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The deep, elongated paralic basin of Kalloni bay has been studied through comparisons between several computed hydrodynamical situations and data collected in similar situations from its water body. These include salinities and phytoplanktonic biomasses. Additionally, sedimentological data, which integrate the environmental variations on the long term, have been collected in order to help in understanding the average biogeological functioning of the system. Depending upon its direction and speed, wind forcing induces different salinity and phytoplanktonic patterns. These generally display rather weak gradients from the entrance and the axial deepest channel towards the farthest northeastern reaches of the basin. Moreover, the ranges of salinities and phytoplanktonic biomasses display a very low degree of restriction from the sea (confinement), while the global phytoplanktonic composition, analysed by flow cytometry, shows the prominent marine influence over the basin. The average hydrodynamical conditions are dominated by the axial influx of marine water on the bottom, and by the surface-reflux of basinal waters along both side banks. Such a prevailing configuration is also displayed by sedimentological features. Kalloni bay appears as one of the less confined systems in the Mediterranean region, due to its shape and bathymetry, the absence of a sill between the basin and the sea, and active exchanges with the sea under the influence of wind activity.

The deep, elongated paralic basin of Kalloni bay has been studied through comparisons between several computed hydrodynamical situations and data collected in similar situations from its water body. These include salinities and phytoplanktonic biomasses. Additionally, sedimentological data, which integrate the environmental variations on the long term, have been collected in order to help in understanding the average biogeological functioning of the system. Depending upon its direction and speed, wind forcing induces different salinity and phytoplanktonic patterns. These generally display rather weak gradients from the entrance and the axial deepest channel towards the farthest northeastern reaches of the basin. Moreover, the ranges of salinities and phytoplanktonic biomasses display a very low degree of restriction from the sea (confinement), while the global phytoplanktonic composition, analysed by flow cytometry, shows the prominent marine influence over the basin. The average hydrodynamical conditions are dominated by the axial influx of marine water on the bottom, and by the surface-reflux of basinal waters along both side banks. Such a prevailing configuration is also displayed by sedimentological features. Kalloni bay appears as one of the less confined systems in the Mediterranean region, due to its shape and bathymetry, the absence of a sill between the basin and the sea, and active exchanges with the sea under the influence of wind activity.

The deep, elongated paralic basin of Kalloni bay has been studied through comparisons between several computed hydrodynamical situations and data collected in similar situations from its water body. These include salinities and phytoplanktonic biomasses. Additionally, sedimentological data, which integrate the environmental variations on the long term, have been collected in order to help in understanding the average biogeological functioning of the system. Depending upon its direction and speed, wind forcing induces different salinity and phytoplanktonic patterns. These generally display rather weak gradients from the entrance and the axial deepest channel towards the farthest northeastern reaches of the basin. Moreover, the ranges of salinities and phytoplanktonic biomasses display a very low degree of restriction from the sea (confinement), while the global phytoplanktonic composition, analysed by flow cytometry, shows the prominent marine influence over the basin. The average hydrodynamical conditions are dominated by the axial influx of marine water on the bottom, and by the surface-reflux of basinal waters along both side banks. Such a prevailing configuration is also displayed by sedimentological features. Kalloni bay appears as one of the less confined systems in the Mediterranean region, due to its shape and bathymetry, the absence of a sill between the basin and the sea, and active exchanges with the sea under the influence of wind activity.

The deep, elongated paralic basin of Kalloni bay has been studied through comparisons between several computed hydrodynamical situations and data collected in similar situations from its water body. These include salinities and phytoplanktonic biomasses. Additionally, sedimentological data, which integrate the environmental variations on the long term, have been collected in order to help in understanding the average biogeological functioning of the system. Depending upon its direction and speed, wind forcing induces different salinity and phytoplanktonic patterns. These generally display rather weak gradients from the entrance and the axial deepest channel towards the farthest northeastern reaches of the basin. Moreover, the ranges of salinities and phytoplanktonic biomasses display a very low degree of restriction from the sea (confinement), while the global phytoplanktonic composition, analysed by flow cytometry, shows the prominent marine influence over the basin. The average hydrodynamical conditions are dominated by the axial influx of marine water on the bottom, and by the surface-reflux of basinal waters along both side banks. Such a prevailing configuration is also displayed by sedimentological features. Kalloni bay appears as one of the less confined systems in the Mediterranean region, due to its shape and bathymetry, the absence of a sill between the basin and the sea, and active exchanges with the sea under the influence of wind activity.

