Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2015-01-27T13:42:09Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Karina Pinheiro dos Santos - 2014.pdf: 3037076 bytes, checksum: df6a8e2dbd116c93aeb46f89072253a7 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-01-28T11:22:01Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Karina Pinheiro dos Santos - 2014.pdf: 3037076 bytes, checksum: df6a8e2dbd116c93aeb46f89072253a7 (MD5) / Made available in DSpace on 2015-01-28T11:22:01Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Karina Pinheiro dos Santos - 2014.pdf: 3037076 bytes, checksum: df6a8e2dbd116c93aeb46f89072253a7 (MD5) Previous issue date: 2014-08-28 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / Maintaining quality of fresh water, sanitary and environmental aspects, is essential. Once the environmental degradation caused by human activities is more intense. In this direction, the main objective of this study was to evaluate the water quality and environmental conditions of stretches of watershed located in watersheds that are used for public water supply of the cities of Trindade (Bacia Hidrográfica do Ribeirão Arrozal), Goianápolis (Bacia Hidrográfica do Ribeirão Sozinha), Terezópolis (Bacia Hidrográfica do Córrego dos Macacos) and Nerópolis (Bacia Hidrográfica do Córrego Água Branca), cities that compose the Metropolitan Region of Goiânia. To this end this research was organized in articles divided into three chapters. The first chapter corresponds to characterize the environmental conditions of the Bacia Hidrográfica do Ribeirão Sozinha. This chapter have been identified and related the main impacts in the watershed and in rivers, furthermore, were verifying the use and occupation of the soil that could cause potential impacts on water resources with the objective to evaluate the combined use of three methodologies the survey of the environmental status of this basin. The second chapter corresponds to functional trophic categorization community of aquatic macroinvertebrates and characterization of ecological conditions of river reaches that compose the four watersheds listed above. The third chapter discusses the evaluation of water quality and assessment of environmental conditions, of the same river reaches studied in the previous article, by evaluating the structure of the macroinvertebrate community, the implementation of a protocol for rapid assessment of habitat conditions evaluation and physico-chemical parameters of water. Moreover, the latter paper aims to inform about the organization of macroinvertebrates front environmental conditions during periods the dry and rain season. The results of the evaluation of ecological conditions indicated that all watersheds studied in this study are suffering or have suffered from human impacts from agricultural activities. This fact may be affecting the water quality of water sources that supply the Trindade, Goianápolis and Nerópolis, because some physico-chemical parameters such as the total nitrogen and the total phosphorus were not in conformity with limits for Class 2, and were within the limit that is recommended for class 4, according to CONAMA resolution 357/2005. The assessment of water quality through of aquatic macroinvertebrates indicated good quality in all segments surveyed. Assessment of trophic groups allowed a better understanding of how macroinvertebrates were organized against the environmental conditions of each region. The seasonal evaluation of macroinvertebrate community indicated that the richness and abundance did not vary significantly between seasons. / A manutenção da qualidade da água doce, em termos sanitários e ambientais, é essencial, uma vez que, a degradação ambiental causada pelas ações antrópicas é cada vez mais intensa. Nesse sentido, o objetivo principal deste trabalho foi avaliar a qualidade da água e as condições ambientais de trechos de mananciais situados em microbacias que são utilizadas para abastecimento público das cidades de Trindade (Bacia Hidrográfica do Ribeirão Arrozal), Goianápolis (Bacia Hidrográfica do Ribeirão Sozinha), Terezópolis (Bacia Hidrográfica do Córrego dos Macacos) e Nerópolis (Bacia Hidrográfica do Córrego Água Branca), municípios que compõem a Região Metropolitana de Goiânia. Com esse fim essa pesquisa foi organizada em artigos divididos em três capítulos. O primeiro capítulo corresponde a caracterização das condições ambientais da Bacia Hidrográfica do Ribeirão Sozinha. Neste capítulo foram identificados e relacionados os principais impactos na bacia hidrográfica e nos cursos d’água, além disso, foram verificados os principais usos e ocupações do solo que poderiam causar possíveis impactos nos recursos hídricos com o intuito de avaliar a utilização conjunta de três metodologias no levantamento do estado ambiental dessa bacia. O segundo capítulo corresponde a categorização trófica funcional da comunidade dos macroinvertebrados aquáticos e a caracterização das condições ecológicas de trechos de rios que compõem as quatro microbacias citadas anteriormente. O terceiro capítulo aborda a avaliação da qualidade da água e avaliação das condições ambientais, dos mesmos trechos de rios estudados no artigo anterior, por meio da avaliação da estrutura da comunidade de macroinvertebrados aquáticos, da aplicação de um protocolo de avaliação rápida das condições dos