987 resultados para Atlantic, (South)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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This work presents analyses of the atmospheric conditions and the hindcast of the surface wave field when six extratropical cyclones formed and displaced over the South Atlantic Ocean (10degreesN, 60degreesS; 75degreesW, 15degreesE) between April and September 1999. These events caused high sea waves associated with hazardous conditions along the south and southeast coast of Brazil. The meteorological composite fields for these cyclones show a strong near-surface wind velocity (up to 14 m s(-1)) during its mature phase. The sea-state wave hindcast was obtained using a third-generation wave model forced by the 10-m above ground level wind field from the National Centers for Environmental Prediction-National Center for Atmospheric Research reanalysis dataset. Closer to the south and southeast Brazilian coast, the hindcast results showed significant wave heights of up to 5 m in some of the events. The wave hindcast results for the significant wave height were compared against satellite altimeter data at 6 h intervals. The statistical index showed a systematic underestimation of the significant wave height by 0.5 m. The correlation between wave hindcast and altimeter measurements was greater than 90%, showing a good phase reproduction by the wave model.
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The population structure and reproductive biology of Mustelus schmitti was analysed during autumn (1994, 1995) and spring (1994) in the Rio dc la Plata occanic front. The samples consisted mainly of a adult males and immature females, indicating that nursery areas are Situated elsewhere. In autumn, the highest female densities occurred between 36 degrees S and 35 degrees S, with densities decreasing further south, and high male densities occurred over all latitudes of the study area. In Spring, both Sexes occurred north of latitude 36 degrees 30 degrees S. Males attained Maturity at. 59 cm total length (TL), and females at 72 cmTL Litter size varied From one to ten in spring and two to nine in autumn, With embryos ranging from 9 to 26 cm and 7 to 26 cm TL respcctivcly the mean TL of embryos was significantly higher in spring (22 cm), suggesting that parturition Occurs ill late spring and summer. Litter size was found to Increase with female TL..
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Eight embryonic thresher sharks Alopias vulpinus (53.9-124 cm total length) were collected from two females caught by commercial longline off southern Brazil in September and November 2004. Morphometric measurements are provided. (c) 2006 the Authors.
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The extent of racemization of aspartic acid (Asp) has been used to estimate the ages of 9 shells of the epifaunal calcitic brachiopod Bouchardia rosea and 9 shells of the infaunal aragonitic bivalve Semele casali. Both taxa were collected concurrently from the same sites at depths of 10 m and 30 m off the coast of Brazil. Asp D/L values show an excellent correlation with radiocarbon age at both sites and for both taxa (r(Site)(2) (9) (B. rosea) = 0.97 r(Site)(2) (1) (B.) (rosea) = 0.997, r(Site)(2) (9) (S.) (casali) = 0.9998, r(2) (Site) (1) (S.casali) = 0.93). The Asp ratios plotted against reservoir-corrected AMS radiocarbon ages over the time span of multiple millennia can thus be used to develop reliable and precise geochronologies not only for aragonitic mollusks (widely used for dating previously), but also for calcitic brachiopods. At each collection site, Bouchardia specimens display consistently higher D/L values than specimens of Semele. Thermal differences between sites are also notable and in agreement with theoretical expectations, as extents of racemization for both taxa are greater at the warmer, shallower site than at the cooler, deeper one. In late Holocene marine settings, concurrent time series of aragonitic and calcitic shells can be assembled using Asp racemization dating, and parallel multi-centennial to multi-millennial records can be developed simultaneously for multiple biomineral systems. (c) 2006 University of Washington. All rights reserved.
