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This datasheet on Magallana gigas covers Identity, Overview, Associated Diseases, Pests or Pathogens, Distribution, Dispersal, Biology & Ecology, Environmental Requirements, Natural Enemies, Impacts, Uses, Management, Genetics and Breeding, Economics, Further Information.

The threat posed by invasive non-native species worldwide requires a global approach to identify which introduced species are likely to pose an elevated risk of impact to native species and ecosystems. To inform policy, stakeholders and management decisions on global threats to aquatic ecosystems, 195 assessors representing 120 risk assessment areas across all six inhabited continents screened 819 non-native species from 15 groups of aquatic organisms (freshwater, brackish, marine plants and animals) using the Aquatic Species Invasiveness Screening Kit. This multi-lingual decision-support tool for the risk screening of aquatic organisms provides assessors with risk scores for a species under current and future climate change conditions that, following a statistically based calibration, permits the accurate classification of species into high-, medium-and low-risk categories under current and predicted climate conditions. The 1730 screenings undertaken encompassed wide geographical areas (regions, political entities, parts thereof, water bodies, river basins, lake drainage basins, and marine regions), which permitted thresholds to be identified for almost all aquatic organismal groups screened as well as for tropical, temperate and continental climate classes, and for tropical and temperate marine ecoregions. In total, 33 species were identified as posing a 'very high risk' of being or becoming invasive, and the scores of several of these species under current climate increased under future climate conditions, primarily due to their wide thermal tolerances. The risk thresholds determined for taxonomic groups and climate zones provide a basis against which area-specific or climate-based calibrated thresholds may be interpreted. In turn, the risk rankings help decision-makers identify which species require an immediate 'rapid' management action (e.g. eradication, control) to avoid or mitigate adverse impacts, which require a full risk assessment, and which are to be restricted or banned with regard to importation and/or sale as ornamental or aquarium/fishery enhancement. (c) 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/)., Cefas Science Excellence fund; [TKP2020-NKA-16], This study is dedicated to our co-author, the late Prof. Olaf Weyl, whose sudden passing during field work in November 2020 was received by us with great sadness. This study represents a contribution to the term of reference 'd' (Advance knowledge base to further develop indicators to evaluate the status and impact of non-indigenous species in marine environments) of the ICES working group on Introductions and Transfers of Marine Organisms. The participation of GHC was supported by the Cefas Science Excellence fund. AW and AF were supported by TKP2020-NKA-16 project.

In the context of global change, increasing mariculture production has raised particular concerns regarding its environmental impact and sustainability. Molluscs and particularly blue mussel account for a significant part of this total production. Although blue mussels are considered to be pretty resilient to environmental disturbances, we report in this study an unprecedented mussel mortality event that occurred during the winter of 2014 in the Breton Sound. 9000 metric tonnes of mussels were lost and mortality rates up to 100% were recorded at some farming areas. Through a coupling approach, the present work aims to better understand the potential environmental drivers associated with those mortalities. Firstly, we analysed long-term in situ and satellite data from environmental monitoring networks (available since 1998) to characterize the variability of seawater masses of the sound during the winter of 2014. Secondly, we used modelling simulations to study the possible relationship between seawater hydrodynamics and observed spatio-temporal patterns of mussel mortalities. From January to April 2014 at the long-line culture site where mortalities started, seawater temperatures ranged from 8.3 to 13.3 °C (10.2 ± 0.8 °C). Salinity and turbidity values showed successive and short drops (below 16; 29.3 ± 2.3) and numerous peaks (above 70 NTU; 17.4 ± 13.4 NTU) respectively. Winter conditions of 2014 were encountered along the entire French Atlantic coastline and linked to the sixth highest positive North Atlantic Oscillation (NAO +) index recorded since 1865. These particular environmental variations characterized the winter of 2014 but also others whereas no comparable mussel mortality rates were reported. Exact causes of the 2014 mortality event are still unknown but we showed these environmental variations could not alone be responsible. These have likely affected the sensitivity of the blue mussel populations that were already weakened by early spawning. Meanwhile, these may have facilitated the apparition of a pathogenic strain of Vibrio splendidus isolated on moribund mussels at that time. Our modelling simulations suggested that this pathogenic strain could spread through hydrodynamic patterns and drive the observed mussel mortalities. If this pathogenic strain recurs in future years, particularly with the added stress associated with climate change, mussel mass mortality events may exceed the resilience of this species.