habitats e da avaliação parâmetros físico-químicos da água. Além disso, este último artigo buscou informar a respeito da organização dos macroinvertebrados frente as condições ambientais em períodos de seca e chuva. Os resultados da avaliação das condições ecológicas indicaram que todas as microbacias estudadas neste trabalho estão sofrendo ou já sofreram com impactos antrópicos provenientes de atividades agropecuárias. Esse fato pode estar afetando a qualidade da água dos mananciais que abastecem Trindade, Goianápolis e Nerópolis, pois alguns parâmetros físico-químicos, como o nitrogênio total e o fósforo total não estavam em conformidade com limites para classe 2, e ficaram dentro do limite que é recomendado para classe 4 de acordo com a resolução do CONAMA nº 357/2005. A avaliação da qualidade da água por meio dos macroinvertebrados aquáticos indicou boa qualidade em todos os trechos pesquisados. A avaliação em grupos tróficos permitiu uma melhor compreensão de como os macroinvertebrados se organizaram frente às condições ambientais de cada região. A avaliação sazonal da comunidade de macroinvertebrados indicou que a estrutura da comunidade de macroinvertebrados não variou significativamente entre as estações.

Nas últimas décadas, tem-se observado uma expressiva queda da qualidade ambiental e perda de biodiversidade nos ecossistemas aquáticos em função de múltiplos impactos advindos de atividades antrópicas. Dessa forma, considerando-se que a estrutura das comunidades pode ser alterada por tais perturbações, diversos métodos têm sido propostos para avaliações da qualidade nesses ecossistemas, destacando-se, entre eles, o uso dos macroinvertebrados bentônicos. Alguns estudos empregando estes indicadores defendem a sua identificação ao nível genérico por fornecer maior número de informações, resultar em classificações ambientais mais confiáveis e apresentar melhor capacidade de distinção entre os pontos, quando comparado aos níveis de resolução mais abrangentes. Entretanto, na maioria dos trabalhos a identificação desse grupo restringe-se ao nível de família, principalmente em função da economia nos recursos despendidos durante a identificação o que não se justifica caso este nível não retenha informações suficientes para que os objetivos sejam alcançados. Neste trabalho, esse conflito foi avaliado através da comparação de avaliações biológicas decorrentes da aplicação de índices estruturais baseados na identificação de Chironomidae, ao nível genérico com o de sub-família/tribo. Foram utilizadas amostras de organismos bentônicos, bem como os dados físicos, químicos e microbiológicos coletados em sete pontos de amostragem que fizeram parte de vários projetos da CETESB (Companhia de Tecnologia de Saneamento Ambiental), conduzidos ao longo de diferentes anos e classificados, de acordo com o ICBRIO (Índice da Comunidade Bentônica para rios) em ambientes de qualidade péssima, ruim, regular, boa e ótima. As coletas foram padronizadas em relação ao período (inverno) e ao tipo de hábitat amostrado (margem deposicional). As amostras foram obtidas em triplicata com o auxílio de pegadores (Ponar e Petersen modificado) e o material selecionado em rede com abertura de malha 0,5 mm. A contagem e identificação dos organismos foram feitas com o auxílio de estereomicroscópio, microscópio óptico e bibliografia especializada. Para definir o gradiente de qualidade, as variáveis ambientais foram submetidas a uma Análise de Agrupamento pelo método de Ward, empregando-se a Distância Euclidiana Simples. Já os valores de densidade foram reunidos em uma matriz de distância de Bray-Curtis agrupada pelo método de média de grupo não ponderada a fim de verificar o grau de similaridade entre os pontos e se o nível de identificação taxonômica interfere nas associações formadas. Com o intuito de verificar a sensibilidade do nível taxonômico do dado ao gradiente de qualidade ambiental, bem como testar a possível influência do refinamento taxonômico na sensibilidade do ICBRIO foram empregadas as métricas Riqueza, Diversidade de Shannon-Wiener, Índice de Comparação Seqüencial, Dominância de Grupos Tolerantes e Riqueza de Táxons Sensíveis. Tendo por objetivo o diagnóstico das condições ambientais, com redução de custos e tempo de manipulação das amostras, mas com informações relevantes que subsidiem os tomadores de decisão, o presente trabalho vem descartar o emprego do nível de resolução genérico na identificação das larvas de Chironomidae. Os resultados expostos confirmaram a aplicabilidade do ICBRIO com a identificação deste grupo aos níveis de sub-família/tribo na avaliação da qualidade ambiental, demonstrando não serem necessárias eventuais alterações nos seus moldes. / In the last decades, it has been observed an expressive deterioration of the environmental quality and biodiversity loss in the aquatic ecosystems as function of anthropogenic activities. Considering that communities' structure can be altered by such disturbances, several methods have been proposed for quality assessment in those ecosystems, standing out, among them, the use of the benthic macroinvertebrates. Some studies using these indicators defend the generic level identification as they supply more information, result in more reliable environmental classifications and present better distinction capacity among sites, when compared to broader levels. However, in