedentedly high abundance of local specimens. The attacks are concentrated on the central cluster of young palms. Feeding behavior is identified as the main cause of the damage as the beetles use their mouthparts to rip the plant tissues, causing wedge-shaped cuts on young fronds that have not yet unfurled. After an attack, the leaflets of the unfurled fronds are partially destroyed.

Asymptomatic plasmodium infection in a residual malaria transmission area in the atlantic forest region: implications for elimination

Abstract INTRODUCTION: Elimination of malaria in areas of interrupted transmission warrants careful case assessment to avoid the reintroduction of this disease. Occasional malaria cases are reported among visitors of the Atlantic Forest area of Brazil, while data on residents of this area are scarce. METHODS: A sectional study was carried out to examine 324 individuals living in a municipality where autochthonous cases were detected. RESULTS: Asymptomatic Plasmodium infections were detected in 2.8% of the individuals by polymerase chain reaction (PCR), with one case of P. falciparum (0.3%), two cases of P. vivax (0.6%), and six cases of P. malariae (1.9%). The thick blood smears were negative in all individuals. Serological tests performed in 314 subjects were reactive in 11.1%, with 3.5% for P. falciparum and 7.7% for P. vivax. A subsample of 42 reactive individuals for any Plasmodium species showed P. malariae in 30.9% of specimens. Individuals who entered the Atlantic Forest region were 2.7 times more likely to exhibit reactive serology for P. vivax compared with individuals who did not enter this region (p<0.05). Children <15 years had a higher chance of reactive serology for P. falciparum and P. vivax than individuals ≥15 years of age (p<0.05). Individuals living in the Paraiso district had a higher chance of reactive serology for P. vivax compared to other districts (p<0.05). No associations were found between sex, past exposure to malaria, or serological response to antibodies of any Plasmodium species. CONCLUSIONS: The implications of these results for the elimination of malaria were discussed.

Regional health network in the Amazonian context: the case in Manaus, Entorno and Alto Rio Negro / Rede regional de saúde no contexto Amazônico: o caso de Manaus, Entorno e Alto Rio Negro

Abstract Objectives: to analyze the dimensions of policy, structure and organization in the construction of Redes de Atenção à Saúde (RAS) (healthcare networks) in the health region of Manaus, Entorno and Alto Rio Negro, focusing on Atenção Primária à Saúde (APS) (primary healthcare) and Rede de Urgência e Emergência (RUE) (urgency and emergency network). Methods: a case study with multidimensional analysis using quantitative and qualitative approach carried out in the first semester of 2016. Results: 37 interviewed key informants, such as managers (States, Cities and Regionals), providers and civil society. The reality was marked by the difficulties in the implementation of RAS's with centralized decision-making powers of State level. Perception of insufficient human resources of limited installed capacity, particularly in the APS, with insufficient priority given to this level of care. Concentration of services in Manaus, priority for urgency and emergency actions expressed in the greatest investment in human resources and mate-rials allocated at this level of care, lack of proposals for promoting equity. Conclusions: the Region was unable to implement RAS to respond to the health demands in the region. The necessity to overcome the dependency relation with the cities and the State and to strengthen its protagonism and fulfillits roles in management network, instituting a plan capable of strengthening APS to be committed in reducing iniquities and with adequate responses in health needs.

Resumo Objetivos: analisar as dimensões da política, estrutura e organização na construção das redes de atenção à saúde (RAS) na região de saúde de Manaus, Entorno e Alto Rio Negro, enfocando a atenção primária à saúde (APS) e rede de urgência e emergência (RUE). Métodos: estudo de caso com análise multidimensional, utilizando abordagem quantitativa e qualitativa, realizado no primeiro semestre de 2016. Resultados: entrevistados 37 informantes-chaves, sendo gestores (estaduais, municipais e regionais), prestadores e sociedade civil. Realidade marcada por dificuldades na implantação das RAS, com poderes decisórios centralizados no nível estadual. Percepção de insuficiência de recursos humanos de limitação na capacidade instalada, em particular na APS, com insuficiente prioridade dada a este nível de cuidado. Concentração de serviços em Manaus, prioridade para ações de urgência e emergência, expressas em maior investimento de recursos humanos e materiais alocados nesse nível de atenção, ausência de propostas para promoção da equidade. Conclusões: região não conseguiu implantar funcionamento das RAS para responder às demandas em saúde na região. Necessidade de superar relação de dependência entre municípios e estado e de potencializar seu protagonismo e o cumprimento dos seus papéis na gestão das redes, instituindo um planejamento capaz de fortalecer a APS comprometida com a redução das iniquidades e com respostas adequadas às necessidades de saúde.

