Navegando por Assunto "Rio Amazonas"

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Aspecto geoquímicos do material particulado da pluma estuarina do rio Amazonas: fatores que controlam as interações com as águas oceânicas
(Universidade Federal do Pará, 2000-02-10) PEREIRA, Simone Baía; EL-ROBRINI, Maâmar; http://lattes.cnpq.br/5707365981163429; https://orcid.org/0000-0001-7850-1217
The geochemical aspects addressed in this investigation are the determination of the chemical composition of the material in suspension in coastal waters under the influence of the mouth of the Amazon River, indicating the possible location of the source of suspended material, as well as the influences that it suffers along the continent transition -ocean. X-ray diffraction analysis indicated the predominance of kaolinite, illite and quartz clay minerals over the other identified inorganic components, observing the presence of chlorite, sometimes as a subordinate mineral in some samples, sometimes as a trace, and smectite in trace grades, which, like chlorite, is also present as a subordinate mineral. The centesimal mineralogical composition of the particulate material was estimated, associating the analytical results with X-ray diffraction data, using stoichiometric calculation, based on the scientific literature. The results obtained through the stoichiometric calculation confirm the tendency shown by the diffractograms. It is observed that the dominant clay minerals are kaolinite (maximum in 51.19%), associated with high levels of aluminum, distinguishing the dominance of this clay mineral in the sample in which this fact occurs, and illite (maximum in 42.43%) associated At high levels of potassium, when this clay mineral dominates the samples, the presence of iron and titanium colloids was also admitted. The content and nature of the organic matter associated with suspended sediments were evaluated, using elemental analysis for carbon, nitrogen and hydrogen, thermogram records and absorption spectra in the infrared region. In the sediments, organic compounds predominate (clay minerals, silica, iron colloids), with organic matter always having a content below 3.6%. Therefore, in interpreting the records of absorption spectra in the infrared region, the most intense bands are related to the dominant clay minerals in the material, that is, the illite and kaolinite mixture. Bands related to chemical bonds in clay minerals dominate in the infrared spectra. The clear and intense vibration band of the Si-O stretching, which extends from 1200 to 1000 cm-1, with its most significant developments around 1180 and 1034 cm-1, is well representative of structures of the illite and kaolinite types. And there is still a clear band, with weak folds around 950 to 915 cm-1, related to the Al-OH bond; bands around 790-800, 750-780, 640-690 cm-1; or in the range of 400 - 600 cm-1, the intense absorption bands recorded in the range of 4000 - 3400 cm-1, with their various developments, related to the bonds with hydroxyl, –OH, so common in clay minerals and an intense and average band recorded around 1640 cm-1 corresponding to the angular deformation of the HOH bond, a characteristic of constitutive water present in clay minerals. The infrared absorption spectra of humic and fulvic acids from different sources are similar but not identical. The (subtle) differences are the result of brief changes in their compositions. Perhaps the most interesting feature of the spectrum of humic acids is the appearance of intense and broad absorption bands related to the stretching vibrations of the C=O bond of several organic functional groups (carboxylic acids and their derivatives, aldehydes, ketones), in the range from 1709 to 1715 cm-1 and vibrations of aromatic compounds around 1600 to 1613 cm-1. The bands recorded around 1698 to 1701 cm-1 and around 1400 cm-1 indicate the presence of carboxyl and carbonyl groups. The most interesting aspects of the recorded spectra concern the appearance of clear (but weak) absorption bands in the range of 2959-2885 cm-1, attributed to methylene groups –CH2- of hydrocarbons; and the presence of a weak (but clear) band around 1385 cm-1 referring to the carboxyl and/or carbonyl groups. Leading to the conclusion that it is humic material present in organic matter from leaching and drainage of typical Amazonian soils, such as podzolic and latosolic. Elementary organic carbon contents range from 1.27% to 2.05%, while nitrogen contents range from 0.03% to 0.13%. These contents produce high C/N ratios (minimum 12.7% and maximum 68.3%) of material rich in cellulose decomposition products of vegetable origin. The integration of data from the chemical analysis of suspended matter with physical-chemical parameters of coastal waters and the variation in phosphorus levels (minimum of 0.06% to maximum of 0.71%, expressed in P2O5), associated with salinity variation (minimum of 24.31‰ and maximum of 39.19‰), used as limiting parameters, defined the existence of three characteristic zones of origin of suspended material: one predominantly terrigenous, one transitional and one predominantly oceanic biogenic.
Acesso aberto (Open Access)
Campylorhamphus procurvoides successor (Aves: Dendrocolaptidae) is a junior synonym of Campylorhamphus trochilirostris notabilis
(2009-09) PORTES, Carlos Eduardo Bustamante; ALEIXO, Alexandre Luis Padovan
The taxonomy of the genus Campylorhamphus Bertoni, 1901 is still uncertain, with many inconsistent evolutionary patterns implied by current taxonomy. A re-analysis of the type-series of Campylorhamphus procurvoides successor Todd, 1948 revealed that the holotype is indistinguishable from Campylorhamphus trochilirostris notabilis Zimmer, 1934, while the paratypes belonged either to the latter taxon or to a second already named taxon (Campylorhamphus trochilirostris snethlageae Zimmer, 1934), and a third and yet undescribed taxon allied to Campylorhamphus procurvoides. Here, we present statistical analyses of morphological data supporting the synonymization of C. p. successor into C. t. notabilis, the name with priority. Our findings resolve the long-standing controversy related to the distribution of Campylorhamphus procurvoides populations in the várzea habitats of the lower Amazon River.
