Lower Amazon Research Articles

PERFIL SOCIOECONÔMICO DOS PESCADORES ARTESANAIS DE DOIS LAGOS PERIURBANOS DE SANTARÉM, ESTADO DO PARÁ

A atividade pesqueira tem um importante papel socioeconômico no estado do Pará, especialmente para as pequenas comunidades ribeirinhas, gerando emprego, renda e oferta de alimentos para a população. O trabalho teve como objetivo identificar o perfil socioeconômico dos pescadores e caracterizar a pesca realizada em dois lagos periurbanos de Santarém (lago Juá e Maicá), Baixo Amazonas (PA). Foram aplicados 68 formulários semiestruturados junto às lideranças, pescadores e demais atores sociais envolvidos com a pesca nas comunidades no entorno dos lagos. A maioria dos entrevistados eram do sexo masculino (69%), com idade entre 19 e 80 anos, baixos níveis de escolaridade e renda inferior a um salário mínimo. Os resultados técnico-operacionais, revelam a atividade como artesanal e de pequena escala, praticada por canoas motorizadas que variam de 2,5 a 12 m, sendo executada por pescadores de dedicação parcial ou exclusiva e com produção destinada em partes à subsistência e ao comércio, utilizando multiplicidade de apetrechos, com destaque para o uso da malhadeira e da captura de pacus, aracus, bocó (juvenil de tambaqui), jaraquis e tucunarés. Em toda extensão dos lagos ocorre a prática da pesca artesanal indicando a relevância destes mananciais como importante meio de subsistência para os pescadores locais. Como pontos negativos foram relatados a falta de fiscalização, a pesca predatória e o mau uso e degradação dos recursos naturais. Estes resultados podem subsidiar a elaboração de políticas adequadas de manejo para a melhoria da atividade pesqueira da região.

Systematic revision of the Potamotrygon scobina Garman, 1913 species-complex (Chondrichthyes: Myliobatiformes: Potamotrygonidae), with the description of three new freshwater stingray species from Brazil and comments on their distribution and biogeography

Potamotrygon scobina Garman, 1913, described from Cametá, rio Tocantins, lower Amazon basin, is taxonomically reviewed through an extensive morphological study of internal and external features. Specimens identified as P. scobina from different locations of the Amazon basin were also studied. The identity of P. scobina, its morphology, and distribution are redefined. In addition, three new species closely related to P. scobina are described from Brazil: Potamotrygon adamastor, sp. nov., from rio Uraricoera, rio Branco system, upper Amazon basin; Potamotrygon amazona, sp. nov., from rio Juruá, upper Amazon basin; and Potamotrygon garmani, sp. nov., from the mid to upper rio Tocantins. These three new species do not occur sympatrically with P. scobina, as far as known. Together with P. scobina and P. limai Fontenelle, Silva & Carvalho, 2014, the new species have three angular cartilages of different sizes, a condition not seen in any other potamotrygonin (which have either one or two angulars). Diagnostic characters in combination are primarily morphometric proportions, especially tail length and width, dermal denticles and tail thorns (their relative size, number, morphology, and distribution), tooth size and number of rows, and color pattern. Printed copy of this book is available from US$24.6 plus postage, Click here to order.

Patterns of Bacterial and Archaeal Gene Expression through the Lower Amazon River

Analysis of metatranscriptomic and metagenomic datasets from the lower reaches of the Amazon River between Obidos and the river mouth revealed microbial transcript and gene pools dominated by Actinobacteria, Thaumarchaeota, Bacteroidetes, Acidobacteria, Betaproteobacteria, and Planctomycetes. Three mainstem stations spanning a 625 km reach had similar gene expression patterns (transcripts gene copy-1) across a diverse suite of element cycling genes, but two tributary-influenced stations at the mouth of the Tapajos River and near the Tocantins River at Belem had distinct transcriptome composition and expression ratios, particularly for genes encoding light-related energy capture (higher) and iron acquisition and ammonia oxidation (lower). Environmental parameters that were useful predictors of gene expression ratios included concentrations of lignin phenols, suspended sediments, nitrate, phosphate, and particulate organic carbon and nitrogen. Similar to the gene expression data, these chemical properties reflected highly homogeneous mainstem stations punctuated by distinct tributary-influenced stations at Tapajos and Belem. Although heterotrophic processes were expected to dominate in the lower Amazon, transcripts from photosynthetic bacteria were abundant in tributary-influenced regions, and transcripts from Thaumarcheota taxa genetically capable of chemosynthetic ammonia oxidation accounted for up to 21% of the transcriptome at others. Based on regressions of transcript numbers against gene numbers, expression ratios of Thaumarchaeota populations were largely unchanged within the mainstem, suggesting a relatively minor role for gene regulation. These quantitative gene and transcript inventories detail a diverse array of energy acquisition strategies and metabolic capabilities for bacteria and archaea populations of the world’s largest river system.

