Territoire uni par la diversité des ressources aquatiques la caractérisant, la traversant et l’enserrant, la France peut s’enorgueillir de bénéficier d’une Eau dont la disponibilité quantitative ne peut être contestée. D’un point de vue qualitatif, la multitude croissante des intérêts les enviant a été générée par un nombre certain d’utilités – individuelles et collectives – ayant nécessité que soit forgé un Modèle d’administration pour les encadrer tous. Dans le but d’appréhender avec le plus d’efficacité les dimensions sociales et économiques de l’Eau et des Milieux aquatiques, ce Modèle a internalisé non seulement le caractère durable de leur gestion mais également celui lié à l’équilibre. En recherchant l’articulation entre ces utilités et ces intérêts, ainsi que, par extension, celle des acteurs les portant, notre Modèle éprouvera sa résilience à l’aune de multiples chocs endogènes et exogènes. Profondément saisi par le marqueur territorial central et local, ce Modèle n’en a pas moins épousé la logiquejuridique tant dans son optique de prescription que de prestation. Lié, intimement, à ces différents axes matériels et immatériels, il s’est progressivement constitué tel un instrument de structuration des liens unissant les hommes, les territoires et les ressources aquatiques. Achoppé et érodé par les coups de boutoir successifs des nombreuses cristallisations de l’Utilitarisme, notre Modèle est en passe de réaffirmer la dimension holiste de l’Intérêt général lui ayant insufflé la vie afin d’armer ce régime juridique des ressources aquatiques face aux conflits internes et externes de l’Eau provenant du Passé, s’ancrant dans le Présent et se diversifiant dans le Futur / Territory united by the diversity of the aquatic resources characterizing it, crossing it and enclosing it, France can be proud to benefit from a Water whose quantitative availability cannot be disputed. From a qualitative point of view, the increasing interests for these environmental resources have been created by some utilities – individual and collective – that required the forging of a model of Administration in order to frame them all. In order to understand more effectively the social and the economic dimensions of Water and aquatic resources, this Model has internalized the sustainability of their management but, also the importance of their balance. By seeking the articulation between utilities and these interests, as well as, by extension, the actors carrying them, we focus our mind on the evolution of our Model when some of its basements are jeopardized. Deeply grasped by the central and the local territorial marker, this Model has been unified with a legal logic, both in terms of prescription andbenefit. Intimately connected to these several material and immaterial axis, our Model has progressively been constituted as a tool for structuring the bonds uniting people, territories and aquatic resources. Criticized and weathered by the successive crystallizations of Utilitarianism, our Model is about to reinforce the holistic dimension of the General Interest that has breathed life into it, in order to arm legal framework of aquatic resources against internal and external conflicts from the Past, the Present and the Future

In light of increasing harmful algal blooms and the need to protect human health and aquatic resources, proactive management approaches merit further study. For this purpose I conducted field samplings to characterize plankton community composition and laboratory experiments to test some approaches to new management schemes in the lower Rincon Delta. On site measurements and microscopic analysis showed that environmental parameters and plankton community composition varied considerably among sampling stations and sampling dates. A recent modeling study suggested that manipulation of freshwater inflow to estuaries might prevent phytoplankton blooms and enhance secondary productivity. To test this theory I conducted three semi-continuous design and flow-through incubation design experiments using natural plankton assemblages. I investigated the effect of two different pulsing regimes of inflow and nutrient loading on zooplankton densities, and phytoplankton biomass and diversity. Despite differences in zooplankton structure and phytoplankton community composition between the two experiment designs, the results confirmed that pulsed inflows might alter plankton dynamics. My findings showed that 3-day pulse treatments consistently supported greater zooplankton densities and higher phytoplankton species diversity when compared to 1-day pulse treatments. In addition, accumulation of phytoplankton biovolume remained low during 3-day pulse treatments. Differences in zooplankton performance between 3-day pulse and 1-day pulse inflow treatments were likely due to the ability of phytoplankton to uptake and store greater amounts of nutrients under conditions of 3-day pulse inflow. This resulted in food of higher quality for zooplankton, and might have supported greater zooplankton population growth rates. Additionally, in an attempt to understand the mechanisms leading to high biodiversity in aquatic ecosystems, I built a resource-storage model and studied the effects of resource-storage on competition of multiple phytoplankton species on multiple abiotic resources. I compared this model with a well-established multi-species competition model. My results showed that for certain species combinations a resource-storage-based model can generate dissimilar outcomes when compared to a model without resource-storage.

In light of increasing harmful algal blooms and the need to protect human health and aquatic resources, proactive management approaches merit further study. For this purpose I conducted field samplings to characterize plankton community composition and laboratory experiments to test some approaches to new management schemes in the lower Rincon Delta. On site measurements and microscopic analysis showed that environmental parameters and plankton community composition varied considerably among sampling stations and sampling dates. A recent modeling study suggested that manipulation of freshwater inflow to estuaries might prevent phytoplankton blooms and enhance secondary productivity. To test this theory I conducted three semi-continuous design and flow-through incubation design experiments using natural plankton assemblages. I investigated the effect of two different pulsing regimes of inflow and nutrient loading on zooplankton densities, and phytoplankton biomass and diversity. Despite differences in zooplankton structure and phytoplankton community composition between the two experiment designs, the results confirmed that pulsed inflows might alter plankton dynamics. My findings showed that 3-day pulse treatments consistently supported greater zooplankton densities and higher phytoplankton species diversity when compared to 1-day pulse treatments. In addition, accumulation of phytoplankton biovolume remained low during 3-day pulse treatments. Differences in zooplankton performance between 3-day pulse and 1-day pulse inflow treatments were likely due to the ability of phytoplankton to uptake and store greater amounts of nutrients under conditions of 3-day pulse inflow. This resulted in food of higher quality for zooplankton, and might have supported greater zooplankton population growth rates. Additionally, in an attempt to understand the mechanisms leading to high biodiversity in aquatic ecosystems, I built a resource-storage model and studied the effects of resource-storage on competition of multiple phytoplankton species on multiple abiotic resources. I compared this model with a well-established multi-species competition model. My results showed that for certain species combinations a resource-storage-based model can generate dissimilar outcomes when compared to a model without resource-storage.