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From 2014 to 2021 during the cyclone seasons, extensive monitoring of the hydrodynamics within a variety of lagoons of New Caledonia was conducted as a part of the PRESENCE project (PRESsures on coral Ecosystems of New CalEdonia). The PRESENCE project is aimed at building an efficient representation of the land–lagoon–ocean continuum at Grande Terre, New Caledonia's main island. Overall, coastal physical observations encompassed five different lagoons (four of which were never before monitored) and at least eight major atmospheric events ranging from tropical depressions to category 4 cyclones. The main objectives of this study were to characterize the processes controlling the hydrodynamics and hydrology of these lagoons (e.g., ocean–lagoon exchanges, circulation, level dynamics, temperature, and salinity variability), and to capture the magnitude of change during extreme events. An additional objective was to compile an adequate data set for future use in high-resolution hydrodynamic models. Autonomous oceanographic instruments were moored at strategic locations to collect time series of temperature, salinity, pressure, and Eulerian currents. Additionally, Lagrangian surface currents were observed through deploying drifter buoys, and cross-shore hydrological profile radials were carried out using CTDs (conductivity, temperature, depth). In total, five survey campaigns were conducted, beginning with the SPHYNX campaign which lasted 15 months (December 2014 to February 2016) in the Hienghène–Touho lagoon and ended with the 9 months NEMO campaign (September 2020 to April 2021) in Moindou lagoon. Between these were the 5 months NOUMEA campaign (December 2016 to April 2017) in Noumea lagoon, the 6 months ELADE campaign (February to August 2018) in the Poe lagoon, and the 5 months CADHYAK campaign (December 2019 to May 2020) in Koumac lagoon. In addition to characterizing these lagoons, the data set identifies important features and processes, such as the presence of internal waves on forereefs, wave-driven fluxes over reef barriers, and exchanges through passes. Signatures from strong events were also identified, including surges, thermal drops inside lagoons, and massive flash flood plume dispersion. Raw data sets were processed, controlled for quality, validated, and analyzed. Processed files are made publicly available in dedicated repositories on the SEANOE marine data platform in NetCDF format. Links (DOI) of individual data sets are provided herein.

International audience; Inspired by agroecology, ecological aquaculture proposes an alternative model that uses ecology as a paradigm to develop innovative, more eco-friendly aquaculture with environmental, economic and social benefits. Integrated multi-trophic aquaculture (IMTA) is one application of this principle. Inspired by the natural trophic chain, it associates primary producers with primary or secondary consumers, providing a new source of biomass without requiring supplementary feed by recycling inorganic and organic wastes. Of these systems, land-based IMTAs demonstrate several advantages, especially easier control of nutrient flows, contaminants and/or predators. This study focused on a land-based marine IMTA, combining a recirculating aquaculture system for fish consecutively with a natural marine polyculture of microalgae and oyster cultivation. The objective was to assess the ability of the microalgal polyculture both to bioremediate fish nutrients and to sustain oyster growth. For the first time in a Mediterranean climate, we confirmed the feasibility of developing a microalgae community of interest for oysters maintained by fish effluent. Despite strong variability in microalgae production, this IMTA system resulted in significant oyster growth over the experimental period of one month, with growth results of the same order of magnitude as natural juvenile growth. In the conditions tested, this IMTA with reduced human intervention allowed a gain in recoverable biomass of 3.7 g of oyster produced per kg of fish feed distributed. By transforming waste into additional biomass, IMTAs offer a more promising, ecological avenue for aquaculture, based on a circular economy, which may in turn increase the social acceptability of fish farming.

From 2014 to 2021, extensive monitoring of hydrodynamics was deployed within a variety of lagoons of New Caledonia during 6 tropical cyclone seasons. Globally, those coastal physical observations encompassed five different lagoons (four of which were never monitored before) and at least eight major atmospheric events ranging from tropical depression to category 4 cyclone. The main objectives were to characterize the processes at stake controlling hydrodynamics and hydrology of these lagoons (e.g ocean-lagoon exchanges, circulation, level dynamics, temperature and salinity variability) and capture their magnitude of change during extreme events. An additional objective was to build an adequate data set for assessment of high-resolution hydrodynamics models. Those field experiments took place within the PRESENCE project (PRESsures on coral Ecosystems of New CalEdonia) which aimed at building an efficient representation of the land-lagoon-ocean continuum of Grande Terre (main land) lagoons. Autonomous oceanographic instruments were moored at strategic locations to collect time-series of temperature, salinity, pressure, eulerian currents which characterize hydrodynamics at best. During field trips, whenever possible, lagrangian drifters releases and cross-shore hydrological profiles radials were additionally carried out. Surveys begun chronologically with SPHYNX campaign which lasted 15 months (December 2014 to February 2016) in the Hienghène-Touho lagoon followed with 5 months records in NOUMEA lagoon (December 2016 to April 2017). ELADE campaign in Poe lagoon encompassed 2 periods of measure (February to April 2018 and June to August 2018). In Koumac lagoon, CADHYAK survey was carried out between December 2019 until the end of May 2020 and finally, data have been recorded continuously for 9 months in Moindou lagoon (NEMO) (September 2020 to April 2021). In addition to characterize these lagoons, this data set stresses out some important features and processes, such as the presence of internal waves on reef slopes, wave-driven fluxes over reef barrier and exchanges through passes. It also contains the signatures of strong events materialized by surges, thermal drops inside lagoons or massive flash flood plumes dispersion. Raw data sets were processed, quality-controlled and validated, and processed files are publicly available in dedicated repositories on Seanoe in NetCDF format. Links (DOI) of individual data sets are provided herein.

The use of detritivores under sea farms is a promising avenue to mitigate the benthic impacts of marine fish farms. Sea cucumbers are interesting candidates for integrated multi-trophic aquaculture (IMTA) due to their prevalence in the marine environment, their diversified diet and their economic value. Yet limited information is available regarding their capacities to be stocked and reared underneath aquaculture cages and the associated effects on their survival, growth rate and body composition. This study focused on Holothuria tubulosa, a Mediterranean sea cucumber species candidate for rearing in the vicinity to marine fish cages. We investigated its potential for co-culture on the seabed more or less influenced by marine fish cages. The farm's waste footprint was predicted using a dispersion model (NewDEPOMOD) to estimate the farm's influence along a transect where we also sampled sediment at four distances from the cages (0 m, 25 m, 100 m from the cages, plus a reference site at 150 m). Organic composition of the sediment was analysed (TOC, TON, TOP, OM, stable isotope signature) and linked to the results from the dispersion model. Based on the model simulation, the maximum flux of matter reached almost 17 kg solids.m−2.year−1 below the cages, and gradually decreased with distance from the cages. An isotopic gradient was also found in the sediments according to the distance from the farm, with an enrichment in δN15 and a depletion in δC13 with increasing proximity to the farm. In parallel we investigated the response of adult sea cucumbers placed at varying distances from the fish cages for a period of one month, measuring their proximate composition, isotopic concentration, and fatty acid and protein composition. We found that despite good survival, growth was null over the experiment. While the isotope signature of the sea cucumbers was significantly affected by distance from the cage, this did not follow the pattern found in sediment. There was a clear difference in fatty acid composition between sites, with sea cucumbers closer to the cages having lower levels of short-chain fatty acids. The protein content was also lower in sea cucumbers reared right below the cages. These results suggest that while adult H. tubulosa can survive the environmental conditions below marine aquaculture cages, they do not nutritionally benefit from fish waste over short periods in the stocking conditions we tested. Their use in IMTA requires further investigation to find optimal stocking conditions.