Hydrodynamics and seed dispersal in the lower Amazon

Abstract The transport of seeds by water, i.e. hydrochory, is a key mechanism of long‐distance dispersal constrained by the attributes of the seed and hydrodynamics. In the freshwater Amazon estuary, river hydrodynamics are influenced by seasonal changes in precipitation and tidal cycles. It is not known to what extent a hydrodynamic model may be able to predict seed dispersal. Here we parameterised a simulation model (SisBaHia) to estimate maximum seed dispersal distances per tidal cycle, which were then compared with data from in situ seed dispersal experiments. The study was conducted along a 27‐km stretch of a tributary of the Amazon estuary, using the seeds of a widely distributed riparian tree—Carapa guianensis (Meliaceae). Based on the simulation model, maximum potential seed dispersal distance was higher in the rainy season (c. 8.7 km) when compared with the dry season (5.6 km), for one tidal cycle (12 hr). The seeds of C. guianensis were dispersed further during the ebb than flood tide during the rainy season, the period of seed dispersal. Average dispersal distances observed in seed dispersal experiments conducted during the rainy season, and those predicted by SisBaHia for the same period were within the same order of magnitude. The results of this study confirm that the period of higher precipitation provides favourable hydrological conditions for hydrochory in the Amazon river‐estuary complex. The fact that the time taken for the tide to fall is longer in relation to the time taken for it to rise also favours the arrival of the seeds in the main channel of the Amazon, thereby increasing the probability of long‐distance dispersal events.

The hydro-geomorphologic complexity of the lower Amazon River floodplain and hydrological connectivity assessed by remote sensing and field control

Hydrological connectivity processes along the lower Amazon River floodplain at Lago Miratuba Floodplain (LMF) were analyzed based on remote sensing and field measurements. Connectivity processes are related to 12 geomorphic sub-units of the floodplain that are interconnected at different stage thresholds through channelized and overbank flow paths, while lakes act as reservoirs for flood waters, local rainfall, and water table saturation-seepage. Hydrological connectivity processes along the floodplain happen through complex internal routings of water flows over space and time, mainly along floodplain channels and breached levees. The contribution of local recharge (mainly rainfall) was decoupled from river recharge (river hydrological connection to floodplain) because precipitations and local runoff also recharge the floodplain. The hydrological connectivity of the 12 geomorphic units varied significantly from each other, because the inundation and the floodplain connections with the river were initiated at specific river stage thresholds for each sub-unit.An interesting finding is that connections with the river for all units were initiated through channelized flows below the bankfull stage of the Amazon River. The connectivity processes over different geomorphic units are also not correlated with their minimum distance (shortest lines) from the river. This implies that a “flood pulse” model largely concerned with lateral connectivity (mostly through overbank diffusion) only partially explains the complex hydrological connectivity processes at a regional scale along the complex lower Amazon River floodplain. Thus, for hydrological connectivity assessments in the Amazon River floodplain, reach-by-reach scale studies have to be carried out, relating the hydro-geomorphologic processes (channelized flow routing paths, overbank diffusion, and local recharge) to the internal geomorphic variability and complexity of the floodplain.

Revision of the complex of Echeta trinotata Reich, 1933: description of two new species (Lepidoptera: Erebiidae: Arctiinae)

Following a large survey of the Neotropical Arctiinae using the DNA barcodes technique (COI gene sequencing), Echeta trinotata Reich, 1933 was found to be in fact a complex of three cryptic highly genetically divergent species. The two new species are described as Echeta apatela sp. nov. from the foothills of the Andean Cordillera and Echeta rhodoptera sp. nov. from the Guianas shield, whereas the true Echeta trinotata is distributed along the lower Amazon from Manaus to Belém. Images of adults, male genitalia, genetic distance tree and distribution map are provided for the whole species group.

Bacterial Biogeography across the Amazon River-Ocean Continuum.

