Tectonic history and the biogeography of the freshwater fishes from the coastal drainages of eastern Brazil: an example of faunal evolution associated with a divergent continental margin

As drenagens costeiras do leste do Brasil correspondem a áreas de grande significado biogeográfico, apresentando um alto grau de endemismo em sua fauna de peixes. Padrões filogenéticos sugerem uma relação próxima entre os rios que correm para o Atlântico a os adjacentes das terras altas do escudo cristalino. Entretanto, pouco tem sido dito sobre a dinâmica dos processos geológicos relacionados aos eventos cladogenéticos entre estas áreas. Padrões de distribuição e filogenéticos sugerem uma íntima associação com a história geológica da margem continental passiva da América do Sul, desde o Cretáceo aos dias atuais. Soerguimentos macrodômicos, rifteamento, movimentos verticais entre blocos falhados e o recuo erosivo da margem leste sul-americana são considerados como as principais forças geológicas atuando sobre a distribuição da ictiofauna de água doce nestas áreas. A atividade tectônica associada à ruptura do Gondwana e separação da América do Sul e África criou seis megadomos que são responsáveis por configurar a maior parte do atual curso das principais bacias hidrográficas do escudo cristalino. Com exceção das bacias localizadas às margens de tais megadomos, estes rios desenvolveram longos e sinuosos circuitos sobre o antigo escudo cristalino brasileiro antes de desaguarem no então recentemente aberto Oceano Atlântico. Eventos cladogenéticos iniciais entre drenagens de terras altas do escudo cristalino e tributários do Atlântico podem estar associados com processos vicariantes desta fase inicial, e alguns táxons antigos, basais, grupos-irmão de táxons muito inclusivos e de ampla distribuição são encontrados nestas bacias hidrográficas. Mais tarde, a denudação erosiva generalizada resultou em um ajuste isostático da margem leste da plataforma. Tal ajuste, concomitantemente a reativações de antigas zonas de falha, resultou em movimentos verticais entre blocos falhados, dando origem, no sudeste do Brasil, a bacias tafrogênicas. Tais bacias, como a de Taubaté, São Paulo, Curitiba e Volta Redonda, entre outras, capturaram drenagens e fauna de terras altas adjacentes. Os peixes fósseis da Formação Tremembé (Eoceno-Oligoceno da Bacia de Taubaté) exemplificam este processo. Outros sistemas tafrogênicos de idade Terciária foram também identificados em outros segmentos da margem continental Atlântica, como na Província Borborema, no NE do Brasil, com marcada influência sobre o padrão de drenagem. Ao mesmo tempo, o recuo erosivo da margem leste da plataforma capturou sucessivamente rios de planalto, os quais se tornaram tributários atlânticos, evoluindo associados aos principais sistemas de falha. A natureza continuada destes processos explica os padrões filogenéticos e de distribuição miscigenados entre os tributários atlânticos e as terras altas do escudo cristalino adjacente, especialmente na margem sudeste do continente, representados por sucessivos, cada vez menos inclusivos, grupos irmãos, associados a eventos cladogenéticos desde o final do Cretáceo ao presente.

Microlepidogaster discus, a new species of Hypoptopomatinae (Siluriformes: Loricariidae) from the rio Jequitinhonha basin, southeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Landscape and soil regionalization in southern Brazilian Amazon and contiguous areas: methodology and relevance for ecological studies

Soils of a large tropical area with differentiated landscapes cannot be treated uniformly for ecological applications. We intend to develop a framework based on physiography that can be used in regional applications. The study region occupies more than 1.1 million km² and is located at the junction of the savanna region of Central Brazil and the Amazon forest. It includes a portion of the high sedimentary Central Brazil plateau and large areas of mostly peneplained crystalline shield on the border of the wide inner-Amazon low sedimentary plain. A first broad subdivision was made into landscape regions followed by a more detailed subdivision into soil regions. Mapping information was extracted from soil survey maps at scales of 1:250000-1:500000. Soil units were integrated within a homogenized legend using a set of selected attributes such as taxonomic term, the texture of the B horizon and the associated vegetation. For each region, a detailed inventory of the soil units with their area distribution was elaborated. Ten landscape regions and twenty-four soil regions were recognized and delineated. Soil cover of a region is normally characterized by a cluster composed of many soil units. Soil diversity is comparable in the landscape and the soil regions. Composition of the soil cover is quantitatively expressed in terms of area extension of the soil units. Such geographic divisions characterized by grouping soil units and their spatial estimates must be used for regional ecological applications.