Acesso aberto (Open Access)
Caracterização morfológica de planícies inundáveis na costa do Amapá: uma análise a partir de modelos digitais de elevação
(Universidade Federal do Pará, 2023-02-22) REIS, Leonardo Nogueira dos; POLIDORE, Laurent
Digital Elevation Models (DEM) consist of the digital representation of elevation values at different points in a specific geographic area. The use of a DEM requires an explicit definition of the physical surface to be modeled, as the term is generic and represents any surface, whether a digital surface model (DSM), which describes the forest canopy and other artificial or natural objects above ground, or a digital terrain model (DTM), which represents altimetric values at ground level. The main products available globally and free of charge, such as the SRTM, are DSM, while many geoscientific studies require ground surface recognition, which is only possible from an DTM. In plains, this problem is accentuated, since the vegetation height, the canopy cover and the errors of the elevation measurement technique can be greater than the real altimetric amplitude of the topographic surface, creating false reliefs and compromising a correct geomorphological interpretation. As an area with extensive vegetation cover, seasonally flooded, difficult to access and extensive periods of precipitation and cloud cover, the Amazon Coastal Zone is challenging for field studies and even for remote sensing analyses. In this context, this study aimed to evaluate and compare the performance of eight DEMs, one DTM obtained from airborne P-band radar and seven DSMs (AW3D30, ASTER GDEM, Copernicus DEM, NASADEM, SRTM, Topodata and an MDS obtained from X-band airborne radar) in the morphological characterization of a floodplain on the Amazon coast. A floodplain on the outskirts of the municipality of Mazagão, in the southern portion of the coast of Amapá, Brazil, was selected as a test area. All DEMs were resampled to the same 30 m mesh size and compared by visual control and statistical analysis based on slope elevation. The behavior of automated extraction from the hydrographic network was also analyzed. The comparison showed that the DTM obtained from P-band radar images was the most consistent with respect to terrain shapes, as it is less sensitive to vegetation. It was also found that even the DTM was not able to detect drainage lines or features corresponding to very small elevation variations. Rather than requiring more refined techniques or better spatial resolutions, which can result in unaffordable operational costs, we suggest that using external 2D data such as satellite imagery or existing databases can provide implicit 3D mapping for watershed modeling. hydrographic surveys in areas where elevations are not accurate enough. The approach was also applied in the detection and characterization of paleodrainages in lowland regions. These features are typically marked by the presence of vegetation on the banks and/or in the center of the paleochannels and record the evolution of river courses throughout the Quaternary. Although DSM are more suitable for this type of analysis, it was possible to verify, with the selection of altimetric points of the DTM, that they are likely to be recognized from the ground surface, although the product error is greater than the height variation. from the margins to the center of the paleochannels.
Acesso aberto (Open Access)
O cenozoico superior do centro-oeste da Bacia do Amazonas: paleobotânica do embasamento cretáceo e evolução do Rio Amazonas
(Universidade Federal do Pará, 2018-11-08) BEZERRA, Isaac Salém Alves Azevedo; NOGUEIRA, Afonso César Rodrigues; http://lattes.cnpq.br/8867836268820998
At the end of the Neogene and during the Quaternary, the development of the Amazon River caused significant paleoenvironmental and geomorphological changes that generated current ladscape at Amazonia. Previous models elaborated on a continental scale were based on data obtained from a drill core carried out on the Atlantic continental shelf, distant 200 km of the Amazon River mouth, suggesting the establishment of this drainage with Andean provenance from the Middle to Upper Miocene. In contrast, studies based on outcrops in the western and central portions of the Amazon have indicated younger ages for this ecosystem, from Pliocene to Quaternary. The sedimentological-stratigraphic study of the fluvial terraces of the Amazon River, exposed in the center-west portion of the Amazon Basin, assisted by luminescence geochronology, allowed to sequence the sedimentation events and discuss the paleoenvironmental and paleogeographic since Late Neogene. The studied Neogene- Quaternary deposits overlies Cretaceous rocks whose sedimentological and paleobotanical study revealed the preservation of impressions and counter-impressions of leaves and other macro-plant remains in pelites interpreted as flood plain and abandoned channel deposits of meandering rivers. The first record of angiosperms in this unit with possible affinities to the families Moraceae, Fagaceae, Malvaceae, Sapindaceae and Anarcadiaceae with appearance from Late Cretaceous, and the family Euphorbiaceae with record starting in the Mid- Cretaceous confirm the Cretaceous age for these rocks. The terraces of the Amazon River informally subdivided into lower and upper units are composed of sand, gravel and clay, organized in finning upward cycles representative of channel filling and overbank deposits. The lower unit was interpreted as a record of the proto-Amazonas, with migration to the east and deposition around 2 Ma. During this stage, the alluvial plain was restricted, preferentially following weakness zones coincident with fractures in the Paleozoic and Cretaceous basement. The climatic oscillations during the Quaternary and the increase of the volume of orographic rains in the headwaters region of the fluvial systems, in the eastern flank of the Andean ridge modified the hydrological regime, amplifying the escarpment erosion. The gradual expansion of the alluvial plain formed a large area of 120 km around 1 Ma to 140 ka, recorded by the upper unit deposits. At this stage, the eastern portion of the Amazon Basin topographically higher restricted the Pleistocene sedimentation in minimum accommodation space. The lower unit deposits are correlate in part to the Miocene-Pliocene deposits of the Amazon Basin, while the upper units are correlate with the Pleistocene deposits of the Solimões and Amazon basins. The dynamics of the construction of the Amazon River valley during the end of the Neogene and Quaternary was influenced by neotectonics (106 yr) and climatic oscillations (104-105 yr). The landscape of the central-eastern portion of the Amazon dominated no Pleistoceno by terra firme in elevated areas was governed by the dynamics of expansion and contraction of the alluvial plain. At the end of the Quaternary, the várzea formed by floodplains within the alluvial plain, which used to occupy a wide area, became increasingly restricted by the continuous processes of fluvial incision during the glacial maximum (18 to 22 ka). The continuous lateral migration of the meandering channel to the north led to the confinement of the channel by the fluvial scarps developed in the Cretaceous basement, which culminated in the current landscape in the Center-East of the Amazon. Testing the reliability and accuracy of some Pleistocene and older OSL ages for Amazon River deposits revealed that are much more minimum ages than buried ages for pre- Quaternary deposits.