Spatial and temporal patterns in microbial biodiversity across the Amazon river-ocean continuum were investigated along ∼675 km of the lower Amazon River mainstem, in the Tapajós River tributary, and in the plume and coastal ocean during low and high river discharge using amplicon sequencing of 16S rRNA genes in whole water and size-fractionated samples (0.2–2.0 μm and >2.0 μm). River communities varied among tributaries, but mainstem communities were spatially homogeneous and tracked seasonal changes in river discharge and co-varying factors. Co-occurrence network analysis identified strongly interconnected river assemblages during high (May) and low (December) discharge periods, and weakly interconnected transitional assemblages in September, suggesting that this system supports two seasonal microbial communities linked to river discharge. In contrast, plume communities showed little seasonal differences and instead varied spatially tracking salinity. However, salinity explained only a small fraction of community variability, and plume communities in blooms of diatom-diazotroph assemblages were strikingly different than those in other high salinity plume samples. This suggests that while salinity physically structures plumes through buoyancy and mixing, the composition of plume-specific communities is controlled by other factors including nutrients, phytoplankton community composition, and dissolved organic matter chemistry. Co-occurrence networks identified interconnected assemblages associated with the highly productive low salinity near-shore region, diatom-diazotroph blooms, and the plume edge region, and weakly interconnected assemblages in high salinity regions. This suggests that the plume supports a transitional community influenced by immigration of ocean bacteria from the plume edge, and by species sorting as these communities adapt to local environmental conditions. Few studies have explored patterns of microbial diversity in tropical rivers and coastal oceans. Comparison of Amazon continuum microbial communities to those from temperate and arctic systems suggest that river discharge and salinity are master variables structuring a range of environmental conditions that control bacterial communities across the river-ocean continuum.

SPATIAL DISTRIBUTION OF ENVENOMATION BY SCORPIONS IN PARÁ STATE, BRAZIL

Scorpionism is recognized by the World Health Organization as a neglected disease and, in Pará State, Brazil, it is considered a public health hazard. The objective of this study was to describe the spatial distribution of envenomation caused by scorpions in Pará. The data related to envenomation were collected from 2007 to 2014 and used for both descriptive and transversal studies. For those studies records obtained from ongoing investigations from the database of the National Notifiable Diseases Information System at the Public Health Department of Pará Statewere used. Envenomation occurs year round, most often in the first half of the year, in males from the countryside, aged 20 to 59 years and taking up to 3 hours to reach medical care. The deaths occurred from ages 15 to 59. Regarding the severity of the cases, class I cases were the most frequent and class III cases were the least frequent, accounting for only 5.1% of all cases.Of the 144 municipalities of Pará State, in 126 the frequency of envenomation ranged from 1 to 1,208 cases per municipality. Thirteen municipalities located in the lower Amazon region and in the southwest of Pará State presented higher occurences, including the highest number of deaths.Scorpionism is present throughout Pará State. However, there were differences in severity and incidence in the various regions, with higher frequency in the southwest of the State and in the lower Amazon region, corresponding to the Tapajós and Guyana endemic areas in the BrazilianAmazon.

Carbon Dioxide Emissions along the Lower Amazon River

A large fraction of the organic carbon derived from land that is transported through inland waters is decomposed along river systems and emitted to the atmosphere as carbon dioxide (CO2). The Amazon River outgasses nearly as much CO2 as the rainforest sequesters on an annual basis, representing ~25% of global CO2 emissions from inland waters. However, current estimates of CO2 outgassing from the Amazon basin are based on a conservative upscaling of measurements made in the central Amazon, meaning both basin and global scale budgets are likely underestimated. The lower Amazon River, from Obidos to the river mouth, represents ~13% of the total drainage basin area, and is not included in current basin-scale estimates. Here, we assessed the concentration and evasion rate of CO2 along the lower Amazon River corridor and its major tributaries, the Tapajos and Xingu Rivers. Evasive CO2 fluxes were directly measured using floating chambers and gas transfer coefficients (k600) were calculated for different hydrological seasons. Temporal variations in pCO2 and CO2 emissions were similar to previous observations throughout the Amazon (e.g. peak concentrations at high water) and CO2 outgassing was lower in the clearwater tributaries compared to the mainstem. However, k600 values were higher than previously reported upstream likely due to the generally windier conditions, turbulence caused by tidal forces, and an amplification of these factors in the wider channels with a longer fetch. We estimate that the lower Amazon River mainstem emits 0.2 Pg C yr-1 within our study boundaries, or as much as 0.48 Pg C yr-1 if the entire spatial extent to the geographical mouth is considered. Including these values with updated basin scale estimates and estimates of CO2 outgassing from small streams we estimate that the Amazon running waters outgasses as much as 1.39 Pg C yr-1, increasing the global emissions from inland waters by 43% for a total of 2.9 Pg C yr-1. These results highlight a large missing gap in basin-scale carbon budgets along the complete continuum of the Amazon River, and likely most other large river systems, that could drastically alter global scale carbon budgets.