most of the works the identification of this group is limited to the family level, mainly due to resources saving during the identification, which is not justified in the case this level misses information to classification aims. In this work, comparison of current biological evaluations through Chironomidae identification structural indexes at the generic level with the one at sub-family/tribe was evaluated. Benthic organisms samples, as well as physical, chemical and microbiological data were collected in seven sampling sites, from several projects taken along different years by CETESB (Company of Technology of Environmental Sanitation), which classified the environment as, according to ICBRIO (Benthic Community Index for rivers), worst, bad, regular, good and excellent quality. The collections were standardized to winter period and to type of sample habitat (depositional river margin). Triplicates were obtained with modified Ponar and Petersen grabs on retained material by 0.5mm-mesh sieve. Counting and identification based on specialized literature were done with the stereomicroscope, and optical microscope. To define the quality gradient, the environmental variables were submitted to a Cluster Analysis by the Ward method, using the simple Euclidean Distance. Density values were lumped on a Bray-Curtis distance matrix by the Unweighted Pair Group method in order to verify the similarity degree among the points and the interferences of taxonomic identification level on the formed associations. Aiming to check the sensibility of the data taxonomic level to the environmental quality gradient, as well as to test the possible influence of taxonomic refinement in the ICBRIO's sensibility, several metrics (Richness, Shannon-Wiener Diversity Index, Sequential Comparison Index, Dominance of Tolerant Groups and Richness of Sensitive Taxa) were used. Seeking the diagnosis of the environmental conditions, reducing costs and manipulation time of the samples, but keeping relevant information to subsidize the policy managers, the present work discards the need of the generic resolution level in the Chironomidae larvae identification. The exposed results confirmed the applicability of ICBRIO with the identification of this group at sub-family/tribe levels on the environmental quality assessment, demonstrating no need of eventual modification in the method.

As áreas de várzea estão entre os ecossistemas mais ameaçados, porém no Brasil essa situação agrava-se devido à falta de uma abordagem ecológica robusta na Lei de Proteção da Vegetação Nativa, o que torna necessário a atuação do poder público municipal para salvaguardar esses sistemas. A presente pesquisa empregou uma abordagem ecológica aplicada (limnologia, macroinvertebrados, macrófitas aquáticas) para avaliar a relação do rio Sorocaba com suas várzeas no município de Sorocaba, o uso e ocupação da terra e a sua influência sobre às variáveis limnológicas, além das demandas dos serviços ambientais fornecidos pelas várzeas ao município. Duas amostragens foram realizadas durante o ano de 2017, sendo uma no período de cheia (fevereiro) e outra na estiagem (junho). Métodos padronizados foram empregados para o desenvolvimento do presente trabalho. Evidenciou-se que a poluição orgânica e o predomino de áreas antropizadas são os principais fatores responsáveis pela alteração das variáveis limnológicas analisadas. Alguns serviços ambientais (i.e. provisão de água, controle do fluxo, regulação dos processos erosivos, regulação de nutrientes, ciclagem da água, pesca voltada ao lazer e valor intrínseco da biodiversidade) prestados pelos ecossistemas de várzea do Município de Sorocaba apresentam um balanço negativo (i.e. demanda superior à oferta). As espécies de macrófitas e famílias de macroinvertebrados encontradas são espécies indicadoras de poluição orgânica. Por fim, destaca-se a contribuição da ação estratégica e o papel da gestão municipal para o manejo dos ecossistemas de várzea. / The wetlands are among the most threatened ecosystems, although in the Brazil that situation is worse because of an ecological approach lack in the Law of Native Vegetation Protection, what makes necessary the public power action to safeguard those systems. The present research employed an applied ecological approach (limnology, macroinvertebrates, aquatic macrophytes) for Sorocaba River and its wetlands assessment in Sorocaba-SP municipality, the land cover and its influence on limnological variables, as well as the environmental services demand supplied by the municipality wetlands. Two samples were performed during 2017, one during the rainy (February) season and other on the dry season (June). Patronized methods were employed in the present research. The organic pollution and the anthropic areas predominance are the mainly factors responsible for limnological variables alteration. Some environmental services (i.e. water provision, water flow control, erosive process control, nutrient control, water cycling, recreation fishing and biodiversity intrinsic value) provided by the studied wetlands showed a negative balance (i.e. demand superior to the provision capacity). The macrophyte species and macroinvertebrate families found are organic pollution indicators. Finally, stand out the strategic action contribution and the municipality governance role for wetlands ecosystem management.

Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2016-09-05T17:54:10Z No. of bitstreams: 1 Cruz, A.P.S Doutorado_2016.pdf: 5094588 bytes, checksum: c2d2f2c5452d77b62cfc4edc84e03851 (MD5) / Made available in DSpace on 2016-09-05T17:54:10Z (GMT). No. of bitstreams: 1 Cruz, A.P.S Doutorado_2016.pdf: 5094588 bytes, checksum: c2d2f2c5452d77b62cfc4edc84e03851 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geociências - Geoquímica. Niterói, RJ / A fim de determinar a influência da dinâmica das massas d'água no fornecimento de nutrientes para o Atlântico Equatorial Oeste e as interações continente-oceano foi analisado a concentração elementar de carbono, a composição isotópica da matéria orgânica (δ13C e δ15N), assim como a composição isotópica de foraminíferos bentônicos e planctônicos (δ13C e δ18O), além da concentração de fósforo total e carbonato no sedimento coletado na plataforma continental do Nordeste do Brasil. Durante os últimos 30kaAP foi possível identificar três diferentes fases relativas as modificações nas massas de água e no aporte de material proveniente do continente. Na primeira fase, o fornecimento de nutrientes foi baixo devido a mistura de massas d’água pobres em nutrientes (baixo δ13C bentônico), o qual promoveu uma redução no δ15N devido a redução do influxo de nutrientes para a zona fótica. A segunda fase mostrou uma drástica redução no δ15N e um aumento da entrada de material terrestre na região (aumento no C/N e baixo δ13C) devido ao deslocamento da ITCZ para sul, aumentando as taxas de precipitação no Nordeste do Brasil. Na terceira fase, o fornecimento de nutrientes para a zona fótica foi mais alta (alto δ13C dos planctônicos), levando ao aumento na produtividade da região e, consequentemente, a um aumento no δ15N sedimentar. Assim, pode-se dizer que as mudanças nas massas d’água tem uma larga influência no fornecimento de nutrientes dentro da nutriclina e que as variações no δ15N podem estar associadas ao fornecimento de nutrientes no oceano e pela entrada de material terrestre durante as mudanças climáticas abruptas. O aumento na precipitação e as mudanças na hidrodinâmica das correntes oceânicas influenciam diretamente na qualidade e quantidade de materiais que chegam aos oceanos. Durante o glacial (30-19ka AP), foi possível identificar uma mistura de fontes de materiais que se depositaram na área de estudo e uma redução da hidrodinâmica das correntes oceânicas levando a um aumento na acumulação de sedimentos finos na região, devido a redução do fluxo da CNB. Também foi possível evidenciar uma redução da temperatura da superfície do mar (TSM) e um aumento da salinidade ligados a expansão do volume de gelo e a aumento das taxas de evaporação. O H2 (26-24kaAP) apresentou um pico de aquecimento oceânico e valores máximos de salinidade devido ao colapso da AMOC, o qual provocou uma maior concentração de calor no oceano sul, alterando o ciclo hidrológico pela mudança na posição da ITCZ. A hidrodinâmica, durante o deglacial, foi marcada por um maior transporte de materiais para o oceano profundo, o qual resultou em um aumento no tamanho do grão durante este período. A TSM e a salinidade apresentaram altos valores, principalmente, durante a primeira fase do H1 (17,4-16kaAP), indicando uma concentração de calor e salinidade no oceano sul. Na segunda fase (16-14,4KaAP), ocorreu um aumento considerável no aporte de terrígenos e uma redução na TSM e na salinidade, corroborando com o início do reestabelecimento da circulação meridional do Atlântico e o deslocamento da ITCZ para áreas mais próximas ao Equador. O YD apresentou um aumento no aporte terrígeno e uma redução inicial da TSM e da salinidade, com um posterior aumento. O Holoceno foi caracterizado por um aumento significativo no tamanho do grão devido a maior umidade e hidrodinâmica ocorrida neste