Les traits fonctionnels sont de plus en plus utilisés en écologie pour expliquer les changements de composition et de structure de la communauté phytoplanctonique en fonction des contraintes environnementales. Ce succès tient au fait que les traits fonctionnels sont des caractéristiques reliées aux processus de croissance et de perte des organismes, et qu'ils déterminent ainsi l'occurrence, la dominance ou l'absence d'une espèce dans des conditions environnementales données. Parmi les traits fonctionnels, on distingue les traits morpho-fonctionnels qui présentent l'avantage d'être facilement observables et mesurables. Les approches basées sur les traits morpho-fonctionnels ont majoritairement été utilisées en lac mais pourraient toutefois s'avérer pertinentes en rivière où l'importance relative des contraintes environnementales agissant sur la communauté phytoplanctonique est très variable d'un système à l'autre. L'objectif de cette thèse a donc été de tester l'hypothèse selon laquelle la communauté phytoplanctonique en rivière pouvait être structurée selon les traits morpho-fonctionnels. Dans les rivières étudiées, nous avons montré que la communauté est structurée selon les traits morpho-fonctionnels reliés à la vitesse de sédimentation, en mettant en évidence le rôle clé de la forme des organismes, mais aussi de leur motilité et de leur densité via la présence de mucilage. A travers la sélection de différentes valeurs pour ces traits morpho-fonctionnels, nous avons pu mettre en évidence l'impact majeur de la turbulence sur la communauté phytoplanctonique de ces rivières. L'effet de ce paramètre a été testé expérimentalement en conditions contrôlées sur une communauté simplifiée afin de tester l'hypothèse selon laquelle sous l'effet de la turbulence, la composition de la structure de la communauté pouvait être prédite par les traits morpho-fonctionnels. Les résultats de cette approche expérimentale ont permis de réitérer le rôle clé de la forme dans la structure de la communauté corroborant ainsi les résultats de rivières et ont également souligné le rôle de la plasticité phénotypique. L'approche basée sur les traits a également été testée en estuaires, mais s'est cependant montré infructueuse. Plusieurs hypothèses ont été proposées pour expliquer ce résultat, notamment l'absence de trait identifié comme étant relié à la salinité. / Functional traits are increasingly used in ecology to explain changes in the composition and structure of phytoplankton community in relation to environmental constraints. Functional traits are related to growth and loss processes, and thus they determine the occurrence, dominance or absence of species in given environmental conditions. Among the functional traits, morpho-functional traits display the advantage of their ease to be measured. Approaches based on morpho-functional traits were mainly used in lakes, but could however be relevant in rivers where the relative significance of environmental constraints acting on the phytoplankton community varies from one system to another. The aim of this thesis was therefore to test the hypothesis that riverine phytoplankton community could be structured according to morpho-functional features. In the rivers studied, we showed that the community is structured according to morpho-functional traits related to sedimentation rate, highlighting the key role of the shape of organisms, but also of their motility and density via the presence of mucilage. Through the selection of different values for these morpho-functional traits, we highlighted the main impact of turbulence on the phytoplankton community within these rivers. The effect of this parameter has been tested experimentally on a simplified community under controlled conditions in order to test the hypothesis that as a result of turbulence, the composition of community structure could be predicted through morpho-functional traits. The results of this experimental approach helped to reiterate the key role of the shape in community structure thus corroborating the results found in rivers. It also stressed the role of phenotypic plasticity. This approach based on features was also tested in estuaries, but was, however, unsuccessful. Several hypotheses have been proposed to explain this result, including the lack of traits identified as related to salinity.

