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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Calibração dos Registros Ambientais em Esqueletos de Colônias do Coral Siderastrea Stellata Verril, 1868

Rocha, Lucas Sarmento Neves da 05 1900 (has links)
Submitted by Everaldo Pereira (pereira.evera@gmail.com) on 2017-02-21T01:16:25Z No. of bitstreams: 1 Lucas Rocha (2015) - mestrado.pdf: 14637707 bytes, checksum: 996b70d370a5333486ee80bf8542477b (MD5) / Made available in DSpace on 2017-02-21T01:16:25Z (GMT). No. of bitstreams: 1 Lucas Rocha (2015) - mestrado.pdf: 14637707 bytes, checksum: 996b70d370a5333486ee80bf8542477b (MD5) / Considerando a indisponibilidade de longas séries temporais para registros instrumentais, torna-se imprescindível a utilização de proxies capazes de fornecerem medidas precisas do clima e de ambientes pretéritos. As bandas alternadas de densidade nos esqueletos de corais permitem quantificar e datar características relacionadas ao seu crescimento. Este padrão anual está diretamente relacionado às variações sazonais de parâmetros ambientais que caracterizam a água do mar. A calibração entre o proxy utilizado e o comportamento da variável ambiental investigada é fundamental para estabelecer a relação entre o estímulo ambiental e sua resposta no organismo. Deste modo, o objetivo deste trabalho foi realizar a calibração dos indicadores proxy de temperatura e turbidez da água do mar nos corais da espécie Siderastrea stellata Verril, 1868, para duas regiões específicas: Baía de Todos os Santos (Salvador, Bahia) e Arquipélago de Tinharé (Cairu, Bahia). Para isto, foram geradas placas de aproximadamente 5 mm de espessura do esqueleto de oito colônias de coral, posteriormente radiografadas e analisadas esclerocronologicamente no software Coral XDS®. A partir desta análise, pôde-se estimar as taxas de extensão linear, densidade e taxas de calcificação médias anuais e mensais para cada uma das colônias. As séries mensais da temperatura da superfície do mar (TSM) foram obtidas através do sistema operacional OSTIA. As séries mensais das variáveis ambientais Radiação Fotossinteticamente Ativa (PAR), Coeficiente de Atenuação Difusa da Luz (K490) e Concentração de Clorofila Superficial (CHLO) foram obtidas dos sensores MODIS e SeaWiFS. A comparação realizada entre os dois sítios de amostragem evidenciou uma diferença estatisticamente significativa para os três parâmetros esclerocronológicos analisados, enfatizando a influência dos fatores locais sobre os padrões de crescimento desta espécie de coral. As taxas de calcificação obtidas para as duas sub-áreas mostraram-se principalmente determinadas pela variabilidade da extensão linear, com a densidade exercendo um papel secundário. Colônias de S. stellata no sitio de amostragem Comunidade coralina do Yatch Clube da Bahia mostraram-se mais sensíveis a possíveis alterações nas variáveis ambientais. TSM e PAR exerceram maior influência sobre o padrão de densidade dos esqueletos desta espécie de coral em comparação às outras variáveis analisadas. / ABSTRACT - Considering the unavailability of long time series for instrumental records, mainly in the South Atlantic Ocean, it is essential to use indirect or proxy indicators to provide accurate measures of past climates and environments. The alternating density bands in coral skeletons allows dating and quantify characteristics related to its growth. This annual pattern is directly related to seasonal changes in environmental parameters that characterize the seawater. The calibration between the proxy used and the behavior of the investigated environmental variables is critical in establishing the relationship between the environmental stimulus and the organism response. Thus, the aim of this work was to perform the calibration of proxy indicators of temperature and turbidity of sea water in the coral specie Siderastrea stellata Verril, 1868, for two specific regions: Todos os Santos Bay (Salvador, Bahia) and Archipelago of Tinharé (Cairu, Bahia). For this, plates of approximately 5 mm were generated from skeletons of eight coral colonies, then x-rayed and analyzed sclerochronologically in the XDS® Coral Software. From this analysis, it was possible to estimate the annual and monthly averages of densities, linear extent and calcification rates for each colony. Sea surface temperature (SST) monthly series were obtained through the operating system OSTIA. The monthly series of environmental variables Photosynthetically Active Radiation (PAR), Diffuse Attenuation Coefficient (K490) and Superficial Chlorophyll Concentration (CHLO) was obtained from the MODIS and SeaWiFS sensors. The comparison between the two sampling sites showed a statistically significant difference for the three sclerochronological parameters analyzed, emphasizing the influence of local factors on the growth patterns of this species of coral. Calcification rates obtained for the two sub-areas were shown to be mainly determined by the variability of the linear extension, with the density as a secondary factor. Colonies of S. stellata in YCB sampling site were more sensitive to possible changes in environmental variables. TSM and PAR had the greatest influence on the pattern density of the skeletons of this species of coral compared to other variables.
2

Some Population Parameters of Quercus Stellata in the Texas Cross Timbers

McCluskey, Richard L. 12 1900 (has links)
This population study of Quercus stellata in the Texas Cross Timbers evaluates that population by observation and sampling of 220 upland forest stands. The Texas Cross Timbers is divided into the East Cross Timbers (ECT) and the West Cross Timbers (WCT) by the Fort Worth Prairie.
3

Caracterização bacteriológica da água do mar e diversidade de bactérias cultiváveis associadas ao coral Siderastrea stellata nos recifes costeiros de Cabo Branco, João Pessoa-PB

Araujo, Gilmara Henriques 22 May 2013 (has links)
Made available in DSpace on 2015-04-01T14:16:02Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1597259 bytes, checksum: eaba4f2d4108bede1b543c3806717952 (MD5) Previous issue date: 2013-05-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Bacteria play a fundamental role in the health of corals. The interest in the study of microorganisms associated with corals has increased since the confirmation that they can be pathogenic or mutualistic. In the coastal reefs of the State of Paraiba the cases of the pigmentation changes of scleractinian Siderastrea stellata, that probably occurs in the process of coral bleaching, are observed. The aim of this work was to analyze the density and diversity of culturable bacteria associated with healthy and with pattern pigmentation altered (pink) colonies of coral S. stellata of coral reefs of Cabo Branco, João Pessoa - PB, as well as the physico-chemical and microbiological parameters of seawater in the study area over one year. Among the environmental variables (temperature, salinity, pH, dissolved oxygen, turbidity) of the reefs and beach water of Cabo Branco, only turbidity showed higher differences among the sites studied. The thermotolerant fecal coliforms, enterococci and Escherichia coli of seawater at the study sites were within the limits recommended for saline water class I (CONAMA 274/00). In general, the values of density of total heterotrophic bacteria and Vibrio spp. were significantly higher in the seawater during the months of December, January and February. According to the results of the partial sequencing of the 16S rRNA gene was found that bacteria isolated from healthy and pink S. stellata belonged to the classes Alpha-Proteobacteria and Gamma-Proteobacteria, and the variety of genera of bacteria were very different among the isolates from the two colonies. The high percentage of Vibrio spp., bacteria that are usually related to the diseases of corals, were observed among the isolates from pink colony. / Bactérias desempenham um papel fundamental na saúde dos corais. Devido à confirmação de que elas podem ser patogênicas ou mutualistas, aumentou o interesse no estudo de microrganismos associados aos corais. Nos recifes costeiros do Estado da Paraíba observam-se casos de alteração de pigmentação no escleractíneo Siderastrea stellata, que provavelmente ocorre no processo de branqueamento de corais. Neste trabalho objetivou-se analisar a quantidade e diversidade de bactérias cultiváveis associadas ao coral S. stellata sadio e com coloração alterada (roxo) dos recifes de corais de Cabo Branco, João Pessoa PB, bem como os parâmetros físico-químicos e microbiológicos de água do mar da área estudada durante um ano. Entre as variáveis ambientais (temperatura, salinidade, pH, oxigênio dissolvido, turbidez) da água dos recifes e da praia de Cabo Branco apenas a turbidez apresentou maiores diferenças entre os locais estudados. Na base das análises de coliformes termotolerantes, Escherichia coli e enterococos foi constatado que a água dos locais analisados se enquadra dentro dos parâmetros para águas salinas de classe I (CONAMA 274/00). Em geral, os valores da densidade de bactérias totais e Vibrio spp. foram significativamente maiores em água do mar nos meses de dezembro, janeiro e fevereiro. Na base de dados de sequenciamento parcial do gene RNAr 16S foi constatado que as bactérias isoladas de S. stellata sadia e roxa pertenceram ás classes de Alfa-proteobactéria e Gama-proteobactéria, sendo que a variedade dos gêneros de bactérias foi bastante distinta entre os isolados das duas colônias. Os isolados da colônia roxa apresentaram um alto percentual de Vibrio spp., que são bactérias geralmente relacionadas com as doenças de corais.
4

Distribuição Espacial e Temporal de Isótopos de Pb: Uso do Coral Siderastrea Stellata Verrill, 1868 como Indicador Paleoambiental de Alta Resolução, da Ocupação Antrópica na Baía de Todos Os Santos – Brasil

Mendonça Filho, Carlos Valério Silveira 03 1900 (has links)
Submitted by Everaldo Pereira (pereira.evera@gmail.com) on 2017-02-19T20:25:16Z No. of bitstreams: 1 Dissertação_Carlos_Filho_2012.pdf: 2253334 bytes, checksum: bb9ff26de80271736ca73e37fb291dff (MD5) / Made available in DSpace on 2017-02-19T20:25:16Z (GMT). No. of bitstreams: 1 Dissertação_Carlos_Filho_2012.pdf: 2253334 bytes, checksum: bb9ff26de80271736ca73e37fb291dff (MD5) / A utilização do esqueleto de coral como indicador paleo-oceanográfico tem sido pouco explorada no Brasil. Neste trabalho, investigou-se o potencial do coral Siderastrea stellata como registro paleo-oceanográfico de alta resolução, da ocupação antrópica da Baía de Todos os Santos – BTS – (BA – Brasil), através das razões isotópicas do Pb incorporado nos esqueletos coralíneos coletados em recifes internos e externos à baía. Para uma melhor compreensão da distribuição espacial, além das possíveis fontes do Pb da BTS, foram igualmente analisadas amostras de sedimentos recifais e estuarinos de diversas localidades da baía. Os resultados mostraram que, de modo geral, no início dos registros coralíneos (1993 – 1997), dos recifes internos à baía, havia empobrecimento em 206Pb, indicando uma maior influencia do Pb proveniente do minério arqueano da mina de Boquira (BA) e beneficiado na antiga metalúrgica Plumbum, extinta em 1993 e localizada na cidade de Santo Amaro – BA, à NO da BTS. As razões isotópicas de Pb das amostras de sedimento mostraram que mesmo extinta, a região da antiga metalúrgica ainda é uma importante fonte contemporânea deste metal para o ambiente da baía. Contudo, a tendência de enriquecimento em 206Pb entre os anos de 1997 e 2007, nas amostras coralíneas dos recifes internos, juntamente com a sincronicidade do comportamento da composição isotópica do Pb das amostras coralíneas coletadas no recife externo à BTS com o desenvolvimento da indústria baiana, mostraram que durante esta última década, o Pb proveniente das industrias Químicas e Petroquímicas configura-se como uma das fontes principais para os recifes e, consequentemente, para a BTS. / ABSTRACT - In Brazil the use of coral skeleton as paleo-oceanographic index is been underexplored. On this paper, the coral Siderastrea stellata potential as a high resolution paleo-oceanographic proxy of antropic occupation of Baía de Todos os Santos – BTS – (BA – Brazil) was investigated through the Pb isotopic ratios incorporated on coral skeletons collected on inner and outer bay reefs. Reef and estuarine sediment samples of several location in the bay had been analyzed for a better special distribution and Pb source understanding. The results showed that at the first inner bay reef coral records (1993 – 1997) there was an 206Pb depleted, indicating a major influence of the Boquira’s mine (BA) archean ore, which was processed at the Plumbum metallurgical, located in NW BTS, Santo Amaro city and closed in 1993. The sediment samples Pb isotopics ratios showed that, even extinguished, the metallurgical industry still is an important source of Pb to the bay. However, the 206Pb enrichment on the inner bay reef coral samples between 1997 and 2007, with the outer bay reef coral samples isotopic composition behavior synchronicity, and Bahia’s industry development showed that during the last decade, the chemical and petrochemical industries are the most important source of Pb to the BTS coral reef environment.
5

Leaf elemental analysis and growth characteristics of mycorrhizal treated post oak seedlings via particle induced X-ray emission spectroscopy.

Boling, Blake C. 05 1900 (has links)
Growth and element assimilation was investigated in post oak seedlings exposed to four different treatment combinations of fertilization and ectomycorrhizal inoculation. Element concentration in excised leaves was analyzed via particle induced X-ray emission spectrometry with a 1.8 MeV proton macrobeam. Mean growth was significantly different across the treatment groups as well as mean concentration of Mg, Al, S, K, Ca, Fe, Cu, and Zn. The data suggest that fertilization rather than mycorrhizal inoculation had a stronger influence on plant growth and nutrient uptake. A follow up study was conducted with a 3 MeV microbeam. A 850 μm2 scanned area of a post oak leaf produced topographical maps of 11 elements.
6

Breeding Site Selection and Breeding Success in Red-throated Divers (Gavia stellata): Implications for Wind Power Development

Lehtonen, Emily January 2016 (has links)
Our alarming rate of resource exploitation and its consequences on the environment is fuelling an increase in sustainable energy production around the world. Wind power appears to be a particularly promising energy source relative to its environmental footprint, with the exception of potential negative effects of wind power on birds. Varying results from impact assessments around the world indicate that knowledge of both abiotic and biotic factors, as well as bird behavior and ecology, is required to assess the cumulative impact of any given wind farm on local bird communities. This study aims to assess the cumulative impact of a proposed wind farm on a threatened seabird, the red-throated diver (Gavia stellata), at one of its breeding "hotspots" in Sweden: the Holmöarna islands. Measurements of environmental variables in lakes on Holmöarna are combined with breeding surveys from 2012 to 2015 to assess which environmental variables may be associated with lakes that red-throated divers do or do not breed in, and which variables are correlated with breeding success. These results are combined with a literature review to assess the potential negative effects of the proposed wind farm on the breeding population on Holmöarna. The results show that average breeding success over the survey period was 0.35 fledged young per pair per year. No difference was found in environmental variables between lakes that divers had or had not bred in. Lake area/perimeter ratio and distance to the sea were significantly negatively correlated with breeding success, although distance to the sea was only significant for lakes with at least one successful breeding attempt during the survey period. Based on these correlations, 33 of a total 40 breeding lakes are shown to have relatively high area/perimeter ratios and long distances to the sea, which may pre-dispose divers breeding within them to low breeding success. These lakes are, therefore, identified as being at high-to-moderate risk of increased breeding failure if breeding success is further reduced as a result of external factors, including that of any negative impacts of the proposed wind farm. 31 of the 40 breeding lakes are also within 1 km of the proposed wind turbine sites, which may render red-throated divers breeding within them vulnerable to displacement as a result of wind farm-related disturbance. The literature review highlights the mechanisms that may determine the cumulative impact of the wind farm on red-throated divers in terms of collision mortality, habitat displacement, and barriers to movement. The strong sensitivity of red-throated divers to disturbance is considered to be the most likely driver of any negative effects of the wind farm. In this context, I thus argue the need for a precautionary approach to planning wind power developments in the vicinity of breeding red-throated diver populations.
7

Population Fluctuation of the Nodular Coral Psammocora stellata in the Galápagos Islands, Ecuador: An Indicator of Community Resilience and Implications for Future Management

Brown, Kathryn 13 April 2016 (has links)
Corals are experiencing a worldwide decline in abundance and diversity. Reasons for this include anthropogenic impacts and associated changes to environmental conditions, including global climate change. Increasing atmospheric CO2 levels lead to a coordinated increase in sea surface temperatures and decrease in oceanic pH. Warming events associated with El Niño-Southern Oscillation (ENSO) amplify the impacts of steadily increasing temperatures. For example, coral communities in the Galápagos Islands experienced mortality rates of up to 95-99% during severe ENSO warming in 1982-1983. Persisting through such extreme conditions imposes additional challenges to survival in already marginal environments for coral growth and development that occur in the eastern tropical Pacific. This study quantifies via photoquadrats population changes in mean live coral cover, density, and colony size over a 7-year period (2004-2011) in a small community of the nodular coral Psammocora stellata located at Xarifa Island in the Galápagos Islands. The physical characteristics of this shallow (1-3 m depth) habitat include shading by tall basalt cliffs and strong water flushing action that may contribute to the persistence of this species at this atypical locality through mitigation of anomalously warm and cold conditions. Coral cover is high for this region, and significantly increased from 39.7% in 2004 to 58.3% in 2011 (p=0.006, Tukey HSD), an overall increase of 47%. Fluctuations in coral cover were associated with anomalous temperatures (up to +3.5° and -4.6° C compared to daily means). Negative temperature anomalies in 2007 were associated with a non-significant decrease in coral cover (55.3% in 2007 to 49.5% in 2009), and coral cover rebounded in 2011 to 58.3%. From 2004 to 2011 colony density increased significantly, from 258±62 to 612±245 colonies m-2 (p2 (pin situ, documenting values that ranged from 16.8° - 28.9° C. The persistence of the Psammocora community through both strong and moderate ENSO events demonstrates the resistance and resilience of the species to these temperature anomalies. Adding to the understanding of this species and its interactions with the surrounding physical processes will aid in the development and improvement of management strategies.
8

Changes in Coral Community Composition at Devil's Crown, Galapagos Islands, Ecuador: A 7,700 Year Perspective

Hendrickson, Katharine Jane 11 December 2014 (has links)
Coral mortality caused by El Niño–Southern Oscillation (ENSO) activity and its related disturbances has been researched throughout the Eastern Pacific. In the past three decades, disturbances related to the El Niño–Southern Oscillation (ENSO) have been shown to influence coral growth in the Eastern Pacific. In the Galápagos Islands, Ecuador, more than 97% of corals experienced mortality after the severe 1982-1983 ENSO episode. However, two of the most dominant coral species found in a coral community adjacent to Devil’s Crown; Psammocora stellata and Diaseris distorta survived this severe ENSO event. By reconstructing sediment cores of the coral community, this study assessed how the coral assemblage has changed over the past 7,700 years of the Holocene epoch. The historical reconstructions were then related to existing records of Holocene ENSO variability in order to determine if changes in the relative abundance of coral species were related to ENSO activity and disturbances. We observed high variability in the relative abundances of P. stellata and D. distorta in the cores, including an increase in the abundance of D. distorta at approximately 2,200 yBP. Between the two species, opposite abundance trends were observed and supported by Detrended Correspondence Analysis (DCA) and Non-metric Multidimensional Scaling (NMDS) ordination analysis. Overall, the high variance in coral composition at the site throughout the Holocene documents repeated disturbance events in this region.

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