No description available.

No abstract available / Thesis (PhD)--University of Pretoria, 2009. / Geology / unrestricted

Indiana University-Purdue University Indianapolis (IUPUI) / The Ordovician (485-444 Ma) was a highly dynamic period, characterized by significant evolutionary and climatic change. Paleozoic fauna which evolved during the Great Ordovician Biodiversification Event (GOBE) populated extensive epicontinental seaways. Major sea level fluctuations during The Hirnantian glaciation are believed to have led to a mass extinction event at the End Ordovician. However, a reassessment of Early Paleozoic fossil assemblages suggests the onset of extinctions began in the mid-Katian, ~3 million years before the Hirnantian. The Kope formation, within the North American succession of the Katian, was deposited during the peak biodiversification of the GOBE at the point which a biological crisis begins. The well-studied series of interbedded shale and fossiliferous limestone beds, deposited within a shallow epeiric sea, provide ideal sedimentological and paleontological context to interpret sediment geochemistry recorded at the onset of a global mass extinction. For a high-resolution section of the Kope, δ34Spyrite show an extraordinary range of variability, up to 64.5‰, with systematic oscillations throughout the core. The isotope signal represents a mix of pyrite formed at the time of deposition and during diagenesis. As sea levels fluctuated, the amount of sediment delivery influenced the connection of sediment porewaters to overlying seawater sulfate and the location of the sulfate reduction zone, which in turn, masked the primary signal. Reactive iron data suggest low oxygen concentrations in the water column, however fossil assemblages found throughout the Kope suggest otherwise. Changes in sedimentation can mask the water column signal, so these data also capture an aggregate signal. δ15Nbulk show an upsection decrease of 4.4‰, followed by a 3.4‰ increase. Though this excursion can be interpreted as a switch to increased denitrification in a low oxygen environment, the fossil record suggests the data capture localized diagenetic reactions that occur below an oxic water column. Perturbations in the ocean-climate system is often based on the interpretation of stable isotope excursions, and although excursions are diagnostic of changes to biogeochemical cycles, they may not fully account for diagenetic reactions that mask primary signals. The results from the Kope demonstrate strong localized, not global, controls on the sediment geochemistry.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-04-26T15:56:41Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) TESECAMARGO2016.pdf: 15058868 bytes, checksum: 6592263913f5c42e961d6608f27df3e1 (MD5) / Made available in DSpace on 2017-04-26T15:56:41Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) TESECAMARGO2016.pdf: 15058868 bytes, checksum: 6592263913f5c42e961d6608f27df3e1 (MD5) Previous issue date: 2016-08-25 / CAPES / A geodiversidade de uma plataforma continental se refere à heterogeneidade de feições geológicas e geomorfológicas e determinam a ocorrência de paisagens submersas e hábitats bentônicos específicos. Muitas vezes, aspectos abióticos do assoalho marinho são usados como indicadores substitutos de hábitats bentônicos e subsidiam iniciativas em prol de sua conservação e manejo. No sentido de investigar a geodiversidade e as paisagens submersas da Plataforma Continental Sul de Pernambuco (PCSPE), as bacias hidrográficas costeiras e o assoalho marinho, entre as profundidades de 10 e 120 metros, foram analisadas através de técnicas de geoprocessamento, levantamentos batimétricos e videográficos. A tese buscou identificar os padrões espaciais da geodiversidade e paisagens submersas e contribuir para a conservação da biodiversidade local, em especial, àquela relacionada aos substratos consolidados. O MDE da porção emersa da área (9.085 km2) permitiu a identificação de feições topográficas, como o Planalto da Borborema e o Lineamento Pernambuco. Além disto, subsidiou a caracterização morfométrica das bacias hidrográficas, evidenciando as do Rio Una e Rio Sirinhaém, como as maiores e mais importantes. No tocante à porção submersa da área, a compilação de 559.365 pontos batimétricos permitiu a geração de um MDE (971 km2), revelando a presença marcante de três canais submersos e de degraus nas faixas de profundidade de 16-20, 20-23, 25-30, 35-40 e 50-55 m. 287 seções transversais realizadas no MDE permitiram identificar e descrever setores topograficamente distintos ao longo dos canais submersos. Tal heterogeneidade provavelmente está relacionada com períodos de estabilização, durante as oscilações do nível do mar. 64 amostras de sedimentos com teores de cascalho, areia, silte e argila, 49 amostras com teores de carbonato de cálcio, bem como a localização de 29 fundos consolidados registrados em sonogramas permitiram a caracterização da cobertura sedimentar da PCSPE. A mesma, mostrou-se predominantemente carbonática, com