Tocantins River Research Articles

Short-term changes in energy allocation by Hemiodontidae fish after the construction of a large reservoir (Lajeado Dam, Tocantins River)

The present study investigated energy allocation patterns in three fish species from the family Hemiodontidae (Argonectes robertsi, Hemiodus microlepis, and Hemiodus unimaculatus), before and after the construction of Lajeado Dam, Tocantins River, Amazon basin. Changes in the use of energy (between somatic and reproductive processes) were indirectly evaluated by means of temporal variations in fish body condition, feeding activity, visceral fat storage, and reproductive effort. Fish were collected from October 1999 to September 2004, in periods that preceded and followed the construction of the dam. We recorded significant changes in all ecological traits for the three analyzed species (for males and females). In general, there was an intense reduction in reproductive activity after river damming, whereas visceral fat and body condition increased consistently. In contrast, there was no clear trend in feeding activity (i.e., stomach weight), with little changes in species diet during the analyzed period. These results indicate that the impoundment changed the energy allocation process between somatic and reproductive activities, since fish started to allocate energy mainly to somatic processes. These changes may have a negative effect on the persistence of populations in Lajeado Reservoir, because improvements in somatic condition will not necessarily translate into increased fitness.

Time-series analysis of Landsat-MSS/TM/OLI images over Amazonian waters impacted by gold mining activities

Water siltation caused by artisanal gold mining has impacted the Tapajós River Basin in Brazil for the past 40years, however spatial-temporal information about changes in water quality and consequences to the aquatic environment is lacking. To address this, the Landsat satellite family sensors were used to retrieve total suspended solids (TSS) of the water of the Tapajós River from 1973 to 2013. An image processing approach that includes atmospheric correction, based on the 6S model, and glint removing, based on shortwave infrared correction, was applied and validated with in situ radiometric data. An optimization of the atmospheric correction having dark dense forest spectra as reference was applied and allowed a robust correction of MSS, TM and OLI signal to surface reflectance values. Sediment concentration was estimated based on a non-linear empirical regression between measured TSS and satellite surface reflectance at red band. The multi-temporal analysis of TSS showed that the sediment load in the Tapajós aquatic system is in synchrony with mining activities, and a constant seasonal variation of water siltation is observed throughout the time frame of this study. At the end of the rainy season, mining activities intensify and, coupled with low water flow, TSS increases. During the high water level, TSS concentrations were consistently lower because of high water dilution and low mining activity. In a decadal analysis, a peak of sediment concentration coincides with a peak of gold production in all sites analyzed during early 1990s. More recently, due to the currently gold rush, an increase in suspended solids has been observed mainly in the Novo and Tocantins rivers where industrial mining has been installed.

Measuring diversity: looking for processes that generate diversity

In this study, we compare the variations of Margalef K and Shannon H diversity indices obtained for a fish community that suffered changes as a consequence of the impoundment of the upper Tocantins River in Goiás, Brazil. The analysis of different sites along the study area showed that the Shannon index was not sensitive to the environmental changes, whereas the Margalef K index varied significantly following the impoundment. Therefore, the Margalef K index appears to be a good diversity indicator as well as a valuable parameter for the temporal data series analysis, from changing environments and for the conservation of natural environments. Although the Margalef K index can be used as a diversity index, it can also be used to consistently indicate the speed of ecosystem evolution.

Memórias de um Rio Afogado: Tocantins 1914-2014

Ao longo dos séculos, o Rio Tocantins tem desempenhado importante papel como caminho fluvial no processo de conquista e ocupação do interior do Brasil. Atualmente, sua importância se destaca também como potencial energético, com a construção de hidrelétricas e como meio de transporte, pela efetivação do projeto da Hidrovia Tocantins-Araguaia. Este artigo visa analisar os vestígios deixados em um diário de viagem de 1914 em contraste com as transformações que estão ocorrendo atualmente no Rio Tocantins. Por meio desta fonte é possível perceber o cotidiano das viagens, as dificuldades e perigos de uma navegação incipiente, a natureza do rio e suas margens e a cultura das populações ribeirinhas.Palavras-Chaves: Região; Rios; História Ambiental; Memória