New evidence for subsistence strategies of late pre-colonial societies of the mouth of the Amazon based on carbon and nitrogen isotopic data

The nature of subsistence strategies employed by the past inhabitants of Amazonia has been a widely debated topic, however little evidence has been found so far in order to support some of the proposed hypotheses. This article contributes to this debate by presenting new δ13C and δ15N data from the human populations that occupied the Maracá region of the mouth of the Amazon river, around 500 BP (years before present). It directly compares these newly generated results to previously published human isotope data from neighbouring Marajó Island (Marajoara phase, 1600 to 700 BP), as well as other areas in the lowland Neotropics, in an attempt to build a bigger picture of the dietary habits of the Lower Amazon pre-colonial populations. The overall results suggest that the populations that occupied the mouth of the Amazon after 2000 BP had diets based on the exploitation of fish and a wide range of C3 plant resources, as well as possibly having a minor C4 or CAM component. The data presented are also consistent with an emerging consensus that there was no single adaptive pattern for ancient Amazonian populations and proposes that diversified economic strategies based on wild and cultivated plants combined with the exploitation of faunal resources could have developed over time and sustained long-term successful patterns of human occupations.

Evaluation of Primary Production in the Lower Amazon River Based on a Dissolved Oxygen Stable Isotopic Mass Balance

The Amazon River outgasses nearly an equivalent amount of CO2 as the rainforest sequesters on an annual basis due to microbial decomposition of terrigenous and aquatic organic matter. Most research performed in the Amazon has been focused on unraveling the mechanisms driving CO2 production since the recognition of a persistent state of CO2 supersaturation. However, although the river system is clearly net heterotrophic, the interplay between primary production and respiration is an essential aspect to understanding the overall metabolism of the ecosystem and potential transfer of energy up trophic levels. For example, an efficient ecosystem is capable of both decomposing high amounts of organic matter at lower trophic levels, driving CO2 emissions, and accumulating energy/biomass in higher trophic levels, stimulating fisheries production. Early studies found minimal evidence for primary production in the Amazon River mainstem and it has since been assumed that photosynthesis is strongly limited by low light penetration attributed to the high sediment load. Here, we test this assumption by measuring the stable isotopic composition of O2 (δ18O-O2) and O2 saturation levels in the lower Amazon River from Obidos to the river mouth and its major tributaries, the Xingu and Tapajos rivers, during high and low water periods. An oxygen mass balance model was developed to estimate the input of photosynthetic oxygen in the discrete reach from Obidos to Almeirim, midway to the river mouth. Based on the oxygen mass balance we estimate that primary production occurred at a rate of 0.39 ± 0.24 g O m3 d-1 at high water and 1.02 ± 0.55 g O m3 d-1 at low water. This translates to 41 ± 24% of the rate of O2 drawdown via respiration during high water and 67 ± 33% during low water. These primary production rates are 2-7 times higher than past estimates for the Amazon River mainstem. It is possible that at high water much of this productivity signal is the result of legacy advection from floodplains, whereas limited floodplain connectivity during low water implies that most of this signal is the result of in situ primary production in the Amazon River mainstem.

RAPID-COMMUNICATION Genetic diversity and differentiation in natural populations of Arapaima gigas from lower Amazon revealed by microsatellites.

Genetic variability is one of the important criteria for species conservation decisions. This study aimed to analyze the genetic diversity and the population differentiation of two natural populations of Arapaima gigas, a species with a long history of being commercially exploited. We collected 87 samples of A. gigas from Grande Curuai Lake and Paru Lake, located in the Lower Amazon region of Amazônia, Brazil, and genotyped these samples using a multiplex panel of microsatellite markers. Our results showed that the populations of A. gigas analyzed had high levels of genetic variability, which were similar to those described in previous studies. These two populations had a significant population differentiation supported by the estimates of FST and RST (0.06), by Bayesian analysis (K = 2), and by population assignment tests, which revealed a moderate genetic distance.