Phlebotominae sand flies (Diptera: Psychodidae): potential vectors of American cutaneous leishmaniasis agents in the area associated with the Santo Antônio Hydroelectric System in Western Amazonian Brazil

INTRODUCTION: An entomological study was conducted as part of a vector-monitoring program in the area associated with the Santo Antônio hydroelectric system in State of Rondônia, Western Amazonian Brazil. METHODS: Fourteen sampling sites were surveyed to obtain data on the potential vectors of Leishmania spp. in the area. Sand flies were collected from 2011 to 2014 during the months of January/February (rainy season), May/June (dry season), and September/October (intermediary season) using light traps arranged in three vertical strata (0.5, 1, and 20m). RESULTS : A total of 7,575 individuals belonging to 62 species/subspecies were collected. The five most frequently collected sand flies were Psychodopygus davisi (Root) (36.67%), Trichophoromyia ubiquitalis (Mangabeira) (8.51%), Nyssomyia umbratilis (Ward & Fraiha) (6.14%), Bichromomyia flaviscutellata (Mangabeira) (5.74%), and Psychodopygus complexus (Mangabeira) (5.25%). These species have been implicated in the transmission of American cutaneous leishmaniasis agents in the Brazilian Amazon region and described as potential vectors of this disease in the study area. CONCLUSIONS: Additional surveillance is needed, especially in areas where these five species of sand fly are found. .

Kudoa spp. (Myxozoa) infection in musculature of Plagioscion squamosissimus (Sciaenidae) in the Amazon region, Brazil / Infecção por Kudoa spp. (Myxozoa) na musculatura de Plagioscion squamosissimus (Sciaenidae) da região amazônica, Brasil

Ninety specimens of Plagioscion squamosissimus captured using fishing tackle in the Outeiro district, state of Pará, were examined. Fish were placed in plastic bags containing water, under conditions of artificial aeration, and transported live to the Carlos Azevedo Research Laboratory (LPCA), in Belém, Pará. They were anesthetized, euthanized and necropsied; small fragments of the epaxial and hypaxial muscles were removed for examination of fresh histological sections by means of optical microscopy. In 100% of the specimens analyzed, parasitic pseudocysts were seen to be interspersed within and between the skeletal muscle. These contained pseudoquadrate and/or star-shaped spores that presented four valves and four polar capsules, which were identified from their morphology as belonging to the genus Kudoa. This is the first report of Kudoa in P. squamosissimus in the Amazon region, Pará, Brazil.

Foram observados 90 exemplares de P. squamosissimus, capturados com apetrechos de pesca no distrito de Outeiro, estado do Pará. Os animais foram acondicionados em sacos plásticos com água do habitat e aeração artificial, transportados vivos até o Laboratório de Pesquisa Carlos Azevedo (LPCA), em Belém-PA. Foram anestesiados, eutanasiados e necropsiados; pequenos fragmentos da musculatura epi e hipoaxial foram retirados para observação, a fresco e para histologia em microscopia de luz (ML). Em 100% dos exemplares analisados, foi observada a presença de pseudocistos parasitários entremeados, dentro e entre as fibras musculares estriadas esqueléticas, onde observou-se a presença de esporos de formato pseudoquadrado e/ou estrelado, com quatro valvas e quatro cápsulas polares, sendo identificados pela sua morfologia como pertencentes ao gênero Kudoa. Este é o primeiro relato de Kudoa em P. squamosissimus na Amazônia, Pará, Brasil.

Tolerância de leguminosas de cobertura do solo a Herbicidas

There is little research regarding to tolerance of soil cover legumes to herbicides. Products that are selective to these plants and show satisfactory control of harmful plants are still scarce. This paper has the objective to evaluate the tolerance to herbicide of four legume plants. The experiment was installed in a greenhouse. The four legumes were sowed in a 2 kg plastic bag. The substratum was homogenized with two seeds of Pueraria phaseoloides, Desmodium ovalifolium, Mucuna aterrima and Mucuna cochinchinensis. The herbicides applied were 2,4-DB, in post-emergence and alachlor, imazaquin and pendimethalin in pre-emergence. The statistical experimental method used was completely randomized in a factorial experiment (4x4x5x4) with four legume species, four herbicides and five doses of each herbicide with four replications. Thirty six days after sowing, P. phaseoloides showed tolerance to the herbicides alachlor and imazaquin and susceptibility to 2,4-DB and pendimethalin. D. ovalifolium was susceptible to herbicides except the alachlor. M. aterrima showed tolerance to alachlor, imazaquin and pendimethalin and was susceptible to 2,4-DB. The herbicides alachlor and imazaquin were not phytotoxic to M. cochinchinensis. However, severe injury was observed with the use of 2,4-DB and pendimethalin.

São poucas as pesquisas de tolerância de leguminosas de cobertura do solo a herbicidas visando selecionar produtos que sejam seletivos a estas plantas e que apresentem controle satisfatório das plantas daninhas. Com o objetivo avaliar a tolerância de quatro leguminosas a herbicidas, instalou-se um experimento em condições de casa-de-vegetação. As leguminosas foram plantadas em sacos plásticos de dois litros, contendo substrato homogeneizado com duas sementes das leguminosas Pueraria phaseoloides, Desmodium ovalifolium, Mucuna aterrima e Mucuna cochinchinensis. Os herbicidas aplicados foram 2,4-DB, em pós-emergência, e alachlor, imazaquin e pendimethalin em pré-emergência. O delineamento experimental foi inteiramente ao acaso, em esquema fatorial de 4x4x5x4 com quatro espécies de leguminosas, quatro herbicidas e cinco doses de cada herbicida, respectivamente, repetidos quatro vezes. Aos trinta e seis dias após o plantio a Pueraria phaseoloides mostrou-se tolerante aos herbicidas alachlor e imazaquin e suscetível ao 2,4-DB e pendimethalin. O Desmodium ovalifolium foi suscetível aos herbicidas nas doses usadas, exceto o alachlor. A Mucuna aterrima apresentou tolerância ao alachlor, imazaquin e pendimethalin e foi suscetível ao 2,4-DB. Os herbicidas alachlor e imazaquin não foram fítotóxicos à Mucuna cochinchinensis, enquanto 2,4-DB e pendimethalin causaram severas injúrias.

Variation of biometric parameters and C, N, and P concentrations of Oryza glumaepatula at different depths of an amazonian lake impacted by bauxite tailings (Lake Batata, Pará, Brazil)

Lake Batata is a typical Amazonian clear water lake which has undergone anthropogenic impacts. Thirty percent of its total area has been covered with bauxite tailings. Thus, it is possible to distinguish two areas in this ecosystem: the impacted and the natural. The goal of this research was to study C, N, and P content variation and the values of biomass, length, density, and culm diameter of Oryza glumaepatula at different depths in the natural and impacted areas of Lake Batata. The results obtained in this research suggest that the availability of P and N, in both water and sediment, is lower at the shallow site when compared to the deeper sites. On the other hand, C concentrations decreased as P and N concentrations increased. This may be explained by the structural function of C in aquatic macrophytes. At shallower sites, due to the reduced water column, individuals invest in supporting structures that display high C concentrations. The higher density and biomass of O. glumaepatula at the intermediate site indicate that this area presents the best conditions for germination and establishment of individuals of this species. The chemical composition and biometric parameters of O. glumaepatula have shown that this population has higher spatial variation in the natural area. In the impacted area, the absence of significant variations in N and P concentrations in O. glumaepatula among the three sampled sites promotes higher homogeneity in the stands. The high C:P and N:P ratios indicate that, in the impacted area, P is more limiting to the development of O. glumaepatula than it is in the natural area. The reduced values of biomass and density of O. glumaepatula in the impacted area suggest that the bauxite tailings limit the development of this population.

O Lago Batata é um típico lago amazônico de águas claras que sofreu impactos antropogênicos. De sua área total, 30% foi recoberta com rejeito de bauxita. Desta forma, pode-se distinguir duas áreas nesse ecossistema: impactada e natural. O objetivo desta pesquisa foi estudar a variação de C, N e P e os valores de biomassa, comprimento, densidade e diâmetro do colmo de Oryza glumaepatula em diferentes profundidades, nas áreas impactada e natural, do Lago Batata. Os resultados obtidos na pesquisa sugerem que as disponibilidades de P e N, tanto na água como no sedimento, são menores no ponto raso quando comparado com os pontos mais profundos. Por outro lado, as concentrações de C diminuíram à medida que as concentrações de P e N aumentaram. Isto pode ser explicado pela função estrutural do C em macrófitas aquáticas. Nos pontos mais rasos, devido à reduzida coluna d'água, indivíduos investem em estruturas de suporte com elevadas concentrações de C. A elevada densidade e biomassa de O. glumaepatula no ponto intermediário indica que essa área apresenta as melhores condições para germinação e estabelecimento de indivíduos dessa espécie. A composição química e os parâmetros biométricos de O. glumaepatula mostraram que essa população possui elevada variação espacial na área natural. Na área impactada, a menor variação nas concentrações de N e P nos três pontos de amostragem promove alta homogeneidade nos estandes. As altas razões C:P e N:P indicam que, na área impactada, o P é mais limitante para o desenvolvimento de O. glumaepatula do que na área natural. Os reduzidos valores de biomassa e densidade de O. glumaepatula na área impactada sugerem que o rejeito de bauxita limita o desenvolvimento dessa população.