In order better to understand brackish ecosystem functioning, this study deals with zooplankton spatial organization in a North-Mediterranean lagoon (etang de Thau). A statistical treatment - spatial contiguity constrained clustering - is used to divide the lagoon into several homogeneous zones with regard to zooplankton communities. Confrontation between biological and physical patterns (hydroclimatic context data together with results of a numerical simulation of hydrodynamic circulation in the lagoon) tends to show that: 1) Zooplankton community spatial patterns have a short-term significance (few days) and do not reveal any seasonal characteristic; 2) Inversion of the water flows between the lagoon and the sea plays a major role in structuring and destructuring the biological system: the zooplankton compartment appears to be particularly sensitive to this hydrodynamic constraint even when it is a very smooth one (e.g. each event affecting only a small percentage of the total volume of the lagoon); 3) Independently of these short-term hydroclimatic events, the general pattern of zooplankton distribution appears very well correlated to the hydrodynamic energy dispersion deduced from a numerical model simulating the water circulation into the lagoon. In agreement with other plankton studies, these results encourage the introduction of physical descriptors into the modelling of biological processes in the aquatic environment. It seems also true that - especially in these kinds of ecosystem (lagoons) - the biology is strongly controlled by the physical system.

In order better to understand brackish ecosystem functioning, this study deals with zooplankton spatial organization in a North-Mediterranean lagoon (etang de Thau). A statistical treatment - spatial contiguity constrained clustering - is used to divide the lagoon into several homogeneous zones with regard to zooplankton communities. Confrontation between biological and physical patterns (hydroclimatic context data together with results of a numerical simulation of hydrodynamic circulation in the lagoon) tends to show that: 1) Zooplankton community spatial patterns have a short-term significance (few days) and do not reveal any seasonal characteristic; 2) Inversion of the water flows between the lagoon and the sea plays a major role in structuring and destructuring the biological system: the zooplankton compartment appears to be particularly sensitive to this hydrodynamic constraint even when it is a very smooth one (e.g. each event affecting only a small percentage of the total volume of the lagoon); 3) Independently of these short-term hydroclimatic events, the general pattern of zooplankton distribution appears very well correlated to the hydrodynamic energy dispersion deduced from a numerical model simulating the water circulation into the lagoon. In agreement with other plankton studies, these results encourage the introduction of physical descriptors into the modelling of biological processes in the aquatic environment. It seems also true that - especially in these kinds of ecosystem (lagoons) - the biology is strongly controlled by the physical system.

In order better to understand brackish ecosystem functioning, this study deals with zooplankton spatial organization in a North-Mediterranean lagoon (etang de Thau). A statistical treatment - spatial contiguity constrained clustering - is used to divide the lagoon into several homogeneous zones with regard to zooplankton communities. Confrontation between biological and physical patterns (hydroclimatic context data together with results of a numerical simulation of hydrodynamic circulation in the lagoon) tends to show that: 1) Zooplankton community spatial patterns have a short-term significance (few days) and do not reveal any seasonal characteristic; 2) Inversion of the water flows between the lagoon and the sea plays a major role in structuring and destructuring the biological system: the zooplankton compartment appears to be particularly sensitive to this hydrodynamic constraint even when it is a very smooth one (e.g. each event affecting only a small percentage of the total volume of the lagoon); 3) Independently of these short-term hydroclimatic events, the general pattern of zooplankton distribution appears very well correlated to the hydrodynamic energy dispersion deduced from a numerical model simulating the water circulation into the lagoon. In agreement with other plankton studies, these results encourage the introduction of physical descriptors into the modelling of biological processes in the aquatic environment. It seems also true that - especially in these kinds of ecosystem (lagoons) - the biology is strongly controlled by the physical system.

In order better to understand brackish ecosystem functioning, this study deals with zooplankton spatial organization in a North-Mediterranean lagoon (etang de Thau). A statistical treatment - spatial contiguity constrained clustering - is used to divide the lagoon into several homogeneous zones with regard to zooplankton communities. Confrontation between biological and physical patterns (hydroclimatic context data together with results of a numerical simulation of hydrodynamic circulation in the lagoon) tends to show that: 1) Zooplankton community spatial patterns have a short-term significance (few days) and do not reveal any seasonal characteristic; 2) Inversion of the water flows between the lagoon and the sea plays a major role in structuring and destructuring the biological system: the zooplankton compartment appears to be particularly sensitive to this hydrodynamic constraint even when it is a very smooth one (e.g. each event affecting only a small percentage of the total volume of the lagoon); 3) Independently of these short-term hydroclimatic events, the general pattern of zooplankton distribution appears very well correlated to the hydrodynamic energy dispersion deduced from a numerical model simulating the water circulation into the lagoon. In agreement with other plankton studies, these results encourage the introduction of physical descriptors into the modelling of biological processes in the aquatic environment. It seems also true that - especially in these kinds of ecosystem (lagoons) - the biology is strongly controlled by the physical system.

