Why, how, and how far should microbiological contamination in a coastal zone be mitigated? An application of the systems approach to the Thau lagoon (France)

Full text : http://archimer.ifremer.fr/doc/00136/24775/22959.pdf (Version "auteur", 0.77 Mo)International audienceThis paper describes the building of an integrated simulation tool based on a systems approach, and its contribution to local political discussion of the mitigation of microbiological contamination of the water in a coastal area. Local management schemes view water quality as a high-priority environmental objective. In practice, how far this objective is achieved depends on trade-offs between the costs of improved water treatment facilities and the acceptable impacts of water contamination. An in-the-field experiment in collaboration with local managers was carried out in the Thau lagoon on the French Mediterranean coast during the SPICOSA (Science and Policy Integration for Coastal System Assessment) project, from 2007 through 2011. It consisted of building a modeling platform and an integrated assessment framework for simulating exploratory scenarios. The modeling platform combines a dynamic contamination model, which represents the sources of microbiological contamination, wastewater treatment facilities, and physical mechanisms of lagoon contamination, with a prospective economic model, which estimates the patterns of development of economic activities in the area through a holistic approach. Exploratory scenarios are used to assess the risk of water contamination and the efficiency of management measures, under various assumptions about the evolution of the system. The contamination simulations suggest that the work currently planned by local authorities will be inadequate for preventing increased water pollution, and that additional but fairly inexpensive management measures for maintaining the current level of water quality should be considered. The integrated assessment framework estimates the ecological and socio-economic impacts of the various pollution mitigation policies in the broader context of possible local development patterns. The results illustrate how the systems approach may aid in the design of an applicable water policy based on operational objectives and feasible technical options. (C) 2013 Elsevier Ltd. All rights reserved

Current Status of Forecasting Toxic Harmful Algae for the North-East Atlantic Shellfish Aquaculture Industry

Across the European Atlantic Arc (Scotland, Ireland, England, France, Spain, and Portugal) the shellfish aquaculture industry is dominated by the production of mussels, followed by oysters and clams. A range of spatially and temporally variable harmful algal bloom species (HABs) impact the industry through their production of biotoxins that accumulate and concentrate in shellfish flesh, which negatively impact the health of consumers through consumption. Regulatory monitoring of harmful cells in the water column and toxin concentrations within shellfish flesh are currently the main means of warning of elevated toxin events in bivalves, with harvesting being suspended when toxicity is elevated above EU regulatory limits. However, while such an approach is generally successful in safeguarding human health, it does not provide the early warning that is needed to support business planning and harvesting by the aquaculture industry. To address this issue, a proliferation of web portals have been developed to make monitoring data widely accessible. These systems are now transitioning from “nowcasts” to operational Early Warning Systems (EWS) to better mitigate against HAB-generated harmful effects. To achieve this, EWS are incorporating a range of environmental data parameters and developing varied forecasting approaches. For example, EWS are increasingly utilizing satellite data and the results of oceanographic modeling to identify and predict the behavior of HABs. Modeling demonstrates that some HABs can be advected significant distances before impacting aquaculture sites. Traffic light indices are being developed to provide users with an easily interpreted assessment of HAB and biotoxin risk, and expert interpretation of these multiple data streams is being used to assess risk into the future. Proof-of-concept EWS are being developed to combine model information with in situ data, in some cases using machine learning-based approaches. This article: (1) reviews HAB and biotoxin issues relevant to shellfish aquaculture in the European Atlantic Arc (Scotland, Ireland, England, France, Spain, and Portugal; (2) evaluates the current status of HAB events and EWS in the region; and (3) evaluates the potential of further improving these EWS though multi-disciplinary approaches combining heterogeneous sources of information.Versión del edito

Devenir de l'atrazine dans le bassin de Marennes-Oléron (France) - Approche par la modélisation hydrodynamique, hydrosédimentaire et biogéochlmique

