Oceanografia Ambiental

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http://repositorio.ufes.br/handle/10/17530
Programa de Pós-Graduação em Oceanografia Ambiental

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Navegando Oceanografia Ambiental por Assunto "Abrolhos"

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    A Plataforma Continental de Abrolhos : contexto paleoambiental, sismoestratigrafia e domínios sedimentares
    (Universidade Federal do Espírito Santo, 2017-04-27) D’Agostini, Danielle Peron; Bastos, Alex Cardoso; Figueiredo Jr, Alberto Garcia de; Baptista Neto, José Antônio; Jovane, Luigi; Moura, Rodrigo Leão de
    The Abrolhos shelf is located in the Eastern Brazillian continental margin between the 17ºS and 20ºS parallels. This shelf embraces the biggest and most important reefal complex in the South Atlantic and also the largest rodoliths bank in the World. The complex relation between geomorphology and diversity of bottom faciology has been associated to an interaction of evolutive, antropic, climate and oceanographic factors. The hypothesis of the anteceding paleotopography was tested as a controlling factor of the facies distribution pattern and modern geomorphology, aiming to understand which evolutive processes influenced the formation of the continental shelf. The dataset was acquired in the shelf and slope of the Abrolhos continental margin, including geophysical (bathymetry and seismic), sedimentological (surficial sediments and cores) and seabed imaging data. The results were presented in three chapters: 1) Shelf-slope system response to distinct evolutive processes, with major developing of carbonate constructions in the North region together with a classic slope morphology of tropical carbonate environments. In other way, the South region shows dominance of the siliciclastic sedimentation and sigmoid morphologies for the shelf-slope system; 2) Investigation of the anteceding paleotopographies influences as an indicative of its control over both the drainage systems and the starting flooding location in the shelf, as well as its differentiation of regions with distinct evolutive processes; 3) Presentation of paleoenvironments of the shelf during the post-last glacial maximum transgression, indicating the most humid climate influenced environments along the shelf during this period. The data became relevant in terms of the interaction between the controlling factors in mixed siliciclastic-carbonate environments and its evolution process.
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    Morfologia de recifes submersos na plataforma de Abrolhos (Brasil): da resposta à variação do nível do mar, à heterogeneidade do habitat
    (Universidade Federal do Espírito Santo, 2025-06-25) Vieira, Fernanda Vedoato; Bastos, Alex Cardoso; https://orcid.org/0000-0002-1272-1134; http://lattes.cnpq.br/2951081353357019; https://orcid.org/0000-0002-5759-9566; http://lattes.cnpq.br/3147534317873473; Salles, Laura Silveira Vieira; http://lattes.cnpq.br/7435312200966903; Almeida, Narelle Maia de; https://orcid.org/0000-0003-2586-4502; http://lattes.cnpq.br/4905966563292686; Rebouças, Renata Cardia; https://orcid.org/0000-0001-7855-7296; http://lattes.cnpq.br/1196270104953172; Araújo, Tereza Cristina Medeiros de; https://orcid.org/0000-0003-2760-6566; http://lattes.cnpq.br/4130469620831742
    Submarine geomorphology directly controls the configuration of the marine landscape and benthic habitats and is primarily influenced by eustatic sea-level fluctuations, sedimentation rates, and accommodation space. During the last deglaciation, variations in sea-level rise rates resulted in periods of relative stabilization (stillstands) and rapid acceleration, shaping distinct geomorphological features on the continental shelf.Reefs play a central role in marine ecosystems and are regarded as priority areas for the establishment of marine protected areas, being fundamental to marine spatial planning. In addition, they act as sensitive indicators of the impacts of climate change. Submerged reefs, in turn, are products of oceanographic conditions and short- and long-term sea-level variations, reflecting in their position, morphology, and extent the history of environmental and ecological changes.The Abrolhos Continental Shelf hosts the largest reef province in the South Atlantic and represents the main study area for reef evolution on the Brazilian continental shelf. However, studies on submerged reefs along this platform remain incipient. Nevertheless, understanding the extent, evolution, and connectivity between these submerged reefs and the emergent reefs is essential to fill knowledge gaps regarding the genesis, evolution, morphology, and