Biogeography of Glandulocaudinae (Teleostei : Characiformes : Characidae) revisited: phylogenetic patterns, historical geology and genetic connectivity

The biogeography of the Glandulocaudinae ( former Glandulocaudini) is reviewed. The major pattern of diversification presented by this group of freshwater fishes can be clearly associated to the main aspects of the tectonic evolution of the southern portion of the Cis-Andean South American Platform. The phylogenetic relationships within the group suggest that the clade represented by Lophiobrycon is the sister-group of the more derived clade represented by the genus Glandulocauda and Mimagoniates. Lophiobrycon and Glandulocauda occur in areas of the ancient crystalline shield of southeastern Brazil and their present allopatric distribution is probably due to relict survival and tectonic vicariant events. Populations of Glandulocauda melanogenys are found in contiguous drainages in presently isolated upper parts of the Tiete, Guaratuba, Itatinga, and Ribeira de Iguape basins and this pattern of distribution is probably the result of river capture caused by tectonic processes that affected a large area in eastern and southeastern Brazil. The species of Mimagoniates are predominantly distributed along the eastern and southeastern coastal areas, but M. microlepis is additionally found in the rio Iguacu and Tibagi basins. Mimagoniates barberi occurs in both SW margin of the upper rio Parana basin and the lower Paraguay and Mimagoniates sp. occurs in the upper Paraguay river basin. Tectonic activations of the Continental Rift of Southeastern Brazil along the eastern margin of the Upper Parana basin promoted population fragmentation responsible of the present day distribution presented by Glandulocauda melanogenys. We hypothesize that occurrence of Mimagoniates along the lowland area around the Parana basin was due to a single or a multiple fragmentation of populations along the W-SW border of the upper Parana Basin, probably due to the major tectonic origin of the Chaco-Pantanal wetland foreland basins since the Miocene as well as Cenozoic tectonic activity along the borders of the upper Parana basin, such as in the eastern Paraguay, in the Asuncion Rift. Distributional pattern of Mimagoniates suggests that its initial diversification may be related to the tectonic evolution of the Chaco-Pantanal foreland basin system and a minimum age of 2.5 M.Y are proposed for this monophyletic group. Previous hypotheses on sea level fluctuations of the late Quaternary as being the main causal mechanism promoting cladogenesis and speciation of the group are critically reviewed. Phylogeographic studies based on molecular data indicate significant differences among the isolated populations of M. microlepis. These findings suggest that a much longer period of time and a paleogeographic landscape configuration of the Brazilian southeastern coastal region explain the present observed phylogenetic and biogeographic patterns.

Amazon landforms and soils in relation to biological diversity

Thirteen main landform units are distinguished for the whole of the forested Amazon region, each with its specific soil pattern and vegetation structure. These landform-soil-vegetation units are delineated on a small-scale map and illustrated by a schematic cross-section. Floristic diversity of the gamma type is to be highest on the steepland-and-valley complexes of the Andean fringe, on the crystalline shield uplands, on the inselberg complexes, and on the eutric variant of the western sedimentary plains. Endemism is expected to be highest on the sandy plains, and parts of the table lands and inselberg complexes. Speciation, linked to the concept of forest refuge areas, is likely to be highest on the sandstone table lands, on the stretches of Amazon planalto, and in the areas of relict valleys, in view of the prolonged geomorphological stability of these units.

Morphology and surface texture of quartz grains from ODP Site 105-645

The shapes and surface textures of sand-sized quartz grains from the sediments cored at Site 645 in southern Baffin Bay during ODP Leg 105 were studied to characterize the terrigenous materials and the settling processes involved in the deposition of these sediments. Here, we show a homogeneous sand fraction that results from mixing grains from various provenances. The characteristics inherited from terrestrial processes (varying degrees of wear; fluviatile, aeolian, and diagenetic features) dominate the characteristics that result from evolution in a high-energy marine environment. Thus, the influence of the last stage of sedimentation in a deep-marine environment was difficult to distinguish. However, fluctuations in the relative proportions of particular features reveal that the terrigenous material derived from sedimentary formations of Baffin Island and East Greenland or from direct abrasion of the crystalline shield, which changed through time as the dominant settling processes evolved. In particular, this study confirms the onset of major ice rafting as old as late Miocene.

