787 resultados para south-eastern Brazilian coast
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Vibrio cholerae is an autochthonous marine bacterium, and its association with diverse planktonic crustaceans has been extensively investigated; however, the presence of V. cholerae on individuals of most phyla of planktonic animals is still incompletely understood. The objective of this study was to analyze the distribution of V. cholerae serogroup O1 associated with specific zooplankton taxa in an estuary and the adjacent continental shelf of the southeastern Brazilian coast. The occurrence of the bacterium was assessed in zooplankton samples, specifically on the most abundant taxa, using direct fluorescence assay (DFA) and direct viable count-direct fluorescence assay (DVC-DFA) methods. Vibrio cholerae O1 was detected in 88% of samples collected from the Santos-Bertioga estuary and in 67% of samples from the shelf. The salinity of the estuarine water ranged from 21.8 to 34.6, significantly lower than the shelf water which was 32.1-36.1. Salinity was the only environmental variable measured that displayed a significant correlation with the presence of V. cholerae (P < 0.05). Vibrio cholerae O1 was detected in chaetognaths, pluteus larvae of echinoderms and planktonic fish eggs (Engraulidae), all new sites for this bacterium.
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There are few environmental studies using biomarkers for the species Atherinella brasiliensis in Brazil. In the present work, the presence of hepatic histopathological lesions and nuclear abnormalities in erythrocytes were investigated in A. brasiliensis from Lamberto, a beach under influence of domestic wastes and marine activities. For comparison, fish were also sampled in Puruba, a non-polluted beach, located in the northeastern of Sao Paulo State. The frequency of lesions found in liver was in higher numbers in individuals from Lamberto than Puruba beach. The most critical injuries observed in A. brasiliensis were the presence of necrotic areas, leucocytes infiltration and piknotic nucleus. A high occurrence of cells with vacuolization was also observed. The hepatic lesion index of the fish from Lamberto beach showed significant high values (I(org)=13) when compared with fish from Puruba beach (I(org)=7) suggesting the influence of the several human activities in the studied site. Notched and blebed nucleous were observed in this study, and significant differences were found between the studied sites. However, these differences did not reflect the total nuclear alterations.
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Along the southern Brazilian coast, Tijucas Bay is known for its unique muddy tidal flats associated with chenier plains. Previous field observations pointed to very high suspended sediment concentrations (SSCs) in the inner parts of the bay, and in the estuary of the Tijucas River, suggesting the presence of fluid mud. In this study, the occurrences of suspended sediments and fluid mud were examined during a larger-scale, high-resolution 2-day field campaign on 1-2 May 2007, encompassing survey lines spanning nearly 80 km, 75 water sampling stations for near-bottom density estimates, and ten sediment sampling stations. Wave refraction modeling provided qualitative wave energy estimates as a function of different incidence directions. The results show that SSC increases toward the inner bay near the water surface, but seaward near the bottom. This suggests that suspended sediment is supplied by the local rivers, in particular the Tijucas. Near-surface SSCs were of the order of 50 mg l(-1) close to the shore, but exceeded 100 mg l(-1) near the bottom in the deeper parts of the bay. Fluid mud thickness and location given by densimetry and echo-sounding agreed in some places, although being mostly discordant. The best agreement was observed where wave energy was high during the campaign. The discrepancy between the two methods may be an indication for the existence of fluid mud, which is recorded by one method but not the other. Agreement is considered to be an indication of fluidization, whereas disagreement indicates more consolidation. Wave modeling suggests that waves from the ENE and SE are the most effective in supplying energy to the inner bay, which may induce the liquefaction of mud deposits to form fluid mud. Nearshore mud resuspension and weak horizontal currents result in sediment-laden offshore flow, which explains the higher SSCs measured in the deeper parts of the bay, besides providing a mechanism for fine-sediment export to the inner shelf.
