Les sédiments déposés dans les fjords norvégiens contiennent des informations précieuses sur la dynamiquepassée de la circulation de surface en mer de Norvège (Courant Nord Atlantique –NAC- et Courant Côtier deNorvège –NCC-), ainsi que sur le climat régional du continent bordier et du domaine océanique adjacent. Letransport méridien par le NAC d’eaux chaudes et salées participe efficacement au fonctionnement de la bouclethermohaline globale. Le NCC, alimenté par les apports continentaux depuis la mer Baltique, contrôlel’hydrologie des fjords norvégiens. L’objectif de la présente étude est de tester l’utilisation, dans le fjord deTrondheim, des isotopes stables benthiques et des assemblages de dinokystes en tant que traceur de lavariabilité hydrologique et climatique locale et régionale. Ce travail repose sur une série exceptionnelle desédiments de surface et de carottes d’interface, recouvrant de façon équilibrée l’ensemble des sous-systèmesdu fjord. Les changements climatiques et océanographiques modernes et récents (derniers 35 à 50 ans) décritspar nos traceurs sont comparés à plusieurs séries temporelles instrumentées de paramètres hydrologiques etclimatiques clés, afin de déterminer les différents mécanismes à l’origine de la signature spatiale et temporelledes proxies. Nos résultats montrent que les isotopes stables benthiques et les assemblages de dinokystestraduisent efficacement les variations hydrologiques et climatiques locales et régionales, le gradient spatial desalinité, l’efficacité du mélange vertical, la température des eaux atlantiques entrantes, et le budget de lasédimentation de matière organique (quantité et origine) expliquant de façon importante les variabilitésspatiales et temporelles de nos traceurs. La dynamique atmosphérique liée à l’Oscillation Nord Atlantiqueexplique l’essentiel des changements récents de la circulation interne du fjord et de la nature de lasédimentation (marine vs. continentale). / Sedimentary archives in Norwegian fjords contain valuable highly resolved information on the past dynamics ofmajor surface circulation features of the Norwegian Sea (North Atlantic Current and Norwegian CoastalCurrent), as well as on the regional climate of the Norwegian continental and surrounding oceanic realms. TheNAC transports significant amounts of warm and saline water poleward and constitutes an essentialcomponent of the global thermohaline circulation. The NCC is supplied by Norwegian rivers and fjords and itslateral and vertical distribution fundamentally controls the hydrology of Norwegian fjords. In the present studywe examine the use of benthic stable isotopes and dinocyst assemblages in the Trondheimsfjord, centralNorway, as proxies of the local and regional hydrological and climate changes. This study is essentially based onan exceptional set of surface sediment samples and multi-cores which are evenly distributed within the variousfjord subsystems. Modern and recent (last 35 to 50 years) oceanographic and climatic changes inferred fromour proxies are discussed in view of time-series of key hydrological and climatic parameters in order todetermine the various mechanisms driving the spatial and temporal variabilities of the proxies. Our resultsshow that benthic stable isotopes and dinocyst assemblages reliably record the local and regional hydrologicalvariations in the Trondheimsfjord and associated climate changes linked to key characteristics and processessuch as salinity gradients, water column mixing, temperatures of the incoming Atlantic water. Changes inatmospheric processes alike the North Atlantic Oscillation explain most of the recorded recent changes in thefjord internal circulation and nature of sedimentation (marine vs. continental).