Acesso aberto (Open Access)
Composição e biogeografia da avifauna das ilhas Caviana e Mexiana, foz do Rio Amazonas
(Universidade Federal do Pará, 1994-01-14) HENRIQUES, Luiza Magalli Pinto; OREN, David Conway; http://lattes.cnpq.br/5451507856491990
The islands of Caviana and Mexiana, located in the mouth of the Amazon River, are composed of fluvial sediments and well consolidated lands that date from the Terciary and that were separated from the continent by tectonic action at the beginning of the Holocene. The composition of the avifauna of these islands is analized both from the biogeographical and the ecological points of view. I registered 148 bird species for Caviana Island and 183 for Mexiana Island. The discrepancy between the size of the two islands (Caviana is larger than Mexiana) and the number of species observed is due to undersampling of Caviana. However, the analysis of faunal composition demonstrated that Caviana is richer in forest species than is Mexiana. In contrast, Mexiana showed a greater richness of birds of open habitats. These differences suggest that the rising of sea level at the beginning of the Holocene caused the extinction of greater part of the fauna of the understory ou Mexiana. The portions of Mexiana Island with "teso" vegetation were not submerged, maintaining their characteristic avifauna, which is also represented on Marajó Island. To analyse of the distribuitions of 157 species I subdivided the avifauna into seven categorias: widespread distribution in South America (77 species); widespread Amazonian distribution (25); distribution restricted to eastern Amazonia (7); distribution restricted to south of the Amazon River and east of the Tapajós River (3); distribution restricted to várzea (19); widespread distribution in northern Amazonia and absent from the Tocantins-Xingu interfluvium (5); and widespread distribution in Central Brasil (21). I did not find elements restricted to the Tocantins-Xingu interfluvium. This fact is related to ecological rather than historical factors. The pattern related to northern Amazonia can be interpreted as the result of recent dispersal, the system of islands at the mouth of the Amazon, or by the formation of the Purás and Gurupá Arches, which, associated with the lowering of sea level during Pleistocene, established a connection between lhe right and left banks of the Amazon River. The dispersal occurred in both directions, explaining lhe existence of a large number of species and subspecies with distributions restricted to eastern Amazonia, as well as the dispersal of Central Brasilian elements to north of the Amazon River. This last component of the avifauna is a1so related to the expansion of open vegetations, characteristic of Central Brazil, during glacial periods.
Acesso aberto (Open Access)
Composição e variação nictimeral do ictioplâncton no estuário do rio Amazonas, Amapá, Brasil
(Universidade Federal do Pará, 2008-08-29) SILVA, Elke Micheline Anijar da; MELO, Nuno Filipe Alves Correia de; http://lattes.cnpq.br/4989238044542736
The Brazilian North Coast is one of the most productive regions of Brazil and the Amazon River as the main source of nutrients, which explains the great potential for primary production in the region. The main purpose of this study was to determine the composition and nycthemeral variation of ictioplâncton the estuary of the Port of Santana, state of Amapá, Brazil. The water sample was collected to measure subsurface following parameters: electrical conductivity, pH, salinity, turbidity, dissolved oxygen and temperature. The samples were taken, making two cycles of 24 hours in a season sets in the fourth moon rising (Quadrature) and a full moon (Syzygy). The collection of samples was done with a network of plankton, type Bongo with 0,60 m of opening of mouth, 1,50 m in length and aperture of 500 μm. To determine the volume of water was filtered into the network combined with a mechanical flowmeter, the sample was collected and packaged in pots with formalin fixed at 4%. transported to the Laboratory of Aquatic Ecology and Tropical Aquaculture - LECAT, Rural Federal University of the Amazon - where the UFRA ichthyoplankton was identified and quantified at the level of family. 2,776 larvae were quantified, these, 842 were sampled in the collection held in the tide of squaring (crescent moon) and 1,924 larvae in the Tide of sizígia (Full). The larvae of fish identified belonging to seven families (Engraulidae, Gobiidae, Sciaenidae, Tetraodontidae, Eleotridae, Pristigasteridae Clupeidae). The families Clupeidae and Gobiidae occurred only in the tide of squaring, while the families and Pristigasteridae Tetraodontidae occurred only in the tide of sizígia. During the trip by squaring (Crescent Moon) was the most abundant family Engraulidae followed by Sciaenidae and Pristigasteridae. At stations where larvae occurred, the density ranged from 137 larvae/100m³ to 15:30 until 2,859 larvae/100m³ to collect from 12:30 pm for the time of sampling time there is a pattern of distribution of the fish larvae influenced by the period of collection (night and day), with the highest values occur during the day. The high number of larvae registered revealed that area of the estuary of the Amazon river is used as an area of breeding and nursery. There are no significant differences in the composition of ichthyoplankton by changes in the lunar phase.