Atrazine is the most widely used herbicide on cultured areas. This pesticide is degraded during its transport in rivers and streams, to the coastal area. Marennes Oleron is the main french oyster farming area, receiving the fresh water from the Charente river and all the drainage coming from the coastal cultivated marshlands. Agriculture is thus claimed to be responsible for shellfish mortality in the aquaculture area. To simulate the changing fate of atrazine in the environment, a modelling strategy has been selected, a) First, using a two-way hydrodynamic model developped by IFREMER, the atrazine dilution trail in the Marennes Oleron area was simulated.Combined with larvae bioassays of Crassostrea gigas (Japanese oyster), the results show atrazine rates above 800 pg/l in the northern part of the area, inducing larval mortalities from 22 to 48%. a) A one way model perpendicular to the shore and incorporating far more processes than the preceding area was designed.Here, equations for sediment transport, diffusion and degradation in sediment were added to the advection model. Under simulations conditions, the model led us to the conclusion that atrazine transfer fluxs in the sediment (deposit and diffusion) are low in comparaison with advective fiuxs (in the order of 1/400th). The degradation represents 3% of the flux entering the sediment. These preliminary results could be improved by additions to the sediment part of the model and by including phenomena affecting water currents speed.L’atrazine est l’herbicide le plus épandu sur les terres agricoles. Ce produit phytosanitaire lors de son transport dans les cours d’eau est dégradé et véhiculé jusqu’à la zone côtière. Or, le bassin de Marennes- Oléron abrite, avec 100000 tonnes d’huîtres en stock, la production ostréicole française la plus importante. Il reçoit les eaux de la Charente et de la Seudre, ainsi que les effluents agricoles des marais littoraux charentais. L’agriculture est ainsi en parti tenue responsable à chaque accident dans la production des mollusques. Afin de déterminer le devenir de l’atrazine dans le bassin, deux approches de modélisation ont été envisagées. a) Un modèle de simulation hydrodynamique bidimensionnel développé par l’IFREMER (MARS 2D), a été utilisé pour simuler des panaches de dilution de l’atrazine dans le bassin de Marennes-Oléron. Couplé à des tests écotoxicologiques réalisés sur des larves de Crassostrea gigas (huître japonaise), les résultats des simulations montrent que les concentrations en atrazine peuvent être supérieures à 800 ng/l au nord du bassin lors de « l’introduction » dans le modèle d’un flux dans la Charente de 400 g/s pendant 5 jours ; ainsi des concentrations comprises entre 250 et 1000 ng/l ont été calculées par le modèle, susceptibles d’induire (selon des tests écotoxicologiques réalisés in vitro) des mortalités larvaires d’huîtres comprises entre 26 à 30%. b) Un modèle unidimensionnel transversal au rivage, intégrant un plus grand nombre de processus que le modèle précédent a été élaboré. Les équations du transport sédimentaire, de la diffusion et de la dégradation dans le sédiment complètent le modèle d’advection. Dans les conditions de simulations proposées, le modèle conclut au fait que les flux de transfert d’atrazine dans le sédiment (dépôt et diffusion) sont faibles par rapport aux flux advectifs (de l’ordre de 1/400eme). La dégradation calculée par le modèle représente 4% du flux entrant dans le sédiment. Mais en raison d’améliorations à apporter au modèle sur le compartiment « sédimént » et sur les phénomènes à l’origine des vitesses du courant, ces résultats doivent être considérés comme exploratoires

Devenir de l'atrazine dans le bassin de Marennes-Oléron. Approche par la modélisation hydrodynamique, hydrosédimentaire et biogéochimique

Atrazine is the most widely used herbicide on cultured areas. This pesticide is degraded during its transport in rivers and streams, to the coastal area. Marennes Oléron is the main french oyster farming area, receiving the fresh water from the Charente river and ail the drainage coming from the coastal cultivated marshlands. Agriculture is thus claimed to be responsible for shellfish mortality in the aquaculture area. To simulate the changing fate of atrazine in the environment, a modelling strategy has been selected. a) First, using a two-way hydrodynamic model developped by IFREMER, the atrazine dilution trail in the Marennes Oléron area was simulated.Combined with larvae bioassays of Crassostrea gigas (Japanese oyster), the results show atrazine rates above 800 µg/l in the northern part of the area, inducing larval mortalities from 22 to 48%. a) A one way model perpendicular to the shore and incorporating far more processes than the preceding area was designed.Here, equations for sediment transport, diffusion and degradation in sediment were added to the advection model. Under simulations conditions, the modelled us to the conclusion that atrazine transfer fluxs in the sediment (deposit and diffusion) are low in comparaison with advective fluxs (in the order of 1/400th). The degradation represents 3% of the flux entering the sediment. These preliminary results could be improved by additions to the sediment part of the model and by including phenomena affecting water currents speedL'atrazine est l'herbicide le plus épandu sur les terres agricoles. Ce produit phytosanitaire lors de son transport dans les cours d'eau est dégradé et véhiculé jusqu'à la zone côtière. Or, le bassin de Marennes Oléron abrite, avec 100000 tonnes d'huîtres en stock, la production ostréicole française la plus importante. Il reçoit les eaux de la Charente et de la Seudre, ainsi que les effluents agricoles des marais littoraux charentais. L'agriculture est ainsi en parti tenue responsable à chaque accident dans la production des mollusques. Afin de déterminer le devenir de l'atrazine dans le bassin, deux approches de modélisation ont été envisagées. a) Un modèle de simulation hydrodynamique bidimensionnel développé par l'IFREMER (MARS 20), a été utilisé pour simuler des panaches de dilution de l'atrazine dans le bassin de Marennes-Oléron. Couplé à des tests écotoxicologiques réalisés sur des larves de Crassostrea gigas (huître japonaise), les résultats des simulations montrent que les concentrations en atrazine peuvent être supérieures à 800 ng/l au nord du bassin lors de « l'introduction » dans le modèle d'un flux dans la Charente de 400 gis pendant 5 jours; ainsi des concentrations comprises entre 250 et 1000 ng/l ont été calculées par le modèle, susceptibles d'induire (selon des tests écotoxicologiques réalisés in vitro) des mortalités larvaires d'huîtres comprises entre 26 à 30%. b) Un modèle unidimensionnel transversal au rivage, intégrant un plus grand nombre de processus que le modèle précédent a été élaboré. Les équations du transport sédimentaire, de la diffusion et de la dégradation dans le sédiment complètent le modèle d'advection. Dans les conditions de simulations proposées, le modèle conclut au fait que les flux de transfert d'atrazine dans le sédiment (dépôt et diffusion) sont faibles par rapport aux flux advectifs (de l'ordre de 1/400,m,). La dégradation calculée par le modèle représente 4% du flux entrant dans le sédiment. Mais en raison d'améliorations à apporter au modèle sur le compartiment « sédiment » et sur les phénomènes à l'origine des vitesses du courant, ces résultats doivent être considérés comme exploratoires