La dynamique des masses d'eaux et les flux de transit semble favoriser un comblement et/ou des limitations de renouvellement d'eau mettant en péril la durabilité de l’environnement de cette lagune Miquelonnaise. La Préfecture de Saint Pierre et Miquelon et la DTAM, en soutien à la gestion durable de cet environnement, ont sollicité l’Ifremer pour l’évaluation des flux d’alimentation de cette lagune. Une mission sur place a été réalisée en juin 2016 afin de coordonner les actions et effectuer les mesures préliminaires portant sur les jaugeages, la bathymétrie du chenal et la courantométrie horizontale. Ces données ont ensuite été complétées par une acquisition continue des vitesses de courant, avec des données disponibles du 2 juin au 15 novembre 2016, puis du 24 janvier au 29 novembre 2017. L’investissement des équipes DTAM a permis le redéploiement de l’appareil dans des conditions relativement extrêmes. Des levés bathymétriques ont été réalisés également par les équipes DTAM ; ils ont été effectués d’octobre 2017 à aout 2018 suite à des problèmes techniques et aux aléas météorologiques. Après traitement de ces mesures, un modèle bathymétrique a été établi. Il a permis les évaluations de flux et de renouvellements des masses d’eaux de la lagune et l’implémentation d’un modèle hydrodynamique MARS3D. Ce rapport présente les données acquises, les traitements réalisés et les résultats obtenus. Ces derniers montrent des vitesses maximales enregistrées par l’ADCP (VDOP) de 2,02m/s et 2,32m/s, en moyenne sur la colonne d’eau en flot et en jusant respectivement. Les flux sortants de la lagune sont beaucoup plus importants que ceux qui entrent par le goulet (5,7 106 Vs 1,4 106 m3) ; ils engendrent des renouvellements moyens de 67% du volume total de la lagune, dont seulement 13 % sont issus des entrées par le chenal. Ces capacités de renouvellement très élevées minimisent fortement les risques de contamination microbienne comme suggérés dans le contexte de cette étude.

Environmental changes due to non-native species introductions and translocations are a global concern. Whilst understanding the causes of bioinvasions is important, there is need for decision-support tools that facilitate effective communication of the potential risks of invasive non-native species to stakeholders. Decision-support tools have been developed mostly in English language only, which increases linguistic uncertainty associated with risk assessments undertaken by assessors not of English mother tongue and who need to communicate outcomes to local stakeholders. To reduce language-based uncertainty, the ‘ecology-of-language’ paradigm was applied when developing the Aquatic Species Invasiveness Screening Kit (AS-ISK), a decision-support tool that offers 32 languages in which to carry out screenings and communicate outcomes to stakeholders. Topics discussed include uncertainty related to language-specific issues encountered during the AS-ISK translation and the potential benefits of a multilingual decision-support tool for reducing linguistic uncertainty and enhancing communication between scientists, environmental managers, and policy and decision makers.

La dynamique des masses d'eau et les flux de transit semblent favoriser un comblement et/ou des limitations de renouvellement d'eau mettant en péril la durabilité de l’environnement de cette lagune Miquelonnaise. La Préfecture de Saint Pierre et Miquelon et la DTAM, en soutien à la gestion durable de cet environnement, ont sollicité l’Ifremer pour l’évaluation des flux d’alimentation de cette lagune. Une mission sur place a été réalisée en juin 2016, pour coordonner les actions et effectuer un certain nombre de mesures préliminaires (jaugeages et bathymétrie du chenal, courantométrie horizontale). Ces données sont complétées par une acquisition continue des vitesses de courant, avec des données disponibles à ce jour du 2 juin au 15 novembre 2016. L’investissement des équipes DTAM a permis le redéploiement de l’appareil dans des conditions relativement extrêmes. Toujours opérationnel, il doit effectuer des mesures jusqu’à l’été 2017. En l’absence des levés bathymétriques suite à des problèmes techniques, les évaluations de flux et de renouvellements, qui en dépendent, ne seront réalisées que courant 2017. Ce rapport présente néanmoins les données et les premiers traitements obtenus montrant des vitesses maximales enregistrées par l’ADCP (VDOP) de 2,02m/s et 2,32m/s en flot et en jusant respectivement, en moyenne sur la colonne d’eau.