L’objectif de ce travail est d’étudier la dynamique du bouchon vaseux, ainsi que la dynamique saline, dans l’estuaire de la Gironde. La stratégie adoptée consiste à examiner, par le biais du modèle de simulation SIAM-3D, l’impact du paramétrage hydro-sédimentaire, du débit fluvial et de la bathymétrie, sur le comportement des sédiments et sur l’évolution de la salinité. L’effet de la vitesse de chute sur la dynamique sédimentaire est l’un des cas étudiés ; son impact sur la distribution des suspensions est considérable. Ainsi, la diminution de ce paramètre entraîne l’homogénéisation de la concentration sur la verticale, mais aussi l’étalement du bouchon vaseux et l’évacuation d’une masse de sédiment hors de l’estuaire. Nous avons également mis en évidence lors d’une période de débits moyens ou faibles précédée par une crue, la partition du bouchon vaseux simulé en deux masses turbides, l’une remonte l’estuaire alors que l’autre se maintient en aval. La dynamique saline a été étudiée, entre autres, par l’analyse des gradients de salinité, calculés dans l’estuaire aval et en situation de forts débits. On observe, la diminution de ces gradients avec l’augmentation de l’intensité de la marée à l’échelle des cycles vives-eaux/mortes-eaux, toutefois, de fortes valeurs sont maintenues lors de la phase d’augmentation de cette grandeur à l’échelle de la marée. D’autres résultats ont permis de vérifier la capacité du modèle à simuler des dynamiques sédimentaires observées in-situ ; on peut citer entre autres, le détachement du bouchon vaseux de la rive gauche dans l’estuaire aval et son transfert vers la rive droite, en situation de forts débits. Afin d’évaluer l’impact de l’évolution du fond des fleuves de 1959 à 2002 sur l’hydrodynamique et les dynamiques sédimentaire et saline, nous avons comparé deux simulations, l’une effectuée avec l’ancienne bathymétrie de 1959, l’autre avec la nouvelle bathymétrie de 2002. Les résultats montrent l’augmentation de la masse sédimentaire dans les fleuves avec la bathymétrie de 2002 comparée à celle de 1959, ainsi que la hausse de la salinité dans la Garonne et l’amplification de la marée dans la Dordogne. Ces résultats sont en accord avec les mesures et observations in-situ. / The aim of this work is to study the turbidity maximum dynamics as well as the salinity dynamics in the Gironde estuary. The adopted strategy consists in analysing, by means of the SIAM-3D simulation model, the impact of hydro-sedimentary parameters, the fluvial flow and the bathymetry on sediment behaviour and salinity evolution. The effect of settling velocity on sediment dynamics is one of the studied cases; its impact on suspended sediment distribution is goodly. Thus, the diminution of this parameter leads to homogenisation of concentration in water column, but also spreading the turbidity maximum and evacuation of a sediment mass outside the Gironde estuary. We gave also prominence to the division of the turbidity maximum into two parts during low or mean water flow preceded by peak high water discharge, one of the parts migrates upstream whereas the other remains downstream. We studied the salinity dynamics, among others things, by means of analysing the calculated salinity gradients in the lower estuary during high water discharge. We observe the decrease of these gradients with increase of the tide intensity on a scale of spring tides/neap tides cycles, however, on a scale of tide, these gradients reach high values during the augmentation phase. Others results indicate the model capacity to simulate in-situ observations of the sediment dynamics; for example, the detachment of turbidity maximum from the left bank in the lower estuary and its transfer to the right bank during high water discharge. In order to evaluate the impact of the bed river evolution from 1959 to 2002 on hydrodynamics, sediment and salinity dynamics, we compared two simulations performed using the former (1959) and recent (2002) bathymetries. The results demonstrate that the sediment mass increase in the rivers with recent bathymetry, as well as, the salinity in the Garonne river and the tide amplitude in the Dordogne river. These results are in accordance with the in-situ measures and observations.

This academic report was composed at the conclusion of a 480 hour internship with the National Performance Network/Visual Artists Network (NPN/VAN), summarized in Chapter Two. This report includes NPN/VAN’s mission, history, and organizational structure within Chapter One. Chapter Three is a SWOT analysis, and Chapter Four includes a summary of best practices, highlighting NPN/VAN’s intermediary and network structure. In conclusion, a series of suggestions are offered for further consideration.