Hydropower expansion and analysis of the use of strategic and integrated environmental assessment tools in Brazil

Abstract In Brazil, over the next two decades, an additional 31.7 GW will be added to the hydropower sector in the northern region, to keep pace with the country׳s growing economy. Due to the socio-environmental vulnerability of this region, there is international concern about its conservation. Since 2007, the hydroelectric potential inventory has employed Integrated Environmental Assessments (IEA), taking into consideration an analysis of the cumulative and synergistic impacts of all the hydropower plants in the river basin. Also available is the Strategic Environmental Assessment (SEA), a tool that has been used by the National Water Agency in its Strategic Water Resources Plan, which aims to support decision making at the political, planning, and program levels in the river basin, employing sustainable development scenarios. Both tools have been recently used in Brazil, and this paper aims to analyze their differences and their main contributions to the decision-making process in the Brazilian power sector. Therefore, we analyzed 3 studies on the implementation of new hydropower plants in the Tocantins–Araguaia River Basins: the Strategic Water Resources Plan for Tocantins and Araguaia River Basins—PERH-TA (using the SEA methodology), the IEA of the Tocantins River Basin and the IEA of the Araguaia River Basin, analyzing their methodologies, scenarios, results and recommendations. We found that the SEA, in contrast to the IEA, provides a broader and more independent vision about the social and environmental impacts. After the conclusion of the integrated and strategic studies, we verified that some recommendations are not being followed in the HPP planning process, since some dams had problems with environmental licenses, as mentioned in the studies. Therefore, we conclude that methodological adjustments, as well as political and institutional enhancements in these processes could make the tools more useful.

Influência da barragem de Tucuruí no desempenho da pesca artesanal, estado do Pará

O objetivo foi analisar a influência da barragem de Tucuruí no desempenho da pesca artesanal, desenvolvida a jusante. Partindo-se da hipótese de que o desequilíbrio do rio Tocantins repercutiu de forma intensa sobre a vida das comunidades humanas locais, afetando o desempenho da atividade pesqueira, procurou-se dar resposta para a seguinte questão: qual a influência da barragem de Tucuruí, estado do Pará, sobre o desempenho da pesca artesanal desenvolvida a jusante? Os dados utilizados são de origem primária e secundária. Utilizou-se o modelo de análise fatorial exploratória (AFE), para construir o Índice de Desempenho da Pesca Artesanal (IDPA). Os resultados mostram que 21% dos pescadores têm baixo desempenho e 79%, desempenho intermediário, fato que aponta para a difícil situação enfrentada pelos trabalhadores da pesca ao longo do tempo.

Description of a New Species ofAspidoras(Siluriformes, Callichthyidae) from the Serra dos Carajás, Lower Tocantins River Basin, Brazil

A new species of Aspidoras (Corydoradinae) is described from the Serra dos Carajas, lower Tocantins River basin, representing the northernmost record of the genus at the edge of the Brazilian Shield into the Amazon basin. Aspidoras gabrieli is easily distinguished from all congeners by having the rays and interradial membranes of the dorsal and pectoral fins entirely and densely pigmented, the inner bony margin of the pectoral spine expanded as a narrow laminar shelf with edge smooth or scarcely serrated; lateral-line canal posterior to the two anterior lateral-line ossicles absent (also in A. taurus), naked predorsal region (also in A. velites and A. psammatides), large brown oval spots on the flank and caudal peduncle that sometimes merge to form irregular patches (also in A. maculosus, A. albater, A. lakoi, and A. depinnai), and several additional morphometric distinguishing features. Comments on generic allocation and interspecific relationships are presented. Uma nova especie de Aspidoras (Corydoradi...