maiores contribuições de areias e cascalhos biogênicos, demonstrando a importância dos organismos secretores de carbonato de cálcio, bem adaptados a águas rasas, quentes e iluminadas. A integração de dados de topografia e de variações eustáticas do nível do mar possibilitou a proposição de um modelo paleogeográfico para a plataforma continental leste brasileira, que apresentou potencial para a ocorrência de pelo menos 15 canais submersos, entre os estados da PB, PE e AL, diante das características morfométricas entre as bacias hidrográficas, influenciadas pelo Planalto da Borborema. A análise da distribuição de declividade na PCSPE demonstrou que a área é predominantemente plana, salvo junto às topografias acidentadas dos canais submersos e da borda da plataforma, e pontualmente na plataforma continental interna. Através da análise de 03 vídeo-transectos, em dois setores distintos do Canal da Zieta, foi evidenciada a vocação da declividade, como indicador substituto de substratos consolidados. Aparentemente, os relevos ondulados da PCSPE indicam a ocorrência de paisagens submersas dominadas por este tipo de substrato. Um número maior e diverso de vídeo-transectos, bem como a integração com dados biológicos, são altamente recomendados, para que, através de análises mais robustas, a relação da declividade do terreno, como indicador substituto de ambientes recifais, seja consolidada. A localização restrita dos relevos acidentados forneceu uma visão da provável reduzida distribuição desses ambientes, podendo contribuir para o desenho mais adequado de Áreas Marinhas Protegidas. O potencial de ocorrência de canais submersos na plataforma continental leste brasileira sugere a replicação dos esforços aqui reunidos. Com dezenas de quilômetros de extensão, profundidades de até 40 metros, e aparentemente, concentrando biodiversidade, os canais submersos devem ser considerados importantes feições topográficas da região, não apenas por suas dimensões, mas também por sua importância ambiental e socioeconômica. / The geodiversity of a continental shelf refers to the heterogeneity of geological and geomorphological features and determine the occurrence of specific seascapes and benthic habitats. Often, abiotic aspects of the seafloor are used as surrogate of benthic habitats and subsidize initiatives for their conservation and management. In order to investigate the geodiversity and seascapes of the South Continental Shelf of Pernambuco (PCSPE), the coastal watersheds and the seafloor, between depths of 10 and 120 meters, were analyzed by geoprocessing techniques, bathymetric and videographic surveys. The thesis sought to identify the spatial patterns of geodiversity and seascapes and contribute to the conservation of local biodiversity, in particular to that related to consolidated substrates. A DEM of the emerged portion of the study area (9,085 km2) allowed the identification of topographic features, such as the Borborema Plateau and the Pernambuco Lineament. In addition, it subsidized the morphometric characterization of the coastal watersheds, evidencing those of Una and Sirinhaém rivers, as the largest and most important. As for the submerged portion of the study area, the compilation of 559.365 bathymetric points allowed the generation of an DEM (971 km2), revealing the remarkable presence of three submerged channels and of steps in the depth ranges of 16-20, 20-23 , 25-30, 35-40 and 50-55 m. 287 cross sections performed in the DEM allowed to identify and describe 11 topographically distinct sectors along the submerged channels. Such heterogeneity is probably related to periods of stabilization during sea level oscillations. 64 sediment samples with gravel, sand, silt and clay contents, 49 samples with calcium carbonate contents, as well as the location of 29 consolidated substrates recorded in sonograms allowed the characterization of the sedimentary cover of the PCSPE. It was predominantly carbonatic, with a higher contribution of biogenic sands and gravel, demonstrating the importance of calcium carbonate secreting organisms, well adapted to shallow, warm and illuminated tropical waters. The integration of topography data and eustatic variations of the sea level allowed the proposal of a paleogeographic model for the East Brazilian Continental Shelf, which presented potential for the occurrence of at least 15 submerged channels, among the states of PB, PE and AL, due to the morphometric similarities between the watersheds, influenced by the Borborema Plateau. The analysis of the slope distribution in the PCSPE showed that the area is predominantly flat except for the rugged topographies of the submerged channels and the shelf edge, and occasionally on the internal continental shelf. Through the analysis of 03 video-transects, in two distinct sectors of the Zieta Channel, the vocation of slope was evidenced as a surrogate of consolidated substrates. Apparently, the wavy reliefs of PCSPE indicate the occurrence of submerged landscapes dominated by this type of substrate. A larger and diverse