Understanding how coral reefs have developed in the past is crucial for placing contemporary ecological and environmental change within appropriate reef-building timescales (i.e. centennial to millennial). On Australia’s Great Barrier Reef (GBR), coral reefs situated within nearshore settings on the inner continental shelf are a particular priority. This is due to their close proximity to river point sources, and therefore susceptibility to reduced water quality as the result of extensive modification of adjacent river catchments following European settlement in the region (ca. 1850 CE). However, the extent of water quality decline and its impact on the coral reefs of the GBR’s inner-shelf remains contentious and is confounded by a paucity of long-term (> decadal) datasets. Central to the on-going debate is uncertainty related to the impact of increased sediment loads, relative to the natural movement and resuspension of terrigenous sediments, which have accumulated on the inner-shelf over the last ~6,000 years. The main aim of this thesis was to characterise and investigate the vertical development of turbid nearshore coral reefs on the central GBR. This aim was achieved through the recovery of 21 reef cores (3 - 5 m in length) from five proximal turbid nearshore reefs, currently distributed across the spectrum of reef ‘geomorphological development’ within the Paluma Shoals reef complex (PSRC). The recovered reef cores were used to establish detailed depositional and palaeoecological records for the investigation of the (1) internal development and vertical accretionary history of the PSRC; and (2) compositional variation in turbid nearshore coral and benthic foraminiferal assemblages during vertical reef accretion towards sea level. Established chronostratigraphic and palaeoecological records were further used to assess the impact of post-European settlement associated water quality change in a turbid nearshore reef setting on the central GBR. Radiocarbon dating (n = 96 dates) revealed reef initiation within the PSRC to have occurred between ~2,000 and 1,000 calibrated years before present, with subsequent reef development occurring under the persistent influence of fine-grained (< 0.063 mm) terrigenous sediments. The internal development of the PSRC was characterised by discrete reef facies comprised of a loose coral framework with an unconsolidated siliciclastic-carbonate sediment matrix. A total of 29 genera of Scleractinian coral and 86 genera of benthic foraminifera were identified from the palaeoecological inventory of the PSRC. Both coral and benthic foraminiferal assemblages were characterised by distinct assemblages of taxa pre-adapted to sediment stress (i.e. low light availability and high sedimentation). At the genus level, no discernable evidence of compositional change in either coral or benthic foraminiferal assemblages was found, relative to European settlement. Instead, variations in assemblage composition were driven by intrinsic changes in prevailing abiotic conditions under vertical reef accretion towards sea level (e.g. hydrodynamic energy, light availability, and sedimentation rate). These findings therefore highlight the importance for considering reef ‘geomorphological development’ when interpreting contemporary reef ecological status. Furthermore, this research emphasises the robust nature of turbid nearshore reefs and suggests that they may be more resilient to changes in water quality than those associated with environmental settings where local background sedimentary conditions are less extreme (e.g. towards the inner/mid-shelf boundary). To this end, this thesis presents new baseline records with which to assess contemporary ecological and environmental change within turbid nearshore settings on the central GBR.

La marge ibérique est un milieu biologiquement productif régit par l'influence d'un upwelling saisonnier et des apports continentaux. Les foraminifères benthiques sont des protistes matins qui présentent une grande sensibilité aux conditions environnementales. Ils apparaissent ainsi comme des bio-indicateurs particulièrement efficaces dans ce type de contexte. Dans le cadre de cette thèse, les faunes de foraminifères benthiques, vivants, morts et fossiles prélevées sur un total de 23 carottes interfaces et deux carottes et deux carottes piston, essentiellement situées au débouché de quatre feluves ouest-ibériques majeurs (Douro, Mondego, Tage et Sado) ont été étudiés.Cette analyse faunistique, conjointe à des mesures sédimentaires et géochimiques a permis d'identifier l'impact de la qualité de la matière organique, et donc des apports fluviatiles sur la distribution des faunes vivantes en période hivernale. La comparaison des faunes mortes et vivantes sur les premiers centimètres de sédiments