Isolamento de Candida no esfregaço cérvico-vaginal de mulheres não gestantes residentes em área ribeirinha do Estado do Maranhão, Brasil, 2012

Este estudio evaluo la prevalencia da candidiasis vaginal y los factores asociados en mujeres no embarazadas, residentes en las costas del rio Tocantins, atendidas por el Programa de Atencion a la Salud de la Mujer, en el Municipio de Imperatriz, Estado de Maranhao, Brasil. Se consideraron los datos demograficos, epidemiologicos, clinicos y citohistologicos oriundos de examen Papanicolau y de cultivo microbiologico para hongos. Para el aislado del hongo se utilizo cultivo en agar selectivo y diferencial para Candida, ademas de placas de Petri. La prevalencia de hongos del genero Candida en el frotis cervicovaginal fue de 42,86%, con mas de 50% de casos sintomaticos. Fue verificado que un 28% de las mujeres con candidiasis vaginal tenia entre 20 y 29 anos de edad, un 37,4% habia cursado ensenanza primaria incompleta, 66,4% era de color pardo, la mayoria (63,6%) era ama de casa, 58% vivia con una renta mensual de uno a tres sueldos minimos y 63,5% relato tener companeros fijos (considerando las casadas y con union estable). Entre las especies de Candida aisladas e identificadas, la C. albicans fue la mas prevalente. Se concluye que la poblacion estudiada no tiene conocimientos suficientes sobre la candidiasis vaginal sugiriendose la necesidad de fortalecerse las practicas educativas, de orientacion y tomada de consciencia de habitos que favorezcan el control y la prevencion de esa infeccion

Floristic and structural comparisons between woody communities of two seasonal forest fragments in the Tocantins river basin and other remnants of this forest physiognomy in Brazil

This work describes the woody layer composition and structure in two seasonal forest fragments in the Tocantins river basin and compares them to other remnants of this forest physiognomy in Brazil. The survey was carried out by using 17 plot samples (20 × 50 m) located in Palmeirópolis, state of Tocantins, and in Minaçú, state of Goiás. All woody individuals showing diameters > 5 cm, at 1.30 cm above ground level, were recorded. The higher floristic similarity of these forest remnants compared with other closer seasonal forests did not show a distinct pattern. The floristic composition was more similar to that of a deciduous seasonal forest in the Paranã valley, and more dissimilar to other forests in this same valley. This result and a higher dissimilarity related to the southern forests in Goiás suggest that the forest fragments showed a floristic composition and structure typical of lowland seasonal forests in the Tocantins river basin. The results also indicated that the forest fragments have distinct floristic compositions with a relatively similar structure and diversity.

Ichthyological Overview and Remarks on Freshwater Fishes from Capim River, Lower Amazon Basin, Brazil

The Capim River drainage should be considered small and thin by comparison with large Amazonian rivers. It rises by confluence of the Surubiú and Ararandeua rivers near 400 m high and their headwaters would be comfortably included in the Dry Emerged Lowland (terra firme) forest area of Sternberg’s Amazonian concept. Because of this reason the freshwater fish fauna of Capim River is comprised mainly by Amazonian fish families found in tributaries also with origin in terra firme areas. The ichthyofauna from the main channel of the poorly sampled Capim River, in the stretch between its confluence with Tauarí River and its mouth at Guamá River, is herein reported by way of rapid assessment. Also broad comparisons were made among freshwater fishes of the Capim with that from Tocantins and Guamá rivers. Two rapid access research surveys of collecting ichthyological material were performed in dry and humid periods of the year 1998 comprising the regional hydrologic cycle. The ichthyological diversity showed by the 461 studied specimens includes 79 species probably derived from Guamá and Tocantins rivers. These species are distributed between two situations: 1) downstream Capim River, at confluence with Guamá River, where is under tidal waters influence and periodically flooded, and 2) upriver Capim that is less humid and with water rapids, independent from sea hydrologic influence. This fish fauna includes local species common at high areas of the Amazonian Dry Emerged Lowland that are in part shared with that from Tocantins River. In view of these observations, we assume that the Capim River freshwater ichthyofauna may reflect diverse origin from the simple transfer of populations from Guamá River, but originate through a more complex process including the past ichthyofauna of the earlier drainages of terra firme forest and their reorganization.