International audience; In the grow-out ponds of the blue shrimp (Litopenaeus stylirostris) farms of New Caledonia, animals with orange gills (OG) have been observed over the last ten years, with up to 70% of the shrimp in a given pond being affected. During the processing and marketing of the product, this coloring leads to reduced quality and selling prices, resulting in lower income for the producers concerned. Individual observations and transfer experiments led us to conclude that gill coloration intensity varies according to the intermolt stages, ranging from white in the postmolt stage to a deep orange in the premolt stage, which then disappeared after molting. Histological, biochemical studies and a semiquantitative analysis by scanning electronic microscopy (SEM + EDX) showed that the coloration is due to layers of iron which settle on the gill tissue surface in a heterogeneous way. Because Cr and Co showed an increase in their concentrations on the whole orange gills but not at their surface, it is possible that elements were mobilized and transported (translocated) from the exoskeleton to the tissue. Animals kept out of contact with sediment show a decrease in OG intensity, suggesting a link with the sediment biogeochemistry. In grow-out ponds, orange gills first appeared in shrimp populations between 10 and 13 weeks after stocking and reached a maximum after 15 weeks. These findings are discussed with a view to identifying the environmental processes that lead to metal accumulation on gills.

International audience; From the 1980's, Indonesian shrimp production has continuously increased through a large expansion of culturedareas and an intensification of the production. As consequences of diseases and environmental degradations linkedto this development, there are currently 250,000 ha of abandoned ponds in Indonesia. To implement effectiveprocedure to undertake appropriate aquaculture ecosystem assessment and monitoring, an integrated indicatorbased on four criteria using very high spatial optical satellite images, has been developed to discriminate activefrom abandoned ponds. These criteria were: presence of water, aerator, feeding bridge and vegetation. Thisindicator has then been applied to the Perancak estuary, a production area in decline, to highlight the abandonmentdynamic between 2001 and 2015. Two risk factors that could contribute to explain dynamics of abandonmentwereidentified: climate conditions and pond locations within the estuary, suggesting that a spatial approach should beintegrated in planning processes to operationalize pond rehabilitation.

Tropical shrimp aquaculture systems in New Caledonia regularly face major crises resulting from outbreaks of Vibrio infections. Ponds are highly dynamic and challenging environments and display a wide range of trophic conditions. In farms affected by vibriosis, phytoplankton biomass and composition are highly variable. These conditions may promote the development of harmful algae increasing shrimp susceptibility to bacterial infections. Phytoplankton compartment before and during mortality outbreaks was monitored at a shrimp farm that has been regularly and highly impacted by these diseases. Combining information from flow cytometry, microscopy, pigment and phylogenetic analysis, the presence of Picocyanobacteria, Prasinophyceae and Diatomophyceae were detected as dominant phytoplankton groups and Cryptophyceae, Prymnesiophyceae and Dinophyceae as minor components. At the onset of the first shrimp mortalities, Bacillariophyceae increased while Cyanobacteria, Prymnesiophyceae and Dinophyceae decreased in the water column, followed by proliferation of Prasinophyceae. Several taxa were identified as potential harmful algae (Cyanobacteria, dinoflagellates and Phaeocystis).

French Mediterranean coastal lagoons have been subject to huge inputs of urban nutrients for decades leading to the eutrophication of these vulnerable ecosystems. In response to new environmental regulations, some of the lagoons have recently been the subject of large-scale management actions targeting the waste water treatment systems located on their watersheds. While the eutrophication of coastal ecosystems is well described, recovery trajectories have only recently been studied. To assess the rapidity and the extent of the effect of the remediation actions, we analysed data from a 14-year time series resulting from the monitoring of nutrients, biomass and the abundance of phytoplankton in the water column of French Mediterranean coastal lagoons covering the whole anthropogenic eutrophication gradient. Following a 50% to 80% reduction in total phosphorus (TP) and total nitrogen (TN) urban loadings from the watershed of hypertrophic and eutrophic ecosystems, the integrative parameters chlorophyll a, TN and TP, provide evidence for a rapid response (1 to 3 years) and for an almost complete recovery, suggesting no hysteresis for the eutrophic lagoon. However, our findings also show that recovery patterns depend on the eutrophication status before remediation and may include feedback responses. The different responses revealed by our results should help stakeholders prioritise remediation actions and identify appropriate restoration goals, especially in light of the targets of the Water Framework Directive (WFD).

International audience; Increases in the intensity of disturbances in coastal lagoons can lead to shifts in vegetation from aquatic angiosperms to macroalgal or phytoplankton communities. Such abrupt and discontinuous responses are facilitated by instability in the equilibrium controlling the trajectory of the community response. We hypothesized that the shift in macrophyte populations is reversible, and that this reversibility is dependent on changes in the pressures exerted on the watershed and lagoon functioning. Biguglia lagoon (Mediterranean Sea, Corsica) is an interesting case study for the evaluation of long-term coastal lagoon ecosystem functioning and the trajectory of submerged macrophyte responses to disturbances, to facilitate the appropriate restoration of ecosystems. We used historical data for a two hundred-year period to assess changes in human activities on the watershed of the Biguglia lagoon. Macrophyte mapping (from 1970) and monitoring data for dynamics (from 1999) were used to investigate the trajectory of the community response. The changes observed in this watershed included a large number of hydrological developments affecting salinity and resulting in changes in macrophyte distribution. Nutrient inputs over the last 40 years have led to a shift in the aquatic vegetation from predominantly aquatic angiosperm community to macroalgae and phytoplankton in 2007 (dystrophic crisis). Changes in hydrological management and improvements in sewage treatment after 2007 led to a significant increase of aquatic angiosperms over a relatively short period of time (4–5 years), particularly for Ruppia cirrhosa and Stuckenia pectinata. There has been a significant resurgence of Najas marina, due to changes in salinity. The observed community shift suggests that Biguglia lagoon is resilient and that the transition may be reversible. The restored communities closely resemble those present before disturbance. These findings demonstrate the need to understand watershed exploitation and ecosystem variability in lagoon restoration.