L'estuaire du Mono est établi dans la partie occidentale du littoral béninois. C'est un estuaire microtidal à dominance de houle qui assure les échanges avec la mer par le biais d'une embouchure tidal connue sous le nom de "Bouche du Roi". Il forme un système hydrosédimentaire côtier associé à trois générations de cordons de barrières témoins des dernières oscillations marines du Quaternaire récent. Ce travail de thèse a permis d'étudier la dynamique des cordons de barrières de l'estuaire du Mono à diverses échelles temporelles et suivant une approche résolument pluridisciplinaire et instrumentale. Les résultats montrent que les deux anciens cordons barrières de l'estuaire se sont construits et détruits au rythme des variations du niveau marin du Quaternaire récent. Par contre, la dynamique contemporaine des cordons barrières actuels (plage actuelle) se traduit par la morphogénèse d'un système de flèche-crique, sous le contrôle du régime de houle et des conditions de marée d'une part, puis des saisons hyrdologiques du fleuve d'autre part. Avant la mise en service du barrage de Nangbéto, du fait du caractère temporaire des écoulements du Mono, la morphodynamique du couple flèche-crique était limitée dans l'espace et dans le temps. Mais depuis la mise en eau du barrage en 1987, cette morphodynamique est devenue persistante, en raison de la consistance et de la permanence des écoulements du Mono désormais régulés par le barrage. Les conséquences de cette morphodynamique anthropique sur l'environnement physique et humain sont incommensurables : pertes des plages à très hautes renommée touristique, engloutissement des terres et des cultures (salicultures, cultures agraires, aquacultures,...) par la mer, destruction d'habitations et autres infrastructures socio-communautaires (écoles, routes,...), déplacements de populations, exhumation des dépouilles de parents défunts,...La solution de mitigation proposée est le déplacement des populations de Hokoué et de Docloboé et la pratique périodiques (tous les 7 ans) des ouvertures mécaniques au niveau de la plage d'Avlo. / The Mono river estuary is established in the Western part of the Benin coastal zone. It's a microtidal estuary with predominance of swell. It ensures the exchanges with the sea by means of a tidal inlet named "Bouche du Roi". It forms a coastal hydro-sedimentary system associated with three generations of sand barrier which attest the last marine oscillations of the recent Quaternary. This thesis work studies the dynamics of these barriers-inlets on various temporal scales and according to a multi-field approach. The results show that the two old sand barriers are built and destroyed at the rhythm of marine level variations of recent Quaternary. On the other hand, the contemporary dynamics of the current barrier results in the morphogenesis of a spit-creek system, under control of littoral drift, tide conditions and hydrological seasons of the Mono river. Before the startup of Nangbeto dam, because of the temporary character of the Mono flows, the spit-creek morphodynamic was limited in space and time. But since the operating of the dam in 1987, the spit-creek morphodynamic became persistent, owing to consistency and permanence of Mono flows from now on controlled by the dam. The effects of this anthropic morphodynamics on the physical and human environment are immeasurable : loss of touristic beach, swallowing up of grounds and cultures (salt productions, agrarian cultures, aquacultures,...), destruction of dwellings and other socio-community infrastructures (schools, roads,...), populations displacements, exhumation of late parents remains,... The migration solution proposed consists in displacement of Hokoue and Docloboe populations and in periodical practice (every 7 years) of mechanical breaches on the level of Avlo beach.