The wind-driven flow in the closed bassin de Thau is reproduced with a two-dimensional numerical model of horizontal ciruclation using an Alternate Direction Implicit scheme. A stochastic analysis of frequencies on a yearly time scale of the velocity fields computed in the model and a spatial and stochastic treatment of the term (H2 y2), similar to an effective coefficient of horizontal dispersion by shear effect are presented. This approach will allow the delineation, in a stochastic manner, of the main structures of the circulation in the lagoon and the spatial heterogeneity of its ecohydrodynamic features. Two attempts of analogical research are presented, with sorne examples of the spatial structure in the phytoplankton biomass and the map of the granulometry of the upper sediment layer., La circulation des eaux sous le seul effet du vent dans le bassin de Thau fermé est simulée par un modèle numérique bidimensionnel horizontal de type ADI. Une analyse des fréquences annuelles des champs de vitesse issus du modèle et un traitement spatial et probabiliste du terme (H2 y2), assimilable à un effet de dispersion horizontal par cisaillement, conduisent à proposer une typologie probabiliste des principales structures d'écoulement dans la lagune, ainsi qu'une discontinuité spatiale de son comportement écohydrodynamique. Deux tentatives de recherche analogique sont présentées, avec quelques exemples de répartitions spatiales de la biomasse phytoplanctonique et avec la cartographie de la granulométrie du sédiment superficiel.

The wind-driven flow in the closed bassin de Thau is reproduced with a two-dimensional numerical model of horizontal ciruclation using an Alternate Direction Implicit scheme. A stochastic analysis of frequencies on a yearly time scale of the velocity fields computed in the model and a spatial and stochastic treatment of the term (H2 y2), similar to an effective coefficient of horizontal dispersion by shear effect are presented. This approach will allow the delineation, in a stochastic manner, of the main structures of the circulation in the lagoon and the spatial heterogeneity of its ecohydrodynamic features. Two attempts of analogical research are presented, with sorne examples of the spatial structure in the phytoplankton biomass and the map of the granulometry of the upper sediment layer., La circulation des eaux sous le seul effet du vent dans le bassin de Thau fermé est simulée par un modèle numérique bidimensionnel horizontal de type ADI. Une analyse des fréquences annuelles des champs de vitesse issus du modèle et un traitement spatial et probabiliste du terme (H2 y2), assimilable à un effet de dispersion horizontal par cisaillement, conduisent à proposer une typologie probabiliste des principales structures d'écoulement dans la lagune, ainsi qu'une discontinuité spatiale de son comportement écohydrodynamique. Deux tentatives de recherche analogique sont présentées, avec quelques exemples de répartitions spatiales de la biomasse phytoplanctonique et avec la cartographie de la granulométrie du sédiment superficiel.

The wind-driven flow in the closed bassin de Thau is reproduced with a two-dimensional numerical model of horizontal ciruclation using an Alternate Direction Implicit scheme. A stochastic analysis of frequencies on a yearly time scale of the velocity fields computed in the model and a spatial and stochastic treatment of the term (H2 y2), similar to an effective coefficient of horizontal dispersion by shear effect are presented. This approach will allow the delineation, in a stochastic manner, of the main structures of the circulation in the lagoon and the spatial heterogeneity of its ecohydrodynamic features. Two attempts of analogical research are presented, with sorne examples of the spatial structure in the phytoplankton biomass and the map of the granulometry of the upper sediment layer., La circulation des eaux sous le seul effet du vent dans le bassin de Thau fermé est simulée par un modèle numérique bidimensionnel horizontal de type ADI. Une analyse des fréquences annuelles des champs de vitesse issus du modèle et un traitement spatial et probabiliste du terme (H2 y2), assimilable à un effet de dispersion horizontal par cisaillement, conduisent à proposer une typologie probabiliste des principales structures d'écoulement dans la lagune, ainsi qu'une discontinuité spatiale de son comportement écohydrodynamique. Deux tentatives de recherche analogique sont présentées, avec quelques exemples de répartitions spatiales de la biomasse phytoplanctonique et avec la cartographie de la granulométrie du sédiment superficiel.

The wind-driven flow in the closed bassin de Thau is reproduced with a two-dimensional numerical model of horizontal ciruclation using an Alternate Direction Implicit scheme. A stochastic analysis of frequencies on a yearly time scale of the velocity fields computed in the model and a spatial and stochastic treatment of the term (H2 y2), similar to an effective coefficient of horizontal dispersion by shear effect are presented. This approach will allow the delineation, in a stochastic manner, of the main structures of the circulation in the lagoon and the spatial heterogeneity of its ecohydrodynamic features. Two attempts of analogical research are presented, with sorne examples of the spatial structure in the phytoplankton biomass and the map of the granulometry of the upper sediment layer., La circulation des eaux sous le seul effet du vent dans le bassin de Thau fermé est simulée par un modèle numérique bidimensionnel horizontal de type ADI. Une analyse des fréquences annuelles des champs de vitesse issus du modèle et un traitement spatial et probabiliste du terme (H2 y2), assimilable à un effet de dispersion horizontal par cisaillement, conduisent à proposer une typologie probabiliste des principales structures d'écoulement dans la lagune, ainsi qu'une discontinuité spatiale de son comportement écohydrodynamique. Deux tentatives de recherche analogique sont présentées, avec quelques exemples de répartitions spatiales de la biomasse phytoplanctonique et avec la cartographie de la granulométrie du sédiment superficiel.