Floristic diversity of two crystalline rocky outcrops in the Brazilian northeast semi-arid region

Floristic composition and structure of vegetation were studied in two rocky outcrop areas in the semi-arid region of northeastern Brazil. From April 2007 to September 2008, 18 monthly field trips were carried out. Vascular plants were randomly collected throughout the outcrop areas. For structural analysis, 30 plots of 1 × 1 m were set in the vegetation islands. The checklist presented combines 211 species (69 families and 168 genera), although only 56 species were collected in the plots. Fabaceae (18 spp.; 8.5%), Asteraceae (17 spp.; 8%), Orchidaceae (13 spp.; 6.1%), Euphorbiaceae (13 spp.; 6.1%), Bromeliaceae (10 spp.; 4.7%), and Poaceae (eight spp.; 3.8%) are the richest families. Overall, 1,792 shrub and herbaceous specimens were counted in the plots. The Shannon-Wiener (H) diversity index values were 2.572 and 2.547 nats individual-1. The species that presented the highest absolute abundance values (number of plants) had low frequencies in the plots and vice-versa. The biological spectrum had a high proportion of phanerophytes and therophytes, followed by cryptophytes, chamaephytes, and hemicryptophytes. The studied flora shares floristic components similar to other rocky outcrop areas of the semi-arid region in northeastern Brazil, including in relation to dominant groups in the vegetation structure.

Analysis and risk estimates to workers of Brazilian granitic industries and sandblasters exposed to respirable crystalline silica and natural radionuclides

Occupational exposure to respirable crystalline silica and to radiation emitted by natural radionuclides present both in rocks and sands was studied in the Brazilian extractive process and granite product manufacture. Respirable airborne dust samples were collected in working environments, where workers perform different tasks with distinct commercial granites types, and also in places where sandblasters work with sands from different origins. The free crystalline silica contents were determined using X-ray diffraction of the respirable particulate fraction of each sample. Dust samples from granite cutting and sandblasting ambient had the natural radionuclides concentrations measured by gamma spectrometry. Dust concentrations in the workplaces were quite variable, reaching values up to 10 times higher than the respirable particle mass threshold limit value (TLV) set by the American Conference for Governmental Industrial Hygienists of 3 mg m(-3). Also the free crystalline silica concentrations were high. reaching values up to 48 times the TLV of 0.025 mg m(-3). Additionally, our results suggest that the risk of radiation-induced cancer in the granite or marble industries is negligible. However, the combined exposure to dust, gamma radiation, and radon daughter products could result in the enhancement of lung cancer risks associated to sandblasting activities. (C) 2010 Elsevier Ltd. All rights reserved.

New species of pyrrhulina (Ostariophysi: Characiformes: Lebiasinidae) from the brazilian shield, with comments on a putative monophyletic group of species in the genus

Pyrrhulina marilynae, new species, is described. The new species can be distinguished among congeners mainly by pre-senting a conspicuous, dark, zigzag shaped primary stripe, extending to distal end of median caudal-fin rays, reduction of the number of precaudal vertebrae, absence of postcleithrum 2, and nine principal rays on caudal-fin dorsal lobe. The pu-tative relationship of the new species with Pyrrhulina australis, P. vittata and P. zigzag, three small-sized species of the genus, is discussed. Copyright © 2013 Magnolia Press.

The Brazilian Experience With the Use of the Shield Wire Line Technology (SWL) for Energy Distribution

This paper presents an analysis of the impact of the lightning overvoltages on the operational performance of the energized shield wire line technology (SWL) implemented in two locations of the State of Rondonia, Brazil. The analysis covers the periods of 1996 to 2000 (SWL Jaru) and 1997 to 2002 (SWL Itapua do Oeste), and shows that lightning is responsible for most of the system outages. The paper describes the satisfactory results achieved with the system, showing that the isolation and energization of the shield wires does not deteriorate the lightning performance of the 230 kV transmission lines. Comparisons between the performances of the SWL technology, conventional 34.5 kV lines, and thermal power plants in operation in the same region are also presented. The results demonstrate the technical and economical viability of the SWL technology and show that its application can lead to a postponement of investments.