La migration des bancs de vase observée le long des côtes Guyanaises génère des problématiques de navigation, particulièrement pour l'unique port de commerce de Guyane localisé dans l'estuaire du Mahury. La dynamique hydrosédimentaire de cet estuaire mésotidal et l'influence des bancs sur cette dernière sont très peu renseignées. Les principaux résultats de cette étude mettent en évidence l'importance relative du débit et des courants de marée sur la dynamique des sédiments fins. Bien que l'asymétrie de la marée soit dominée par le flot, les courants de jusant sont prédominants en saison humide et équivalents aux courants de flot en saison sèche. La dynamique des sédiments fins est gouvernée par la remise en suspension, bien que des épisodes de stratification puissent fortement atténuer la turbulence durant les premières heures du jusant. Les flux résiduels de sédiments sont généralement orientés vers l'amont durant la saison sèche et vers l'aval en saison humide, excepté lorsque les débits sont inférieurs aux moyennes saisonnières. L'évolution des fonds de l'estuaire sur 20 ans indique néanmoins une stabilité des dépôts et souligne la capacité de l'estuaire à évacuer les sédiments apportés durant la phase d'envasement. L'interdépendance entre l'estuaire du Mahury et le banc de Kaw sera ainsi soumise à discussion. Elle permettra d'évaluer la capacité du banc de Kaw à influencer la sédimentologie de l'estuaire et inversement d'évaluer la capacité de l'estuaire à perturber la migration du banc. / The mud banks migration observed along the Guyanese coastline generates navigating issues, especially for the unique harbor of French Guiana located in the Mahury Estuary. The hydro-sedimentary dynamic of this mesotidal estuary and the influence of the mud banks migration is poorly documented. The main results have brought to light the relative importance of the river discharge and tidal currents on the fine sediment dynamics. Even though the tidal asymmetry is dominated by the flood, the ebb currents are predominant during the wet season and are equivalent to the flood currents during the dry season. The fine sediment dynamics are mainly governed by the resuspension even though some stratification events can highly damp turbulence during the first hours of the ebb. The residual fluxes of sediment are generally landward during the dry season and in the wet season when river discharges are lower than the seasonnal averages. However, the bathymetric evolution over 20 years indicates the stability of the deposits and underlines the estuary's capacity of flushing sediments brought from the mud bank. The interdependence between the Mahury Estuary and the Kaw mudbank will therefore be subject to discussion. It will allow us to evaluate the mud bank influence on the estuarine sedimentology or, inversely, evaluate the capacity of the estuary to interfere with the mud bank migration and slowing down its progression with the currents.

O objetivo deste estudo é compreender a dinâmica das partículas no estuário do rio Araranguá (SC) em termos de transporte em suspensão, deposição e exportação, em diferentes condições físico-químicas da água, com pH baixo (<4,5) e normal (>=7), e sob condições de regime transiente da descarga fluvial. O estuário do rio Araranguá é classificado como altamente estratificado e dominado pela descarga fluvial. Um aspecto fundamental nos processos que controlam a dinâmica de materiais em suspensão no estuário é a atividade de lavra e beneficiamento do carvão, que gera uma drenagem ácida no rio Mãe Luzia. O seu pH baixo (&#732;3) indica que o processo de floculação é intensificado no interior do estuário. Com o objetivo de melhor entender a hidrodinâmica do estuário, um modelo tridimensional foi implementado para a região. O modelo foi calibrado e validado com dados observados. Simulações com diferentes picos de descarga fluvial (100, 400, 700 e 1000 m3.s-1) e baixa descarga (30 m3.s-1) foram realizadas. Para calcular o transporte do material particulado em suspensão foi desenvolvido um modelo Lagrangeano da trajetória da partícula. O modelo da trajetória utiliza os resultados do modelo hidrodinâmico e a velocidade de decantação das partículas. O estuário respondeu rapidamente às variações da descarga fluvial. A cunha salina foi transportada para fora do estuário durante os picos de 700 e 1000 m3.s-1. A descarga fluvial é o fator dominante no controle da intrusão da salinidade no estuário e, em condições de baixa descarga, o transporte advectivo de sal é dominado pelo termo dispersivo da circulação gravitacional. O tempo de residência médio das partículas no estuário foi menor em condições de pH baixo. A exportação das partículas aumentou com o aumento da descarga fluvial (pico de 1000 m3.s-1), sendo que 27% e 30% foram exportadas para a plataforma interna durante os experimentos com pH baixo e pH normal, respectivamente. A região de deposição das partículas indica que com a diminuição do pH, as partículas passam a depositar mais à jusante no estuário. O evento de descarga de 1000 m3.s-1 