Influence of Seasonality on Buffalo Semen

The present study was undertaken with the objective to compare the influence of seasonal temperature variations on parameters of ejaculates of Murrah buffalo bulls raised in the humid tropical Amazonian climate. Five buffaloes were selected from a batch of 12 adult bulls, pre-evaluated for clinical and andrological examination, and were used as semen donors, using as criterion the best ejaculate quality. The objective of the present study was, therefore, to test the hypothesis that season affects buffalo semen quality in tropical regions. The experimental period was divided into two phases: rainy season (RS), from February to May, and non rainy season (nRS), from August to November 2016. The ejaculates were collected twice a week (n=30) per bull, namely 10 ejaculates in the RS and 20 ejaculates in the nRS period, totaling (n=150) samples for analysis. The evaluations of the semen samples were performed with fresh semen, immediately after each collection. The immediate analyzes pertinent to the physical and morphological characteristics of the ejaculates showed that a significant statistical difference was observed for the parameters wave motion, motility, vigor, major defects, minor defects, total defects and plasma membrane integrity between the both periods (P<0.05). In the mesoregion of the Lower Amazon, a tropical region, the ideal period for experiments using buffalo ejaculates, are the months of the rainy season. For in this period a better quality without ejaculate of buffaloes was observed.

Amazonia in the Anthropocene: People, Soils, Plants, Forests by Nicholas C. Kawa

Reviewed by: Amazonia in the Anthropocene: People, Soils, Plants, Forests by Nicholas C. Kawa Antoinette WinklerPrins Amazonia in the Anthropocene: People, Soils, Plants, Forests. Nicholas C. Kawa. Austin: University of Texas Press, 2016. xiii + 186 pp. Photos, maps, tables, notes, references, appendix, and index. $75.00 cloth (ISBN 978-1-4773-0799-1); $24.95 paper (978-1-4773-0844-8). Nicolas Kawa has crafted a refreshing and quite evocative ethnography of rural life in Amazonia in the era of the Anthropocene. As I read the pages I found myself back in the Amazon doing fieldwork, on the floodplain, talking with farmers about their livelihoods, hanging in my hammock, and dealing with the assorted travails that are fieldwork in the region (WinklerPrins, Between the floods: Soils and agriculture on the lower Amazon flood-plain, Brazil, 1999). Kawa’s attention to details of the luta de vida (fight for life) that locals endure and his own vie quotidienne while doing research, bring a humanity to a place the popular media often wraps up in overgeneralizations and supersized pronouncements. This attention to detail brings Kawa’s discussion about the Anthropocene—what it is, and how we might envision and engage with it—down to the local, personal, and tangible, thereby making it accessible to many more readers than much of the existing literature. Most importantly his book helps us (re)conceptualize the Anthropocene as something longer and deeper than its start at the Industrial Revolution that many attach to it. To have the reader understand that the Anthropocene is something much longer than commonly envisioned, Kawa guides us through the ways in which people have long been subtly altering the soils, plants, and forests of the Amazon rainforest. His work is focused on the human-environmental relationships in the municipality of Borda, in Amazonas State, along the Madeira River, Brazil. Based on his dissertation in anthropology at the University of Florida as well as other related research in the region, Kawa has produced a succinct volume with a refreshingly accessible prose that will likely find use as a text is a variety of courses about Amazonia, Latin America, rural livelihoods, and the Anthropocene. It is a short book, with 133 pages of narrative, making it a relatively quick read and thereby attractive as assigned reading even for freshman and sophomore courses. Except for the first and last of the six chapters, the crisp chapter titles—”People,” “Soils,” “Plants,” and “Forests”—make them easy to assign and then build on, depending on the course. The author frames his perspective in the first chapter, taking the Anthropocene as a given but pointing to its inherent Eurocentrism and a need to unpack and disentangle the term and its application. He follows with a chapter on the history and livelihoods of the people who currently embody the Amazon as a humanized space, the caboclos, the region’s indigenous peasantry, a people of mixed heritage yet long-time occupancy and engagement with its resources. In the next chapter Kawa discusses the fertile terra preta do índio (TPI: black soil of the Indians) found in patches throughout the region and how locals use [End Page 203] these in agricultural practice. In the fourth chapter the focus is on the region’s plants, especially ones found around human inhabitation, used for their magical and healing powers. Next is a chapter on forests in which Kawa confronts the debate about the nature-culture divide. Although TPI soils clearly signal greater human agency in the Amazon than many have thought, the debate about the degree to which humans have manipulated forest composition is really where the differences in ideas about human agency in the “natural” world reach a crescendo. Kawa lays out the terms of the debate and infuses his discussion with post-human agency and local folklore. Last is a chapter that considers the future of the region, especially as linked to global environmental change. I like this book for its accessibility, but I wish Kawa had engaged more fully with research by non-anthropologists, including geographers, who have long worked on similar topics. It is clear this book is derived from his dissertation in anthropology, but it could have...