Since resting cysts are a potential seeding source for blooms, the presence of these cysts in sediments is a marker of an established population for a number of harmful algal species. The spatial patterns of cyst density in relation to sediment characteristics and hydrodynamics are still largely misunderstood. This study investigated the spatial distribution of resting cysts belonging to the Alexandrium tamarense species complex (Dinophyceae) in sediments of a Mediterranean coastal lagoon (Thau Lagoon, France). This lagoon, hosting shellfish farming, is regularly impacted by toxic Alexandrium catenella blooms. The average cyst density across the whole lagoon was rather low

Abiotic and biotic variables of coastal lagoons are highly heterogeneous in both space and time, and this heterogeneity complicates the assessment of their ecological status. These variables are essential to the monitoring and preservation of these fragile ecotones and the resources and services they sustain. 2 An integrative approach for evaluating the ecological status of coastal lagoons, based on field investigations of the key parameters driving their functioning and a set of selected ecological indicators matching lagoon management information needs for societal benefits, is investigated. Consistency in lagoon status evaluation from multiple and different variables was estimated, through a case study comparing three adjacent yet contrasting French Mediterranean shallow water lagoons. 3 French Mediterranean shallow water lagoons are used to demonstrate the potential of such an approach and to underline the need for a multi-faceted framework, for correctly evaluating lagoon status, and underlining the need for high-frequency lagoon monitoring to avoid errors in status assessment and resulting management plans. 4 Based on the results, a continuous monitoring system is proposed that would record high frequency biotic and abiotic data in the lagoons. The use of such an ad hoc observatory system, based on appropriate diagnostic indicators and risk estimators would simplify interactions between scientists and managers and would improve the efficiency of their analyses. 5 A lagoon management plan based on a holistic approach is proposed to help scientists and local managers to reach a consensus about the set of ecological indicators to monitor in the lagoons needed to assess their 'global health' status in accordance with both conservation and/or societal needs.

We explored the role of natural and anthropogenic environmental perturbations in shaping the community structure and dynamics of pico- and nanophytoplankton in coastal waters. The distribution patterns of phycoerythrin-rich picocyanobacteria (PE-CYAN) and phycocyanin-rich picocyanobacteria (PC-CYAN), autotrophic picoeukaryotes (PEUK) and nanophytoplankton (NANO) were examined over a period of 3 yr in 24 Mediterranean coastal lagoons displaying wide trophic gradients (from 0.2 to 630 mu g chlorophyll a [chl a] l(-1)) and salinity gradients (from fresh to marine waters). In summer, picoplanktonic abundances reached 3 x 10(8) cells l(-1), 5 x 10(9) cells l(-1) and 6 x 10(10) cells l(-1) for PE-CYAN, PC-CYAN and PEUK, respectively. PE-CYAN and PC-CYAN showed opposing responses to environmental gradients, resulting in a restricted dominance of PE-CYAN in oligotrophic marine lagoons and a dominance of PC-CYAN in some eutrophic brackish lagoons. Most lagoons exhibited steady-state nutrient conditions, giving competitive advantages to small eukaryotic algae, even in eutrophic and hypertrophic waters. Among the picophytoplankton, picoeukaryotes (ca. 2 to 3 mu m) are the most competitive with increasing nutrient availability; in terms of abundance and biomass, their relative and absolute importance tended to increase with increasing total chl a biomass. Freshwater discharges resulted in large pulses of nutrient and more turbulent systems that altered the structure of the phytoplankton community and stimulated fast-growing NANO composed of phytoflagellates and diatoms (ca. 3 to 6 mu m, up to 1.6 x 10(9) cells l(-1)). Members of the microphytoplankton (ca. 20 to 200 mu m) were rarely observed in eutrophic and hypertrophic lagoons and were composed of harmful dinoflagellates in oligotrophic lagoons. These results show that anthropogenic and meteorological changes are highly influential on the composition and size structure of phytoplankton communities.

1. Transitional waters, described as critical transition zones because of their position at terrestrial, freshwater and marine interfaces, provide essential goods and services to the biosphere including human populations. These ecotones face increasing human influence mainly due to population density increase in coastal areas. 2. Transitional water bodies have, to date, received little attention in the development of ecological status indicators; this is a critical deficiency when trying to meet the Water Framework Directive objective of all significant water bodies achieving good ecological status by the year 2015. 3. In order to assess changes in transitional water communities many taxonomic-based indicators have already been proposed but there are a number of concerns for their use such as taxonomic classification difficulties, their unsuitability for multi-site comparisons and their inconsistent relationships with disturbance or stress. 4. Alternative methods based on body size, abundance distribution among functional groups, functional diversity and productivity descriptors are proposed. These methods offer the opportunity to compare sites with different taxonomic compositions and allow derivation of indicators related to ecological status of communities under scrutiny. 5. Finally, the suitability of these taxonomic-free descriptors to provide relevant information for each of the four main biotic compartments in coastal lagoons is discussed. The use of biomass distribution among functional groups for fish, benthos and macrophyte and to use body-size distribution for benthos and plankton is proposed. Copyright © 2006 John Wiley & Sons, Ltd.

Ensuring the sustainability of fish resources necessitates understanding their interaction with coastal habitats, which is becoming ever more challenging in the context of ever increasing anthropogenic pressures. The ability of coastal lagoons, exposed to major sources of disturbance, to provide resources and suitable habitats for growth and survival of juvenile fish is especially important. We analysed three lagoons with different ecological statuses and habitat quality on the basis of their eutrophication and ecotoxicity (Trix test) levels. Fish abundances were sampled using fishing and horizontal beaming acoustic surveys with the same protocols in the same year. The relative abundance of Anguilla anguilla, Dicentrarchus labrax or the Mugilidae group was not an indicator of habitat quality, whereas Atherina boyeri and Sparus aurata appeared to be more sensitive to habitat quality. Fish abundance was higher in the two lagoons with high eutrophication and ecotoxicity levels than in the less impacted lagoon, while fish sizes were significantly higher in the two most severely impacted lagoons. This leads us to suggest low habitat quality may increase fish growth rate (by the mean of a cascading effect), but may reduce lagoon juvenile abundance by increasing larval mortality. Such a hypothesis needs to be further validated using greater investigations which take into account more influences on fish growth and recruitment in such variable environments under complex multi-stressor conditions.

Full text : http://archimer.ifremer.fr/doc/00136/24775/22959.pdf (Version "auteur", 0.77 Mo); International audience; This 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.

Atmospheric concentrations and deposition fluxes of PCDD/F and PCB have been evaluated over a 1-year period in a Mediterranean coastal lagoon (Etang de Thau, France). Indicative PBDE air concentrations in the hot season are also reported in this work. Sigma 2,3,7,8-PCDD/Fs and Sigma 18PCBs (gas + particulate) air concentrations ranged from 67 to 1700 fg m(-3) and from 13 to 95 pg m(-3), respectively whereas Sigma 8PBDEs (gas + particulate) summer time levels varied from 158 to 230 pg m(-3). The PCDD/F and PCB atmospheric occurrence over Thau lagoon and subsequent inputs to the surface waters are determined by an assemble of factors, being the seasonality of atmospheric concentration, the air mass origin and meteorological conditions important drivers. Total (wet + dry) Sigma 2,3,7,8-PCDD/Fs and Sigma 18PCBs deposition fluxes to Thau Lagoon waters are 117 and 715 pg m(-2) d(-1), respectively.