Three new species of Lebiasina (Characiformes: Lebiasinidae) from the Brazilian Shield border at Serra do Cachimbo, Para, Brazil

Lebiasina marilynae n. sp., L. melanoguttata n. sp., and L. minuta n. sp. are described from the headwaters of the rio Curua in Serra do Cachimbo, Para, Brazil, and represent the only members of the Lebiasininae in the Brazilian Shied, so far. A close relationship among these species is proposed based on: I) the presence of a pair of foramina through which the rain us palatinus of the facial nerve passes, a modification unique in Lebiasinidae and apparently in the Characiformes, 2) the enlargement of the extrascapular bone, 3) the absence of the secondary stripe, and 4) the nearly equal length of caudal-fin lobes. Lebiasina marilynae additionally differs from all congeners in having the primary stripe extending from the tip of the snout to the distal border of the caudal-fin peduncle, the possession of two series of dark blotches parallel to the primary stripe, and a rounded dorsal surface of the mesethmoid. Lebiasina melanoguttata and Lebiasina minuta additionally differ from all congeners in the absence of the primary stripe and the caudal blotch, and the presence of three longitudinal series of dark blotches at the base of the scales of series 3-5. Lebiasina melanoguttata differs from Lebiasina minuta in the absence of a dark blotch at the base of the median rays of the dorsal fin, second infrapharyngobranchial bearing conical teeth, the reddish overall coloration of the eye and fins, and the dark blotches never coalescing (vs. dark dorsal-fin blotch present; the second infrapharyngobranchial being edentulous; dark, olive green eyes, and the yellowish overall color of body and fins; and the dark blotches of longitudinal series 3 and 4 coalescing where scales of adjacent longitudinal series overlap). The occurrence of species of the Lebiasininae on the Brazilian Shield is discussed, and the distribution pattern of the species described herein is compared to that of other endemic species of the Serra do Cachimbo, a highly biodiverse area isolated from the rest of the Amazon basin.

Three new species of Lebiasina (Characiformes: Lebiasinidae) from the Brazilian shield border at Serra do Cachimbo, Pará, Brazil

Lebiasina marilynae n. sp., L. melanoguttata n. sp., and L. minuta n. sp. are described from the headwaters of the rio Curuá, in Serra do Cachimbo, Pará, Brazil, and represent the only members of the Lebiasininae in the Brazilian Shied, so far. A close relationship among these species is proposed based on: 1) the presence of a pair of foramina through which the ramus palatinus of the facial nerve passes, a modification unique in Lebiasinidae and apparently in the Characiformes, 2) the enlargement of the extrascapular bone, 3) the absence of the secondary stripe, and 4) the nearly equal length of caudal-fin lobes. Lebiasina marilynae additionally differs from all congeners in having the primary stripe extending from the tip of the snout to the distal border of the caudal-fin peduncle, the possession of two series of dark blotches parallel to the primary stripe, and a rounded dorsal surface of the mesethmoid. Lebiasina melanoguttata and Lebiasina minuta additionally differ from all congeners in the absence of the primary stripe and the caudal blotch, and the presence of three longitudinal series of dark blotches at the base of the scales of series 3-5. Lebiasina melanoguttata differs from Lebiasina minuta in the absence of a dark blotch at the base of the median rays of the dorsal fin, second infrapharyngobranchial bearing conical teeth, the reddish overall coloration of the eye and fins, and the dark blotches never coalescing (vs. dark dorsal-fin blotch present; the second infrapharyngobranchial being edentulous; dark, olive green eyes, and the yellowish overall color of body and fins; and the dark blotches of longitudinal series 3 and 4 coalescing where scales of adjacent longitudinal series overlap). The occurrence of species of the Lebiasininae on the Brazilian Shield is discussed, and the distribution pattern of the species described herein is compared to that of other endemic species of the Serra do Cachimbo, a highly biodiverse area isolated from the rest of the Amazon basin.

