Middle Rio Negro Research Articles

High Frequency of Deletions in the pfhrp2 and pfhrp3 Genes of Plasmodium falciparum in the Middle Rio Negro Region of the Brazilian Amazon.

Several countries are reporting natural populations of P. falciparum with deletions in the pfhrp2/3 genes that can lead to false-negative results in rapid diagnostic tests. To investigate the prevalence of deletion in the pfhrp2/3 genes in the Rio Negro basin in the Brazilian Amazon and identify whether there is clinical differentiation between individuals infected by these parasites, clinical samples collected from 2003 to 2016 were analyzed from symptomatic and asymptomatic P. falciparum-infected individuals. The molecular deletion of pfhrp2 and pfhrp3 genes was evaluated using the protocols recommended by the WHO. From 82 samples used, 28 (34.2%) had a single deletion in pfhrp2, 19 (23.2%) had a single deletion in pfhrp3, 15 (18.3%) had a double deletion (pfhrp2/3), and 20 (24.4%) did not have a deletion in either gene. In total, 29.3% of individuals had an asymptomatic plasmodial infection and were 3.64 times more likely to have parasites with a double deletion (pfhrp2/3) than patients with clinical malaria (p = 0.02). The high prevalence of parasites with pfhrp2/3 deletions shows the need to implement a surveillance program in this area. Deletions in parasites may be associated with the clinical pattern of the disease in this area. More studies must be carried out to elucidate these findings.

Mercury biomagnification in the food chain of a piscivorous turtle species (Testudines: Chelidae: Chelus fimbriata) in the Central Amazon, Brazil.

Due to their natural history and ecological attributes, turtles are excellent organisms for studies of heavy metal contamination. Turtles have a large geographical distribution, occupy different aquatic habitats, and occupy various trophic levels. The present study investigated mercury bioaccumulation in the carnivorous chelonian Chelus fimbriata (Matamata turtle) and Hg biomagnification in relation to its aquatic food chain in the middle Rio Negro, AM-Brazil. Tissue samples of muscle, carapace and claws were collected from 26 C. fimbriata individuals, as well as collections of autotrophic energy sources found in the turtle's aquatic habitat area. The samples were collected in February-March/2014 and analyzed for THg concentrations and carbon (δ13C) and nitrogen (δ15N) stable isotopes. The highest THg levels were found in claws (3780 ng.g-1), carapace (3622 ng.g-1) and muscle (403 ng.g-1), which were found to be significantly different [F(2.73) = 49.02 p < 0.01]. However, THg concentrations in muscle tissue were below the consumption threshold indicated by the WHO and Brazilian Health Ministry. The average δ13C and δ15N values in Matamata samples were -31.7‰ and 11.9‰, respectively. The principal energy source sustaining the food chain of C. fimbriata was found to be terrestrial shrubs, with smaller contributions from emergent aquatic herbaceous plants and algae, while δ15N values showed its trophic position to be two levels above the autotrophic energy sources. There was a positive correlation between THg and turtle size, while a significant relationship was found between THg and δ15N, showing strong biomagnification in the food chain of C. fimbriata: y = 0.21x + 0.46; r2 = 0.45; p < 0.001, for which the slope presented a value of 0.21.

Radiometric and stimulated luminescent characterization of Amazonian sediments from the Middle Rio Negro, Western Amazon

The sediments were collected from paleodunes, river terraces, islands, and sand bars at Mariuá Archipelago, Rio Negro, Brazil. XRD analysis revealed that quartz is the predominant mineral along with a trace quantity of kaolinite. Neutron activation analysis of the sediments revealed the assembly of rare-earth elements, metals and semi-metals. The values of U and Th were found to be 3–5 ppm in paleodunes and 9–16 ppm in terraces, and K-40 concentration is below detectable limit. The OSL of quartz (dune) is composed of three components with decay times of 0.2, 11.0 and 350 s, respectively. This OSL emission is related to the TL peaks below 380 °C. Also, photo-transferred TL is observed in the temperature range of 190–250 °C for a blue stimulation of 500 s. TL peaks kinetic parameters were calculated and discussed. The lifetimes of TL peaks at 272 and 355 °C are approximately 4.0×104 and 1.5×109 years, respectively. Using the conventional SAR protocol, 11 samples were dated, including two old paleodunes with ages of 124.4 and 169.7 ka, increasing the age interval of the site, the other samples were younger sediments, with ages between 0.39 and 53.9 ka.