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In the present study Cathorops spixii, was evaluated as a bioindicator fish for trace metal pollution. Concentrations of cobalt (Co), iron (Fe), selenium (Se) and zinc (Zn) were determined by Instrumental Neutron Activation Analysis in liver. Mercury (Hg) and methyl-mercury (MeHg) were analyzed by Cold Vapor Atomic Absorption Spectrometry in muscles and livers. High concentrations of Co, Fe, Se and Zn were observed in C. spixii from Santos Bay in comparison to fish collected in a non-polluted site in the same Brazilian coast. These trace metal concentrations were out of the permissible levels for human consumption. Although, Hg and MeHg levels were low, the C. spixii could still be used as an effective bioindicator to observe trace metal behaviors in the environment in function of the bioaccumulation process observed mainly by other analyzed trace metals. Thus, the use of this species is strongly recommended to monitor the effects and behavior of trace metal pollution in aquatic ecosystems in Brazil due to its bioaccumulation function.
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Temporally-growing frontal meandering and occasional eddy-shedding is observed in the Brazil Current (BC) as it flows adjacent to the Brazilian Coast. No study of the dynamics of this phenomenon has been conducted to date in the region between 22 degrees S and 25 degrees S. Within this latitude range, the flow over the intermediate continental slope is marked by a current inversion at a depth that is associated with the Intermediate Western Boundary Current (IWBC). A time series analysis of 10-current-meter mooring data was used to describe a mean vertical profile for the BC-IWBC jet and a typical meander vertical structure. The latter was obtained by an empirical orthogonal function (EOF) analysis that showed a single mode explaining 82% of the total variance. This mode structure decayed sharply with depth, revealing that the meandering is much more vigorous within the BC domain than it is in the IWBC region. As the spectral analysis of the mode amplitude time series revealed no significant periods, we searched for dominant wavelengths. This search was done via a spatial EOF analysis on 51 thermal front patterns derived from digitized AVHRR images. Four modes were statistically significant at the 95% confidence level. Modes 3 and 4, which together explained 18% of the total variance, are associated with 266 and 338-km vorticity waves, respectively. With this new information derived from the data, the [Johns, W.E., 1988. One-dimensional baroclinically unstable waves on the Gulf Stream potential vorticity gradient near Cape Hatteras. Dyn. Atmos. Oceans 11, 323-350] one-dimensional quasi-geostrophic model was applied to the interpolated mean BC-IWBC jet. The results indicated that the BC system is indeed baroclinically unstable and that the wavelengths depicted in the thermal front analysis are associated with the most unstable waves produced by the model. Growth rates were about 0.06 (0.05) days(-1) for the 266-km (338-km) wave. Moreover, phase speeds for these waves were low compared to the surface BC velocity and may account for remarks in the literature about growing standing or stationary meanders off southeast Brazil. The theoretical vertical structure modes associated with these waves resembled very closely to the one obtained for the current-meter mooring EOF analysis. We interpret this agreement as a confirmation that baroclinic instability is an important mechanism in meander growth in the BC system. (C) 2008 Elsevier B.V. All rights reserved.
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The second species in the genus Chlamydoconcha is described. Chlamydoconcha avalvis new species, occurs off the coast of Rio de Janeiro coast, in southeastern Brazil. The new species has very reduced valves acid a mantle surrounding the entire body, two features of the genus. The outer surface of the mantle lacks papillae except for a single cite located close to the excurrent siphon. These are distinctive characters of Chlamydoconcha orcutti Dall, 1884, from the eastern Pacific coast of North America, the single other known species of the genus. Some of the more interesting anatomical characters of the new species are: posterior pair of retractor muscles Of foot free front valves, absence of adductor muscles, gastric style sac totally separated from intestine, and the presence of a single (excurrent) siphon.
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Fissurella mesoatlantica n. sp. is endemic to the Saint Peter and Saint Paul Archipelago, Brazil, located approximately in the middle Atlantic (00 degrees 55N. 29 degrees 20W). The species is very similar to F. clenchi from the mainland Brazilian coast, differing in having a taller. more richly sculptured shell and by anatomical details. such its the papillae of mantle border and epipodial tentacles. A complete anatomical description is included.
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The Castniidae, or butterfly moths, are characteristically colourful diurnal moths, distributed throughout the tropics except in Africa. The Neotropical representatives forage almost exclusively on monocotyledonous plants and many species are crop pests with more than 60% of the Neotropical castniids found or endemic in Brazil. Research studies that focus on taxonomy, systematics, and morphology of this group are scarce. In this study, Yagra Oiticica, a small genus restricted to south-eastern South America, is revised and the diagnostic morphological characters of male and female genitalia are illustrated. This research is part of long-term study on the Castniidae for future phylogenetic analysis.