illustre la variation saisonnière de la réponse faunistique à l'upwelling et aux apports continentaux. Elle met également en évidence l'impact des processus taphonomiques sur la conservation de ces bio-indicateurs en vue de permettre une meilleure compréhension du signal fossile de ces faunes. L'application paléoenvironnementale de ces bio-indicateurs a été menée sur une carotte longue prélevée au large du Tage qui permet une reconstruction des derniers 5700 ans cal. BP. Elle a permis de mettre en évidence des périodes caractérisées par des apports importants de matière organique issus du fleuve ainsi que des variations de l'intensité de l'upwelling. / The Iberian Margin is a highly productive system driven by coastal upwelling and river inputs. Benthic foraminifera are marine protists particularly sensitive to environmental conditions. Hence they appear well suited bio-indicators for such environment. In the framework of this thesis, living, dead and fossil benthic foraminifera were analized on 23 surface sediment cores and two piston cores essentially from locations off the major rivers of the Portuguese Coast (Douro, Mondego, Tagus and Sado). This faunal analysis, combined with sedimentary and geochemical measurements allow thhe identification of the impact of fluvial exports and organic matter quality during the late winter period. The comparison of dead and living communities, on the first few centimeters of the sediment, shows the seasonal variation of faunas controlled by upwelling activity and riverine discharges intensity. The impact of taphonomical processes on the preservation of these bio-indicators is also investigated in the perspective of a better understanding ofthe fossil signal of these faunas. The paleoenvironmental application of these bio-indicators was then conducted on a 10 m long core from the Tagus shelf that allows paleoreconstruction for the last 5,700 cal. yr BP. The fossil benthic foraminifera record shows that some periods were characterized by intense river runoff and others by variable intensity of the seasonal upwelling.

Submitted by Jean Medeiros (jeanletras@uepb.edu.br) on 2016-02-29T13:12:51Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) PDF - Maria José Pinheiro Anacléto.pdf: 6289419 bytes, checksum: a5bad1c5254340842bfb8f794c251188 (MD5) / Approved for entry into archive by Secta BC (secta.csu.bc@uepb.edu.br) on 2016-03-10T16:58:14Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) PDF - Maria José Pinheiro Anacléto.pdf: 6289419 bytes, checksum: a5bad1c5254340842bfb8f794c251188 (MD5) / Made available in DSpace on 2016-03-10T16:58:14Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) PDF - Maria José Pinheiro Anacléto.pdf: 6289419 bytes, checksum: a5bad1c5254340842bfb8f794c251188 (MD5) Previous issue date: 2015-08-31 / This study evaluated the temporal distribution of macroinvertebrate community relating one year of normal rainfall (2010) and one year of atypical rainfall (2014), in order to investigate the changes in the composition and structure of benthic macroinvertebrate communities in a hydropower project reservoir in a rain atypical scenario. The study was conducted in the same sampling area and sampling sites in the years 2010 and 2014, at the reservoir of Nova Ponte Hydroelectric Plant, located in the Triangulo Mineiro region, in Nova Ponte, River Basin Araguari, by using benthic macroinvertebrates as bioindicators in the environmental assessment. The results showed a low abundance and diversity of related organisms in 2014 year of atypical rain. The areas around the reservoir showed changes according to the use and occupation of land. However, human activities have tightly changing the water resources, interfering with the communities that live there. / O presente trabalho avaliou a distribuição temporal da comunidade de macroinvertebrados relacionando um ano de pluviosidade normal (2010) e um ano de pluviosidade atípica (2014), com o intuito de investigar as alterações na composição e estrutura de comunidades de macroinvertebrados bentônicos em um reservatório de empreendimento hidrelétrico em um cenário de chuva atípica. O estudo foi realizado na mesma área amostral e nos mesmos sítios amostrais nos anos 2010 e 2014, do reservatório da Usina Hidrelétrica de Nova Ponte, localizada na região do Triângulo Mineiro, no município de Nova Ponte, Bacia do Rio Araguari. Usando os macroinvertebrados bentônicos como bioindicadores na avaliação ambiental. Os resultados apresentaram uma baixa abundância e diversidade de organismos relacionado em um ano de chuva atípica. As áreas do entorno do reservatório apresentaram alterações de acordo com o uso e ocupação do solo. No entanto, as atividades humanas vem alterando fortemente os recursos hídricos, interferindo as comunidades que lá habitam.