This study aims to assess the hydrological fluxes between the ‘Grand Etang’ of Miquelon and the oceanic part. Bathymetric surveys and Doppler current meter data acquisitions were carried out from August 14th, to November 5th, 2014 and from April 1st, to end of July 2015 to allow the following estimates : Total area (227 Ha) and characteristics volumes (total : 6,7 106 m3; oscillating 2,8 106 m3 (40 %); half-tide 5,2 106 m3) Velocity Index of channel to evaluate the average current speed at cross-section channel Fluxes, on flood and ebb tide respectively : Instantaneous flow: maxima at 94,2 et 65 m3/s mean 37.2 et 24.5 m3/s. in 2014 and maxima 85,03 et 73,62 m3/s mean 26,22 et 28,20 m3/s in 2015. Circulating fluxes by tide : maxima 1,06 and 1,09 106 m3, mean 0,66 and 0,71 106 m3 in 2014 maxima 0,93 and 1,13 106 m3, mean 0,44 à 0,75 106 m3 in 2015 Renewal rate per tide is decreasing: the main channel providing less inputs from ocean waters (from 13 to 8%). This is balanced by water inputs probably dripping under the sandbank (from 1 to 22%). They seemed to be compatible with a sustainable aquaculture activity. Meteorology has an effect by the way of atmospheric pressure (negatively correlated to flood fluxes) and by wind effect (negatively correlated in 2014, and less in 2015, more on ebb fluxes). Tidal asymetry duration was reported: flood time was lower than the ebb one (4,9 h. vs 7,4 h.), which results in outflow fluxes significantly greater than inflow through the channel. Hypothesis of secondary inflow by percolation from ocean is formulated. The coastal channel seems to be in a filling phase. Grand Etang’s renewal is more and more carried out by another origin, maybe with a filtration effect, not favorable to filter feeders. Hydrodynamic modelling has been carried out, facilitating the renewal time estimates (about one day) and flushing time from 1 to 7 days., Le programme vise à évaluer les flux hydrologiques entre le Grand Etang de Miquelon et l'océan, en soutien à la décision de politique publique. Il a débuté fin 2013 et se termine début 2016. Au niveau opérationnel, des levés bathymétriques (DTAM 2013 & 2014), des campagnes de courantométrie (2014 & 2015) et leurs traitements ont permis d’implémenter un modèle hydrodynamique. Les principaux résultats obtenus sur les trois années sont les suivants : L'évaluation des surfaces (227 Ha) et volumes caractéristiques (total : 6,74 10(6)m(3), oscillant 2,9 10(6)m(3) (43 %) mi-marée 5,2 10(6)m(3)) L'estimation d'un indice de vélocité du chenal pour l'évaluation de la vitesse moyenne des courants L'évaluation des flux, en flot et jusant respectivement, soit : - débits instantanés : maxima à 94,2 et 65 m(3)/s moyens 37,2 et 24,5 m(3)/s. en 2014 et 85,03 et 73,62 m(3)/s et des moyennes de 26,22 et 28,20 m(3)/s en 2015. - flux circulants par marée : maxima à 1,06 et 1,09 10(6)m(3), moyens 0,66 et 0,71 10(6) m(3) en 2014 maxima de 0,93 et 1,13 106m3, moyens 0,44 à 0,75 10(6)m(3) en 2015 Les renouvellements sont en évolution. En effet, le goulet d’alimentation amenant de moins en moins d’eau de l’océan (de 13 à 8%), est probablement compensé par une source de percolation sous le cordon dunaire en augmentation (de 1 à 22%). Ils restent compatibles avec une exploitation aquacole raisonnée. La météorologie exerce un effet sur ces volumes du fait de la pression atmosphérique (corrélée négativement aux flux de flot), de la force et direction du vent (corrélées négativement en 2014, et de moindre façon en 2015, et surtout aux flux de jusant). Les deux saisons analysées étant relativement similaires du point de vue des vents, les effets sont plus délicats à faire ressortir. Le constat d'asymétrie du temps de marée : le temps de flot est inférieur à celui de jusant (4,9 h. vs 7,4 h), avec des temps de flux sortants bien supérieurs à ceux entrants par le chenal. Le goulet semble en phase de comblement. Son alimentation paraît de plus en plus assurée par des eaux de percolation (donc filtrée), dont la qualité est moins favorable aux animaux filtreurs. La modélisation permet l’évaluation d’indices hydrodynamiques de temps de renouvellement (de l’ordre de la journée) et de temps de résidence (de 1 à 7 jours du Nord au Sud).