International audience; The Thau lagoon, located in southern France, suffers episodically from anoxic crises locally known as 'malaigue'. Such crises mostly occur under warm conditions, low winds leading to a strong eutrophication of the lagoon. The development of a sulphur bacterium sometimes gives locally to the waters a 'milky turquoise' appearance and leads to shellfish mortality. One of the indicators of the eutrophication status of the lagoon can be surveyed by the chlorophyll product provided by remote sensing images such as Medium Resolution Imaging Spectrometer (MERIS). In this paper we compare chl2 (or algal2) estimations provided by MERIS level 2 products and the ground measurements of chlorophyll a concentrations in water and we propose a linear correction of the chl2 MERIS product. The corrected chl2 estimations obtained over four years are analysed to understand the seasonal evolution of the trophic status of the Thau lagoon. We also study the influence of the anoxic crises of summers 2003 and 2006 on the chl2 estimations and we find a strong correlation between chl2 and the oxygen percentage at 1 m depth (0.70 for measurements in summers 2003 and 2006).

Ce rapport présente les résultats de l’étude de dossier, de l’inspection du littoral et des campagnes de localisation des gisements de tellines réalisés dans le cadre de l’étude sanitaire de la zone de production n°34.09 «Bande littorale de Port Ambonne au feu ouest du Brise Lames extérieur du port des quilles», sous financement de la Direction Générale de l’Alimentation (DGAL), et à maîtrise d’ouvrage de la Direction Départementale des Territoires de la Mer (DDTM). Les principales sources potentielles de pollution de la zone de production n°34.09 semblent être, par ordre de criticité décroissant : le ruissellement pluvial de la ville de Sète, le ruissellement pluvial de Marseillan-Ambonne, le port de Marseillan-Ambonne, les installations en assainissement non-collectif d’Agde et de Sète, les rejets des stations d’épuration d’Agde et de Sète, les déversoirs d’orage de Marseillan-Ambonne, les campings du Lido et les oiseaux. Le croisement des informations collectées sur les sources de pollution, la localisation des gisements, la climatologie et la courantologie de la zone d’étude, a permis de définir la stratégie d’échantillonnage à mettre en œuvre au cours de l’étude de zone. Trois points de prélèvements de tellines devront être suivis dans le cadre de l’étude de zone, dans la mesure où la DDTM déciderait la poursuite de l’étude, malgré les faibles rendements de pêche de telline observés au cours de cette première partie d’étude.

En 2009, 24 classements sanitaires en A, 11 en B et 3 en C étaient définis par arrêtés préfectoraux dans les départements de l’Hérault et du Gard. Peu de données fiables sont disponibles sur la production de coquillages en Languedoc-Roussillon. Selon les informations récoltées auprès des organisations professionnelles et de la DDTM la production annuelle dans l’Hérault et le Gard se situeraient en 2009 entre 11 600 tonnes et 8 400 tonnes d’huîtres, autour de 85 tonnes de tellines, aucune donnée n’étant disponible pour les palourdes et les coquillages du groupe 1. En 2009, 20 points de prélèvements de coquillages filtreurs, répartis dans 11 zones de production ont été échantillonnés dans l’Hérault et le Gard. Les résultats acquis sur la période 2007-2008-2009 permettent d’estimer la qualité microbiologique selon les seuils microbiologiques définis par le règlement européen (CE) n°854/2004, modifié par le règlement (CE) 1021/2008, en B pour 8 zones, en C pour une zone, en D pour une zone et en A pour une zone. Ces estimations ne sont pas conformes aux classements sanitaires pour 4 des 11 zones suivies. En 2009, les teneurs en métaux réglementés suivis dans le cadre du réseau d'observation de la contamination chimique (ROCCH sanitaire), en 8 points de prélèvements représentatifs de ces zones de production, sont inférieures aux seuils fixés par le règlement modifié (CE) n°466/2001. En 2009, 33 alertes ont été déclenchées dans l’Hérault et le Gard, donnant lieu à quatre mesures de gestion des zones de production de coquillages par le Préfet de l’Hérault. Plusieurs Toxi-Infections Alimentaires Collectives (TIAC) impliquant les coquillages de la zone d’élevage de la lagune de Thau ont été déclarées par les services de l’Etat en février 2009

A cross-ecosystem comparison of data obtained from 20 French Mediterranean lagoons with contrasting eutrophication status provided the basis for investigating the variables that best predict chlorophyll a (Chl a) concentrations and nutrient limitation of phytoplankton biomass along a strong nutrient enrichment gradient. Summer concentrations of dissolved inorganic nitrogen (DIN) and phosphorus (DIP) comprised only a small fraction of total nitrogen (TN) and total phosphorus (TP). On the basis of inorganic nutrient concentrations, the most oligotrophic lagoons appeared to be phosphorus-limited, with a tendency towards the development of nitrogen limitation as eutrophication increased, as evidenced by decreasing DIN:DIP ratios. A weak but significantly positive relationship was found between dissolved silicate (DSi) and Chl a, reflecting DSi accumulation in the water column along the trophic state gradient and implying a progressive shift away from potential Si limitation of phytoplankton growth. Observed concentrations of Chl a were far better explained by TN and TP than by DIN and DIP concentrations, suggesting that a total nutrient based approach is likely to be the most appropriate for managing eutrophication in Mediterranean lagoons and other coastal waters. These results give credence to the idea that marine and freshwater environments respond in a similar fashion to nutrient enrichment., Une comparaison inter-sites des concentrations de nutriments et de chlorophylle a (Chl a) issues de 20 lagunes de Mediterranee francaise de degres divers d'eutrophisation a ete menee afin de rechercher la meilleure variable expliquant le niveau de Chl a et d'explorer la limitation de la production primaire par les nutriments au long d'un fort gradient d'enrichissement en azote et phosphore. En ete, l'azote et le phosphore inorganiques dissous (DIN et PID respectivement) constituaient une faible fraction des concentrations d'azote et de phosphore totaux (TN et TP respectivement). Sur la base des concentrations en nutriments inorganiques, la plupart des lagunes oligotrophes semblaient limitees par le phosphore avec une tendance vers des rapports DIN:DIP decroissants, et donc une limitation par l'azote, lorsque l'eutrophisation augmentait. Une correlation positive mais faible a aussi ete obtenue entre les concentrations de silicates (DSi) et Chl a, indiquant une accumulation de DSi dans la colonne d'eau et donc une diminution de la limitation de la croissance du phytoplancton par la silice au fur et a mesure que l'eutrophisation augmentait. Le fait que Chl a etait beaucoup mieux expliquee par TN et TP que par DIN et DIP suggere meme que l'approche limnologique basee sur l'ensemble des nutriments est vraisemblablement la meilleure pour gerer l'eutrophisation dans les lagunes mediterraneennes et dans d'autres ecosystemes marins cotiers. Ces constats renforcent l'idee que les ecosystemes marins et d'eau douce repondent de facon similaire a l'enrichissement en nutriments.

Le RSL véritable outil de veille et d’aide à la décision, produit chaque année un diagnostic des lagunes de la Région Languedoc-Roussillon vis-à-vis de l’eutrophisation.Il permet ainsi d’alimenter les réflexions dans le cadre des démarches de gestion concertée, d’orienter la mise en œuvre d’action et les travaux de restauration prioritaires.