Os estudos de ecologia descritiva de comunidades marinhas bentônicas, tanto as de substratos consolidados (costões rochosos, recifes de corais, recifes de arenitos e bancos de algas calcárias) como as de substratos inconsolidados (areia, silte e sedimentos de baixa granulação), apontam para uma busca, ainda não finalizada, por padrões de distribuição que possam apresentar-se como modelo recorrente, sendo capazes de predizer sobre a composição de uma comunidade local. Como exemplos bem sucedidos, na busca de padrões, sendo marcos históricos no desenvolvimento da ecologia descritiva de comunidades marinhas bentônicas, temos as abordagens da zonação e de níveis de fundo, que buscaram encontrar um meio prático para descrições generalistas em larga escala que se apresentassem universais. No Brasil são caracterizados 3 momentos históricos sobre ecologia descritiva de comunidades marinhas bentônicas de substrato consolidado, que se caracterizam pelo uso de espécies como unidade operacional, recorrendo pouco a abordagens alternativas para ganho de conhecimento sobre grandes áreas. Neste estudo foi utilizado o método alternativo Caracterização fisionômica de comunidades marinhas de substrato consolidado para descrição dessas comunidades no infralitoral e busca por padrões de estruturação gerais visualmente evidentes. Este estudo foi realizado no Parque Estadual da Ilha Anchieta, Ubatuba SP, no infralitoral do costão oeste da Enseada das Palmas, compreendido entre as coordenadas 23°31\'44.37\"S / 045° 3\'38.07\"O e 23°32\'1.62\"S / 045° 3\'39.17\"O. Como principais resultados foram encontrados 24 povoamentos descritos na Abordagem 1, 20 povoamentos no inverno e 23 no verão . Na Abordagem 2, 19, povoamentos no inverno e, na Abordagem 3., 22 no verão. Os resultados quantitativos mostram, discriminados no costão estudado, a formação de 2 grupos gerais, que se mantiveram os mesmos no inverno e no verão, permitindo a conclusão de que há um padrão geral de estruturação da comunidade visualizada. Os povoamentos determinantes na divisão dos 2 grupos foram: Colônia de Palythoa, Tapete de Amphiroa e Jania, Banco de Dichotomaria e Região de Substrato Inconsolidado. Constata-se o mundo natural como um lugar desigual, que se manifesta em manchas ou remendos distintos, apresentando-se de muitas formas e com uma ampla gama de escalas. Os resultados foram vistos sob uma perspectiva exploratória, uma vez que se buscou encontrar padrões de distribuição das comunidades apenas a partir da unidade visual povoamento, sem o registro de dados de condições ambientais. Nessa busca, visualizando tal mosaico de distribuição de formas, cores, estrutura e composição em diferentes escalas encontramos padrões gerais de distribuição da comunidade, aqui representados por 2 grandes grupos, caracterizados por estarem em um nível acima de povoamentos ou supra povoamentos / The studies on descriptive ecology of marine benthic communities, hard bottom (Rocky Shores, Coral Reefs, Sandstone Rock Reefs and Rodolith Beds) as much as soft bottom communities (sand, silt and soft substrate of low granular material), lead to a non finished search for distribution patterns that may present it as a model able to predict about the local communities composition. As successful examples on searching for patterns as historical reference on the developing of descriptive ecology of marine benthic communities we have the zonation and bottom level approaches, that seek for a practical way to describe on a general and large scale universal patterns of distribution. In Brazil we found 3 historical moments about studies dealing with descriptive ecology of hard bottom marine benthic communities, which are characterized by the use of species as an operational unit, taking advantage of few alternative approaches to acquire knowledge about the communities in large areas. In this study the alternative methodology Physiognomic characterization of hard bottom marine benthic communities was applied, to describe such communities in infra-littoral regions and to search for general structural patterns visually evident. This study was made in Anchieta Island State Park, Ubatuba SP, Brazil, on the west rocky shore of Palmas Bay, located between the geographical positions 23°31\'44.37\"S / 045° 3\'38.07\"W and 23°32\'1.62\"S / 045° 3\'39.17\"W. As main results, 24 settlements described by the first approach were found; 20 settlements in winter season and 23 in summer season by the second approach ; 19 settlements in winter season e 22 in summer season by the third approach. The quantitative results show 2 general groups found on the studied rocky shore that were the same both in winter and summer seasons, allowing that we come to the conclusion that there is a general structural pattern visualized in the communities. The determinant settlements to the formation of the 2 groups were Palythoa Colony, Amphiroa and Jania Turf, Dichotomaria Bed and Soft Bottom Region. We face the fact that nature is an unequal place, which manifests this visual difference on patches of different sizes, showing many forms and colors on a huge range of scales. The results were reviewed under an exploratory perspective, searching first for structural patterns of these communities only from the visual unit called settlement, without the data of environmental conditions. On this search, visualizing the distribution of forms, colors, structure and composition mosaic on different scales we found general patterns of communities distribution that here are represented by 2 large groups, characterized by being on a higher level than the one of the settlement