Fish on Fire: Shifts in Amazonian fish communities after floodplain forest fires

Abstract Severe droughts can lead to fires that cause massive tree mortality in even the wettest and most isolated Amazonian forests. After repeated fires, blackwater floodplain forests can remain in an open vegetation state of arrested succession that facilitates a transition towards a white‐sand ‘savanna‐like’ vegetation. These vegetation shifts, from closed‐canopy floodplain forests to open fire scars and eventually white‐sand savannas, may have profound implications for fish communities that depend on floodplain forests for food and recruitment. In turn, changes in fish communities may contribute to the arrested forest recovery after fires as fish are important seed dispersal agents for many floodplain tree species. To explore the impacts of floodplain forest fires on fish communities, we sampled fish in unburnt forests, fire scars, and white‐sand savannas in the middle Rio Negro basin (Brazil) during two consecutive flooding seasons. We compared the abundance, species richness, and the taxonomic and trophic composition of fish assemblages across the three habitat types. We found significant shifts in fish assemblages in fire scars compared to unburnt floodplain forests. Also, as fire scars increased in size, total fish biomass decreased strongly. Fish communities in unburnt floodplain forests seem to be characterized by a higher proportion of smaller and omnivorous fish species than fish communities in burned floodplain forests and white sand savannas. Fish assemblages in fire scars and white‐sand savanna were not significantly different. Synthesis and Applications. Amazonian fish communities change after floodplain forest fires. Unburnt forests have diverse fish communities, with a large proportion of unique and small omnivorous species. In contrast, carnivores and detritivores become more common in fire scars and white‐sand savannas formed after forest fires. Less omnivore fish after forest fires can reduce tree seed dispersal and forest regeneration, affecting ecosystem functioning and the services provided by Amazonian forests. Fish are also a primary source of food and income for people living in Amazonian floodplains. Preventing forest fires is therefore of fundamental importance for the conservation of Amazonian aquatic and terrestrial ecological communities as well as for the livelihood of people.

Morphological, cytochemical and ultrastructural aspects of blood cells in freshwater stingray species in the middle Rio Negro basin of Amazonian Brazil

In the present work, we examined the morphology, dimensions, cytochemical staining reactions and ultrastructure of blood cells from three freshwater stingray species, Potamotrygon wallacei, Potamotrygon motoro and Paratrygon aiereba, living in the waters of the middle Rio Negro basin (Barcelos, Amazonas, Brazil). We identified erythrocytes, erythroblasts, thrombocytes and four types of leukocytes (basophils, heterophils, lymphocytes and monocytes) in the blood of these stingray species. In all the freshwater stingray species studied, the shapes and dimensions of these cells were similar to those of marine elasmobranchs. Positive PAS staining occurred in heterophils and thrombocytes, and weak staining occurred in lymphocytes and monocytes, while metachromasia only occurred in basophils. Positive Sudan Black B staining was observed in thrombocytes and lymphocytes, and weak staining occurred in heterophils. Basophils and heterophils were the only cells with positive bromophenol blue staining, while no peroxidase staining was observed in any of the four leukocyte types. This is the first study to establish the dimensions and cytochemical staining profiles of blood cells in Amazonian stingray species. Because these elasmobranch species are exported as ornamental fish to countries worldwide, this study can contribute to establishing standards for blood constituents that may be helpful in assessing the health and welfare of these fish in artificial systems.

Eratyrus mucronatus St&amp;aring;l, 1859 and Panstrongylus rufotuberculatus (Champion, 1899) (Hemiptera, Reduviidae, Triatominae): first records in a riverside community of Rio Negro, Amazonas state, Brazil

The present work reports the first record of Eratyrus mucronatus St&amp;aring;l, 1859 and Panstrongylus rufotuberculatus&amp;nbsp;(Champion, 1899) (Hemiptera, Reduviidae, Triatominae) in a riverside community of Rio Negro in the Brazilian Amazon. Health promotion activities were carried out with the population and agent to combat endemic diseases. The entomological findings reinforce the importance of community participation in the surveillance and control of triatomines. The use of knowledge dissemination actions on Chagas disease and vectors strengthened the entomological surveillance in the middle Rio Negro, Amazonas state.