Acesso aberto (Open Access)
Composição, abundância e pesca da ictiofauna como indicadores do estado de conservação de dois lagos de várzea no baixo Rio Amazonas (Brasil)
(Universidade Federal do Pará, 2010) ALMEIDA, Morgana Carvalho de; ISAAC, Victoria Judith; http://lattes.cnpq.br/3696530797888724
The Amazon floodplain has a rich biodiversity and its characteristics influence the economically and ecologically important natural aquatic resources for the people. On the basis of these information, the objective of this research was to characterize the composition and abundance of ichthyofauna in two floodplain lakes in the Santarem region, and to understand the use I buy fishers in the Piracãoera and Campos fishing communities, in the Urucurituba region, and Barreira and Correio communities in the Tapará region. Samples were taken in the Aramanaí and Curiquara lakes considering the four hydrological periods (rising, flood, low, dry) for the period between July of 2006 and April of 2007. For the fish sampling were used set gillnets batteries. To collect data on catches of fishermen, forms were used that contained information about the characteristics of the fisheries. We caught 10,146 fish, which were distributed in 156 species, 27 families and 8 orders. The most abundant families in number of individuals were Sciaenidae and Loricariidae. In Aramanaí Lake, the Loricaria sp, was the species with the highest CPUAn with 0.02 individuals per m². hour. In terms of CPUAp featured species Potamotrygon motoro, with 0.13 g.m ². hour and Pterygoplichthys pardalis with 0.11 g. m². hour. In Curiquara Lake, the main catch in number of individuals was represented by the Pachypops fourcroi with 0,001 individuals per m² of gillnet. Curiquara and Aramanaí lakes 9 trophic guilds were identified and for both lakes fish piscivores and detritivores showed the largest catch by weight. The average length of individuals caught in the lakes was 20.27 ± 7.53 cm. The highest mean length of individuals was in the flood and lower in the low period. When fishing is practiced by fishermen used a variety of fishing gear devices highlighting the gill netting. The use of gear depends on the environment exploited, target species, and in addition to the season, and there may be combinations of more than one gear during the catch. The average yield of the fisheries in the two regions was 10 kg.fishermen.dia-1. In Urucurituba region the CPUE average was 16kg.fishermen.dia-1, in Tapará was 4.5 kg.fishermen.dia-1. The Urucurituba’s fishermen showed the higher catch volume and fish marketing. These communities are partially fulfilling the rules of the fisheries agreements.
Acesso aberto (Open Access)
Cytogenetic and DNA barcoding reveals high divergence within the trahira, Hoplias malabaricus (Characiformes: Erythrinidae) from the lower Amazon River
(2013-06) MARQUES, Diego Ferreira; SANTOS, Fabíola Araújo dos; SILVA, Simoni Santos da; SAMPAIO, Maria Iracilda da Cunha; RODRIGUES, Luis Reginaldo Ribeiro
Molecular and cytogenetic data have provided evidence of cryptic speciation in the widespread South American trahira, Hoplias malabaricus. In the present study, karyotypes and DNA barcode sequences of specimens from seven populations inhabiting the lower Amazon River were analyzed in order to characterize the levels of genetic divergence within a single karyomorph. All the specimens presented karyotypes with 2n = 40 chromosomes (20m+20sm) that were consistent with the species' C karyomorph. The DNA barcodes revealed six haplogroups, with clear divergence between populations from Brazil and Argentina. The results support the species complex hypothesis and indicate that a single karyomorph of H. malabaricus may harbor more than one species.
Acesso aberto (Open Access)
Descolonizando a cartografia histórica amazônica: representações, fronteiras étnicas e processos de territorialização na Capitania do Pará, Século XVIII
(Universidade Federal do Pará, 2018) CARDOSO, Alanna Souto; ACEVEDO MARIN, Rosa Elizabeth; http://lattes.cnpq.br/0087693866786684
The spaces, territories and territorialities of present-day indigenous peoples of Brazil and of Amazonia has been much researched, especially by anthropology, sociology and geography, but little has been invested in a framework of an (ethno)historic cartography that maps the space of the past of these peoples from a plural perspective and with a dialectic that is in dialogue with time, therefore the tridimensional spatial formation, the space conceived (of representations of space), the space perceived (of spatial practices) and the space lived (the space of representations) with respect to the territories and territorialities that were experienced by these peoples in certain phrases of processes of colonial territorialization through which they had passed, and currently, many disintegrated not only through invaded lands, but also dispersed in the memory of contemporary indigenous peoples, especiallymas “emergent” and resistant communities of caboclo riverside peoples of the Lower Tapajós that since the end of the 1990s have reclaimed their indigenous identities, urging the necessity of a “return trip” in the direction of an ethnohistoric cartography of indigenous peoples of the Colonial Amazon through an interdisciplinary and decolonizing methodology of references, documentation, maps, colonial censuses and travel diaries which anchor the current analysis in the first moment to problematize the indigenous representations portrayed in cartography in the era of conquest and in the maps of inhabitants; still debating the ethno-racial question in the labor market through these spatial practices of of Pombaline management envisaged in the colonial censuses; and in the second part of the thesis inward towards lived territory, on the ethnic borders and in the first two phases of processes of territorialization of the colonial Tapajós valley during the 18th century, indeed shining a light on the historical situations that antecede this century, as well as connections with the present time made at the end of that “trip.”