Cumáceos são crustáceos peracáridos cosmopolitas que se distribuem desde a zona entre-marés até os fundos abissais. Habitam fundos arenosos e lodosos e eventualmente são encontrados no ambiente pelagial. Apesar de sua importância na dieta de diversos organismos, e de serem considerados bons indicadores ambientais, poucos estudos ecológicos foram realizados com o grupo no Brasil, não havendo uma avaliação do papel que desempenham na estruturação e funcionamento do ecossistema bêntico. O presente estudo tem por objetivo descrever a composição e a distribuição espaço-temporal das espécies de Cumacea, investigar a existência de comunidades e sua estrutura, identificar os principais fatores responsáveis pelos agrupamentos encontrados e avaliar o efeito das mudanças sazonais da estrutura oceanográfica sobre os descritores utilizados. Para tanto, foi realizada uma campanha oceanográfica no inverno de 2005 e outra no verão de 2006, em uma grade de 21 estações situadas na plataforma continental sudeste, entre São Sebastião e Peruíbe, amostradas por meio de Box Corer e Draga. Os resultados mostraram a presença de 31 espécies de Cumacea em toda a área, sendo 24 no inverno e 28 no verão. Os valores mais elevados de densidade, diversidade e riqueza situaram-se nas estações próximas a isóbata de 50m em ambas as campanhas, podendo ser atribuídos à presença da Água Central do Atlântico Sul sobre essas áreas, uma vez que ela promove intensa eutrofização da coluna da água e também confere maior estabilidade ambiental devido a formação de termoclina na coluna da água. Os resultados mostraram ainda que a profundidade e as características granulométricas do sedimento foram os principais fatores determinantes da composição e distribuição das comunidades de Cumacea. Desta forma foram evidenciadas três faixas de profundidade paralelas à costa com comportamento oceanográfico próprio: zona rasa, zona intermediária e zona profunda, cada qual apresentando espécies características e organizadas em estruturas ecologicamente distintas, caracterizando comunidades. A utilização de diferentes aparelhos, como Box Corer e Draga, permitiu complementação amostral da fauna, propiciando um conjunto de informações abrangentes e que permitiu a realização de um estudo mais robusto. / Cumaceans are Peracarid crustaceans distributed worldwide, occurring from intertidal zone to abyssal plains. They inhabit sandy and muddy bottoms, and are eventually found in the pelagic environment. Despite their importance as food for many organisms and their role as environmental indicators, few ecological studies have been conducted in Brazil up to now, and there are no efforts for understanding their role in structuring benthic communities. The aim of the present study is to describe the composition and spatio-temporal distribution of the cumaceans species in the continental shelf offshore of Santos, to investigate the existence and strucuture of ecological communities and the main factors responsible for their functioning, trying to assess the effects of the oceanographic changes upon the community descriptors. The samples were obtained on 21 stations placed in the southeastern continental shelf, between São Sebastião and Peruíbe, in winter 2005 and summer 2006, by means of a 0,09m2 box corer and a rectangular dredge. The results showed the presence of 31 species of cumaceans in the whole area, being 24 in winter and 28 in summer. Higher values of density, diversity and richness obtained in stations near the 50m isobath in both campaigns can may be attributed to the South Atlantic Central Water presence on these areas, since it promotes intense eutrophication of the water column and environmental stability by means of the stablishment of a sub-superficial thermocline. The present study also showed that depth and sediment grain size were the main factors determining the composition and distribution of the cumacean communities. Three zones parallel to the coast with distinct depth ranges and oceanographic features were observed: shallow zone, intermediate zone and deeper zone, each one presenting characteristic species and ecologically structurated in different ways. The use of different sampling gears, as Box corer and dredge, allowed the complementation of data and enlarged the data set adding robustness to the study.