período. No entanto, um aumento significativo no tamanho do grão foi evidenciada durante o evento 8,2kaAP, o qual aumentou a hidrodinâmica local devido as maiores taxas de precipitação. Além disso, houve uma redução na TSM e na salinidade devido ao aumento das taxas de precipitação em relação a evaporação, promovendo maior entrada de águas frias e menos salinas no oceano. / In order to analyze the influence of the water masses dynamic in the nutrients supply to the western equatorial Atlantic and the land-ocean interactions was analyzed the elemental concentration of carbon isotopic composition of organic matter (δ13C and δ15N), benthic and planktonic foraminifera (δ13C and δ18O), the total phosphorus and carbonate concentration in sediment recovery on the continental slope off Northeastern Brazil. Over the past 30kaBP was possible to identify three different phases related to water masses distribution and the input of land material. In the first stage, the nutrient supply was low due to the mixing of water masses nutrient-poor (low benthic δ13C), promoting a reduction on δ15N signal due the reduction in nutrient influx. The second stage showed a drastic decrease in δ15N and an increase of terrigenous input (high C/N and Corg values and low δ13Corg signal) as consequence of the southward displacement of Intertropical Convergence Zone, which promoted an increase in the moisture at Northeastern Brazil. During the third stage, the nutrient supply was higher in the photic zone (high planktonic δ13C), leading to increase the productivity of that region, increasing the sedimentary δ15N. Thus, we argue that water masses changes have a large influence in nutrient influx within the nutricline and these variations in δ15N could be associated with the ocean nutrient supply and terrigenous input during abrupt climate changes. The increase in precipitation and changes in ocean hydrodynamics have influence in the quality and quantity of material that arrives in the oceans. During the glacial, it was possible to identify a mixture of source materials and a reduction of the ocean hydrodynamic, leading to an increase in the accumulation of silt due to reduction of the CNB flow. It was also possible to show a reduction in sea surface temperature (SST) and increasing salinity due to the expansion of ice volume and the increase in evaporation. The H2 (26-24kaBP) showed a peak of ocean warming and maximum salinity values due to the AMOC collapse, which caused a greater concentration of heat in the Southern Ocean, altering the hydrological cycle by displacement of the ITCZ. The hydrodynamic during deglacial was marked by a larger materials input for the deep ocean, which resulted in an increase in grain size during this period. The SST and salinity showed higher values during the first phase of H1 (17.4-16kaBP), indicating a concentration of the heat and salinity in the Southern Ocean. In the second phase (16-14.4KaBP), there was a considerable increase in terrigenous intake and a reduction in SST and salinity, corroborating the beginning of the reestablishment of the southern Atlantic circulation and the displacement of the ITCZ to areas closer to the Equator. The YD experienced an increase in the terrigenous contribution and an initial reduction of SST and salinity, with a subsequent increase in the end of this event. The Holoceno was characterized by a significant increase in grain size due to high moisture and hydrodynamic occurred during this period. However, a significant increase in grain size was observed during 8.2kaAP event, which increased the hydrodynamic due to the larger precipitation rates. In addition, there was a reduction in the SST and salinity due to increased precipitation rates relative to evaporation, promoting greater incoming of cold and less saline water in the ocean.