Morphometric and biotic variables as potential predictors ofLudwigia sedoides(Humb. & Bonpl.) Hara in a large Amazonian reservoir

Reservoirs cause hydrological changes (i.e. , water level stabilization) that favor the colonization of aquatic macrophytes. Knowing the ecological factors that determine the occurrence of these plants is critical for water management (e.g. , plant control) and biodiversity conservation. In this sense, the present study investigated colonization patterns of Ludwigia sedoides in Lajeado reservoir (Tocantins River, Amazon Basin), in order to identify variables that influence colonization at habitat scale. We investigated the relationship between colonization (coverage area and occurrence) and morphometric (fetch, slope, depth and distance from shoreline) and biotic variables (local diversity of macrophytes and co-occurrence patterns). Stepwise regression selected fetch, depth and slope as the best variables to explain the variation in L. sedoides coverage, which together explained 46% of data variability. Fetch and slope were negatively correlated with coverage, whereas depth showed a positive correlation. No biotic variable was included in the model (P >0.05). However, the investigation of the geometric shape of bivariate correlations (null models) showed positive relationships with local species richness and richness of life forms (i.e. , submerged, emergent, floating and epiphytic). In addition, an analysis of species co-occurrence (C -score) revealed that L. sedoides is negatively associated with some macrophyte species. We believe, however, that these results may be associated with species preferences for particular environmental conditions. In conclusion, the present study indicated that morphometric variables are potential predictors of the colonization of L. sedoides in Lajeado reservoir. Sheltered sites with low slope and moderate depths represent favorable environment for colonization and growth.

Levantamento regional na arqueologia amazônica: o uso de sistema de informação geográfica e sensoriamento remoto

Recentes avanços tecnológicos no sensoriamento remoto e nos Sistemas de Informação Geográfica (SIG) têm proporcionado resultados promissores para as pesquisas arqueológicas, em especial nos levantamentos de campo (prospecção) para a identificação de sítios amazônicos. Imagens de satélite, radar e aerofotogrametria proporcionam a análise de variáveis ambientais relacionadas aos sítios arqueológicos, permitindo estabelecer padrões da ocupação humana no espaço e construir modelos preditivos para identificar novos sítios em áreas com as mesmas características ambientais. Entre essas variáveis, destacam-se a proximidade de rios e lagos e a declividade do terreno, além do tipo de vegetação e dos ecossistemas (áreas com solo exposto, várzeas e matas de igapós). Pesquisas realizadas no rio Trombetas, na serra de Carajás e no rio Tocantins, no estado do Pará, Brasil, apresentaram resultados positivos após a criação e o teste de modelos preditivos para cada uma das regiões. Novos sítios arqueológicos foram identificados e as análises espaciais inter e intra-sítios, realizadas com o SIG, permitiram criar hipóteses sobre possíveis rotas de circulação e a escolha, por antigos grupos indígenas, de áreas para captação de recursos naturais e assentamento.

Feeding ecology of stream-dwelling Characidae (Osteichthyes: Characiformes) from the upper Tocantins River, Brazil

In this contribution we studied the trophic ecology of four Characidae species from the Cavalo Stream, upper Tocantins River, considering diet overlap and trophic niche breadth. The diet of the four species was composed of adult and immature insects, both autochthonous and allochthonous in origin. Autochthonous items dominated the diet of Moenkhausia dichroura (Kner, 1858), Bryconamericus sp., and Creagrutus atrisignum Myers, 1917. By contrast, allochthonous items were dominant in the diet of Astyanax bimaculatus (Linnaeus, 1758). Trophic niche breadth varied among species, with the highest value recorded for M. dichroura (0.48), followed by Bryconamericus sp. (0.39), A. bimaculatus (0.33) and C. atrisignum (0.29). Similarity analysis revealed two groups with different patterns of food preference. The first group was composed of insectivorous and the second by omnivorous species. The overlap in food items consumed by the four species studied was high. We suggest that resources are not limited in this stream and that competition might not be regulating these populations. This is one more case corroborating the general pattern registered for Tropical environments, where resource partitioning and specialization are responsible by the organization of fish communities.

English

  In this study, we used a portion of mitochondrial cytochrome b to evaluate the current genetic structure of the Hypophthalmus marginatus Valenciennes 1840, from the Tocantins River in the eastern Amazonia. Genetic diversity was measured in two downstream (Abaetetuba and Cametá), and two upstream (Tucuruí and Itupiranga) stocks under influence of the Tucuruí Hydroelectric Dam. Additionally, one stock from the Araguaia River system was included in the analysis. Our findings provide evidence for the existence of reduced levels of genetic diversity in H. marginatus of the Tocantis basin. The pattern of distribution of haplotypes observed in the present study appears to reflect the migratory characteristics of H. marginatus (short distance migratory), suggesting gene flow mainly in the upstream to downstream. Alternatively, presence of rare sequences only in Cametá and Abaetetuba may result from recent mutations, since they differ from connecting haplotypes by only one nucleotide substitution.   Key words: Hydroelectric dam impact, Hypophthalmus marginatus, population genetic structure.

QUEDA DA PRODUTIVIDADE DE PESCADO NO RIO TOCANTINS: A PERCEPÇÃO DOS PESCADORES DE MARABÁ - PARÁ

RESUMO: A ação combinada entre a falta de políticas públicas adequadas para a Amazônia e as alterações do regime hidrológico do rio Tocantins tem provocado o aumento da prática da pesca e afetado a disponibilidade do pescado no Rio Tocantins. A complexidade da organização das relações sociais organizadas às margens do rio Tocantins, leva a discutir as formas de apropriação e manejo dos recursos hídricos, enfoque de âmbito ecológico, refletir também a sobrevivência social e econômica de núcleos e localidades. É neste contexto que este trabalho objetivou mostrar as percepções dos pescadores moradores às margens do rio sobre a produtividade do pescado no rio Tocantins em Marabá. Para tanto, foram aplicados questionários semi-estruturados nas principais comunidades de pescadores moradores da margem esquerda do rio Tocantins na área urbana de Marabá (bairros Francisco Coelho, Santa Rita e Santa Rosa) de forma aleatória. Os pescadores consideraram que a construção da hidrelétrica de Tucuruí foi a principal causa da queda da produtividade de pescado na região, e, além disso, faltam ações do Estado de maneira a qualificar esta atividade de acordo com os interesses locais. PALAVRAS CHAVE: impactos ambientais, organização social, recursos hídricos.

Co-management and Spatial Features Contribute to Secure Fish Abundance and Fishing Yields in Tropical Floodplain Lakes

Empirical data are needed to show the efficacy of co-management, which is regarded as a promising approach to achieve conservation goals. In this study, we addressed the potential influence of fisheries co-management to increase fish abundance and fishing yields in the lower Tocantins River Basin (Brazilian Amazon), downstream from a large dam. We analyzed 590 fish landings (6.7 t of fish) from five fishing villages and 48 fish samples obtained using gillnets (10,378 fish from 101 species) in 12 floodplain lakes in four regions: two with incipient co-management and two unmanaged. The fish species richness did not differ among the regions, but the lakes in the regions that were co-managed had higher fish abundance (biomass and number of individuals) and a higher mean proportion of fish reproducing during the high water season. Fishers had higher catches per unit of effort in the co-managed regions than fishers in the non-managed regions. These results were also influenced by geographic factors (distance and accessibility of lakes), as fish biomass was higher in lakes that were distant from the main river and from the main city in the region. Managers should thus consider strategic selection of the geographic locations of managed sites, even in remote areas. However, the fish biomass sampled in lakes was more related to region than to the lakes’ geographical location. Therefore, co-management has at least partially contributed to increased fish abundance and fishing yields in the studied region, through the protection of an important fish habitat (lakes). We provide empirical evidence that co-management can contribute to the maintenance of fish abundance, sustainability of fisheries, and food security in large tropical rivers impacted by damming.