não foi capaz de remover a grande maioria das partículas do estuário, mas foi responsável por redistribuir as partículas ao longo do médio estuário, onde se depositaram em condições favoráveis com baixas velocidades e ausência de salinidade. O trabalho demonstra que apesar da alta estratificação do estuário, a acidez de suas águas, seu padrão de circulação, com baixas velocidades e a presença da cunha salina, possuem um papel fundamental no transporte das partículas, resultando em maior potencial de retenção do material em suspensão no estuário do rio Araranguá. / The present study assessed the dynamics of particles of the Araranguá (SC) river estuary in terns of suspended transport, deposition and exportation in different conditions of physical-chemical of water, with low (<4,5) and normal pH (>=7), and transient of river discharge conditions. The Araranguá river estuary is a highly stratified flash-flood dominated. The river basin of the Mãe Luzia river, one of the main tributaries of the Araranguá river, is performed the activity of mining and coal processing, wich generates an acidic drainage. Its low pH indicates that flocculation process is intensified in estuary inner. With the objective of better understanding the estuarine processes, a three-dimensional hydrodynamics model was implemented. The model was calibrated and verified using observational data. Simulations were conducted with freshet peak ranged over 100, 400, 700 and 1000 m3.s-1. Lagrangian particle tracking algorithms was developed to represent the suspended particle transport at estuary. The particle tracking used the montion resulting from hydrodynamics model and the particle settling velocity. The estuary responded quickly the river discharge variations. During the pulse event the velocities at water column were unidirectional down-estuary is shown the barotropic dominates over baroclinic component. During the highest flash flood event (700 and 1000 m3.s-1) the salt water was pushed out of the estuary. The river discharge is a dominating factor affecting the salinity intrusion in the estuarine system and under low discharge conditions the advective salt transport is dominated by dispersive term of gravitational circulation. The mean residence time of the particles was lowest in pH low conditions. The particles export is great as the river discharge is rising (1000 m3.s-1) with 27% and 30% exported to inner shelf during the experiments with low and normal pH, respectively. The particles deposition local indicates that with the pH decrease the particles become to be deposited further downstream. The discharge event of 1000 m3.s-1 was not able to remove all particles out, but was response to redistribute the particles along of the meddle estuary, where settling in favorable conditions at low velocities and absence of salinity. The study shows that although high stratification of estuary, the acidity of water, the pattern of circulation, at low velocities, and the salt wedge presence play a fundamental role in the transport of particle matter resulting in increased the potential retention of suspended matter in the Araranguá river estuary.

O modelo numérico Delft3D-Flow foi utilizado nos estudos da distribuição e variabilidade de propriedades termohalinas, e da circulação tridimensional do sistema estuarino dos rios Caravelas e Peruípe-SERCP. Os resultados do modelo foram validados quantitativamente usando dados experimentais de marés de quadratura e de sizígia de correntes e salinidades em quatro estações fixas (duas em cada um dos estuários de Caravelas e Nova Viçosa). No processamento foram aplicadas inicialmente condições iniciais homogêneas da salinidade, densidade e dos coeficientes cinemáticos de viscosidade e difusividade vertical, e após quatro semanas de simulação foram extraídos resultados de diferentes condições. Esses resultados foram utilizados como condições iniciais mais realistas, tendo o campo espacial variado das propriedades termohalinas, e dos parâmetros físicos. Essas novas condições iniciais permitiram pular o tempo transiente otimizando assim as simulações subsequentes. A validação das simulações foi feita com base nas medições da campanha de verão, por causa do atraso do período chuvoso a vazão do rio Peruípe foi bem representativa para condições de inverno e, portanto, seria redundante usar as forçantes dos rios com valores tão próximos na validação, além da necessidade da demanda de um tempo muito maior nas analise comparativas dos resultados. Durante o verão (janeiro de 2008), os dados de vazão do rio Peruípe obtidos na Agência Nacional de Águas (ANA) levaram a estimativa da descarga fluvial de ~ 20 m3.s-1, com a extrapolação de ~ 4 m3.s-1 para vazão conjunta dos dois principais afluentes do canal estuarino do rio Caravelas (rios Cúpido e Jaburuna). As oscilações da maré foram simuladas satisfatoriamente para as quatro estações de controle utilizadas na validação, com valores médios do parâmetro Skill superiores a 0,97. As amplitudes da maré calculadas numericamente foram de aproximadamente 1,3 