The role of quantum confinement and crystalline structure on excitonic lifetimes in silicon nanoclusters

The emission energy dependence of the photoluminescence (PL) decay rate at room temperature has been studied in Si nanoclusters (Si-ncl) embedded in Si oxide matrices obtained by thermal annealing of substoichiometric Si oxide layers Si(y)O(1-y), y=(0.36,0.39,0.42), at various annealing temperatures (T(a)) and gas atmospheres. Raman scattering measurements give evidence for the formation of amorphous Si-ncl at T(a)=900 degrees C and of crystalline Si-ncl for T(a)=1000 degrees C and 1100 degrees C. For T(a)=1100 degrees C, the energy dispersion of the PL decay rate does not depend on sample fabrication conditions and follows previously reported behavior. For lower T(a), the rate becomes dependent on fabrication conditions and less energy dispersive. The effects are attributed to exciton localization and decoherence leading to the suppression of quantum confinement and the enhancement of nonradiative recombination in disordered and amorphous Si-ncl. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3457900]

Surface effects in the magnetic properties of crystalline 3 nm ferrite nanoparticles chemically synthesized

We have systematically studied the magnetic properties of ferrite nanoparticles with 3, 7, and 11 nm of diameter with very narrow grain size distributions. Samples were prepared by the thermal decomposition of Fe (acac)(3) in the presence of surfactants giving nanoparticles covered by oleic acid. High resolution transmission electron microscopy (HRTEM) images and XRD diffraction patterns confirms that all samples are composed by crystalline nanoparticles with the spinel structure expected for the iron ferrite. ac and dc magnetization measurements, as well in-field Mossbauer spectroscopy, indicate that the magnetic properties of nanoparticles with 11 and 7 nm are close to those expected for a monodomain, presenting large M(S) (close to the magnetite bulk). Despite the crystalline structure observed in HRTEM images, the nanoparticles with 3 nm are composed by a magnetically ordered region (core) and a surface region that presents a different magnetic order and it contains about 66% of Fe atoms. The high saturation and irreversibility fields in the M(H) loops of the particles with 3 nm together with the misalignment at 120 kOe in the in-field Mossbauer spectrum of surface component indicate a high surface anisotropy for the surface atoms, which is not observed for the core. For T < 10 K, we observe an increase in the susceptibility and of the magnetization for former sample, indicating that surface moments tend to align with applied field increasing the magnetic core size. (C) 2010 American Institute of Physics. [doi:10.1063/1.3514585]

Characterization and greenhouse evaluation of Brazilian calcined nonapatite phosphate rocks for rice

Little information is available on the agronomic effectiveness of calcined nonapatite phosphate rock (PR) sources containing crandallite minerals in the form of Ca-Fe-Al-P for flooded and upland rice (Oryza sativa L.). We conducted laboratory and greenhouse studies to (i) characterize the mineralogical composition, (ii) investigate the solubility and dissolution behavior, and (iii) evaluate the agronomic effectiveness of two nonapatite PR sources (Juquia and Sapucaia) from Brazil and compared them with (i) a highly reactive Gafsa PR (Tunisia) containing apatite in the form of Ca-P and (ii) a reference water-soluble triple superphosphate (TSP) for flooded and upland rice. After calcination at 500 degrees C for 4 h, the solubility of Juquia PR and Sapucaia PR in neutral ammonium citrate (NAC) significantly increased from almost nil to a maximum of 39.3 and 114 g P kg(-1), respectively. X-ray diffraction showed that crystalline crandallite mineral was transformed to an amophorus form after calcination. The solubility behavior of the two calcined PR sources followed the same trend as Gafsa PR, that is, P release decreased with increasing equilibrium pH in the 0.01 M KCl solution (PH 3.0-8.0). At PH 3, the solubility followed: Gafsa PR > calcined Sapucaia PR > calcined Juquia PR. No P release was detected from any of the PR sources at pH >= 5.0 in the solution, indicating the Ca-P characteristic of the Ca-Fe-Al-P mineral controlled P dissolution of the calcined PR. Without calcination, both Juquia PR and Sapucaia PR were totally ineffective for upland rice grown on a Hiwassee clay loam (fine, kaolinitic, thermic Rhodic Kanhapludult) with pH 5.4 whereas a significant P response was observed with the calcined PR samples. For flooded rice grown on Hiwassee soil, the calcined Juquia PR and Sapucaia PR were 66 and 72%, respectively, as effective as TSP in increasing rice grain yield whereas Gafsa PR was ineffective. For upland rice grown on the unlimed soil, Gafsa PR was as effective as TSP in increasing rice grain yield whereas calcined Juquia PR and Sapucaia PR were 89 and 83% of TSP. The effectiveness of Gafsa PR was reduced to 0% after the soil was limed to pH 7.0 whereas the two calcined PR sources were reduced to 49% of TSP. Soil available P extracted by iron oxide impregnated filter paper (Pi test) or anion-exchange resin after rice harvest correlated well with P uptake by rice grain for flooded and upland rice.