Representação Espacial da Pesca de Brachyplatystoma rousseauxii (Siluriformes - Pimelodidae) em Paisagens Fluviais do Complexo Fluvio-Lacustre do Ituqui, Baixo Amazonas, Brasil

Intensive fishing of dourada, Brachyplatystoma rousseauxii, and the consequences for the reduction of their natural stock and its traditional activity are not well understood and documented. Good management of a resource requires frequent detailed assessments spatially numbers and distributions of species. Thus, this study making use of traditional methodology dourada fishing aimed georreference points gillnet launches, fish harvest sites and capture individuals, demonstrating the timely presence of the species during the 2015 season, and associating data raised with systematic tools of geographic information easily accessible, as the free software QGIS (version 2.8), performing interpolation and vectorization of data operations. Introducing a model of presence of the species, and spatially represent the main fishing grounds and classification of lowland landscapes, according to specialist literature. The results show low occurrence of catfish in the lake landscape and high presence in parana, which justifies the higher interest of fishermen by this site. With this, spatial models presented here provide information that can be used as a support tool in decision-making to promote the conservation of the species and the fishing activity in the fluvial-lacustrine complex Ituqui, Lower Amazon, Brazil, as well as along its migration route. Keywords: Geographic information systems; dourada; floodplain; conservation.

Solar-Aligned Pictographs at the Paleoindian Site of Painel do Pilão along the Lower Amazon River at Monte Alegre, Brazil.

The archaeological sites near Monte Alegre, along Brazil's lower Amazon River, provide new information on the little-known activities and symbolism of South American Paleoindians toward the end of the Ice Age. While paleoindian sites like Monte Verde in Chile, or Guitarrero Cave in Peru, are located near the pacific coast, Monte Alegre lies much further inland, 680 km upriver from the mouth of the Amazon River and the Atlantic Coast. With excavated wood charcoal radiocarbon dated as early as 13,200 calibrated years ago, the hill—as a source of sandstone and quartz lithics—supplied early pioneers with adequate tools needed for colonizing the interior of the continent. Once there, they painted rock art on the landscape, which bears a record of the sun's horizon positions throughout the year. At just 2° south of the equator, Monte Alegre shows no overt seasonal changes beyond fluctuating rainfall amounts, unlike at higher latitudes where temperature, amount of daylight, foliage, and forms of precipitation markedly change. Near the equator, solar and stellar horizon sightings most visibly track the passage of time and seasonal cycles. However, horizons are often hidden behind high forest canopy throughout much of the Amazon Rainforest; but in the Monte Alegre hill ridges looming above the river, paleoindians could hike above the canopy to peer at the horizon, more effectively synchronizing their activities to ecological cycles. This research suggests that Monte Alegre paleoindians delimited the azimuthal range of the sun in a solar year with notational pictographs aligned to horizon sightings at Painel do Pilão, and leaving a painted grid of tally marks that might have served as a rudimentary early calendar. The broad-reaching implication for early Americans is that through the strategic placement of rock art, these ancient artists fostered predictive archaeorecording from which resources could be optimally extracted, ceremonial activities could be consistently scheduled, and gatherings for social and economic exchange could be more efficiently coordinated.

A new species of Moenkhausia Eigenmann, 1903 (Characiformes: Characidae) from Amazon basin, Brazil.

A new species of Moenkhausia is described from tributaries of the lower Amazon basin, Pará State, Brazil. The new species is morphologically similar to Moenkhausia collettii, M. copei, and M. venerei by the presence of a dark horizontal stripe across the middle portion of the eye, a conspicuous slightly rounded humeral blotch, a dark longitudinal midlateral stripe and a dark stripe along the anal-fin base. However, the new species can be distinguished from M. collettii, M. copei, and M. venerei mainly by the number of cusps on the inner row of the premaxillary, maxillary and dentary teeth, and by the number of scales in transversal series above and below the lateral line.