A qualidade da matéria orgânica e a magnitude de suas deposições estão entre os principais fatores que controlam as respostas dos organismos bênticos marinhos. Uma vez depositada nos sedimentos, a matéria orgânica é degradada por processos biogeoquímicos microbianos, que podem ser acelerados mediante a bioturbação da macrofauna. Entretanto, em regiões costeiras, a dinâmica das forçantes ambientais influencia tanto a qualidade dos recursos alimentares, quanto os mecanismos de utilização pelos organismos, implicando em alterações na remineralização da matéria orgânica. Este estudo visou investigar o sistema bêntico da área costeira de Ubatuba frente às variações da qualidade e quantidade da matéria orgânica, incluindo os impactos da bioturbação na diagênese recente e regeneração de nutrientes. Observou-se que os processos físicos da região atuaram na variação da qualidade da matéria orgânica e na estruturação dos organismos bênticos. Os microorganismos exploraram matéria orgânica de diferentes composições, exercendo também importante papel para a comunidade macrobêntica, enriquecendo os detritos orgânicos disponíveis como alimento. A meiofauna não apresentou relação direta com alta qualidade da matéria orgânica, já a macrofauna foi estruturalmente modificada pela passagem de frentes frias e pela presença de compostos lábeis, quando os mesmos apareceram em maiores concentrações. Experimentalmente, verificou-se que a mistura de partículas foi significativa somente quando altas densidades da macrofauna estiveram presentes na superfície do sedimento. Além disso, foi demonstrado em laboratório que a macrofauna exerceu pouca influência nos fluxos de oxigênio e nutrientes do sedimento para a água, porém suficiente para estimular a decomposição de material orgânico verticalmente na coluna sedimentar. Portanto, a dinâmica dos processos físicos e as variações estruturais da macrofauna são importantes fatores ecológicos na modulação de funções fundamentais do ecossistema costeiro de Ubatuba, como produtividade, metabolismo bêntico, degradação da matéria orgânica e fluxos de energia. / The magnitude and quality of organic matter inputs to the seafloor are among the main factors regulating the responses of marine benthic communities. Once deposited on the sediments, the organic matter is degraded by several microbial biogeochemical processes that may be stimulated through macrofauna bioturbation. However, in coastal regions the dynamics of environmental forcing not only influences the quality of food sources, but the food uptake by organisms, resulting in changes on remineralization rates of organic material. This study aimed to investigate the benthic system of Ubatuba coastal area in relation to quality and quantity of organic matter as well as bioturbation impacts on early diagenesis and nutrient regeneration. Data suggests that physical stresses influenced the quality of organic matter and the structure of benthic organisms. Different compositions of organic matter were assimilated by microorganisms, which in turn played an important role to the macrobenthic community, enriching the organic detritus available as food. The meiofaunal organisms did not numerically respond to the deposition of high quality organic matter, while macrofauna community structure was modified by the incidence of cold fronts and by the presence of labile compounds, whenever available. Experimentally, sediment reworking was only significant at higher levels of macrofaunal density on the sediment surface. In addition, it was demonstrated in laboratory that macrofauna imposed weak effects on the fluxes of oxygen and nutrients from sediments to the water column, but those changes were enough to stimulate vertically in the sediments, the decomposition of organic matter. Therefore, the dynamics of physical processes and the variability on macrofaunal structure are both important ecological factors modulating fundamental functions of the coastal ecosystem in Ubatuba, including productivity, benthic metabolism, degradation of organic matter and energy flow.