Acesso aberto (Open Access)
Desenvolvimento de técnicas de filtragem e sua aplicação a dados aeromagnéticos da Bacia Amazônica
(Universidade Federal do Pará, 1976-08) SILVA, João Batista Corrêa da; LOURENÇO, José Seixas
In this thesis two filtering methods were combined in order to enhance some features in an aeromagnetic map such as lineaments and anomalies caused by sources of large proportions. The visual filtering consisted of stereoscopic examination of pairs of maps. The numeric filtering involved the elimination of the undesirable spectral components (noise) and the enhancement of the desired spectral components (signal). Both methods were tested on aeromagnetic maps of the Middle Amazon Basin. All the numeric filtering operations were done in the space domain by convolving the aeromagnetic data with a 13x13 filter matrix. Special attention was paid to the preliminary analysis of the spectrum, as a guide in filter design. The results of the application of each filter was discussed in detail. A further topic also dealt with was basement fault models. The model analysis established a complementary interpretation method to the filtering methods. A structural interpretation of the Middle Amazon Basin's basement was provided. The dominant aeromagnetic trends were E-W, N60°W, N-S, N45°E and N60°E. Two grabens were quite evident. The younger one trends N-S, while the older one strikes N45°E. Two anomalies caused by sources of intermediate and large proportions (15-60km) exhibit remanent magnetization and high values of negative inclination, which shows that the Amazon Basin would be southernmost in the Paleozoic. In performing the integration of aeromagnetic data with other geophysical data avaiIable, the interpretation from other data proved consistent with the aeromagnetic interpretation, illustrating the reliability of the techniques employed in this thesis.
Acesso aberto (Open Access)
Dinâmica espaço-temporal da pesca industrial de camarão-rosa Farfantepenaeus subtilis na plataforma continental do Amazonas
(Universidade Federal do Pará, 2011-05-18) MARTINS, Déborah Elena Galvão; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252; CAMARGO-ZORRO, Mauricio; http://lattes.cnpq.br/5423657235023988
Knowledge of spatial distribution of fishing resources is essential to fisheries management. The southern brown shrimp Farfantepenaeus subtilis (Perez-Farfante, 1967) is an industrial fishing fleet target on the Amazon Continental Shelf. This study aimed to evaluate F. subtilis relative abundance spatial-temporal patterns from commercial fishery data, using Geographic Information System tools. Catch per unit effort (CPUE), used as index of relative abundance, was related to bathymetry, substrate characteristics, Amazon river flow and the oceanographic variables obtained by remote sensing: sea surface temperature and chlorophyll-a concentration. Analyzing substrate characteristics, the commercial shrimp trawls were concentrated at the mottled mud region, where the overlap of environmental factors was crucial for a higher incidence of F. subtilis. In this region, features such as substrate (mud), sedimentation rate (<1 cm.yr-1) and salinity (> 30) are the ideal habitat for F. subtilis. Higher CPUE values were associated with lower temperatures and higher values of chlorophyll-a concentration, which occur at the greatest flow of the Amazon river, during the first six months of the year. It was observed the occurrence of three periods with different levels of production along the year: from February to April, with higher CPUE of southern brown shrimp, from May to July, and August to September, with lower CPUE. The results showed that relative abundance of F. subtilis is not distributed uniformly in space nor in seasonal variation.
Acesso aberto (Open Access)
Diversidade de espécies no complexo Monodelphis brevicaudata (Didelphimorphia:Didelphidae), inferida por dados moleculares e morfológicos
(Universidade Federal do Pará, 2009) PAVAN, Silvia Eliza D´Oliveira; ROSSI, Rogério Vieira; http://lattes.cnpq.br/0447251112059340
Short‐tailed opossums of the Monodelphis revicaudata complex inhabit northern South America, and comprise three described species ‐ M. brevicaudata, M. glirina, and M. palliolata ‐ and two undescribed forms already recognized in prior studies. Species delimitation based solely on morphological features is difficult, and because of that many nominal taxa have been associated with this species complex, and several taxonomic arrangements have been proposed. Previous molecular phylogenetic studies using specimens of this species complex revealed substantial genetic divergence rates. The present study aims to elucidate the systematics of the M. brevicaudata species complex through the analyses of molecular and morphological characters. We performed phylogenetic analyses on two mitochondrial genes (cyt b and 16S), studied the external and cranial morphology, and investigated whether observed genetic variation is congruent with morphological differences. Our morphological results were generally concordant with the molecular results. We recognize nine species in the species complex. M. brevicaudata, M. palliolata, and M. glirina are considered valid species; M. touan is re‐established from the synonymy of M. brevicaudata and two new species are described and named; the species M. domestica proved to be closely related to specimens of the M. brevicaudata complex, and thus are considered as part of that group; we also recognized two new species without formallly naming them; M. maraxina is considered a synonym of M. glirina. Sexual dimorphism is observed in the species, and in two species males showed skulls significantly larger than females. Major rivers seem to have played an important role in generating genetic differentiation and phylogeographical structure of the species. The phylogeographical pattern suggests at least two diversification centers for the group, one in the Guiana shield, comprising species ranging north of the Amazon river, and another in the Brazilian shield, comprising M. glirina and M. domestica.