Developed for carrying out risk assessments under the European Commission (EC) Council Regulation No 708/2007 concerning the use of alien and locally absent species in aquaculture (ASR), the European Non-native Species in Aquaculture Risk Assessment Scheme (ENSARS) is briefly summarised, and the ‘Organism’ module is applied to the 24 species listed in ASR's Annex IV. Four other ENSARS modules (Infectious Agent, Facility, Pathway, and Socio-economic) were used to assess two case study species (European catfish Silurus glanis L. and red swamp crayfish Procambarus clarkii Girard). No Annex IV species was categorised as low risk, 10 as moderately low risk, 12 as medium risk, two as moderately high risk and none as high risk. The results are discussed and recommendations are made on further development of the scheme as well as the need to have multiple assessors of multidisciplinary expertise from the Member States concerned carry out the assessments using an approach similar to that carried out by EU Reference Laboratory proficiency tests.

0000-0001-8628-0514 WOS: 000422633100004 Electronic decision-support tools are now an essential component of government strategies to battle non-native species, with taxon-specific, paper-based risk analysis schemes often being replaced by taxon-generic tools. This study reports on the development of a decision-support tool for aquatic species, the Aquatic Species Invasiveness Screening Kit (AS-ISK), which replaces five taxon-specific toolkits for amphibians, freshwater and marine fish and invertebrates (FISK, MFISK, FI-ISK, MI-ISK, Amph-ISK). Adapted from Pheloung et al.'s Weed Risk Assessment (WRA), the "-ISK" toolkits were also "self-automated workbooks" in Excel (R) VisualBasic (R) architecture of the 'WRA. In creating AS-ISK, we incorporated the conceptual approach (questions and guidance) of the generic risk screening module of the European Non-native Species in Aquaculture Risk Analysis Scheme (ENSARS) into a single "turnkey application" that was based on the Excel (R) VisualBasic (R) architecture used by the WRA and its "-ISK" derivatives. Applicable to virtually all climatic zones and all aquatic plants and animals regardless of ecosystem (marine, fresh, brackish water), AS-ISK comprises 49 basic questions on the taxon's biogeographical and historical traits and its biological and ecological interactions. In compliance with the "minimum requirements" for use with the new EU Regulation on invasive alien species of EU concern, AS-ISK includes a preamble of background information on the species as well as questions on its potential socio-economic impacts and those on ecosystem services, and an additional section (six questions) for the assessor to predict how forecasted changes in climate are likely to influence the risks of introduction, establishment, dispersal and impact of a species. Following a concise but detailed description of AS-ISK, an example assessment of the Manila clam Ruditapes philippinarum is provided, with the French northern coastline as the risk assessment area, to demonstrate use of this decision-support tool. AS-ISK is available for free download at: http://www.cefas.co.uk/nns/tools/. UK Department of Environment, Food and Rural AffairsDepartment for Environment, Food & Rural Affairs (DEFRA); Cefas Seedcorn grant [DP372]; Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [2221]; Department of Science Fellowships and Grant Programmes (BIDEB) This work was funded initially and in large part by the UK Department of Environment, Food and Rural Affairs and a Cefas Seedcorn grant (DP372). Further contributions by LV were through a 2221 Fellowship Programme grant from the Scientific and Technological Research Council of Turkey (TUBITAK) and the Department of Science Fellowships and Grant Programmes (BIDEB). We thank E. Tricarico for providing assisting with the Italian language component of AS-ISK, and anonymous reviewers for comments to an earlier version of the manuscript.