Sex steroid hormones and the associated morphological changes in the reproductive tract of free-living males of the cururu stingray Potamotrygon wallacei

This study analyzed sex steroid hormones and morphology of the reproductive tract in free-living adult males of the cururu stingray (Potamotrygon wallacei). These stingrays were captured during the transition between drought and rising waters in the middle Rio Negro basin, which coincides with the reproductive period (spermatogenesis and copulation) of this endemic species. Levels of the plasma steroid hormones testosterone (T), 17 β-estradiol (E2), and progesterone (P4), the gonadosomatic and hepatosomatic indices, as well as histological characteristics of the testis and epididymis were evaluated. Three reproductive maturational stages were observed: regression males, capable to reproduce males, and active males. Plasma T levels were increasing and parallel with the rising water period in the middle Rio Negro basin and were associated with the progress of spermatogenesis. This was not observed for E2, which did not vary significantly among the different reproductive stages. The high P4 concentrations in males in regression and males capable of reproducing appeared to regulate the progression of spermatogenesis. Increases in this hormone in the plasma of active males was associated with spermiogenesis and spermiation events. These findings have not been previously observed in Amazonian freshwater stingrays and demonstrate that the reproductive activity of P. wallacei males is concomitant to the period of rising waters in the middle Rio Negro basin, and is regulated by the action of gonadal steroids, mainly testosterone.

White-Sand Savannas Expand at the Core of the Amazon After Forest Wildfires

Across the tropics, climate change is increasing the frequency and severity of wildfires, exposing tropical forests to the risk of shifting into an open vegetation state. A recent satellite analysis of the Amazon basin suggests this might happen first in floodplains where forests are particularly fragile. We studied floodplain landscapes of the middle Rio Negro, covering ~ 4100 km2 at the Central Amazon region, where forest ecosystems are dominant. We used Landsat images to map 40 years of wildfire history and test the hypothesis that repeatedly burnt forests fail to regenerate and can be replaced by white-sand savanna ecosystems. In the field, using a chronosequence of ‘time after the first fire’, we assessed changes in tree species composition, herbaceous cover and topsoil properties. Here we show that when these forests are repeatedly disturbed by wildfires, their soil gradually loses clay and nutrients and becomes increasingly sandy. In synchrony, native herbaceous cover expands, forest tree species disappear and white-sand savanna tree species become dominant. This drastic ecosystem shift happened within 40 years, likely accelerated by topsoil erosion. When recurrent fires maintain floodplain forests in an open vegetation state, topsoil erosion intensifies, transforming clay-rich soils into white-sand soils that may favour savanna tree species. Our findings reveal that white-sand savannas may expand through seasonally flooded ecosystems at the core of the Amazon, facilitated by wildfires.

Relativas em Nheengatú ou Ingatú

O presente estudo trata das orações relativas da língua Nheengatú ou Ingatú, falada como primeira língua por aproximadamente 1.300 baníwas e 1.000 werekénas na região do Alto Rio Negro, e por aproximadamente 5.600 barés no Alto Rio Negro e no Médio Rio Negro. Rodrigues (1986) foi o primeiro linguista a tratar dos efeitos do contato do Nheengatú com o Português ao longo de 300 anos, destacando, como resultado desses efeitos, o desenvolvimento de orações relativas em Nheengatú. No presente estudo, com base em Keenan e Comrie (1977, 1979), Keenan (1985) e Payne (1997) descrevo as Orações Relativas do Nheengatú demonstrando que, nessa língua, sujeito, objeto direto, objeto indireto, oblíquo e nome possuído são relativizáveis, que as orações relativas são externas ao núcleo e que o sintagma nominal relativizado na oração relativa pode exercer as funções de sujeito, de objeto direto, objeto indireto e oblíquo. Mostro também que, em Orações Relativas do Nheengatú, que têm por núcleo um nome ou um adjetivo, o sintagma nominal relativizado é representado por uma lacuna (gap), podendo também ser representado por um pronome demonstrativo em certas condições.