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Rhynchonelliform brachiopods were diverse and often dominant benthos of tropical seas in the Paleozoic. In contrast, they are believed to be rare in open habitats of modern oceans, especially at low latitudes. This study documents numerous occurrences of rhynchonelliform brachiopods on a modern tropical shelf, particularly in areas influenced by upwelling. Extensive sampling of the outer shelf and coastal bays of the Southeast Brazilian Bight revealed dense populations of terebratulid brachiopods (>10(3) individuals /m(2) of seafloor) between 24 and 26 S. on the outer shelf, brachiopods are more abundant than bivalves and gastropods combined. However, brachiopod diversity is low: only four species belonging to the genera Bouchardia, Terebratulina, Argyrotheca, and Platidia were identified among over 16000 examined specimens. Brachiopods occur preferentially on carbonate bottoms and include two substrate-related associations: Bouchardia (40-70% CaCO3, weight content) and Terebratulina-Argyrotheca (70-95% CaCO3). All four species display a broad bathymetric range that contrasts with a narrow depth tolerance postulated for many Paleozoic rhynchonelliforms. The most abundant populations occur in the depth range between 100 and 200 m, and coincide with zones of shelf-break upwelling, where relatively colder and nutrient-rich water masses of the South Atlantic Central Water are brought upward by cyclonic meanders of the South Brazil Current (a western boundary current that flows poleward along the coast of Brazil). This is consistent with previous biological and paleontological studies that suggest upwelling may play a role in sustaining brachiopod-dominated benthic associations. The presence of abundant brachiopods in the open habitats of the tropical shelf of the western South Atlantic contrasts with current understanding of their latitudinal distribution and points to major gaps in our knowledge of their present-day biogeography. The ecological importance of rhynchonelliform brachiopods in modern oceans and their role as producers of biogenic sedimentary particles may be underestimated.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Five species of smooth-hound sharks genus Mustelus (Family Triakidae) are know in the western South Atlantic, as follows: Mustelus canis (Mitchell 1815); Mustelus fasciatus (Garman 1913); Mustelus higmani Springer & Lowe 1963; Mustelus norrisi Springer 1939; and Mustelus schmitti Springer 1939. In the present paper, new data on the anatomy, morphometrics and meristic characters are given. Taxonomic aspects and comparison between the species are discussed. Most general body morphologic measurements and proportions are useless as a tool for species identification, since many of them show remarkable intraspecific variations. Head proportions and structures related seem to be a more adequate procedure to identify the species of Mustelus. The labial folds proportions, internasal distance and orbit diameter were the most useful character to separate the western South Atlantic species. The buccopharingeal pattern of denticles as well as tooth counts not was useful to distinguish the Mustelus species from western South Atlantic adequately, due great intraspecific variation.
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To study the production and propagation of fast secondaries particles in the atmosphere, data collected during eleven quiet-time balloon flights are analysed. Comparisons of these data with those obtained in different geomagnetic rigidity regions permit to estimate the contributions of the proton and electron components in the measured intensities. Derivations of this last component in the «upward» and «downward» moving electrons fluxes indicate that in the anomaly region a fraction of these particles, produced by the primary protons, are leaving the atmosphere and will not return to the Earth. © 1991 Società Italiana di Fisica.
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Apatite fission-track analysis was used for the determination of thermal histories and ages in Precambrian areas of southeast Brazil. Together with geological and geomorphologic information, these ages enable us to quantify the thermal histories and timing of Mesozoic and Cenozoic epirogenic and tectonic processes. The collected samples are from different geomorphologic blocks: the high Mantiqueira mountain range (HMMR) with altitude above 1000 m, the low Mantiqueira mountain range (LMMR) under 1000 m, the Serra do Mar mountain range (SMMR), the Jundiá and Atlantic Plateaus, and the coastline, all of which have distinct thermal histories. During the Aptian (∼120 Ma), there was an uplift of the HMMR, coincident with opening of the south Atlantic Ocean. Its thermal history indicates heating (from ∼60 to∼80 °C) until the Paleocene, when rocks currently exposed in the LMMR reached temperatures of ∼100 °C. In this period, the Serra do Mar rift system and the Japi erosion surface were formed. The relief records the latter. During the Late Cretaceous, the SMMR was uplifted and probably linked to its origin; in the Tertiary, it experienced heating from ∼60 to ∼90 °C, then cooling that extends to the present. The SMMR, LMMR, and HMMR were reactivated mainly in the Paleocene, and the coastline during the Paleogene. These processes are reflected in the sedimentary sequences and discordances of the interior and continental margin basins. © 2002 Elsevier Science Ltd. All rights reserved.
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Equatorial F region vertical plasma drifts, spread F and anomaly responses, in the south American longitude sector during the superstorm of 30 October 2003, are analyzed using data from an array of instruments consisting of Digisondes, a VHF radar, GPS TEC and scintillation receivers in Brazil, and a Digisonde and a magnetometer in Jicamarca, Peru. Prompt penetrating eastward electric field of abnormally large intensity drove the F layer plasma up at a velocity ∼1200 ms -1 during post dusk hours in the eastern sector over Brazil. The equatorial anomaly was intensified and expanded poleward while the development of spread F/plasma bubble irregularities and GPS signal scintillations were weaker than their quiet time intensity. Significantly weaker F region response over Jicamarca presented a striking difference in the intensity of prompt penetration electric field between Peru and eastern longitudes of Brazil. The enhanced post dusk sector vertical drift over Brazil is attributed to electro-dynamics effects arising energetic particle precipitation in the South Atlantic Magnetic Anomaly (SAMA). These extraordinary results and their longitudinal differences are presented and discussed in this paper. Copyright 2008 by the American Geophysical Union.