Many studies based on bioenergetics growth models have investigated the effects of environmental factors on oyster (Crassostrea gigas) growth and physiology. However, most of these models are site-specific and cannot be app lied to other culture sites without the re-estimation of parameters or re-formulation of some processes. We aimed to develop a gen eric growth model suitable for application in contrasting environments, with a constant set of parameters. We tested the oyster-DEB model (Bourles et al. 2009) for the stimulation of C. gigas growth in different cohorts (spats and adults) at major shellfish culture sites in France, in several years: Arcachon (1993-1994); Marennes-Oleron (2007); Quiberon (1999, 2000, 2001); Rade de B rest (2008); Baie du Mont-Saint-Michel (2003); Baie-des-Veys (2002). These different ecosystems offer a w ide range of values for the two forcing variables of the model: water temperature (range: 6-24 °C) and phytoplankton concentration (annual average: 110-700 x 10 3 cell.l -1 ). The validation data (dry flesh mass of C. gigas) were obtained from various growth surveys carried out by IFREMER. The oyster-DEB model simulated the oyster growth dynamics of both spat and adult stages of C. gigas accurately over time at the various culture sites. The model captures: i) the active spring growth; ii) the timing and amplitude of spawning events; and iii) the lean periods (i.e. loss of dry flesh mass) in autumn and winter. The half-saturation coefficient Xk is the only model parameter that varied between sites and years. This environment-specific coefficient reflects variability in the food of the oysters: quantitative and qualitative effects of the inorganic material and of the phytoplankton species on the feeding response of C. gigas. With a single set of parameters (other than for Xk), this is thus the first bio-energetic growth model for C. gigas robust enough and of a sufficiently generic nature for the accurate simulation of oyster growth in different Atlantic ecosystems. Highlights ► A generic growth model of the oyster Crassostrea gigas that is suitable for a generic application, i.e. with a constant set of parameters, in contrasting Atlantic environments and for different cohorts (spats and adults) was developed. ► The resulting oyster-DEB model simulated the oyster growth dynamics of both spat and adult stages of C. gigas accurately over time at the various culture sites. The model captures: i) the active spring growth; ii) the timing and amplitude of spawning events; and iii) the loss of dry flesh mass in autumn and winter. ► The half-saturation coefficient Xk is the only model parameter that varied between sites and years. This environment-specific coefficient reflects variability in the food of the oysters.

In tropical shrimp ponds, the increasing of feed input, concomitantly with the stocking shrimp biomass, induces an eutrophication of the ecosystem. Although difficult to maintain, its stability is required to guarantee the success of the culture. A 110-day period of phytoplankton and bacterioplankton stock and dynamics in an earthen pond (1.2 ha area, 1 m depth) was monitored using flow cytometry to provide baseline information on community characteristics and ecosystem instability. Seven autotrophic cell types were identified over the whole sampling period. Prokaryotic cells included Synechococcus sp., a group named UNK which presented an atypical new flow cytometric signature and picoeukaryotes (PEUK). Nanophytoplankton cells were represented by 4 groups: NAN1, NAN2, NAN3 and Cryptophytes. During the first part of the survey, picophytoplankton dominated the phytoplanktonic assemblage. The mean abundance of total cells (up to 8 x 10(6) cells mL(-1)) was among the highest recorded in marine and brackish waters. Bacterial abundance and production ranged from 0.8 to 5.1 x 10(7) cells mL(-1) and from 30 to 110 mu g C L-1 h(-1). A shift from pico to nanophytoplankton abundance was observed for a few days from d 96. During this period, heterotrophic bacteria production and abundance suddenly dropped, implying a change in the functioning of the microbial loop. This shift was concomitant with a significant shrimp mortality outbreak due to Vibrio penaeicida, the etiological agent of a disease known as Syndrome 93, which affects the shrimp industry in New Caledonia. This survey suggests that flow cytometric analysis could be used for the monitoring of aquaculture systems to improve our understanding of the complex phytoplankton and bacterial dynamics of these systems and its potential influence on disease development. (c) 2010 Elsevier B.V. All rights reserved.