Revalidation of Saguinus ursula Hoffmannsegg (Primates: Cebidae: Callitrichinae).

In this study, we review the taxonomy of Saguinus niger (É. Geoffroy) and revalidate Saguinus ursula Hoffmannsegg as a distinct species. The revalidation is based on pelage coloration, and the pattern of morphological divergence is corroborated by molecular data. Samples from the east bank of the Tocantins River (S. ursulus) were distinct from specimens of S. niger from the west bank in having mid-dorsal hair with an wide (5.0-55 mm) intermediary band of bright and golden buffy color; long (ca. 23-26 mm) dorsal hair at the inter-scapular region; and naked (not noticeably haired) face, hands and fingers. Saguinus ursulus and S. niger are allopatric, and Tocantins River is putatively acting as an effective barrier for gene flow. A lectotype to S. ursulus from syntypes was designated.

A New Cryptic Species of South American Freshwater Pufferfish of the Genus Colomesus (Tetraodontidae), Based on Both Morphology and DNA Data

The Tetraodontidae are an Acantomorpha fish family with circumglobal distribution composed of 189 species grouped in 19 genera, occurring in seas, estuaries, and rivers between the tropical and temperate regions. Of these, the genus Colomesus is confined to South America, with what have been up to now considered only two species. C. asellus is spread over the entire Amazon, Tocantins-Araguaia drainages, and coastal environments from the Amazon mouth to Venezuela, and is the only freshwater puffers on that continent. C. psittacus is found in coastal marine and brackish water environments from Cuba to the northern coast of South America as far south as to Sergipe in Brazil. In the present contribution we used morphological data along with molecular systematics techniques to investigate the phylogeny and phylogeography of the freshwater pufferfishes of the genus Colomesus. The molecular part is based on a cytochrome C oxidase subunit I dataset constructed from both previously published and newly determined sequences, obtained from specimens collected from three distinct localities in South America. Our results from both molecular and morphological approaches enable us to identify and describe a new Colomesus species from the Tocantins River. We also discuss aspects of the historical biogeography and phylogeography of the South American freshwater pufferfishes, suggesting that it could be more recent than previously expected.

Impacts of hydroelectric dams on alluvial riparian plant communities in eastern Brazilian Amazonian

The major rivers of the Amazon River basin and their biota are threatened by the planned construction of large hydroelectric dams that are expected to have strong impacts on floodplain plant communities. The present study presents forest inventories from three floodplain sites colonized by alluvial riparian vegetation in the Tapajós, Xingu and Tocantins River basins in eastern Amazonian. Results indicate that tree species of the highly specialized alluvial riparian vegetation are clearly distinct among the three river basins, although they are not very distinct from each other and environmental constraints are very similar. With only 6 of 74 species occurring in all three inventories, most tree and shrub species are restricted to only one of the rivers, indicating a high degree of local distribution. Different species occupy similar environmental niches, making these fragile riparian formations highly valuable. Conservation plans must consider species complementarily when decisions are made on where to place floodplain forest conservation units to avoid the irreversible loss of unique alluvial riparian vegetation biodiversity.

Redescription of Phalotris labiomaculatus (Serpentes, Dipsadidae, Elapomorphini), with notes on the taxonomic boundaries within the nasutus group.

Phalotris labiomaculatus Lema, 2002 was described based on a single specimen from Porto Franco, south of the Brazilian state of Maranhão, being rediscovered three years later in Mateiros, a municipality in the north of the state of Tocantins, attesting to its occurrence in the cerrado of both banks of the Tocantins River. The discovery of 28 new specimens from other localities during field expeditions (2009-2011) allowed a redescription of the species, adding new data on meristic and morpho-qualitative traits. These results enable a better diagnosis of intraspecific, ontogenetic and sexual variation, consolidating its taxonomic relationships with other species belonging to the nasutus group. The distribution map of P. labiomaculatus, as well as an identification key to the species of the natusus group, are provided. The type-locality is fixed to the municipality of Porto Franco, state of Maranhão.