A l’échelle de l’Atlantique Nord-Est, la Manche se situe à un carrefour biogéographique entre les provinces boréale et lusitanienne. Ainsi, de nombreuses espèces y sont en limite d’aire de distribution. L’objectif de cette thèse est d’évaluer les effets du changement climatique récent sur la distribution de la macrofaune benthique subtidale, peu étudiée à ce jour, en se basant sur la comparaison de données collectées à l’échelle de la Manche lors une période froide (i.e. années 1960-70) et lors d’une période chaude (i.e. 2012 et 2014) dans les sédiments grossiers circalittoraux. L’étude de la structure des assemblages inféodés à cet habitat a mis en évidence deux grandes communautés benthiques : la communauté des sédiments grossiers sablo-graveleux et celle des cailloutis et graviers. L’analyse de l’évolution des températures de fond au cours des 30 dernières années a montré l’hétérogénéité spatiale du réchauffement, variant de 0,1 à 0,5°C par décennie d’ouest en est. Ce réchauffement ne se s’est pas traduit par d’importants déplacements de l’aire de distribution des espèces mais par une forte diminution du nombre d’occurrences des espèces d’eaux froides et une forte augmentation de celui des espèces d’eaux chaudes. Le développement de modèles de distribution d’espèces a permis de déterminer l’importance relative des facteurs climatiques et édaphiques dans la distribution des invertébrés benthiques en Manche et d’apprécier l’aptitude des espèces à ajuster leur distribution à la hausse de températures. L’ensemble de ces résultats suggère que le changement climatique en cours pourrait entraîner une diminution de la biodiversité benthique aux limites d’aires de distribution, en particulier si la connectivité entre populations limite l’arrivée de nouveaux individus. / In the North-East Atlantic, the English Channel constitutes a biogeographical transition zone between the Boreal and Lusitanian provinces. Thus, many species reach there their distribution range limits. The aim of this thesis is to assess the effects of recent climate change on the distribution of the subtidal benthic macrofauna, poorly studied to date, basing on the comparison of data collected during a cool period (i.e. 1960s-70s) and during a warm period (i.e. 2012 and 2014) in the circalittoral coarse sediments. Two large communities were highlighted in the study of the structure of the assemblages found in this habitat: the gravelly coarse sand community and the pebbles and gravels community. The analysis of the evolution of seabed temperature for the last 30 years showed the spatial heterogeneity of the warming, varying from 0.1 to 0.5°C per decade from West to East. This warming did not translate into large species distribution shifts but into a sharp decrease in the number of occurrences of cold-water species and a sharp increase in the number of occurrences of warm-water species. Development of species distribution models allowed to identify the relative importance of climatic and edaphic factors in the distribution of benthic invertebrates in the Channel and to assess the species’ ability to adjust their distribution to the rise in temperature. The whole results suggest that ongoing climate change could lead to a decrease in benthic biodiversity at range limits, especially where connection routes are lacking for new migrants.

Dans les vasières intertidales dominées par les diatomées, la production primaire est particulièrement forte à marée basse. Ce microphytobenthos peut être limité par les nutriments azotés en lien avec les communautés de procaryotes impliquées dans le cycle de l’azote. Ainsi, ce travail de thèse cherche, via une approche écologique, à décrire le rôle des communautés de procaryotes benthiques notamment liées au cycle de l’azote et ce, suivant différentes échelles temporelles liées aux cycles du microphytobenthos. Des échantillons de sédiment ont été prélevés dans la baie de Marennes-Oléron (Côte Atlantique, France) entre 0 et 10 cm de profondeur suivant 5 couches (0-0,5 cm, 0,5-1 cm, 1-2 cm, 2-5 cm, 5-10 cm). Différents facteurs biotiques et abiotiques ont été mesurés et mis en relation avec la production bactérienne, les activités enzymatiques et les gènes fonctionnels liés au cycle de l’azote (impliqués dans la nitrification, la dénitrification et l’anammox). De plus, la diversité bactérienne et archéenne a été évaluée par pyroséquençage 454 afin de caractériser les communautés et leurs dynamiques en lien avec les facteurs forçants biotiques et abiotiques. Dans le but d’évaluer l’influence des paramètres abiotiques et de la production du microphytobenthos, des mesures in situ ont été couplées avec des mesures en conditions semi-contrôlées. / In diatoms-dominated intertidal mudflats, at low tide the primary production is particularly high and microphytobenthos that can be limited by nitrogen-related nutrients is linked with N-related prokaryotic communities. Thus, this PhD thesis aim at describing by ecological approach, the role of benthic prokaryotic communities especially N-related ones, at various temporal scales linked to microphytobenthos life cycles. Sediment samples from Marennes-Oleron mudflat (Atlantic coast, France) were collected according to 5 layers : 0-0.5 cm, 0.5-1 cm, 1-2 cm, 2-5 cm and 5 to 10 cm below sediment surface (bsf). Various biotic (i.e. chlorophyll a) and abiotic parameters (i.e. nutrients, exopolymeric substances, water content, salinity, pH, temperature…) were recorded and linked with benthic bacterial production, enzymatic activities and N-related functional genes (i.e. implied in nitrification, denitrification, and anammox). Furthermore, the bacterial and archaeal diversity was assessed by 454 pyrosequencing in order to characterize the communities and shift in link with biotic and abiotic drivers. Aiming at evaluating the influence of abiotic parameters and microphytobenthic activities on the prokaryotic communities, in situ measurements were coupled to a semi-controlled approach.