Politics and Ritual in Large Villages in Santarém, Lower Amazon, Brazil

The character and development of complex societies has been one of the major interests of Amazonian archaeology. This article presents an ontological interpretation to explain the socio-political organization and importance of ritual in the Santarém area, Lower Amazon, Brazil, during the late pre-colonial period (ad 1000–1600), drawing from the contributions of Viveiros de Castro on Amazonian ontologies and Pierre Clastres on the constitution of power in the South American tropical lowlands. This approach affords new insights into the spatial organization of large habitation sites, the settlement patterns of nearby smaller sites and the pragmatic role of ritual objects. The data point to demographic growth, elaborate spatial organization and the existence of independent villages, probably resulting from fissions. The distribution of objects used in ritual contexts suggests a network employing a mytho-cosmological iconography that emphasizes bodily metamorphosis, indicating a predatory ontology related to Amerindian perspectivism and the presence of institutionalized shamanism. The text argues for the existence of distinct cosmopolitical strategies used to maintain the egalitarian order and that the flows of knowledge, sacred artefacts and religious specialists within the wider social sphere structured regional relations.

Seasonal and spatial variability of dissolved organic matter composition in the lower Amazon River

We analyzed the molecular composition of dissolved organic matter (DOM) in the lower Amazon River (ca. 850 km from Obidos to the mouth) using ultrahigh-resolution mass spectrometry and geochemical tracers. Changes in DOM composition along this lower reach suggest a transition from higher plant-derived DOM to more algal/microbial-derived DOM. This result was likely due to a combination of autochthonous production, alteration of terrigenous DOM as it transits down the river, and increased algal inputs from floodplain lakes and clearwater tributaries during high discharge conditions. Spatial gradients in dissolved organic carbon (DOC) concentrations varied with discharge. Maximal DOC concentrations were observed near the mouth during high water, highlighting the importance of lateral inputs of DOM along the lower river. The majority of DOM molecular formulae did not change within the time it takes the water in the mainstem to be transported through the lower reach. This is indicative of molecules representing a mixture of compounds that are resistant to rapid alteration and reactive compounds that are continuously replenished by the lateral input of terrestrial organic matter from the landscape, tributaries, and floodplains. River water incubations revealed that photo- and bio-transformation alter at most 30% of the DOM molecular formulae. River discharge at the mouth differed from the sum of discharge measurements made at Obidos and the main gauged tributaries in the lower Amazon. This indicates that changes in hydrology and associated variations in the source waters along the lower reach affected the molecular composition of the DOM that is being transported from the Amazon River to the coastal ocean.

Spatial genetic structure and dispersal of the cacao pathogen Moniliophthora perniciosa in the Brazilian Amazon

Moniliophthora perniciosa is the causal agent of witches’ broom in Theobroma cacao (cacao). Three biotypes of M. perniciosa are recognized, differing in host specificity, with two causing symptoms on cacao or Solanaceae species (C‐ and S‐biotypes), and the third found growing endophytically on lianas (L‐biotype). The objectives of this study were to clarify the genetic relationship between the three biotypes, and to identify those regions in the Brazilian Amazon with the greatest genetic diversity for the C‐biotype. Phylogenetic reconstruction based on the rRNA ITS regions showed that the C‐ and S‐biotypes formed a well‐supported clade separated from the L‐biotype. Analysis of 131 isolates genotyped at 11 microsatellite loci found that S‐ and especially L‐biotypes showed a higher genetic diversity. A significant spatial genetic structure was detected for the C‐biotype populations in Amazonia for up to 137 km, suggesting ‘isolation by distance’ mode of dispersal. However, in regions containing extensive cacao plantings, C‐biotype populations were essentially ‘clonal’, as evidenced by high frequency of repeated multilocus genotypes. Among the Amazonian C‐biotype populations, Acre and West Amazon displayed the largest genotypic diversity and might be part of the centre of diversity of the fungus. The pathogen dispersal may have followed the direction of river flow downstream from Acre, Rondônia and West Amazon eastward to the rest of the Amazon valley, where cacao is not endemic. The Bahia population exhibited the lowest genotypic diversity, but high allele richness, suggesting multiple invasions, with origin assigned to Rondônia and West Amazon, possibly through isolates from the Lower Amazon population.