m e 2,5 m na quadratura e sizígia, respectivamente. Os resultados numéricos das simulações das velocidades foram melhores em condições de sizígia com valores médios do parâmetro Skill entre 0,77 e 0,93, enquanto que na quadratura esse parâmetro variou entre 0,38 a 0,65. Para a estrutura de salinidade durante as condições de maré de sizígia, melhores resultados no SERCP do skill e, portanto abrangendo as quatro estações de controle, foram confirmados pelos parâmetros Skill médios superiores a 0,83. Na maré de quadratura os correspondentes valores médios também foram relativamente altos, variando entre 0,73-0,85. Entretanto, houve dificuldades em simular adequadamente a alta estratificação (vertical e longitudinal) do estuário de Nova Vicosa, podendo-se atribuir esse fato à maior vazão do rio Peruípe, que é muito maior do que a do rio de Caravelas. Com os resultados da estrutura de salinidade a intrusão da massa de Água Tropical (AT) foi adequadamente representada nos quilômetros iniciais do canal estuarino do rio Caravelas, e na parte interna da desembocadura na região de Nova Viçosa. Movimentos bidirecionais foram observados nos resultados das simulações na preamar e baixamar, na região de desembocadura dos estuários da Caravelas e Nova Viçosa, movimentos estes forçados pela componente baroclínica da força de gradiente de pressão. Vale ressaltar que o efeito baroclínico ficou mais visível nos instantes da baixamar. Na preamar para a maior parte destas duas regiões verificou-se apenas um pequeno desvio no sentido das correntes entre superfície (Z = -0,1) e fundo (Z = -0,9) e em geral inferior a 30 graus. Usando os traçadores lagrangeanos virtuais lançados ao longo dos canais estuarinos das entradas norte (Caravelas) e sul (Nova Viçosa) do SERCP foi obtido como resultado um tempo de residência relativamente pequeno e comparável ao estuário tropical do rio Curimataú. No trecho analisado no canal estuarino do rio Caravelas, a ~ 3 km e ~ 12 km distantes da Boca do Tomba o tempo de residência médio foi ~ 4,2 dias e ~10,3 dias, respectivamente. Já no estuário de Nova Viçosa, ou canal estuarino do rio Peruípe, apenas o trecho inicial de 5 km foi considerado para o lançamento dos traçadores, e os tempos de residência de ~ 1,5 dias e 2,5 dias foram estimados para as posições de ~2,5 km e 5,0 km distantes da desembocadura. O modelo analítico proposto e usado no cálculo de tempo de residência teve resultados comparáveis aos obtidos pelas simulações pelo método lagrangeano do Delft-3D Flow. Diferentemente, o modelo LOICZ apresentou valores bem diferentes do tempo de residência para os seis estuários analisados (Caravelas, Nova Viçosa, Curimataú, Hudson, Conwy and Mersey), em geral bem inferiores aos do modelo proposto, indicando assim uma possível estimativa maior do fluxo difusivo na formulação do modelo LOICZ. / The numerical model Delft-Flow was used to study the spatial distribution and variability of the termohaline properties, and the tridimensional circulation in the estuarine system of the rivers Caravelas and Peruípe. The model results were validated quantitatively using field data of tidal oscilation and currents, and salinity measurements during neap and spring tides at four mooring stations, two in each estuary. In the data processing homogeneous conditions were used initially for the fields of salinity, density and the vertical kinematic coeficients of viscosity and diffusivity, then after four weeks of running simulation those fields were saved with spatially varied conditions. Those results were used for a more realistic initial condition, thus having a varied field of the termohaline properties, and of the physical parameters. The new initial conditions allowed avoiding the transient time and thus optimizing the following simulations. The model evaluation was done based on measurements undertaken during the summer season, because of the delay in the raining season, the Peruípe river discharge was low and more representative of dry season condition, for those reasons we just used the measurement taken in the January 2008. In the summer the measurements of the Peruíbe river discharge taken from the Agência Nacional de Águas (ANA), and the river flow of was estimated at ~ 20 m3.s-1, with the extrapolation of ~ 4 m3.s-1 for the unified flow from the rivers Cúpido and Jaburuna, with contribute to the flow in the Caravelas estuary. Tidal oscillation at neap and spring tides were well simulated for the 4 controling sites used to the validation, and with the mean skill values over 0.97. The tidal amplitudes were numerical calculated and nearly between 1.3 and 2.5 meters at neap and spring tides, respectively. The numerical results of the velocities were better simulated in spring tides with the mean skill values in the range of 0.77 and 0.93, while at neap tides this parameter varied between 0.38 and 0.65. For the salinity structure at spring tides good results in the estuarine system were achieved, hence comprising all the controling station for validation, with all mean skill values over 0.83. At