The Florida Reef Tract (FRT) extends from the tropical Caribbean northward along the Florida coast into a warm temperate environment where tropical reef communities diminish with increasing latitude. This study was designed to map the nearshore benthic habitats including coral reefs and evaluate how the benthic communities differ between habitats and along the coast. Benthic communities across the northern FRT from Key Biscayne to Hillsboro Inlet (25.5°-26.3° N) were digitized from aerial photography taken in 2013 at a 1:1,000 scale. Three main hard-bottom habitat types were identified that ran parallel to shore and consecutively further away from shore: Colonized Pavement, Ridge, and Inner Reef. Five 1-km wide cross-shelf corridors (numbered 1-5, south to north) were designated and spaced as evenly as possible throughout the region. Five sites per habitat per corridor (70 total) were randomly selected and quantitative data collected within 4,200 m2. Significant differences in percent benthic cover among habitats were found in all corridors and within habitat types between corridors, indicating cross-shelf and latitudinal variation. Mean stony coral density increased with depth, with the Inner Reef habitat being significantly higher than both the Colonized Pavement and Ridge. Mean stony coral species richness also increased with depth, with all habitats significantly different from one another. A total of 22 stony coral species were identified within the mapped region, the three most abundant being Porites astreoides, Siderastrea siderea, and Acropora cervicornis. Results from this study support the ecosystem regions denoted in the Walker (2012) study. Corridor 1, located in the Biscayne Region, was the only corridor to contain any seagrass. In addition, Corridor 1 Inner Reef had significantly higher values for mean stony coral density, mean stony coral species richness, mean gorgonian density of the plume morphotype, and mean density of stony corals infected with Cliona spp. Corridors 2-4, located in the Broward-Miami Region, had some variability associated with them, but were generally similar in benthic composition. Corridor 5, likewise located in the Broward-Miami Region but in close proximity to the Deerfield Region, also had differences associated with it. Both the Colonized Pavement and Ridge habitats in Corridor 5 had the lowest mean coral species richness, as well as total absence of both sponge species noted in this study. Corridor 5 Inner Reef also had significantly lower mean stony coral densities compared to Corridors 1, 2, and 4. As such, these results support the idea of different biogeographic regions occurring off the southeastern Florida coast. This study produced two key findings. It discovered over 110 large (>2 m) resilient coral colonies, of which 50 were alive in various conditions. This study also found 38 acres of dense Acropora cervicornis patches, tripling the previously known area within the study region. These are the largest dense patches in the continental United States.

Animals living in marine sediments (the second largest habitat on earth) play a major role in global biogeochemical cycling. By feeding on organic matter from settled phytoplankton blooms they produce food for higher trophic levels and nutrients that can fuel primary production. In the Baltic Sea, anthropogenic stresses, such as eutrophication and introductions of invasive species, have altered phytoplankton dynamics and benthic communities. This thesis discusses the effects of different types of phytoplankton on the deposit-feeding community and the importance of benthic biodiversity for fate of the phytoplankton bloom-derived organic matter. Deposit-feeders survived and fed on settled cyanobacterial bloom material and in doing so accumulated the cyanobacterial toxin nodularin. Their growth after feeding on cyanobacteria was much slower than on a diet of spring bloom diatoms. The results show that settling blooms of cyanobacteria are used as food without obvious toxic effects, although they do not sustain rapid growth of the fauna. Since all tested species accumulated the cyanotoxin, negative effects higher up in the food web can not be ruled out. Both species composition and richness of deposit-feeding macrofauna influenced how much of the phytoplankton bloom material that was incorporated in fauna or retained in the sediment. The mechanism behind the positive effect of species richness was mainly niche differentiation among functionally different species, resulting in a more efficient utilization of resources at greater biodiversity. This was observed even after addition of an invasive polychaete species. Hence, species loss can be expected to affect benthic productivity negatively. In conclusion, efficiency in organic matter processing depends both on pelagic phytoplankton quality and benthic community composition and species richness. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 4: In press. Paper 5: Manuscript.</p>