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This paper provides a paleoenvironmental reconstruction of a Late Quaternary lagoon system in the Jaguaruna region of Santa Catarina state, southern Brazil. Integrated results of bulk sedimentary organic matter characterization (delta C-13, delta N-15 and C/N), microfossil (pollen and diatom) and grain-size analysis from three shallow cores (similar to 2.5m depth) allowed us to propose an evolving paleogeographic scenario in this coastal region for the last ca. 5500 cal a BP. The lagoonal system in this area was more extensive during the mid-Holocene than today, with a gradual and continuous lagoon-sea disconnection until the present. We add to the debate regarding relative sea-level (RSL) variations for the Brazilian coast during the Holocene and discuss the importance of sedimentary dynamics for interpreting changes in coastal ecosystems. The multi-proxy analysis suggests that changes in coastal ecosystems could be directly related to local sedimentary processes, which are not necessarily linked to RSL fluctuations and/or to climatic variations. Copyright (c) 2011 John Wiley & Sons, Ltd.
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We describe and illustrate Paepalanthus sphaeroides (Eriocaulaceae, Paepalanthoideae) from the Mantiqueira Range in South-eastern Brazil and compare it with the morphologically most similar species: Paepalanthus aequalis and Paepalanthus eriophaeus. Paepalanthus sphaeroides has unique membranaceous sheaths tightly adpressed to the scapes, patent involucral bracts slightly surpassing the capitula, and sepals of the staminate flowers fused from the base to the middle as distinctive characteristics. Comments on morphological variation, geographical distribution, ecology, conservation status, as well as a distribution map, line drawings, and photos are provided.
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Leaf and wood plasticity are key elements in the survival of widely distributed plant species. Little is known, however, about variation in stomatal distribution in the leaf epidermis and its correlation with the dimensions of conducting cells in wood. This study aimed at testing the hypothesis that Podocarpus lambertii, a conifer tree, possesses a well-defined pattern of stomatal distribution, and that this pattern can vary together with the dimensions of stem tracheids as a possible strategy to survive in climatically different sites. Leaves and wood were sampled from trees growing in a cold, wet site in south-eastern Brazil and in a warm, dry site in north-eastern Brazil. Stomata were thoroughly mapped in leaves from each study site to determine a spatial sampling strategy. Stomatal density, stomatal index and guard cell length were then sampled in three regions of the leaf: near the midrib, near the leaf margin and in between the two. This sampling strategy was used to test for a pattern and its possible variation between study sites. Wood and stomata data were analysed together via principal component analysis. The following distribution pattern was found in the south-eastern leaves: the stomatal index was up to 25 higher in the central leaf region, between the midrib and the leaf margin, than in the adjacent regions. The inverse pattern was found in the north-eastern leaves, in which the stomatal index was 10 higher near the midrib and the leaf margin. This change in pattern was accompanied by smaller tracheid lumen diameter and length. Podocarpus lambertii individuals in sites with higher temperature and lower water availability jointly regulate stomatal distribution in leaves and tracheid dimensions in wood. The observed stomatal distribution pattern and variation appear to be closely related to the placement of conducting tissue in the mesophyll.
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This paper is part of an extensive study on the biodiversity of the macroalgal flora of So Paulo state, SE Brazil. Previous assessments were based only on morphological descriptions. Here, we tested the effectiveness of DNA barcoding, in comparison with morphological observations for the recognition and cataloging of species. The focus of this study is the genus Porphyra, which is a conspicuous component of the upper intertidal on rocky shores of this region. With five currently accepted species, we have sequenced three short markers: cox1, cox2-3 spacer and UPA to establish the first DNA barcode database for the Porphyra species from the Brazilian coast. The three markers, although with different evolution rates, recovered a cryptic species (Porphyra sp. 77), grouped two different species (Porphyra drewiana and Porphyra spiralis) that are being synonymized, and finally indicated that varieties within P. acanthophora and P. spiralis are merely morphological, with no sequence divergence in the studied molecular markers.