The history of French oyster culture consists of a succession of developmental phases using different species, followed by collapses caused by diseases. The indigenous species Ostrea edulis was replaced first with Crassostrea angulata, then C. gigas. France is now the top producer and consumer of oysters in Europe, producing around 120,000 t of the cupped oyster C. gigas annually, and an additional 1500 t of the flat oyster O. edulis. Cupped oysters are produced all along the French coast from natural and hatchery spat. Various structures are used to collect spat from the wild. After a growing-on period, oysters are Cultivated by three main methods: (1) on-bottom culture in the intertidal zone or in deep water, (2) off-bottom culture in plastic mesh bags in the intertidal zone, or (3) suspended Culture on ropes in the open sea. The main recent development is the increasing use of hatchery oyster spat, especially triploids. Almost all oyster production is sold fresh and eaten raw straight from the shell. There is marked seasonality in sales, with the majority being made during Christmas and New Year. Abundant production and the lack of market organization induce strong competition among the production areas, causing prices to fall. Oyster farmers have developed strategies of sales promotion and regional quality labeling to overcome this difficulty. There are numerous production hazards, including environmental crises (microbiological pollution), unexplained mortality, and overstocking, and recent problems with toxic algae have disrupted oyster sales. However, oyster Culture has many assets, including a coastal environment offering favorable sites for Mollusc growth and reproduction. Oysters have been consumed in France since ancient times, and their culture is now well established with a concession system that favors small family firms. There is a young, well-educated farmer population, with technical expertise and savoir faire. Careful seawater quality monitoring ensures good consumer protection, and research is making innovative contributions (,selection and polyploids). These points and opportunities for market expansion should bolster this industry's future, although the problem of toxic algae, probably linked to global warming and anthropogenic factors, and the threat of new diseases, pose vital questions for future research.

This study aims to assess the hydrological fluxes between the ‘Grand Etang’ of Miquelon and the oceanic part. Bathymetric surveys and Doppler currentmeter data acquisitions were carried out from August 14th, 2014 to November 5th, 2014 to allow the following estimates : Total area (227 Ha) and characteristics volumes (total : 7,1x106 m3; oscillating 42,8x106 m3 (40 %); half-tide 5,2 106 m3) Velocity Index of channel to evaluate the average current speed at cross-section channel Fluxes, on flood and ebb tide respectively : - Instantaneous flow : maxima at 85,3 and 65,3 m3/s ; mean 34,2 and 26,4 m3/s. - Circulating fluxes by tide : maxima 0,96 and 1 x106 m3, mean : 0,28 and 0,41 m3 - Mean renewal : 10,7% each tide. Tidal asymetry duration was reported: flood time was lower than the ebb one (4,9 h. vs 7,4 h.), which results in outflow fluxes significantly greater than inflow through the channel. Hypothesis of secondary inflow by percolation from ocean is formulated., Le programme vise à évaluer les flux hydrologiques entre le Grand Etang de Miquelon et l'océan. Les levés bathymétriques et les acquisitions courantométriques réalisés du 14/08/2014 au 05/11/2014 ont permis : L'évaluation des surfaces (227 Ha) et volumes caractéristiques (total : 7,1x106 m3, oscillant 42,8x106 m3 (40 %) mimarée 5,2 106 m3) L'estimation d'un indice de vélocité du chenal pour l'évaluation de la vitesse moyenne des courants L'évaluation des flux, en flot et jusant respectivement, soit : - débits instantanés : maxima à 85,3 et 65,3 m3/s moyens 34,2 et 26,4 m3/s. - flux circulants par marée : maxima à 0,96 et 1 x106 m3, moyens : 0,28 à 0,41 m3 - renouvellements moyens : 10,7% par marée. Le constat d'asymétrie du temps de marée: le temps de flot étant inférieur à celui de jusant (4,9 h. vs 7,4 h), qui implique des flux sortants bien supérieurs à ceux entrants par le chenal. L'hypothèse d'une alimentation secondaire par percolation est émise.