Thermohaline circulation of shallow tidal seas

The mechanisms controlling the temperature and salinity structure of shallow continental shelf seas have been understood for over thirty years, yet knowledge of what drives their large-scale circulation has remained relatively unknown. Here we describe a decade long programme of measurements, using satellite-tracked drifting buoys on the northwest European shelf, to draw attention to a striking picture of highly organised thermohaline circulation consisting of narrow, near surface, fast flowing jets. These are ubiquitous above sharp horizontal gradients in bottom temperatures and/or salinities. The circulation phenomena we describe are likely to be prevalent on all similar, wide, tidally energetic continental shelves including those off north-eastern China, Argentina and parts of the Arctic. The robust, repeatable observation of the key role of jets above bottom fronts results in a fundamental reassessment of how we view the dynamics of shelf sea

Modeling Soft Institutional Change and the Improvement of Freshwater Governance in the Coastal Zone

Disponible en ligne sur Archimer: http://archimer.ifremer.fr/search.jsp?record=0International audienceThe contribution of soft institutional change to improve freshwater governance in the coastal zone will be examined. Freshwater management seeks to reduce losses due to overexploitation of the common-pool resources provided by river catchments and their associated ecosystems. Due to the complexity of the governance system, improving the performance of one coastal social-ecological system means searching for the appropriate "soft" institutional change. In the Pertuis Charentais region, increasing scarcity of freshwater in summer threatens the health of the coastal ecosystem and the sustainability of human activities, which depend on the use of natural resources. The allocation of freshwater among competing uses or concerns is a core issue for integrated coastal zone management. To address this issue, we have constructed an analytical framework that combines the ecosystem services approach with the institutional analysis of common-pool resources, and have developed an integrated simulation tool based on the system dynamic modeling approach. Freshwater scarcity generates three kinds of user conflict: (1) conflict between two extractive uses of freshwater (irrigation and drinking water), (2) conflicts between extractive uses (provisioning services) and other services (support, regulatory, and cultural) provided by freshwater, and (3) competition within a given activity sector (agriculture or shellfish farming). Participation by local managers led to the identification of realistic soft institutional changes that might mitigate conflicts and improve the governance system. These possible institutional changes were then integrated as fixed exogenous parameters in the simulation model. The simulated scenarios suggest that innovative collective arrangements involving farmers could be an alternative to other more restrictive top-down measures. This participatory experiment also illustrates the potential of social-ecological modeling for exploring acceptable new institutional arrangements

Reducing PEC uncertainty in coastal zones: a case study on carbamazepine, oxcarbazepine and their metabolites.