In order to better understand environmental disturbances in the French coastal Mediterranean lagoons, we used an ecotoxicological approach based on the measurement of the toxicity of the sediments using oyster embryo bioassay that provides a basis for assessing the effects on the fauna of contaminants adsorbed on the sedimentary particles. The study covers all of the main lagoons of the French Mediterranean coasts of Languedoc Roussillon, Camargue, and Provence (Berre and Bolmon lagoons), where 188 stations were sampled. The toxicity tests provide evidence of variable levels of toxicity in sediments. Contaminated lagoons such as La peyrade, Le canet, and Ingrill and locally affected lagoons such as Bages-Sigean, Vaccares, Bolmon, and Berre have sampling stations with 100% of larval abnormalities during 24-h development. In all of the lagoons, the toxicity was mainly located close to local harbors and rivers. Salses Leucate (Languedoc roussillon) lagoon was found very clean, with no important toxicity. The results are discussed in terms of environmental disturbances of the coastal lagoons and with regard to the long-term monitoring of the impact of contaminants on the coastal environment.

Time series data have been examined in Thau lagoon (Southern France) from 1972 to 2006 for water temperature, salinity, nutrients and from 1987 to 2006 for phytoplankton. A first main trend identified is an increase in mean annual water temperature (1.5 degrees C over 33 years or 0.045 degrees C/year) that was not evenly distributed among seasons. The highest rate of increase was in the spring (+ 3.0 degrees C over 33 years), followed by summer (+ 2.0 degrees C and fall (+ 1.7 degrees C. In winter, no significant increase over the 33 year period could be found. A second clear trend is a large decrease in soluble reactive phosphorus (SRP) concentration over the same 33 year period (summer values decreased from 10 mu M to 1 mu M. while winter values decreased from 3 mu M to undetectable at present). Nitrate concentrations depended mainly on rainfall events and watershed runoff. Ammonium data were too fragmentary to be useful. N/P ratios expressed the traditional way of DIN/SRP cannot be used for phytoplankton that are not strict autotrophs. The recent and almost simultaneous appearance of both picocyanobacteria (mostly Synechococcus) and the toxic dinoflagellate Alexandrium catenella in Thau seem to be related to reduced nutrient loading and the increase in water temperature. A. catenella blooms occur either in the spring or the fall when water temperature is near 20 degrees C and remains so for several weeks with winds speeds below 2-3 m s(-1). Picocyanobacterial growth is stimulated by increased summer temperatures, and lowered SRP levels provide picocyanobacteria an ecological advantage over other phytoplankton classes, in particular diatoms such as Skeletonema costatum whose cell densities have decreased over the last 8 years in summer and fall, but not in winter. An hypothesis is presented according to which A. catenella is not stimulated by increased temperatures, but is able to use picocyanobacteria for growth, and this provides this organism an additional resource over other strictly autotrophic phytoplankton. On a more general level, our data do not support the hypothesis that increased nutrient loading leads to harmful blooms of dinoflagellates. Instead, a combination of habitat disturbance and species displacement seems to lead to such blooms. (C) 2008 Elsevier B.V. All rights reserved.

Ambient concentrations, congener patterns and multi-media distribution of PCDD/Fs and PCBs were determined in air, water, sediment and mussels in a semi-enclosed marine ecosystem (Thau lagoon, France). Sigma 2,3,7,8-PCDD/F and Sigma 7ICES PCB air concentrations (0.2-1.4 and 31-57 pg m(-3), respectively) were typical of rural areas. Concentrations in the water column were very low for PCDD/Fs (163-476 fg L-1) and low for PCBs (138-708 pg L-1). PCDD/F and PCB concentrations found in surface sediment (0.15-1.6 and 2.5-33 ng g(-1) d.w., respectively) and mussel (13-21 pg g(-1) d.w. and 10-39 ng g(-1) d.w., respectively) were medium levels. PCDD/F congener patterns observed in air, water particulate phase and sediments were similar suggesting direct coupling among these compartments and atmospheric inputs of PCDD/Fs into the lagoon. Conversely, for the same set of samples, similar patterns were not observed for PCBs in the mentioned compartments. (C) 2007 Elsevier Ltd. All rights reserved.

Ce rapport présente les résultats de l'étude de la zone de la «Bande littorale de l’est du port de Palavas au feu sud du Port de la Grande Motte», menée du 07/02/2006 au 29/01/2008 par le Laboratoire Environnement Ressources du Languedoc Roussillon de l'Ifremer de Sète, avec le concours du Comité Local des Pêches du Grau du Roi pour la réalisation des prélèvements de coquillages. Le traitement des données acquises permet d’estimer en B la qualité microbiologique de cette zone pour le groupe 2 selon les seuils microbiologiques définis par l’arrêté du 21 mai 1999 et par le règlement 854/2004iv. Les résultats des analyses chimiques sont compatibles avec cette estimation en B de la qualité. La surveillance régulière de la zone 34.33 «Bande littorale de l’est du port de Palavas au feu sud du Port de la Grange Motte», pour le groupe 2 est basée sur le point Le Grand Travers, il a été intégré au dispositif de surveillance REMI en février 2008.

A monitoring program with a weekly sampling frequency over a 15-month period indicates that urea concentrations above a certain threshold level may trigger the blooms of Alexandrium catenella in Thau lagoon. However, urea concentrations were also sometimes related to ammonium and dissolved organic nitrogen concentrations, indicating that the role of urea may not be a direct one. An original approach is used to assess the relative contribution of several nitrogen sources (nitrate, nitrite, ammonium, urea) to growth of A. catenella by comparing nitrogen uptake rates to nitrogen-based growth rates estimated from dilution experiments during four blooms over a 4-year period (2001-2004) in Thau lagoon. Nitrate and nitrite contributed 0.1-14% and 0.1-5% respectively of growth requirements. Ammonium and urea were the main N sources fueling growth of A. catenella (30-100% and 2-59%, respectively). Indirect estimates indicated that an unidentified N source could also contribute significantly to growth at specific times. Concerning ammonium and urea uptake kinetics, half-saturation constants varied between 0.2 and 20 mu gat NL-1 for ammonium and between 0.1 and 44 mu gat N L-1 over the 4-year period, indicating that A. catenella can have a competitive advantage over other members of the phytoplankton even under low concentrations of ammonium and urea. However, the observed large changes in ammonium and urea uptake kinetics on a short time scale (days) during blooms preclude more precise estimates of those contributions to growth and require further investigation. (C) 2007 Elsevier B.V. All rights reserved.