number of video transects, as well as integration with biological data, are highly recommended, so that, through more robust analyzes, the relationship of the terrain slope as a surrogate of reef environments would been consolidated. The restricted location of the rugged reliefs provided an insight into the likely reduced distribution of these environments and could contribute to the most appropriate design of Protected Marine Areas. The potential of submerged channels in the East Brazilian Continental Shelf suggests the replication of the efforts gathered here. The submerged channels, with tens of kilometers of depth, depths of up to 40 meters, and apparently concentrating biodiversity, should be considered important topographic features of the region, not only because of their size, but also because of their environmental and socioeconomic importance.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-08-03T11:52:14Z No. of bitstreams: 1 2011 - Gabriela Bueno B. Silva.pdf: 16499028 bytes, checksum: f77bf195f420f4227c29b60a75895d0d (MD5) / Made available in DSpace on 2016-08-03T11:52:14Z (GMT). No. of bitstreams: 1 2011 - Gabriela Bueno B. Silva.pdf: 16499028 bytes, checksum: f77bf195f420f4227c29b60a75895d0d (MD5) Previous issue date: 2011-04-15 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior, CAPES, Brasil. / BITTENCOURT-SILVA, Gabriela Bueno. Insular Anuran (Amphibia) Communities of the Southeast Coast of Brazil: Taxonomic Composition and Relationship to the History of the Islands. 2011. 72p. Dissertation (Master of Science in Animal Biology). Instituto de Biologia, Departamento de Biologia Animal, Universidade Federal Rural do Rio de Janeiro, Serop?dica, RJ, 2011. A data set containing a list of the known species of frogs that occur near shore and on eight islands of the south coast of the State of Rio de Janeiro and north of the State of S?o Paulo was produced. For that, I compiled data from the literature and conducted inventories of a few of the islands. This list included 67 anuran species belonging to 11 families for eight islands and 117 species and 14 families for two localities on the mainland. The pattern of richness between islands was analyzed in respect to the island area and the composition of habitats used by the anurans for reproduction. Insular structural complexity was also evaluated in this regard. The results of correlation analyses of area vs. species richness and species richness vs. number of reproductive habitats were highly significant indicating that species richness prediction in fragmented environments depends on both factors. Nestedness analyses using the metric NODF was performed in an attempt to investigate whether shared species absences among the islands are the result of a random process or represents a pattern indicative of ordered loss of species. The predicted pattern was confirmed ? that is, that species loss is nonrandom and that this was possibly caused by habitat loss. The role played by climatic events at the beginning of the Holocene and of the availability of reproductive habitats in the islands upon species loss is discussed. Furthermore, it is discussed how these results can help to guide conservation strategies of anuran species. / BITTENCOURT-SILVA, Gabriela Bueno. Comunidades de Anf?bios Anuros Insulares do Litoral Sudeste do Brasil: Composi??o Taxon?mica e Rela??es com a Hist?ria de Forma??o das Ilhas. 2011. 72p. Disserta??o (Mestrado em Biologia Animal). Instituto de Biologia, Departamento de Biologia Animal, Universidade Federal Rural do Rio de Janeiro, Serop?dica, RJ, 2011. Atrav?s de invent?rios e compila??o de dados da literatura levantou-se a composi??o de esp?cies de anf?bios anuros de oito ilhas, sendo seis da Costa Verde do Estado do Rio de Janeiro e duas do litoral norte do Estado de S?o Paulo. Al?m das ilhas, foram tamb?m compilados da literatura os invent?rios de duas comunidades representativas do litoral dos dois Estados. Adicionalmente, foram registradas 67 esp?cies, pertencentes a 11 fam?lias de anuros nas ilhas e 117 esp?cies e 14 fam?lias para o continente. O padr?o de distribui??o de riqueza das ilhas foi avaliado em rela??o ? ?rea das ilhas, ? composi??o de ambientes usados pelos anuros para reprodu??o e ? complexidade estrutural das ilhas. As an?lises de correla??o da riqueza de esp?cies vs. ?rea e riqueza de esp?cies vs. n?mero de ambientes reprodutivos apresentam resultados significativos, que s?o indicativos que a riqueza de esp?cies em ambientes fragmentados depende da intera??o de ambos os fatores. A fim de avaliar se as aus?ncias compartilhadas de esp?cies entre as ilhas ocorrem ao acaso ou encontram-se estruturadas, realizou-se uma an?lise de aninhamento com o aux?lio da m?trica NODF. O padr?o previsto foi confirmado e a perda de diversidade ? discutida em rela??o ? eventos clim?ticos do in?cio do Holoceno e ? disponibilidade de ambientes reprodutivos nas ilhas. Discute-se ainda como os resultados desse estudo podem servir para orientar programas de conserva??o de esp?cies de anf?bios anuros