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The fishes of the present study were collected in the headwater streams of the Sorocaba, Paranapanema and Ribeira de Iguape river basins during the dry period in 2010. A total of 2892 fishes, grouped in 53 species, were captured. The composition of the ichthyofauna captured in the streams of Sorocaba and Paranapanema river basin was greatly similar. On the other hand, the fish fauna of the streams of Ribeira de Iguape river basin were quite different from the ones captured in the others basins, with the occurrence of endangered species (Isbrueckerichthys epakmos and I. duseni) and exotic species (Misgurnus anguillicaudatus). The previous list of fish for the Sorocaba river basin increased with the addition of seven species of Characiformes, one Gymnotiformes and four Siluriformes. © 2012 Check List and Authors.
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Studies focusing on communities of helminths from Brazilian lizards are increasing, but there are many blanks in the knowledge of parasitic fauna of wild fauna. This lack of knowledge hampers understanding of ecological and parasitological aspects of involved species. Moreover, the majority of research has focused on parasitic fauna of lizards from families Tropiduridae and Scincidae. Only a few studies have looked at lizards from the family Leiosauridae, including some species of Enyalius. This study presents data on the gastrointestinal parasite fauna of Enyalius perditus and their relationships with ecological aspects of hosts in a disturbed Atlantic rainforest area in the state of Minas Gerais, south-eastern Brazil. Two nematode species, Oswaldocruzia burseyi [(Molineidae) and Strongyluris oscari (Heterakidae) were found. Nematode species showed an aggregated distribution in this host population, with O. burseyi being more aggregated than S. oscari. The present study extends the range of occurrence of O. burseyi to the Brazilian continental area. © 2011 Cambridge University Press.
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The reproductive biology of the guitarfish Rhinobatos percellens was studied from 751 specimens caught by bottom pair trawlers off the coast of São Paulo, Brazil, between c. 24° 00′ S; 45° 15′ W and c. 25° 10′ S; 47° 52′ W, from September 2007 to August 2009. The total length (LT) and total mass (MT) relationship for males and females combined was MT = 1·29E-06 LT 3·15 (r = 0·99, n = 751). The mean LT of sexually mature specimens was 548 mm for males and 583 mm for females. Clasper growth was allometric and showed three distinct phases. Most claspers were calcified in specimens of c. 550 mm LT. The mean diameter of the largest oocyte was 29·8 mm, the mean ovarian fecundity was seven oocytes and ovulation occurred between August and November. Uterine fecundity ranged from two to 13 embryos (mean of five embryos). Larger females had higher litter sizes and larger embryos; the size-at-birth was c. 200 mm LT. The hepato-somatic index oscillated seasonally for males and females; the gonado-somatic index had little variation in males, but varied seasonally in females. The presence of many non-pregnant adult females and of encapsulated eggs during two consecutive seasons suggests a resting period between gestations and the possibility of diapause. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.
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Some crustaceans show variations of their reproductive biology within their geographical distribution, and knowledge about such variations is important for the comprehension of their reproductive adaptations. This study compared two populations of the fiddler crab Uca uruguayensis from two locations on the south-western Atlantic coast: Ubatuba Bay, São Paulo, Brazil and Samborombón Bay, Buenos Aires, Argentina. The population features analysed were the body size variation (carapace width = CW) and the size at the onset of sexual maturity (SOM) in order to test the hypothesis that the size at SOM, should be the same in relative terms (RSOM), independently of the latitudinal position. In the Brazilian population the CW ranged from 4.18 to 11.60 mm for males and 3.90 to 9.80 mm for females, and in the Argentinean population from 3.60 to 14.10 mm for males and 2.85 to 12.00 mm for females. In the Brazilian population the SOM was 7.1 (RSOM = 0.58) and 5.9 mm CW (RSOM = 0.57) for males and females, respectively, and in the Argentinean population it was 7.0 (RSOM = 0.42) and 6.75 mm CW (RSOM = 0.53) for males and females, respectively. This fact is probably related to a great plasticity in the life history features of Uca uruguayensis under different environmental conditions. © 2012 Marine Biological Association of the United Kingdom.