Indigenous Activism, Territorialization and Ethnicity in the Middle Rio Negro

Abstract This paper addresses the processes of territorialization, formation of indigenous associations and ethnogenesis in the Middle Rio Negro that have led to the most recent struggles for official recognition of indigenous lands. The central focus of description and analysis is the antagonism between the aviamento regime and the “community” as modalities of natural resource consumption and strategies for social reproduction. In the Upper Rio Negro, in the mid-1980s, at the heart of a process of inversion of ethnic stigma, crisis of missionary tutelage and developmentalist militarization; the community became the territorial base for political codification of the emerging formation of associations. At the beginning of the 21st century, indigenous associations gained new life in the Middle Rio Negro, clashing with the aviamento regime and intensifying the fight for territorial rights.

Mosquitoes (Diptera: Culicidae) From the Northwestern Brazilian Amazon: Araçá River.

The mosquito fauna (Diptera: Culicidae) from two remote localities along the Araçá River, within the Municipality of Barcelos, towards the northern border of the Brazilian State of Amazonas, were sampled using CDC, Shannon, Malaise, and Suspended traps, along with net sweeping and immature collections. During June 2010, 111 collections yielded more than 23,500 mosquitoes distributed in 15 genera, representing 119 different species, together with eight morphospecies, which may represent undescribed new taxa. Among the species collected, there is one new distributional record for Brazil and nine new distributional records for the State of Amazonas. With the highest number of species, the genus Culex Linnaeus also had the largest number of individuals followed by Aedes Meigen with the second highest number of species. The most abundant species was Culex (Melanoconion) gnomatos Sallum, Hutchings & Ferreira followed by Culex (Melanoconion) portesi Senevet & Abonnenc, Culex (Culex) mollis Dyar & Knab, Aedes (Ochlerotatus) fulvus (Wiedemann), Culex (Melanoconion) pedroi Sirivanakarn & Belkin, Culex (Melanoconion) crybda Dyar, Aedes (Ochlerotatus) nubilus (Theobald), and Anopheles (Anopheles) peryassui Dyar & Knab. The epidemiological implications of mosquito species found are discussed and are compared with other mosquito inventories from the Amazon region. As the first standardized mosquito inventory of the Araçá River, with the identification of 127 species level taxa, the number of mosquito species which have been collected along the northern tributaries of the middle Rio Negro Basin (i.e., Padauari and Araçá Rivers) increased significantly.

Ethnobotanical study of antimalarial plants in the middle region of the Negro River, Amazonas, Brazil

ABSTRACT The middle Rio Negro region is an interesting place to seek novel antimalarial compounds because of the traditional knowledge of the Amazon population in conjunction with the high biodiversity of the region. The objective of this work was to study the use of antimalarial plants in Barcelos, state of Amazonas, Brazil. Fifty-two local specialists from eight different communities were interviewed over one year. The identified plants were collected with the assistance of local specialists, classified to species level and deposited in herbarium. In total, 55 antimalarial plants were identified in use in the region, of which 16 had not been previously reported in other published studies. Many factors could be involved with the use of antimalarial plants by the Barcelos population, such as the accessibility of these medicinal plants, efficiency and safety of using these plants, the accessibility to drugs or other medical treatments, plant bitterness, and the gender of the interviewees. Our results indicate that the population of Barcelos possesses an extensive knowledge on the use of a diverse array of antimalarial plants, and may contribute to the development of novel antimalarial compounds.

Biologia reprodutiva e hábitos alimentares do rodóstomo (Hemigrammus bleheri) um peixe ornamental da Bacia do Médio Rio Negro, Estado do Amazonas, Brasil.