International audience; The consequences of the development of activities (tourism, fishing, aquaculture, urbanization, airport port operations, landfills, etc.) centered on regional ponds and / and lagoons in Languedoc Roussillon raise the problem of their management for local authorities ("decision-makers and managers ”). These environments are characterized by their high biological productivity which is favored by their location at the land (watershed) –sea interface, their shallow depth (less than 1 meter) and their connection to the sea by canals; they are often considered important "nursery" areas for many species of fish and some are classified as protected areas. The aim of this work is to propose in situ indicators of the state of pelagic ichthyological lagoon resources in order to be able to determine the impact of the watershed on the fish resource and to rank the habitats hierarchically in relation to their degree of eutrophication. Direct observations were carried out in situ during the State-Region XI Planning Contract (CNRS-UMII / IRD / CREOCAN). The results mainly relate to scientific fishing operations and acoustic experiments. The latter have implemented, in a fixed and horizontal position, two acoustic bases: a high resolution multi-beam Reson Seabat 6012 sonar (455 kHz) and a shared beam echo sounder Simrad EY 500 (70 kHz). The variations in the direction and amplitude of the current in the channels were measured at the same time as the observations of schools of fish by active acoustics. Environmental data were recorded throughout 1999 with regard to meteorological data and periodically with regard to the salinity and temperature of the ponds and the Mediterranean. The results obtained concern, for each pond, the descriptors, the current values, the diel flows per hour for isolated fish and structures of the "school of fish" type as well as the specific diversities and catches per unit of effort. The flows of pelagic fish as well as their acoustic characteristics: sonar dimensions (Lw and Cw, size of schools) and the reflectivity index (TS, of fish isolated with sounder) were compared by pond and by observation period. The ichthyological characteristics defined in the form of indicators were compared with the indicators of the level of eutrophication of the ponds obtained by the Lagoon monitoring network (RSL) whose very detailed data agree with our local observations (RedOx potential of the sediments, etc.) . The interest of the study lies in the coupling of the data obtained between the environment (watershed / lagoons) and the fish resource, which provide valuable indicators for better understanding and managing such complex systems. Fishing operations complement acoustic observations and improve biomass estimates made by echo integration as well as knowledge of the ecological functioning of lagoons. Our preliminary results indicate a weak influence of the level of eutrophication of ponds on the biological diversity of pelagic fish, but more marked on the presence of juveniles inversely proportional to the level of "eutrophication" of their habitat. The potential for application to other so-called "shallow" environments is manifold.; Les conséquences du développement des activités (tourisme, pêche, aquaculture, urbanisation, exploitation portuaire aéroportuaire, décharges etc..) centrées sur les étangs ou/et lagunes régionales en Languedoc Roussillon soulèvent le problème de leur gestion pour les autorités locales (« décideurs et gestionnaires »). Ces milieux sont caractérisés par leur forte productivité biologique qui est favorisée par leur situation à l’interface terre (bassin versant)–mer, leur faible profondeur (inférieure à 1 mètre) et leur connexion avec la mer par des canaux ; ils sont souvent considérés comme d’importantes zones de « nurseries » pour de nombreuses espèces de poissons et certains sont classés comme espaces protégés. Le but de ce travail est de proposer des indicateurs in situ de l’état des ressources pélagiques ichtyologiques lagunaires afin de pouvoir déterminer l’impact du bassin versant sur la ressource en poisson et de classer hiérarchiquement les habitats par rapport à leur degré d’eutrophisation. Des observations directes ont été réalisées in situ au cours du Contrat de Plan Etat-Région XI (CNRS-UMII/IRD/CREOCAN). Les résultats portent principalement sur des opérations de pêche scientifique et des expérimentations acoustiques. Ces dernières ont mis en oeuvre, en position fixe et horizontale, deux bases acoustiques : un sonar multi-faisceaux de haute résolution Reson Seabat 6012 (455 kHz) et un écho sondeur à faisceaux partagés Simrad EY 500 (70 kHz). Les variations de direction et d’amplitude du courant dans les canaux ont été mesurées en même temps que les observations des bancs de poisson par acoustique active. Les données environnementales ont été enregistrées tout au long de l’année 1999 pour ce qui concerne les données météorologiques et de manière périodique pour ce qui est de la salinité et de la température des étangs et de la Méditerranée. Les résultats obtenus concernent, pour chaque étang, les descripteurs, les valeurs de courants, les flux nycthéméraux par heure pour les poissons isolés et les structures du type « bancs de poissons » ainsi que les diversités spécifiques et les captures par unité d’effort. Les flux de poissons pélagiques ainsi que leurs caractéristiques acoustiques : dimensions sonar (Lw et Cw, taille des bancs) et l’index réflectivité (TS, de poisson isolé au sondeur) ont été comparés par étang et par période d’observation. Les caractéristiques ichtyologiques définies sous forme d’indicateurs ont été comparées aux indicateurs du niveau d’eutrophisation des étangs obtenus par le réseau de suivi Lagunaire (RSL) dont les données très détaillées concordent avec nos observations locales (potentiel RedOx des sédiments etc..). L’intérêt de l’étude réside dans le couplage des données obtenues entre le milieu (bassin versant/lagunes) et la ressource en poissons, qui fournissent de précieux indicateurs pour mieux comprendre et gérer de tels systèmes complexes. Les opérations de pêche complètent les observations acoustiques et permettent d’améliorer les estimations de biomasse faites par écho intégration ainsi que la connaissance du fonctionnement écologique des lagunes. Nos résultats préliminaires nous indiquent une influence faible du niveau d’eutrophisation des étangs sur la diversité biologique en poissons pélagiques, mais plus marquée sur la présence des juvéniles inversement proportionnelle au niveau de « l’eutrophisation » de leur habitat. Les potentialités d’application à d’autres milieux dits de « faible profondeur » sont multiples.

Ce rapport présente les résultats de l’étude de la zone « Etang d’Ingril » n° 34.16, menée de mars 2006 à août 2008 par l’Ifremer avec le concours du Comité Local des Pêches du Grau du Roi et le GIE des Vénériculteurs de Frontignan pour la réalisation des prélèvements de palourdes. La qualité microbiologique de cette zone est estimée en C la pour le groupe 2 selon les seuils microbiologiques définis par l’arrêté du 21 mai 1999 et par le règlement (CE) n° 854/2004. Sur les 110 échantillons prélevés au niveau des 4 points de suivi, répartis dans le Nord et le Sud en fonction des principales sources de pollution et des principaux gisements de palourdes, 12 (soit 10,9%) sont supérieurs au seuil de 4 600 E.coli/100 g de chair et de liquide intervalvaire (CLI) et aucun ne dépasse le seuil de 46 000 E.coli/100 g de CLI. Les deux points de prélèvement localisés dans le Nord de la lagune présentent des profils de contamination microbiologique d’origine fécale plus dégradés que ceux localisés dans Sud. A la demande de la Direction Inter Départementale des Affaires Maritimes de l’Hérault et du Gard, la qualité microbiologique a également été estimée pour les secteurs Nord et Sud de la zone n°34.16, localisés de part et d’autre du canal du Rhône à Sète. La qualité microbiologique estimée du secteur Ingril Sud est B car 5,3% des résultats dépassent le seuil de 4 600 E.coli/100 g. Dans le Nord, 17% des résultats sont supérieurs à ce seuil ce qui oriente l’estimation de la qualité microbiologique en C. Les résultats des analyses de métaux sont largement inférieurs aux critères chimiques fixés par le règlement modifié (CE) n° 1881/2006, et sont compatibles avec un classement en A, B ou C de la zone de l’étang d’Ingril.

Since recent decades, nutrient-related eutrophication, originating from agricultural use of fertilizer and population enhancement, can be considered worldwide as the main disturbance for coastal lagoons. Since coastal lagoons are very shallow and enclosed, their functioning is tightly linked to meteorological conditions. The aim of this study is to compare different rainfall levels and eutrophication response on coastal lagoons of the Languedoc-Roussillon (Western Mediterranean coast), subject to different nutrient loads from their watershed, in order to check the possibility to distinguish the effects of watershed management or rainfall conditions on water quality (waste water treatment plant improvement, decrease of fertilizer spreading).