This paper investigates the biological responses of Crassostrea gigas under traditional culture conditions on a mudflat in Marennes–Oleron bay. Summer mortality has been regularly observed in recent years in oysters reared using “on bottom” culture conditions. The present study attempts to provide a better understanding of the mortality phenomenon through biological parameters. Classical ‘field parameters’ such as mortality and growth rates, and quality index (dry meat weight / dry shell weight × 1000) were monitored. Additional parameters, as biochemical composition of oyster meat and glucose incorporation capacity, were included as potential new bioindicators. The work highlighted a critical timing (May–June) preceding the summer mortality and characterised by an arrest in lipid synthesis and a decrease in carbohydrate content. During this period, growth (especially gonad maturation) either slowed down significantly or even stopped. The first mortality event occurred during a growth renewal period at the end of June. Short-term analysis (15 days) provided information to identify such responses which may indicate a physiological stress and demonstrating the need for further investigation. The seasonal food availability (estimated from chlorophyll a levels) did not facilitate the mortality understanding which occurred after water temperature went above 18–19 °C. Nevertheless, this study shows carbohydrate anabolism contributed in the physiological stress leading to mortality events.

To assess the effect of the anti-marine-borer timber preservative CCA (a pressure-impregnated solution of copper, chromium, and arsenic compounds) on nontarget epibiota, fouling community development was investigated. Panels of Scots pine treated to target retentions of 12, 24, and 48 kg CCA per m3 of wood (covering the range of retentions recommended for marine use) plus untreated controls were submerged at seven coastal sites (Portsmouth, UK; La Tremblade [two sites], France; Ria Formosa, Portugal; Sagres, Portugal; Kristineberg, Sweden; Athens, Greece). The fouling community on the surfaces of the panels was assessed both qualitatively and quantitatively after 6, 12, and 18 months of exposure. Multivariate statistical methods were used to compare community structure between panel treatments. Panels treated to the three CCA loadings supported very similar fouling assemblages, which in most cases had higher numbers of taxa and individuals than assemblages on untreated panels. No detrimental effects on epibiota due to CCA preservatives were detected at any of the treatment levels at all seven exposure sites, suggesting that the range of environmental conditions at the sites had no bearing on preservative impact on fouling biota. Differences in community structure between CCA-treated and untreated panels may be due to enhanced larval settlement on CCA-treated timber by some species as a result of modifications to the surface properties of the timber by the preservative. Possible reasons for the higher numbers of certain species on the surface of CCA-treated panels are discussed.

This paper reports a comparative study of two cupped oysters, Crassostrea gigas and C angulata, and their hybrids reared in the Marennes-Oleron Sound (France) under usual farming conditions. The relative proficiency of these species was characterized in terms of growth, survival and reproduction, three major concerns for oyster farming. Four populations of each taxon were sampled (C gigas: Japan and France; C angulata: Taiwan and Spain) and used as progenitors to produce six different progenies under common hatchery and nursery conditions (transfer of 5 to 6 g of seed oysters at sea and rearing in bags for 2 years). Mortality profiles differed greatly among the progenies. The C angulata progeny of Taiwanese origin gave the poorest results, with 100% mortality during the second year. For the entire rearing period, the highest yield (+22%) was obtained with the C. gigas progeny of French origin. The sexual maturation index, lipid cycles and dry weight loss after spawning showed that spawning of C angulata was delayed by about two weeks compared to that of C gigas. A clear maternal effect was observed for the growth and reproductive characteristics of the hybrids. On the whole, C gigas of French origin gave the best aquacultural results. However, severe episodes of C gigas mortality have been observed in France in recent years, indicating that this species might not be entirely suitable for sustained oyster farming in this country., Cette étude présente une analyse comparative des deux taxons d'huîtres creuses Crassostrea gigas et Crassostrea angulata et de leurs hybrides élevés dans des conditions d'élevage traditionnel. L'objectif principal est de caractériser leurs performances de croissance, survie et reproduction, trois caractères génétiques d'intérêt essentiel pour l'ostréiculture. Quatre populations des deux taxons (C. gigas: Japon et France; C. angulata: Taiwan et Espagne) servent de géniteurs pour produire six populations (descendance) en écloserie et nurserie. Les jeunes huîtres de 5-6 g sont ensuite transférées en mer et élevées en poches ostréicoles pendant 2 ans suivant les pratiques culturales des professionnels du Bassin de Marennes Oléron (France). La dynamique de mortalité est différente selon les descendants. La plus mauvaise réponse est obtenue pour C. angulata d'origine taiwanaise qui présente 100 % de mortalité durant la seconde année. Durant toute la période d'élevage, le meilleur rendement de production (+22 %) est obtenu pour la descendance C. gigas d'origine française. L'indice de maturité sexuelle, les cycles lipidiques de la chair des huîtres ou la perte de poids de chair lors de la ponte, montrent que la ponte de C. angulata est plus tardive, décalée d'une quinzaine de jours par rapport à celle de C. gigas. Un effet maternel sur la croissance et la reproduction des hybrides est nettement mis en évidence. Globalement, C. gigas d'origine française présente les meilleures performances d'élevage de toutes les populations étudiées. Toutefois, les manifestations d'épisodes de mortalité de C. gigas en France ces dernières années, montrent que cette espèce n'est pas toujours parfaitement adaptée à son environnement ostréicole.