Cumáceos são crustáceos peracáridos cosmopolitas que se distribuem desde a zona entre-marés até os fundos abissais. Habitam fundos arenosos e lodosos e eventualmente são encontrados no ambiente pelagial. Apesar de sua importância na dieta de diversos organismos, e de serem considerados bons indicadores ambientais, poucos estudos ecológicos foram realizados com o grupo no Brasil, não havendo uma avaliação do papel que desempenham na estruturação e funcionamento do ecossistema bêntico. O presente estudo tem por objetivo descrever a composição e a distribuição espaço-temporal das espécies de Cumacea, investigar a existência de comunidades e sua estrutura, identificar os principais fatores responsáveis pelos agrupamentos encontrados e avaliar o efeito das mudanças sazonais da estrutura oceanográfica sobre os descritores utilizados. Para tanto, foi realizada uma campanha oceanográfica no inverno de 2005 e outra no verão de 2006, em uma grade de 21 estações situadas na plataforma continental sudeste, entre São Sebastião e Peruíbe, amostradas por meio de Box Corer e Draga. Os resultados mostraram a presença de 31 espécies de Cumacea em toda a área, sendo 24 no inverno e 28 no verão. Os valores mais elevados de densidade, diversidade e riqueza situaram-se nas estações próximas a isóbata de 50m em ambas as campanhas, podendo ser atribuídos à presença da Água Central do Atlântico Sul sobre essas áreas, uma vez que ela promove intensa eutrofização da coluna da água e também confere maior estabilidade ambiental devido a formação de termoclina na coluna da água. Os resultados mostraram ainda que a profundidade e as características granulométricas do sedimento foram os principais fatores determinantes da composição e distribuição das comunidades de Cumacea. Desta forma foram evidenciadas três faixas de profundidade paralelas à costa com comportamento oceanográfico próprio: zona rasa, zona intermediária e zona profunda, cada qual apresentando espécies características e organizadas em estruturas ecologicamente distintas, caracterizando comunidades. A utilização de diferentes aparelhos, como Box Corer e Draga, permitiu complementação amostral da fauna, propiciando um conjunto de informações abrangentes e que permitiu a realização de um estudo mais robusto. / Cumaceans are Peracarid crustaceans distributed worldwide, occurring from intertidal zone to abyssal plains. They inhabit sandy and muddy bottoms, and are eventually found in the pelagic environment. Despite their importance as food for many organisms and their role as environmental indicators, few ecological studies have been conducted in Brazil up to now, and there are no efforts for understanding their role in structuring benthic communities. The aim of the present study is to describe the composition and spatio-temporal distribution of the cumaceans species in the continental shelf offshore of Santos, to investigate the existence and strucuture of ecological communities and the main factors responsible for their functioning, trying to assess the effects of the oceanographic changes upon the community descriptors. The samples were obtained on 21 stations placed in the southeastern continental shelf, between São Sebastião and Peruíbe, in winter 2005 and summer 2006, by means of a 0,09m2 box corer and a rectangular dredge. The results showed the presence of 31 species of cumaceans in the whole area, being 24 in winter and 28 in summer. Higher values of density, diversity and richness obtained in stations near the 50m isobath in both campaigns can may be attributed to the South Atlantic Central Water presence on these areas, since it promotes intense eutrophication of the water column and environmental stability by means of the stablishment of a sub-superficial thermocline. The present study also showed that depth and sediment grain size were the main factors determining the composition and distribution of the cumacean communities. Three zones parallel to the coast with distinct depth ranges and oceanographic features were observed: shallow zone, intermediate zone and deeper zone, each one presenting characteristic species and ecologically structurated in different ways. The use of different sampling gears, as Box corer and dredge, allowed the complementation of data and enlarged the data set adding robustness to the study.