Après une présentation des caractéristiques et des sources de pollution microbiologiques des zones de production n°11.04 « Etang de Mateille » et n°11.03 « Etang des Ayguades », ce rapport présente la méthodologie employée dans le cadre de l’étude de la qualité microbiologique et chimique ces zones (indicateurs de contamination et méthodes d’analyses, critères d’évaluation des niveaux de contamination, stratégie d’échantillonnage), ainsi que les résultats obtenus. Le traitement des données acquises de mars 2008 à mars 2009 avec le concours de la société P2A Développement pour la réalisation des prélèvements de palourdes, permet de proposer de nouvelles délimitations géographiques des zones de production, en prenant en compte la localisation de la ressource et des principales sources de pollution, et d’estimer la qualité microbiologique et chimique de ces zones pour le groupe 2 selon les seuils microbiologiques définis par l’arrêté du 21 mai 1999 et par le règlement européen (CE) n°854/2004.

This survey was conducted in July 2013 within the AMBIO project in new Caledonia. The survey aims at assessing fish communities and associated habitats in the Merlet Reserve, part of the World Heritage. 144 underwater unbaited rotating video observations, using the STAVIRO (141 stations) and the MICADO (3 stations) technique were validated., Cette campagne a été réalisée en juillet 2013 dans le cadre du projet AMBIO en Nouvelle-Calédonie. L’objectif est d’évaluer l’état de santé des communautés de poissons et habitats associés de la réserve de Merlet, une zone inscrite au Patrimoine Mondial de l’Humanité. A cet effet, 141 stations STAVIRO (STAtion VIdéo ROtatives) et 3 stations MICADO ont été validées.

Ce rapport présente les résultats de l'étude de la zone de production n°34.22 « Etang de Vic » initiée à l’automne 2008 par le Laboratoire Environnement Ressources de l’Ifremer de Sète suite à une demande de la Direction Interdépartementale des Affaires Maritimes de Sète. Quatre points de suivi de la qualité microbiologique des palourdes ont été échantillonnés entre le 16/09/2008 et le 10/11/2009 dans le cadre de cette étude. Les prélèvements ont été effectués par la société P2A Développement sur les gisements naturels en septembre et octobre 2008, puis dès novembre 2008 à partir de palourdes placées au minimum 15 jours dans des casiers, en raison de la raréfaction de la ressource. Au total, 96 prélèvements de palourdes ont été réalisés au niveau des 4 points de suivi de la zone de production. Les résultats permettent d’estimer en B la qualité microbiologique de la zone de production « Etang de Vic », pour le groupe 2, selon les critères du règlement européen (CE) 854/2004. Les résultats des analyses de métaux sont inférieurs aux critères chimiques fixés par le règlement modifié (CE) n° 1881/2006, et sont compatibles avec un classement en A, B ou C de la zone. Suite au classement sanitaire de cette zone pour le groupe 2, le point de prélèvement « Etang de Vic – Diamantis » sera échantillonné mensuellement dans le cadre de la surveillance régulière REMI, sous réserve de la présence de palourdes en quantité suffisante.

The poster presents the approach that led to the construction of a network of cooperation between managers and scientists for coastal lagoon management in the region of Languedoc-Roussillon, its architecture and modus operandi, its achievements and developments over time. At the end of the ninety’s, eutrophication and lack of knowledge were identified as issues to enhance the management of coastal lagoons on the Mediterranean coast of France. In 2000, in the region of Languedoc-Roussillon, scientists (Ifremer) and institutional managers (Regional Council of Languedoc-Roussillon and Water Agency Rhône-Méditerranée & Corse) joined their forces in building a network to address this need. The core of this network consists of an operational tool for the diagnosis of eutrophication based on a battery of indicators within several ecological compartments of coastal lagoons (water column, phytoplankton, macrophytes, sediments). This tool routinely is operated at a regular time according to ecological compartments. The innovative aspect of this network was its management support component. The aim of the network is not only to supply with informations about the eutrophication state of the lagoons, but also to provide to local management structures support to their operational management and development. This support takes a variety of forms: studies on specific site on various issues, model application to test management scenario, dissemination of results to various audiences. Over the years, the structure and modus operandi of the network has evolved, especially by increasing the involvement of local coastal lagoon managers. After nearly 10 years of operation, it appears that cooperation between science and management is possible and potentially fruitful for the conservation of coastal lagoons. However, its success is subject to the establishment of a perennial frame such as the Coastal Lagoon Monitoring Network of Languedoc-Roussillon, a major effort in dissemination at different levels and obviously, the whole requires perennial significant financial resources., Le poster présente la démarche qui a conduit à la construction d’un réseau de coopération entre gestionnaires et scientifiques pour la gestion des lagunes côtières de la Région du Languedoc-Roussillon, son architecture et son mode de fonctionnement, les résultats acquis et son évolution au cours du temps. A la fin des années 90, l’eutrophisation et le déficit de connaissances sur le fonctionnement des écosystème furent identifiés comme des problématiques majeures en vue d’une amélioration de la gestion des lagunes côtières sur la façade méditerranéenne française. En 2000, au niveau de la Région du Languedoc-Roussillon, scientifiques (Ifremer) et gestionnaires institutionnels (Conseil régional du Languedoc-Roussillon et Agence de l’Eau Rhône-Méditerranée & Corse, Cépralmar) se sont associés pour construire un réseau (le RSL) afin de pallier à ce besoin. Le cœur de ce réseau est constitué d’un outil opérationnel de diagnostic de l’eutrophisation basé sur une batterie d’indicateurs de l’état de différents compartiments des lagunes côtières (colonne d’eau, phytoplancton, macrophytes, sédiments), outil opéré en routine à pas de temps régulier, mais différent selon les compartiments. Outre l’importante part liée à la communication, l’aspect novateur de ce réseau est sa composante d’aide à la gestion. Le but du réseau n'est pas seulement de donner une indication sur le niveau d'eutrophisation des lagunes, mais également d'apporter aux structures de gestion des étangs côtiers une aide opérationnelle dans la gestion et l'aménagement des sites lagunaires dont elles ont la charge. Cette aide à la gestion revêt plusieurs formes : études spécifiques à un site sur diverses thématiques, application de modèles pour test de scenarii de gestion, diffusion des résultats vers divers publics. Au cours des années, la structure et le mode de fonctionnement du réseau a évolué avec notamment une implication de plus en plus importante des gestionnaires et usagers locaux. Après presque 10 ans de fonctionnement, constat est fait que la coopération entre science et gestion est possible et potentiellement fructueuse pour la préservation des lagunes côtières. Néanmoins, sa réussite est assujettie à la mise en place d’un cadre pérenne comme le Réseau de Suivi Lagunaire, d’un effort conséquent de mise à disposition de l’information à différents niveaux, l’ensemble nécessitant évidemment des moyens financiers importants.