neap tides the corresponding mean skill values were relatively high, varing in the range of 0.73-0.85. In addition, there were difficulties in simulation adequately the highly vertical and longitudinal stratification of the Nova Vicosa estuary. That was caused by the stronger river inflow of the Peruípe River, which is much higher than the inflow by Caravelas River. The intrusion of the Tropical Water mass (TW) was properly simulated given the right distribution of the salinity along the first quilometers of the estuarine channel of Caravelas, and the internal part of the Nova Viçosa estuarine mouth. Bidirectional movements were observed from the model outputs at the high and low tides, at the region near the mouth of both, Caravelas and Nova Viçosa estuary. Those moviments are forced by the baroclinic component of the pressure gradient. Is worth to mention the the baroclinic effect was better observed at the low tides of these regions. At high tide most of areas showed only a small change in the current direction between surface (Z = -0.1) and bottom (Z = -0.9) and usually smaller than 30 degrees. The virtual lagrangian drifters released along the estuarine channels of Caravelas (north) and Nova Viçosa (south) have shown a residence time relatively short, and comparable to the Curimataú tropical estuary. In the released location between 3 and 12 km of distance from the Caravelas mouth, the residence time was in the range of 4.2 and 10.3 days. Differently, at the Nova Viçosa estuary, only the first 5 km were studied and the residence time of 1.5 and 2.5 days was estimated for the respectives positions of 2.5 and 5.0 km away from the mouth. The analytical model proposed and used to calculate the residence time leaded to results comparable to the results from the numerical simulation using the Lagrangian method of the Delft-3D Flow. Differently, the LOICZ model has shown results really different of the residence time for all the six estuaries (Caravelas, Nova Viçosa, Curimataú, Hudson, Conwy and Mersey), and in general much smaller then the results from the proposed formula, thus indicating a possible overestimation of the diffusive flux assumed in the LOICZ formulation.

A dispersão dos efluentes do emissário submarino de Santos foi estudada por meio de modelagem numérica, acoplando-se modelos hidrodinâmico, de dispersão no campo próximo e no campo distante. As simulações foram realizadas para o projeto original do emissário de 1979, para a nova configuração de 2009 e para terceiro arranjo sugerido por este estudo, que dobra o comprimento do duto em relação ao projeto original. As diluições foram modeladas em cenários ambientais com propriedades marinhas e estuarinas climatológicas de verão, juntamente com forçantes atmosféricas climatológicas da mesma estação, simulando ausência de vento, presença de vento médio e presença de vento médio seguido por passagem de frente fria climatológica (obtida por este estudo). Com as devidas validações do modelo hidrodinâmico, a diluição, tanto no campo próximo quanto no campo distante, foi fortemente regida pela estratificação da coluna dágua e pela velocidade das correntes. O cenário sem vento apresentou as maiores estratificações, menores velocidades e originou as menores diluições em oposição ao cenário que simulou a passagem de frente fria. Dentre os projetos de emissário analisados, aquele proposto por este estudo apresentou plumas com menores comprimentos horizontais e menores profundidades, atingindo a costa uma só vez. O projeto original e o novo que será implantado em 2009 apresentaram, comparativamente, plumas mais extensas e profundas, interceptando a costa em diversas situações. / Sewage plume dispersion for the Santos outfall was studied using numerical models, coupling hydrodynamic, near field and far field models. Experiments were conducted for the 1979 original outfall design, for the new 2009 outfall configuration and also for a third arrangement suggested here, which duplicates the emissary length comparatively to the original 1979 project. Dilutions were modeled in environmental sceneries with summer climatological estuarine and marine properties, together with climatological atmospheric forcing for the same season, simulating no wind conditions, mean wind forcing and mean wind followed by a climatological cold front (developed at this study) passage. After the appropriate hydrodynamic numerical model validation, the dilution, at the near field as well as at the far field, was strongly determined by the vertical water stratification and by the current velocities. The no-wind scenery presented the highest stratifications, smallest velocities and originated the smallest dilutions, in opposition to the cold-front-scenery. Among the sewage outfall projects considered, the one presented at this study showed the shallowest plumes, with the smallest horizontal lengths, reaching the coast only once. The original 1979 project and the 2009 configuration showed, comparatively, the deepest and widest plumes reaching the coast in several situations.