International audienceConcentrations of the antiepileptic drugs carbamazepine (Cbz), oxcarbazepine (OxCz) and their main metabolites were predicted in a wastewater treatment plant (WTP) and in the vicinity of its submarine outfall located in a Mediterranean coastal zone. Refined predicted environmental concentrations (PECs) were calculated in effluents based on consumption data and human excretion rates. PECs were estimated in the sea using the hydrodynamic MARS 3D model integrating meteorological data, oceanic conditions (wind, tide, atmospheric pressure), freshwater and sewage inputs. Measured environmental concentrations (MECs) were compared to PECs to assess the estimation relevance. In the coastal zone, PEC and MEC were in the same magnitude range. Modeling of Cbz diffusion and advection just above the submarine outfall showed the influence of the thermocline during summer, with low diffusion of Cbz from the bottom to the surface. This work allowed understanding the dispersion of target compounds and deserved further development for a better acknowledgement of vulnerability at local scales

Scénarios de changements institutionnels pour une gouvernance améliorée de la gestion de l'eau douce dans la zone côtière

International audienceThis paper examines the potentialities of soft institutional changes toward the improvement of freshwater governance in the coastal zone. Freshwater management seeks to reduce welfare losses due to overexploitation of common-pool resources provided by river catchments and their associated ecosystems. Due to the complexity of the governance system, improving the performances of one coastal social-ecological system is then a matter of searching for the adequate soft institutional changes. In the Pertuis Charentais region, increasing scarcity of freshwater during summer threatens the health of this coastal ecosystem and the sustainability of human activities which depend on the use of natural resources. The allocation of freshwater between competing uses or concerns is a core issue for integrated coastal zone management; it reveals the necessary trade-offs between the services that freshwater is expected to deliver to the natural system but also to households, land farmers, recreational fishermen and shellfish farmers. In order to address this issue, we built a conceptual framework which combines the ecosystem services approach with the institutional analysis of common-pool resources. Stakeholder involvement allowed the identification of the realistic soft institutional changes which could improve the governance system. The simulated scenarios suggest that innovative collective arrangements involving farmers could provide some leeway for other more restrictive top-down measures. This participative experiment illustrates also the demonstrative potential of social-ecological modelling for the exploration of acceptable new institutional arrangements

Predicted environmental concentrations of carbamazepine, oxcarbazepine and their main metabolites in a coastal system

Pharmaceuticals are widely released in aquatic environment through treated wastewaters. They reach coastal zone indirectly via streams or directly though marine outfalls however data concerning this contamination in coastal waters are scarce. Environmental Risk Assessment (ERA) of pharmaceuticals have been conducted mostly in surface waters and has not been performed in coastal zone. The first step of ERA is to evaluate the exposure through predictive environmental concentration (PEC) values. The aim of this study was to predict the occurrence of some pharmaceuticals in a coastal aera subjected to treated wastewater (TWW) reject through a marine outfall (Fig 2.). Among pharmaceuticals, Carbamazepine, Oxcarbazepine and their main metabolites (Fig 1.) were chosen. CBZ has been proposed as an indicator of wastewater contamination and has been already detected in Mediterranean (Munaron et al., 2011). Prediction was performed based on local pharmaceuticals consumption recording and a review of pharmacokinetics data. PECs values were estimated in TWW and at the marine outfall and compared with MECs obtained by direct quantification and with POCIS implementation

Cloud filling of ocean colour and sea surface temperature remote sensing products over the Southern North Sea by the Data Interpolating Empirical Orthogonal Functions methodology.

Optical remote sensing data is now being used systematically for marine ecosystem applications, such as the forcing of biological models and the operational detection of harmful algae blooms. However, applications are hampered by the incompleteness of imagery and by some quality problems. The Data Interpolating Empirical Orthogonal Functions methodology (DINEOF) allows calculation of missing data in geophysical datasets without requiring a priori knowledge about statistics of the full data set and has previously been applied to SST reconstructions. This study demonstrates the reconstruction of complete space-time information for 4 years of surface chlorophyll a (CHL), total suspended matter (TSM) and sea surface temperature (SST) over the Southern North Sea (SNS) and English Channel (EC). Optimal reconstructions were obtained when synthesising the original signal into 8 modes for MERIS CHL and into 18 modes for MERIS TSM. Despite the very high proportion of missing data (70%), the variability of original signals explained by the EOF synthesis reached 93.5 % for CHL and 97.2 % for TSM. For the MODIS TSM dataset, 97.5 % of the original variability of the signal was synthesised into 14 modes. The MODIS SST dataset could be synthesised into 13 modes explaining 98 % of the input signal variability. Validation of the method is achieved for 3 dates below 2 artificial clouds, by comparing reconstructed data with excluded input information. Complete weekly and monthly averaged climatologies, suitable for use with ecosystem models, were derived from regular daily reconstructions. Error maps associated with every reconstruction were produced according to Beckers et al. (2006) [6]. Embedded in this error calculation scheme, a methodology was implemented to produce maps of outliers, allowing identification of unusual or suspicious data points compared to the global dynamics of the dataset. Various algorithms artefacts were associated with high values in the outlier maps (undetected cloud edges, haze areas, contrails, cloud shadows). With the production of outlier maps, the data reconstruction technique becomes also a very efficient tool for quality control of optical remote sensing data and for change detection within large databases.RECOLOU