Esse estudo teve como objetivo descrever a biologia reprodutiva e os hábitos alimentares de Hemigrammus bleheri do médio Rio Negro, estado do Amazonas-Brasil, ao longo de um ciclo hidrológico. Para tanto, analisaram-se os estádios de maturação gonadal, tamanho de primeira maturação sexual (L50), fecundidade e perí­­odo reprodutivo de 260 indiví­­duos, assim como pesquisou-se o conteúdo estomacal e calculou-se do í­­ndice de repleção estomacal de 177 indiví­­duos. Os resultados obtidos demonstram que a espécie possui desova parcelada, com oócitos variando entre 0,06 e 0,66 mm de dií­¢metro e fecundidade entre 101 e 721 oócitos. O L50 foi estimado em 2,8 cm para fêmeas e 2,6 cm para machos. As fêmeas amadurecem com a subida do rio (dezembro a maio) e as desovas ocorrem em maior proporção no final da enchente (março a maio). A espécie é oní­­vora, consumindo grande parte dos alimentos de origem autóctone. A dieta básica mostrou variações sazonais em sua composição, pois observou-se que microcrustáceos são frequentes nos perí­­odos de enchente/cheia, e que algas filamentosas, quironomí­­deos e fragmentos vegetais são mais frequentes na vazante/seca. Alterações sazonais na atividade alimentar foram registradas provavelmente influenciadas pelo pulso de inundação. O grau de repleção estomacal foi maior na enchente/cheia e menor na vazante/seca.

Exploring the Manufacture of Bifacial Stone Tools from the Middle Rio Negro Basin, Uruguay: An Experimental Approach

ABSTRACTThe Río Negro is the most important inner fluvial course of the Uruguay Republic. Along its basin, the archaeological record is characterized by flaked stone tools of remarkable workmanship. As part of a long-term experimental program to explore and understand diverse aspects of lithic technologies from the Americas, this paper reports an experiment devoted to reproducing carefully reduced bifacial knives to explore the techniques and stages of manufacture from obtaining the blank to the finished product. Resulting from the experiment a reduction sequence manufacturing model is proposed. It takes into account the techniques, flaking implements, stages of manufacture and other significant data useful to discuss topics related to the traditional technological knowledge involved in the manufacturing process of the studied bifaces. In light of this investigation, various issues related to the reduction trajectory reflected in the archaeological record are discussed.

Cyrilia sp. (Apicomplexa: Haemogregarinidae) in the Amazonian freshwater stingray Potamotrygon wallacei (cururu stingray) in different hydrological phases of the Rio Negro.

Intraerythrocytic parasites are frequently found in fish, including elasmobranchs. The Amazonian rivers present well defined annual hydrological cycles that results in drastic modifications of the environmental conditions with deep implications in the life cycle of the whole associated biota in those fluvial systems. The freshwater stingray Potamotrygon wallacei (stingray cururu) is a new species restricted to the Middle Rio Negro basin and it is subject to strong alterations in their natural habitats (igapós) a result of the constant variations in the water level of Rio Negro. This work demonstrates the occurrence of intraerythrocytic parasite Cyrilia sp. in this stingray species. Additionally, the prevalence and quantification of hemoparasites in different phases of Rio Negro were also established. Field sampling was carried in the Archipelago of Mariuá, Middle Rio Negro, involving different stages of the water cycle. The intraerythrocytic parasites were quantified by direct counting in blood smears using a total counting of 2000 erythrocytes in each blood smear. The presence of parasites intraerythrocytic generates changes in the morphology of blood cell. The largest amount of the hemoparasites was recorded in the drought period. We observed a decreasing tendency in the number of parasites in the blood between the drought periods and inundation. We concluded that the level of Negro River influences the incidence of intraerythrocytic parasites in the cururu stingray and the drought represents the period of larger susceptibility to the infestation.

Evidence of mercury biomagnification in the food chain of the cardinal tetra Paracheirodon axelrodi (Osteichthyes: Characidae) in the Rio Negro, central Amazon, Brazil.

In this study, nitrogen stable isotope (δ(15) N) and total mercury (THg) analyses were conducted on algae, submersed and emergent macrophytes, shrubs and trees, Macrobrachium sp. and Paracheirodon axelrodi collected in three streams that drain a large interfluvial region in the middle Rio Negro, Amazonas State, Brazil. Samples were collected during different hydrological periods over 12 months in lower stream reaches and their headwaters; the latter being characterized by shallow, open-canopy swamps. Additionally, δ(15) N values and mercury concentrations of Paracheirodon simulans and Cichla spp. from the middle Rio Negro were analysed to demonstrate THg biomagnification in the food web. The highest mercury levels of P. axelrodi were found in small individuals, which were collected principally in the low water period. The log10 THg-δ(15) N relationship of vascular plants and algae, Macrobrachium sp., Paracheirodon spp. and Cichla spp. showed significant mercury biomagnification among trophic levels, with regression slopes of 0·15 and 0·25 for the entire food web and heterotrophs-only food web, respectively. The mean ± s.d. THg concentrations for Macrobrachium sp., P. axelrodi, P. simulans and Cichla spp. were 63·6 ± 23·7, 104·5 ± 40·0, 112·3 ± 31·4 and 418·5 ± 188·1 ng g(-1) wet mass, respectively. Elevated levels of mercury found in Paracheirodon spp. and top predators such as Cichla spp. in a remote area far from anthropogenic inputs provide evidence that high mercury concentrations occur naturally in Rio Negro aquatic food webs.

Growth of the Cichla temensis Humboldt, 1821 (Perciformes: Cichlidae) from the middle rio Negro, Amazonas, Brazil

This study aimed to estimate age and growth of the peacock bass Cichla temensis from the rio Negro (Brazilian Amazonia) by analyzing scale annuli. Specimens were captured between October 2011 and September 2012 in the main channel of the river and in adjacent lakes in the municipality of Barcelos, AM, Brazil. Six growth checks were identified on the scales of specimens. The annual variation in body condition observed suggests that fat is accumulated during the dry season. Results for the GSI (gonadosomatic index) showed that peak reproduction occurred in the receding-water period, indicating that the fish had energy deficiencies as a result of reproductive activity. RMI (relative marginal increment) analysis revealed that an annulus is formed once a year during the receding-water period. The population parameters estimated were L50 (length at sexual maturity) = 31.11 cm, L∞ (asymptotic length) = 68.05 cm, k (growth coefficient) = 0.20.year-1 and A0.95 (longevity) = 14 years. Our results corroborate the validity of using growth rings in scales as indicators to estimate the age and growth rate of Cichla temensis in the middle rio Negro.

Can urban migration contribute to rural resistance? Indigenous mobilization in the Middle Rio Negro, Amazonas, Brazil

Given the importance of land for indigenous peoples, rural out-migration is usually associated with a disruption of indigenous culture. This paper suggests that instead of being a disruptive process, migration can serve as the means for a ‘scale shift’ that transports mobilization capacity from one location to another. This contribution presents the case of Barcelos, in the Brazilian Amazon, where an indigenous movement first arose in an urban area, due to the migration of indigenous activists from other locations, and later spread to rural communities as a result of local migratory circulation. Through alliances with the regional indigenous movement, these rural communities became part of a broader mobilization network that supported the indigenous resurgence in Barcelos.

Ecclinusa campinae (Sapotaceae), a new species from the Middle Rio Negro region, Amazonas, Brazil

Ecclinusa campinae is here described as new species from South America. It is known from a single area of lowland non-flooded or occasionally flooded forests on nutrient-poor white-sand soils locally known as campina or campinarana forests in the Parque Nacional do Jau, Middle Rio Negro region in northwestern Amazonia. Illustrations are provided, in addition to a key to species of the genus and a comparison of the morphological differences between E. campinae and similar species.

Urban‐Rural Livelihoods, Fishing Conflicts and Indigenous Movements in the Middle Rio Negro Region of the Brazilian Amazon

This paper discusses how changing urban–rural relationships pose new opportunities and challenges for resource management in the municipality of Barcelos, Middle Rio Negro, Brazilian Amazon. The conflicts arising from poor delimitation of the rights of different resource users, as well as increasing rural–urban connections, have mobilised indigenous peoples to seek to protect traditional fishing territories. However, people's mobility challenges resource management models that are based on permanent residence. This complexity underscores the urgent need for new ecological and political management models to deal with the flux of both people and natural resources, without excluding minority groups.