Guide de reconnaissance et de suivi des principales espèces de macrophytes dans les lagunes du Languedoc-Roussillon. Les lagunes du Languedoc-Roussillon sont étudiées depuis plusieurs années par le laboratoire Ifremer de Sète dans le cadre du RSL (Réseau de Suivi Lagunaire; http://rsl.cepralmar.com). Plusieurs compartiments (chimique et biologique) sont suivis pour étudier la principale pression qui s’exerce sur les lagunes : l’eutrophisation. Les peuplements de macrophytes présents dans les lagunes sont un bon indicateur de la qualité du milieu vis à vis de l’eutrophisation. Une méthode de suivi par les macrophytes est développée, qui nécessite la reconnaissance des espèces. Le guide de reconnaissance des macrophytes, destiné aux techniciens et aux gestionnaires des lagunes, a pour vocation d’être un support d’aide à la reconnaissance des espèces. Il s’inscrit dans une série de 3 guides (avec la note technique sur les flux d’azote et de phosphore en sortie de station d’épuration et le guide eutrophisation) réalisés pour valoriser les connaissances acquises dans le cadre des suivis du RSL. Le guide comporte deux parties : • Un chapitre de connaissance générale sur les macrophytes, leur biologie, leur écologie et les différentes méthodes de suivi des macrophytes. • 41 fiches de description des espèces de macrophytes parmi les plus fréquentes dans les lagunes. Les fiches de description des espèces sont illustrées de photos sous-marines, de photos de détails illustrant les éléments importants et de photos microscope quand cela est nécessaire à la reconnaissance.

Ce rapport présente les résultats de l'étude de la qualité microbiologique et chimique de la zone n°34.02 "Bande littorale de l'embouchure de l'Aude au Grau d'Agde"menée par l'Ifremer. Les prélèvements de tellines ont été réalisés entre le 06/02/2006 au 06/11/2007 avec le concours du Comité Local des Pêches de Valras. Les résultats permettent d’estimer en B la qualité microbiologique de cette zone pour le groupe 2 selon les seuils microbiologiques définis par l’arrêté du 21 mai 1999 et par le règlement 854/2004ii. Les résultats des analyses chimiques sont compatibles avec cette estimation en B de la qualité.

L'aquaculture est une activité importante du paysage économique de la Nouvelle-Calédonie., La crevette Bleue du Pacifique, Litopenaeus stylirostris est aujourd’hui l’espèce cible, élevée en semi-intensif, dans des bassins de terre de 4 à 10 hectares. Une coloration orange prononcée au niveau des branchies, comparable à celle observée suite à un stress hypoxique alors qu’aucun déficit en oxygène n’est constaté, est apparue récemment engendrant une décote du produit à la vente et donc un risque économique supplémentaire pour cette filière déjà fragilisée par des mortalités à vibrioses. Le phénomène se déclare à un poids moyen des animaux compris entre 10 et 18 g pour une durée moyenne d’élevage de 70 jours. L'intensité de la couleur évolue avec le stade de mue, les animaux au stade de pré-mue étant les plus touchés. Cette coloration disparaît avec la mue pour réapparaître au cycle suivant. Différentes techniques ont montré qu'elle était due à un dépôt d'oxyde de fer à la surface des tissus. Une micro-analyse par MEB montre un taux de fer dissous jusqu’à dix fois supérieur dans les branchies orange par rapport aux branchies non colorées ainsi qu'une répartition non homogène de ce métal. Par ailleurs une colonisation de cette surface branchiale par des bactéries est visible indiquant une implication potentielle de ces microorganismes dans le processus de précipitation du fer et donc dans l'apparition de cette coloration. De très fortes concentrations en fer dissous, jusqu'à 70 µM, ont été mesurées dans les eaux interstitielles des sédiments suggérant une origine environnementale à ce phénomène. Les prochains travaux devraient se focaliser sur (1) les conditions de milieu favorables à la production de fer dissous dans les sédiments, (2) les mécanismes impliqués dans sa précipitation à la surface des branchies et (3) les conséquences de ce dépôt sur la physiologie de l'animal.

1 - In the Thau lagoon (Southern Mediterranean Coast) the main anthropogenic pressure is represented by the urban development in the watershed, whilst oyster and mussel farming represents one of the main economical activities in the region. 2 - During the last decade, the increasing organic loads from watershed and urban settlements in the lagoon surroundings have caused a diffuse contamination by faecal bacteria. Also toxic algal blooms have been occurring, impairing water quality with major impacts on shellfish farming, fishery and bathing. 3 - In this study, indicators and scenarios identified for the lagoon have been integrated in a Decision Support System (DSS) to evaluate the best solutions for reducing pressures and improving both water quality and ecosystem status. 4 - The watershed has been analysed with reference to indicators of pollution sources and transfer rates to the lagoon. In parallel, socio-economic indicators and descriptors of urban growth and development have been assessed. Numerical models have been run in order to simulate the lagoon hydrodynamics in relation to both meteorological factors and watershed runoff. The impact of faecal bacteria contamination has been evaluated in terms of economical losses and social conflicts, arising from the restriction of shellfish farming and marketing during contamination events. Finally, the DSS prototype has been applied to the lagoon in support to management and future planning.

The Mediterranean benthic network proposes an integrated approach in term of scientific research and monitoring networks dealing with benthic biocenosis in the Mediterranean Sea (French part) ; it gives a state of the art as well as future needs, regarding regulatory aspects and data storage., L’avant projet sommaire du REBENT Méditerranée propose une approche intégrée des recherches et surveillances portant sur les biocénoses benthiques en Méditerranée ; il dresse un état de l’art des connaissances en la matière ainsi que des besoins futurs, en ciblant sur l’écoute de la demande sociétale et des cadres de gestion, ainsi que la bancarisation des données

Expertise 22-029 relative à l’effondrement du stock de palourdes européennes en lagune de Thau.

Ce séminaire de réflexion, souhaité et organisé conjointement par la province Nord et l’IRD, en association avec l’ensemble des organismes de recherche scientifique présents en Nouvelle-Calédonie, avait pour objectif à la fois de : • dresser et présenter un bilan des recherches scientifiques conduites par les différents organismes de recherche en province Nord, mais également de • poser les bases prospectives d’une recherche scientifique qui, dans le futur, réponde au mieux aux attentes et besoins exprimés par la province Nord. Deux questions générales et transversales ont donc sous-tendu, du 19 au 21 juin 2013, les réflexions et travaux des trois journées d’échanges et de discussions : • Quelles recherches scientifiques développer pour venir en appui de l’exercice des compétences publiques provinciales en province Nord ? • Comment organiser ou réorganiser dans le futur les activités scientifiques pour répondre à la volonté politique exprimée, que soit progressivement mis en œuvre un rééquilibrage de l’effort scientifique vers la province Nord ? Après deux jours d'exposés, la troisième journée a été construite autour d’un ensemble d’ateliers thématiques destinés à jeter les bases de réflexions scientifiques prospectives (évolutions possibles, thématiques négligées, domaines scientifiques à privilégier, moyens nécessaires, verrous à lever, etc.). Cette fiche de synthèse restitue les discussions menées au cours de l'atelier n°7.