Dentre os ambientes costeiros, os estuários são as principais fontes de sedimento para os oceanos. Sua dinâmica sensível é amplamente suscetível a modificações de origem natural e antrópica impactando no balanço sedimentar destes ambientes. O presente trabalho busca compreender a importância da maré meteorológica causada por frentes frias sobre os processos sedimentares do complexo estuarino de Santos aplicando o modelo numérico XBeach com três cenários. O primeiro foi forçado apenas pela maré astronômica outro representando uma condição de frente fria média e um terceiro representando uma frente fria extrema. Buscou-se detectar as frentes utilizando dados de reanálise do NCEP/NCAR. Foram extraídos os cinco dias mais intensos das frentes escolhidas e aplicaram-se ao inicio da série de dados de input do modelo para os ensaios numéricos. Os resultados permitiram compreender que os sistemas frontais atuam como agentes essenciais no balanço sedimentar tendo um papel erosivo compensando os processos deposicionais atuantes no período sem frentes. Frentes muito intensas agravam as feições erosivas e deposicionais, desbalanceando o sistema além da sua capacidade de recuperação. / Among the coastal environments, the estuaries are the main sediment source for oceans. Its sensible dynamic is widely susceptible to changes of natural and anthropogenic impacts the sediment balance of those environments. This work applies the Xbeach numerical model in Santos estuary to understand the storm surges forced by cold fronts on the sediment transport through three scenarios. The first scenario input was astronomic tide sea surface high, the second scenario input was the median cold front and the last scenario input was an extreme cold front. To get the cold front condition we use the NCEP/NCAR reanalysis data. We applied the five most intense days from each cold front condition in the beginning astronomic tide series. With the numerical model results we could understand the erosive action from the cold fronts and how it compensates the depositional period without any cold fronts. The extreme cold fronts intensify the depositional/erosion process unbalancing the system beyond the resilience capacity.

Seagrasses are important foundation species in coastal ecosystems. Genetic diversity of seagrasses can influence a number of ecological factors including, but not limited to, disturbance resistance and resilience. Seagrasses in the Indian River Lagoon (IRL), Florida are considered to be highly disturbed due to frequent events, like algal blooms, that impair water quality, reducing available light for seagrass growth. Halodule wrightii is a dominant seagrass throughout the IRL, but its genetic diversity has only been quantified in a few Gulf of Mexico and Florida Bay populations and little is known about its potential ecological consequences. I quantified the genetic variation of H. wrightii using microsatellite markers in the southern IRL to determine: (i) how disturbance history influenced genetic diversity, (ii) if morphology of clones was, in part, genetically controlled and related to disturbance history, and (iii) if genotypes showed phenotypic plasticity in response to disturbances. In the IRL, H. wrightii populations exhibited moderate genetic diversity that varied with disturbance history. The disturbance history of a population was classified by the variance in the percent occurrence of H. wrightii over a 16-year period. Genotypic richness and clonal diversity of H. wrightii increased with increasing disturbance histories. Other genetic diversity measures (e.g., allelic richness, observed heterozygosity) did not change with disturbance history. These findings suggest that impacts to seagrass coverage over time can change the genotypic composition of populations. When different genotypes of H. wrightii were grown in a common garden, differences in leaf characteristics among genotypes provided evidence that morphological trait variation is, in part, explained by genetic variance. The disturbance history of genotypes did not directly affect morphological traits. However, significant genotype x site (within disturbance history) interactions found greater variation in shoot density and below ground traits of H. wrightii genotypes from sites of intermediate disturbance history. Traits of H. wrightii were shown to be phenotypically plastic. Significant genotype x environment interactions for shoot density and height demonstrated that genotypes responded differently by increasing, decreasing, and not changing sizes in response to light reduction. Genetic diversity of H. wrightii has strong implications for ecological function in coastal communities. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection