The Grand Bay National Estuarine Research Reserve (GBNERR) adjoins two costal embayments in the eastern Mississippi Sound, Grand Bay and Point Aux Chenes Bay, which encompass a late Pleistocene/ Holocene delta of the Pascagoula-Escatawpa fluvial system. Historical maps and aerial imagery indicate that the GBNERR shoreline has experienced long-term retreat at spatially variable rates. The research presented here investigates the relationship between the coastal geomorphological evolution of GBNERR and the underlying geological framework. Coastal morphology and stratigraphy were characterized by analyzing 85 km of chirp sonar sub-bottom seismic profiles and 45 sediment cores. Shoreline retreat rates were determined through geospatial regression analysis of 11 historical shorelines surveyed between 1850 and 2015. Results indicate that Pleistocene paleochannels in the underlying fluvial distributary ravinement surfaces are spatially correlated with shoreline segments that exhibit elevated retreat rates and should be accounted for in future models of local as well as regional coastal evolution.

Coastal marshes serve important ecologic and economic functions, such as providing habitat, absorbing floodwaters and storm surges, and sequestering carbon. Throughout the northern Gulf of Mexico, coastal marshes are disappearing due to wave attack, sea-level rise, sediment export, and subsidence. Marsh area increases when sediments accumulate at the marsh shoreline, accrete vertically, and when non-marsh areas are colonized by marsh vegetation. Marsh shoreline erosion results in net marsh loss when transgression rates at the marsh-water edge exceed upland-marsh migration. The balance between marsh destroying and marsh creating processes determines the long-term survivability of a marsh system. Thus, processes of shoreline change are important considerations when evaluating the overall health and vulnerability of coastal marshes. Shoreline erosion can be measured using remotely sensed data in a geographic information system. Using shoreline position delineated from aerial imagery, historic maps, and field surveys, shoreline change analysis estimates long- and short-term shoreline movements to identify erosion or accretion for coastal marshes at the Grand Bay National Estuarine Research Reserve (GBNERR) and Wildlife Refuge (GBNWR) on the border of Mississippi and Alabama, USA. However, these techniques do not directly provide information on sediment deposition on the marsh surface. To understand sediment deposition, four study sites provide in-situ measurements of sediment deposition using sediment plates and sediment tracers (silica beads) that were collected every three months. Analysis of the shoreline change data and in-situ sediment data for the GBNERR showed that in 2017, all of the shorelines at the study sites are eroding at rates between -0.50 m/yr and -3.39 m/yr, an average rate of -1.45 m/yr. Positive sediment deposition rates were measured from 5-20 meters inland of the marsh shoreline during each season (3-month period) (0.19 ± 0.05 cm [Fall], 0.26 ± 0.11 cm [Winter], 0.48 ± 0.12 cm [Spring], 0.63 ± 0.15 cm [Summer]), indicating sediment deposition increased with every season. Sediment tracer (silica-bead) counts confirmed that sediment was transported onto the marsh surface from eroding marsh shorelines. Higher energy sites had more beads deposited on the sediment plates than the low energy tidal creek site, due to the different wave and tidal conditions between the sites. Increased wave and tidal energy correlated to increased sediment transport further into the marsh. The relative importance of this marsh cannibalism for the long-term marsh survival depends on factors, such as wave attack, as they control the rate of persistent lateral marsh loss. This findings in this thesis suggests that material from eroding marsh edges contributes to the ability of the interior of marshes to maintain their elevation with respect to rising sea levels.

Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2016-05-02T17:17:55Z No. of bitstreams: 1 Tese final toda (11_agosto_2015).pdf: 3292855 bytes, checksum: bbd17ebdbe647b364c4a07ba7475191a (MD5) / Made available in DSpace on 2016-05-02T17:17:56Z (GMT). No. of bitstreams: 1 Tese final toda (11_agosto_2015).pdf: 3292855 bytes, checksum: bbd17ebdbe647b364c4a07ba7475191a (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geociências-Geoquímica. Niterói, RJ / As baías do Estado do Rio de Janeiro são ecossistemas de grande importância econômica, ecológica e social. Entretanto, estes ambientes vêm sofrendo impactos antropogênicos, oriundo de diversas origens. Dentre as diversas fontes de poluição dos ecossistemas de baías, pode-se destacar a contaminação por hidrocarbonetos policíclicos aromáticos (HPA), uma vez que estes compostos estão presentes em grande parte das atividades urbano-industriais, atingindo os ambientes aquáticos após derramamentos acidentais de petróleo. Os HPA são carcinogênicos, mutagênicos e genotóxicos. Desta forma são considerados poluentes prioritários em monitoramentos ambientais. Para avaliação da contaminação de ambientes aquáticos por HPA como parte de programas de monitoramentos ambientais do EUA e de alguns países da Europa têm sido utilizados, de forma crescente, os chamados biomarcadores. Estes podem ser definidos como alterações bioquímicas, celulares, moleculares ou mudanças fisiológicas nas células, fluidos corpóreos, tecidos ou órgãos de um organismo indicativos da exposição ou efeito de um xenobiótico. A utilização de biomarcadores em peixes tem se mostrado bastante eficaz na avaliação dos efeitos da contaminação por esta classe de compostos. Diante disso, o objetivo deste trabalho foi avaliar a contaminação por HPA em bagres (Genidens genidens) das baías de Guanabara (BG), Sepetiba (BS) e Ilha Grande (BIG) através do uso de biomarcadores. Para tanto, analisou-se uma série de biomarcadores em bagres coletados nas baías de Guanabara, Sepetiba e Ilha Grande, a saber: avaliação do fator de condição; determinação de metabólitos de HPA em bile; determinação de etoxireosrufina- O-desetilase (EROD) hepática; avaliação da frequência de micronúcleos (MN) e anormalidades nucleares eritrocitárias (ANE); avaliação das alterações histopatológicas hepáticas; e formação de adutos de HPA-DNA. O fator de condição evidenciou diferenças na saúde geral dos peixes nas áreas estudadas, tendo os peixes da BG os piores índices de saúde. Foi observada diferença estatisticamente significativa entre a BG e BIG e BS e BIG, para todos os metabólitos de HPA estudados. A indução de EROD também se mostrou mais elevada na BG comparativamente a BS e BIG, com diferenças estatisticamente significativas entre as áreas. Da mesma forma, o MN elucidou estas diferenças. Novamente, a BG mostrou os piores efeitos entre as áreas estudadas. No caso das alterações histopatológicas, a BS mostrou as maiores prevalências de injúrias. Na avaliação do aduto de BPDE-DNA, os peixes da BG possuíram os piores efeitos genotóxicos, com diferença estatisticamente significativa em relação a BIG. A realização de estudos que utilizam ferramentas de avaliação da contaminação em áreas de grande importância social, econômica e ecológica, como o litoral do estado do Rio de Janeiro, é fundamental para o real conhecimento dos impactos causados pelos poluentes, pré requisito essencial para um efetivo plano de conservação e restauração destes ecossistemas / The bays of the state of Rio de Janeiro are ecosystems of great economic, ecological and social importance. However, these environments are suffering anthropogenic impacts, arising from diverse backgrounds. Among the several pollution sources, the pollution caused by polycyclic aromatic hydrocarbons (PAH) is under concern since these compounds are present in many urban and industrial activities. This class of chemistry can cause severe damages in the aquatic biota and suggesting the necessity for environmental monitoring to assess the effects of PAH in fish. The PAH are carcinogenic, mutagenic and genotoxic, being considered priority pollutants in environmental monitoring. For evaluation of contamination by PAH in aquatic environments as part of environmental monitoring, US programs and of some countries in Europe has been used, increasingly, biomarkers. These can be defined as biochemical changes, cellular, molecular or physiological changes in cells, body fluids, tissues or organs of an organism indicative of exposure or effect of a xenobiotic. The use of biomarkers in fish has been shown quite effective in evaluation of the contamination effects by this class compounds. Thus, the objective of this study was evaluate the PAH contamination in fish from Guanabara, Sepetiba and Ilha Grande Bay, using biomarkers. Therefore, we analyzed a series of biomarkers in catfish collected in these bays, namely: assessment of the condition factor; determination of PAH metabolites in bile; determination of the activity of O – ethoxy- resorufin - deetilase (EROD) in fish liver; evaluation of the frequency of micronucleus (MN) and erithrocytic nuclear abnormalities (ENA); evaluation of histopathological hepatic injuries and; formation of PAH-DNA adducts. The condition factor demonstrated differences in the general health of fish arising distinct studied areas. Fish from BG showed the worst health index. There was a statistically significant difference between BG and BS and BG and BIG for all PAH metabolites analyzed. The EROD induction was also higher in BG compared to BS and BIG, with statistically significant differences between areas. Likewise, the micronucleus elucidated these differences. Again, BG showed the worst effects of the studied areas. In the case of the histopathological changes, BS revealed the highest prevalence of injuries. In assessing the BPDE-DNA adduct, fish BG possessed the worst genotoxic effects, with statistically significant difference from BIG. The knowledge of the impacts of pollutants in aquatic biota, based on use of biomarkers in areas with significant social, economic and ecological importance, like Rio de Janeiro cost, is essential for effective conservation and restoration plan of these ecosystems.