Acesso aberto (Open Access)
Estruturação morfológica e gênica das populações de Corallus hortulanus (Linnaeus, 1758) (Serpentes, Boidae) ao sul da bacia Amazônica, Brasil
(Universidade Federal do Pará, 2014) DUARTE, Mel de Oliveira; GRAZZIOTIN, Felipe Gobbi; http://lattes.cnpq.br/7181242437810644; PRUDENTE, Ana Lúcia da Costa; http://lattes.cnpq.br/1008924786363328
Corallus hortulanus is a species known to exhibit great variation in color pattern, as well as presenting the greatest geographical and ecological distribution among Neotropical snakes. The aim of this study was to determine the patterns of morphological variation in color and design, verify that these patterns are related to the presence of Amazonian rivers, verify the degree of genetic structure among populations of C. hortulanus throughout its distribution and verify that the major south interfluves of the Amazon basin represent genetically structured populations. For morphologic data were analyzed the color pattern of 125 specimens and for molecular data were generated 103 sequences of COI and 38 of CITB. Six morphotypes were described for populations from south of the Amazon River. It was observed that the rivers of south of the Amazon River showed a mixed pattern, which Tocantins, Xingu and Madeira rivers did not influence the genetic structure, while Purus and Tapajós rivers acted as a geographical barrier for populations of C. hortulanus, and only in one case the genetic structure was found in all analyzes (Purus).
Acesso aberto (Open Access)
Estudo das diferentes formas de fósforo nas águas da plataforma continental do Amazonas
(2007-06) SANTOS, Maria de Lourdes Souza; COSTA, Katia Muniz Pereira da; FEITOSA, Fernando Antonio do Nascimento; BARROS NETO, Benício de
Hydrological samples were collected on the continental shelf of the Amazon river to determine particulate organic and inorganic matter, dissolved organic phosphorus (DOP), phosphate, total particulate phosphorus (TPP), chlorophyll a, temperature, salinity, pH, water transparency, dissolved oxygen (DO) and saturation rate. The objective was to study the forms of DOP, phosphate and TPP. In the euphotic layer, the fluvial discharge from the Amazon river favored the distribution of phosphate, TPP and DOP. In the aphotic layer, the phosphate concentration increased due to the decomposition of DOP and TPP. This increase is due to the absence of photosynthetic processes.
Acesso aberto (Open Access)
Hidrodinâmica, transporte e proveniência sedimentar no baixo rio xingu e sua importância como “Tidal River” amazônico
(Universidade Federal do Pará, 2022-07-14) MEDEIROS FILHO, Lucio Cardoso de; LAFON, Jean Michel; http://lattes.cnpq.br/4507815620234645; ASP NETO, Nils Edvin; http://lattes.cnpq.br/7113886150130994
This research is based on the investigation of the processes (geological and hydrodynamic) that govern the recent evolution of a large tributary of the lower Amazon, the Xingu River. The aim was to investigate its aspects of sedimentary evolution and hydrological flows, from already consolidated data on the filling of its ria and how its patterns of transport and sediment trapping, its seasonal and tidal effects have been established, in addition to understanding the role of the Amazon River as a regulator in the dynamics of its tributary. Hydrodynamic measurements of flow, velocity and water level along with bottom sediment and MPS samples were collected at 3 annual seasons (February, June and November). The results provided support for the investigation of the Xingu-Amazonas interaction and the evolution of the bottom morphology of the lower Xingu. The results suggest a filling of the ria both by the Xingu River, forming a prominent headwater delta, and the Amazon River, where tidal variations transport sediments upstream in the Xingu River. On the other hand, large areas in the central part of the ria indicate muddy sedimentation. Elementar geochemistry allowed us to trace part of the history of sediments and source rocks, together with the analysis of immobile elements (Al, Ti, Zr, Hf, Th) and rare earth elements (REE) because they are poorly fractionated during weathering processes. and they are concentrated in the bottom sediments to the detriment of the dissolved fraction of the rivers. The deposits preserved in the lower Xingu River, despite draining cratonic regions in higher areas, confirm that the bottom material is derived from heterogeneous sources with predominantly intermediate igneous compositions and that they underwent important recycling during fluvial transport. The hydrodynamic modeling allowed to indicate the fluvial discharge as the most relevant forcing for the muddy deposition dynamics in the Xingu estuary. From a numerical model, it was possible to extrapolate the flow and transport dynamics beyond the open boundaries, that is, the central portion of the ria, elucidating the interaction mechanism between river and tidal discharge and the associated sedimentary dynamics. The determination of the amplitudes and phases of the tidal components, whether of purely astronomical origin or resulting from shallow waters, as well as the average level and the hourly discharge proved to be fundamental for the understanding of the governing processes.