Increasing concentrations of atmospheric CO2 are in dynamic equilibrium with the oceans. The absorption of CO2 by seawater causes a decrease in seawater pH and calcite saturation state (SS). This process, termed ocean acidification, exerts deleterious effects on marine calcifiers. Studies of symbiont-bearing large benthic foraminifera (LBF) have reported a generally unfavorable response to increased concentrations of carbon dioxide ([CO2]). Experiments and analyses were undertaken to examine the effect of increased [CO2] on the growth rate, ultrastructure, stable isotopes of carbon and oxygen, as well as Mg/Ca of the high-Mg miliolid Archaias angulatus and the low-Mg rotalid Amphistegina gibbosa. A CO2-injection culture study was performed at pH 8.0, 7.8 and 7.6, corresponding to CO2 concentrations of approximately 400 ppm, 800 ppm, and 1,300 ppm. After 2, 4, or 6 weeks of treatment, bags containing groups of approximately 20 previously-imaged live specimens were removed and prepared for the aforementioned analyses. Archaias angulatus responded to increased [CO2] by reducing test growth rate at 1,300 ppm CO2 (pH 7.6) by 50% (p < 0.01, r2 = 36%), increasing its pore area (F(2,3477) = 103.37, p West Florida shelf LBF carbonate production attributed to LBF was estimated by combining interpolations of SS calcite at three treatment levels, corresponding to pH 8.1 (400 ppm CO2), pH 7.8 (800 ppm CO2), and pH 7.6 (1,300 ppm CO2), with a map of the carbonate fraction of seafloor sediment. Growth rates for 10 species were estimated in a meta-analysis of culture studies; these rates were used to model the response of miliolids and rotalids to increased [CO2]. In the model, rotalids responded to higher CO2 concentrations by reducing their average adult size by 20% at 800 ppm CO2 and 40% at 1,300 ppm CO2. Miliolids responded by reducing their average adult size by 40% at 800 ppm CO2 and 75% at 1,300 ppm CO2. Modeled LBF carbonate production for the west Florida shelf is 7 Mt at 400 ppm, 4.8 Mt at 800 ppm, and 2.5 Mt at 1,300 ppm. In a high CO2 world, low-Mg rotalids exhibit modest reductions in test growth rates and carbonate production, whereas high-Mg miliolids exhibit major reductions in test growth rates and carbonate production.

Mass animal migrations represent large movements of biomass, energy, and nutrients with predictable patterns and important ecosystem-level consequences. Diel vertical migration (DVM) in aquatic systems, the daily movement of organisms from deeper depths during the day to shallower depths in the water column at night, is widespread in freshwater and marine systems. Recent studies, however, suggest partial migration behavior, whereby only some portion of a population migrates, is the rule rather than the exception in a range of migratory fauna, including those that undergo DVM. Hypotheses to explain why partial migrations occur complicate traditional views on DVM and challenge conventional theories. I address intraspecific variation in DVM behavior of an aquatic omnivore, Mysis diluviana, to test several long-standing assumptions about benthic-pelagic DVM in Mysis. I evaluated the extent of partial DVM and several potential drivers within a Lake Champlain Mysis population. I used traditional net-based field observations, a novel deep-water video camera system, and a laboratory experiment, to compare distributions, demographics, abundance estimates, hunger-satiation state, and feeding behavior, of migrant and non-migrant Mysis across multiple seasons, habitats, and different times of the day. Findings from my dissertation suggest Mysis partial DVM is common, and is associated with body size and demographic differences among individuals. Partial DVM behavior, however, did not correspond to strong differences in feeding preference or hunger-satiation state of individuals. My results contribute toward a more comprehensive understanding of migration theory and mysid biology, by including the often overlooked, but important, benthic habitat component of DVM studies, and fills in several ecological knowledge gaps regarding a key omnivore in many deep lake food webs across North America where Mysis serve as both predators and prey to many organisms.