Coastal marine ecosystems are among the most impacted globally, attributable to individual and cumulative effects of human disturbance. Anthropogenic nutrient loading is one stressor that commonly affects nearshore ecosystems, including seagrass beds, and has positive and negative effects on the structure and function of coastal systems. An additional, previously unexplored mechanistic pathway through which nutrients may indirectly influence nearshore systems is by driving blooms of benthic jellyfish. My dissertation research, conducted on Abaco Island, Bahamas, focused on elucidating the role that benthic jellyfish have in structuring systems in which they are common (i.e., seagrass beds), and explored mechanistic processes that may drive blooms of this taxa. To establish that human disturbances (e.g., elevated nutrient availability) may drive increased abundance and size of benthic jellyfish, Cassiopea spp., I conducted surveys in human-impacted and unimpacted coastal sites. Jellyfish were more abundant (and larger) from human-impacted areas, positively correlated to elevated nutrient availability. In order to elucidate mechanisms linking Cassiopea spp. with elevated nutrients, I evaluated whether zooxanthellae from Cassiopea were higher from human-disturbed systems, and whether Cassiopea exhibited increased size following nutrient input. I demonstrated that zooxanthellae population densities were elevated in human-impacted sites, and that nutrients led to positive jellyfish growth. As heightened densities of Cassiopea jellyfish may exert top-down and bottom-up controls on flora and fauna in impacted seagrass beds, I sought to examine ecological responses to Cassiopea. I evaluated whether there was a relationship between high Cassiopea densities and lower benthic fauna abundance and diversity in shallow seagrass beds. I found that Cassiopea have subtle effects on benthic fauna. However, through an experiment conducted in a seagrass bed in which nutrients and Cassiopea were added, I demonstrated that Cassiopea can result in seagrass habitat modification, with negative consequences for benthic fauna. My dissertation research demonstrates that increased human-driven benthic jellyfish densities may have indirect and direct effects on flora and fauna of coastal marine systems. This knowledge will advance our understanding of how human disturbances shift species interactions in coastal ecosystems, and will be critical for effective management of jellyfish blooms.

Les zones humides (ZH) alluviales constituent des secteurs à forte valeur écologique etpatrimoniale. Pour comprendre et prédire l’évolution à long terme de ces zones, en particulierface aux changements globaux, il apparaît primordial de traduire les perturbationshydrologiques attendues en termes de perturbations biologiques, afin d'estimer lesconséquences potentielles de ces changements pour la biodiversité et le fonctionnement globalde ces écosystèmes. Cette thèse s’articule donc autour de deux objectifs: proposer un modèleconceptuel de fonctionnement écologique des ZH soumises à des assèchements saisonniers etestimer la vulnérabilité écologique de communautés faunistiques vivant dans ces ZH, enconsidérant conjointement les peuplements benthiques et interstitiels (principalementCrustacés).Nos résultats démontrent que la morphologie des ZH (eau relativement courante, eaustagnante, apports phréatique) et leurs modes d’assèchement (formation de mouilles isoléesou assec complet) sont essentiels dans la structuration des communautés microbiennes etd’invertébrés et dans la réponse saisonnière de la biodiversité et des processus écologiques.L’intensification probable des étiages et des assèchements augmentera l’hétérogénéité spatialeet temporelle des habitats et leur richesse spécifique mais réduira la biodiversité globale desplaines alluviales (disparition des espèces rares). Ces étiages plus sévères modifieront lesprocessus écologiques, diminuant le recyclage de la matière organique et la qualité des eauxsuperficielles. Les recherches futures devraient s’orientées vers des stratégies et des moyensefficaces pour garantir la durabilité écologique des ZH. / Alluvial wetlands offer many ecological goods and services. In order to evaluate thelong term impact of global changes, it appeared essential to translate the hydrological changesin term of biological perturbation, so as to estimate the consequences on biodiversity andecosystem functioning. This PhD thesis focuses on two points: to propose a conceptual modelof ecological functioning of the wetlands that are subjected to seasonal drying and to estimatethe ecological vulnerability of aquatic invertebrate communities of the wetlands facing theincreasing drought risk, by considering both the benthic and interstitial assemblages (with aparticular interest on Crustaceans).Our main results demonstrate that wetlands’ morphology (running water, groundwaterupwelling, stagnant water) and their drying modalities (formation of isolated pools orcomplete drying) influence both the microbial and invertebrate community structures andcontrol the seasonal responses of biodiversity and ecological processes. The potential increasein the low flow period and drying intensity may increase the spatial and temporalheterogeneity of habitats and their specific richness but may decrease the global biodiversityof floodplain (rarefaction of sensible species). Severe low flow periods may also disturb theirecological functioning, reducing the organic matter recycling and the surface waters quality.Future studies should develop efficient strategies to support the ecological durability ofwetlands.