spatial distribution of the largest reef complex in the South Atlantic. The use of high-resolution multibeam bathymetry, combined with geomorphological analysis methods, constitutes the scope of this research, aiming to elucidate the processes of formation, evolution, and drowning of both previously known and still poorly mapped reefs on the Abrolhos Shelf.Based on morphological data, two main groups of submerged reefs were identified in the southern portion of the Abrolhos Shelf, between depths of 14 and 35 meters. These groups are associated with different seabed features, including linear forms (longitudinal and transverse), sedimentary banks, and incised valleys, indicating a diversity of geomorphological processes and distinct origins. In contrast, in the northern portion of the Abrolhos Shelf, high resolution acoustic mapping revealed more than 34,000 reef structures, ranging from pinnacles to banks, evidencing significant morphological heterogeneity. Finally, the areas were compared in terms of morphological aspects and correlated with post–Last Glacial Maximum eustatic events and the presence of remnant Pleistocene structures.Thus, the Abrolhos Continental Shelf preserves unique features that record paleoenvironmental changes, functioning as geological archives of deglacial pulses and sea-level variations. The interaction between eustasy, pre-existing topography, and sedimentation has shaped the present-day geodiversity, highlighting the importance of submerged reefs in understanding the evolution of the largest reef complex in the South Atlantic.
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    Variabilidade espacial e temporal do estresse térmico sobre o banco de Abrolhos, Atlântico Sul
    (Universidade Federal do Espírito Santo, 2021-02-24) Monteiro, Natiely Priscila Paiva; Ghisolfi, Renato David; https://orcid.org/0000000196956442; http://lattes.cnpq.br/3746397954560718; https://orcid.org/0000-0002-4844-3973; http://lattes.cnpq.br/4582924186468874; Kikuchi, Ruy Kenji Papa de; https://orcid.org/0000-0002-6271-7491; http://lattes.cnpq.br/8391627429679768; Sá, Fabian; https://orcid.org/0000000339645685; http://lattes.cnpq.br/9329106914297651
    Thermal stress (ET), which is associated with a change in temperature that can be severe enough to cause unfavorable or even lethal conditions to aquatic organisms, populations, community structure, or ecosystems, has also been associated with coral bleaching. In this sense, it is essential to monitor the spatial-temporal variability of seawater temperature everywhere, including in the Abrolhos Bank region. Coral Reef Watch (CRW) provides ex-situ daily sea surface temperature measurements for this area. Although TSM is an essential source of data, especially in the absence of in situ measurements, it is necessary to evaluate this measurement's spatial-temporal representativeness compared to those taken in the field. Thus, it will be possible to assess whether the thermal stress indicated by CRW is representative, i.e., it is similar to that estimated from on-site seawater temperature measurements. This study's general objective is to evaluate the space-time representativeness of the temperature measurements and thermal stress estimates obtained in situ and ex-situ on the Abrolhos Bank. The results obtained showed that the thermal pattern observed in Abrolhos is characterized by a heating-cooling cycle, with the peak temperature observed at the end of the summer beginning of autumn. When comparing the alerts generated by a single point temperature series by CRW with in situ measurements obtained at different depths and locations, it was seen that the spatial extrapolation is not valid. The comparison between in situ and CRW data showed that, both in the alert's duration and intensity, the differences between the ex-situ temperature estimate and the temperature that acts on the corals could be considerable. These differences partly reflect the vertical stratification on the Abrolhos Bank in the critical months of liquid heat flow towards the ocean (end of the rainy season and beginning of the dry season). Temperature measurements of the deep corals and the outer bow showed values below the Maximum Mean Monthly Temperature, preventing thermal stress on the corals. In the dry season, the thermal homogeneity of the water column occurs. Finally, for coastal and shallow reefs (but relatively distant from the coast), the bleaching alerts compare with each other. However, this does not mean that the whitening will effectively occur at the predicted level. It needs to be evaluated punctually and individually since physical-chemical processes can affect them distinctly in different locations.