Acesso aberto (Open Access)
Model of wetland development of the Amapá coast during the late Holocene
(2010-06) GUIMARÃES, José Tasso Felix; COHEN, Marcelo Cancela Lisboa; FRANÇA, Marlon Carlos; LARA, Rúben José; BEHLING, Hermann
The modern vegetation types, sedimentary sequences, pollen records and radiocarbon dating obtained from three sediment cores from Calçoene Coastal Plain were used to provide a palaeoecological history during the late Holocene of Amapá coastal wetland according to flood regime, sea-level and climatic changes. Based on these records, four phases of vegetation development are presented and they probably reflect the interaction between the flow energy to the sediment accumulation and the brackish/freshwater influence in the vegetation. This work suggests interchanges among time periods characterized by marine and fluvial influence. The longitudinal profile did not reveal the occurrence of mangrove in the sediment deposited around 2100 yr B.P. During the second phase, the mud progressively filled the depressions and tidal channels. The mangrove probably started its development on the channel edge, and the herbaceous field on the elevated sectors. The third phase is characterized by the interruption of mangrove development and the increase of "várzea" vegetation that may be due to the decrease in porewater salinity related to a decrease in marine water influence. The last phase is represented by the mangrove and "várzea" increase. The correlation between current patterns of geobotanical unit distribution and palaeovegetation indicates that mangrove and "várzea" forests are migrating over the herbaceous field on the topographically highest part of the studied coast, which can be related to a relative sea-level rise.
Acesso aberto (Open Access)
Morfotectônica e evolução paleogeográfica da região da Calha do rio Amazonas
(Universidade Federal do Pará, 1997-09-15) BEMERGUY, Ruth Léa; COSTA, João Batista Sena; http://lattes.cnpq.br/0141806217745286
This work constitutes an example of intraplate application of the modern concept of Structural Geomorphology, which characterizes landforms and drainage patterns within the framework of the neotectonics of the Amazon region. The neotectonics conception adopted here comprises the various structural systems, the sedimentary 'sequences, the land systems and the pattern and anomalies of drainage which were developed during the Upper Terciary and Quatemary. Controversy is particularly intensive over the channel of the Amazon river, between the cities of Manaus and Belém, where plains are found in uplifted areas and also a large diversity of drainage patterns and anomalies. The main goal of the work is to establish a correlation between the complex geomorphological patterns and the structures derived from the transcurrent movements of the Miocene-Pliocene and Upper Pleistocene-Holocene. This implies in a revision of the concepts based on morphoclimatic conditions or domain of vertical movements. The scale of the geomorphological problems dictated the methodology, on a regional basis, which led to the characterization of six morphotectonic compartments as follows: Manaus-Nhamundá, Tupinambarana, Baixo Tapajós, Comandai, Gurupá e Marajoara. 1. The Manaus-Nhamundá compartment shows system landforms with hills where remnants of an erosion surface are present; it is found in the sediments of the Alter do Chão Formation and is controlled by compressive structures of the Upper Terciary. The trellis-type drainage pattern dips southeastward and the more important rivers follow NW-SE normal faults of Quatemary age. 2. The Tupinambarana compartment has a NE-SW rectangular shape. It comprises low relief gradients associated to a strong structural control of the drainage seen on the linear channels of rivers, linear borders of lakes and anomalies of the arch- and elbow of capture types which are derived from the NE-SW lineaments connected to less developed E-W lineaments. The NE-SW lineaments are interpreted as dextral strike-slip faults while the E-W lineaments represent normal faults, both as Quatemary age. 3. The Baixo-Tapajós compartment is characterized by relief of various types - cuesta, dome, volcanic and uplifted blocks which are morphostructures in advanced stages of erosion. Relief and drainage show control by two neotectonic systems: NE-SW and ENE-WSW folds of Upper Terciary age which gave rise to a strong relief gradient shown in landform systems with a widespread regional distribution including cuestas and the Monte Alegre dome. The Quaternary structures are defined by triple junctions of normal and strike-slip faults. 4. The Comandai compartment is observed on the northern margin of the Amazon river with cuestas systems, a morphology defined by the channels of the Jaraú river and its tributaries which cut those structures giving a trellis-type pattern.. The other important feature of this compartment is the residual hills system with flat tops at about 300 m and intrenched streams which channels are modelled by structures giving anomalies of the arch- and elbow of capture types. The landform hills forro a planation surface at 100 m with rectilinear slopes giving a dendritic-rectangular pattern of drainage. Structural control of the relief and drainage as well as the anomalies in the channel of the Amazon river are found to be related to the transcurrent branch of the Baixo-Tapajós triple junction. The other interpretation of those structures relates to the origin of the hills to remnants of the Gurupá Arch therefore associated to normal faults of Mesozoic age. 5. The Gurupá compartment shows, as an important feature in the Amazon plain, the archipelago in the mouth of the Amazon river with an anastomotic pattern. Islands here show NE-SW orientation and are rectangular in shape. In the continent, relief is the flat interfluvial surface type in the sandstones of the Alter do Chão Formation and in the sediments of the Barreiras Group. Drainage shows a subdendritic pattern. Tectonic activity is registered since the Mesozoic with NE-SW dextral strike-slip faults along which pull-apart basins were formed. These tectonics were active until the Upper Terciary. The landscape is modelled by dextral strike-slip systems with orientation NE-SW and ENE-WSW normal faults. 6. The Marajoara compartment comprises the Marajó Island and the northeastern region of the State of Pará with estuarine morphology and was subjected to subsidence tectonics since the Mesozoic. NW-SE normal faults were developed during the Upper Terciary and these and dextral strike-slip faults controlled the deposition of the Pirabas-Barreiras sequences. These movements were active still in the Quatemary and explain the coastal landforms. The development of these compartments is not directly related to the evolution of the northern and westem borders of the South-American plate.
Acesso aberto (Open Access)
Mudanças sociais e gestão ecológica em questão: a experiência de Mamirauá
(2012-08) MOURA, Edila Arnaud Ferreira; CASTRO, Edna Maria Ramos de
Study on the social changes involving traditional population after the creation, in 1990, of an environmental conservation unit in the Mid-Solimões River, Brazilian Amazon aimed to conserve an area known as the largest wetland ecosystem in the world. The analysis places local producers in relation to the ecological market and agents of sustainable development. The study covers 49 localities of the Amazon flooded forest, with information obtained between 1991 and 2006. The analysis identifies the social agents who integrate the socio environmental field constructed with social environmental intervention policies.
Acesso aberto (Open Access)
O Neógeno e Pleistoceno da Amazônia Central: Palinoestratigrafia, Paleoambiente e relação com os eventos evolutivos do Rio Amazonas
(Universidade Federal do Pará, 2021-03-19) LIMA JÚNIOR, Walmir de Jesus Sousa; JARAMILLO, Carlos Alberto; NOGUEIRA, Afonso César Rodrigues; http://lattes.cnpq.br/8867836268820998
Outcrop-based facies analysis of 25 m-thick Neogene succession was carried out in the Eastern Solimões Basin, Central Amazonia. The Miocene Solimões Formation includes lake/overbank, suspended-load meandering fluvial channel with subdelta crevasse, and flood plain/crevasse splay deposits, confirming the previously interpreted Pebas-Solimões megawetland system. The Upper Pleistocene Içá Formation unconformably overlies the Solimões Formation and comprises mixed load to bedload meandering fluvial channel and floodplain deposits. The Solimões Formation's palynostratigraphy was carried in this exposed succession and a drill core (196-291 m), generally in organic matter-rich mudrock. The occurrence of exclusively continental fossils associated with phytoclasts and freshwater algae such as Ovoidites confirm the wetland setting restricted to Western Amazonia. Monoporopollenites annuulatus and other grasses indicate an oscillation between shrub and tree phases linked to dry and humid interval fluctuations. The upper Miocene-Pliocene ages for the Solimões Formation obtained since amplitudes zones identified mainly Crassoretitriletes vanraadshovenii, Echiperiporites akanthos, Echiperiporites stelae, Fenestrites spinosus, Psilastephanoporites tesseroporus, Grimsdalea magnaclavata, and Alnipollenites verus. The first appearance of Alnipollenites verus is modified for the Miocene. Reworked palynomorphs found in this succession indicate autocyclic processes related to the environmental dynamic, while acritarchs indicate erosion of Paleozoic source areas. The Andean tectonics affected Central Amazonia dramatically, causing the progressive uplift of the Solimões Basin and the emergence and demise of the Pebas-Solimões mega-wetland succession. This progradation event was amplified by the expressive sea-level fall in the middle-Tortonian (11-8 Ma), resulting in the Andean Amazon River's onset. The generated unconformity resulted in a gap and bypass sediment of ~ 9,5 Ma. Only in the Late Pleistocene, the Solimões Basin subsided, causing the implantation of a mixed- to bedload meandering system that represents the sedimentation restart of the Amazon River in the Central Amazonia.
Acesso aberto (Open Access)
Radar-observed spatial and temporal rainfall variability near the Tapajós-Amazon confluence
(Universidade Federal do Pará, 2014-12) COHEN, Júlia Clarinda Paiva; FIZJARRALD, David Roy; D'OLIVEIRA, Flávio Augusto Farias; SARAIVA, Ivan; BARBOSA, Illelson Rafael da Silva; GANDU, Adilson Wagner; KUHN, Paulo Afonso Fischer
Standard Amazonian rainfall climatologies rely on stations preferentially located near river margins. River breeze circulations that tend to suppress afternoon rainfall near the river and enhance it inland are not typically considered when reporting results. Previous studies found surprising nocturnal rainfall maxima near the rivers in some locations. We examine spatial and temporal rainfall variability in the Santarém region of the Tapajós-Amazon confluence, seeking to describe the importance of breeze effects on afternoon precipitation and defining the areal extent of nocturnal rainfall maxima.We used three years of mean S band radar reflectivity from Santarém airport with a Z-R relationship appropriate for tropical convective conditions. These data were complemented by TRMM satellite rainfall estimates. Nocturnal rainfall was enhanced along the Amazon River, consistent with the hypothesis that these are associated with the passage of instability lines, perhaps enhanced by local channeling and by land breeze convergence. In the daytime, two rainfall bands appear in mean results, along the east bank of the Tapajós River and to the south of the Amazon River, respectively.