France is currently one of theleading shellfish production countries inEurope, harvesting more than 150,000 metrictons of the Pacific cupped oyster (Crassostrea gigas) and 60,000 tons ofmussels (Mytilus edulis and M.galloprocincialis) each year. Amongrearing areas, the Charentais Sounds and theMarennes-Oleron Bay rank first in Europe,with an annual production of 40,000 and 15,000tons of oysters and mussels respectively. Morethan a third of French production is marketedfrom the Marennes-Oleron area. As naturalC. gigas and M. edulis spatfall islimited to the Atlantic coast, theMarennes-Oleron Bay and the CharentaisSounds play a critical role nationally,representing more than half of French oysterand mussel spat production. The stockingbiomass in this area was recently estimated at125,000 and 20,000 tons of oysters and musselsrespectively. This biomass is deployed over4,000 ha of leasing grounds along the coastalarea and 3,000 ha of wetlands (oyster ponds),which are environmentally sensitive and subjectto numerous recent regulations. Although a traditional, century-old activity,the shellfish industry now has to addressvarious new internal and external constraintsaffecting overall economic yield andsustainability. These include the management offreshwater inputs into the coastal area,impacted at the watershed level by agriculturefrom a qualitative and quantitative point ofview (e.g. irrigation activity). Moreover, theCharentais Sounds need to remain competitive onthe open market with other French and Europeanproduction sites, whereas its biological yieldremains one of the lowest in France. This hasprompted the industry to optimize spatialdistribution, restructure current leasinggrounds and assess new management practices aswell as new rearing techniques (offshore, longlines), which have led to conflicts overavailable space. In addition to technicalconstraints, local, national and Europeanregulations have increased significantly. Thecoastal law, water law, bird directives, andregulations concerning the preservation ofnatural habitats, wild flora and fauna andprotected areas are among the acts likely tohave an impact on the shellfish industry in thenear future. These internal and external constraints onaquaculture sustainability are analyzed, andcertain case studies in the Charentais Soundsthat have led to user conflicts are reviewed.The diversity of habitats, human activities andinterests along this coast have resulted inhighly complex situations in which somemanagement attempts have been partly successfuland others have failed. These managementoptions are analyzed, and ongoing newapproaches are described, including cooperativestrategies among marine biologists,sociologists, economists, managers, coastalusers, and the shellfish industry. Based onthis analysis, requirements for the developmentof an integrated CZM plan in the CharentaisSounds are suggested, including the use of aproactive approach, geomatics and operationalmodels, as well as the development ofintegrated decision making structure to developCZM and then, the use of a stepwise model ofagreement-focused negociation for furtherconsensus building.

The workshop, “Aquaculture and its role inIntegrated Coastal Zone Management” held inOstende, Belgium in April 2001, aimed to provideinformation to help develop recommendations forwise management of aquaculture in coastal andmarine environments. This paper focuses on thetwo main objectives of the workshop, 1) to aidthe development of stronger interdisciplinarycommunication between the natural and socialsciences and to improve the utility ofavailable scientific information and knowledge;and 2) to promote new perspectives on thesustainable use of coastal areas and naturalresources. The paper also summarizes thedebates following each of the three workshopthematic sessions: aquaculture and ICZM;socio-economic and political dimensions;developing sustainable production systems; andidentifies the key recommendations that may beapplied to the formulation of policy onintegrated aquaculture management in coastaland marine environments.

This work, conducted in 2013 , is a first monitoring of marine invasive species in Saint-Pierre and Miquelon archipelago. In global changing context on coastal ecosystems , accentuated by direct or indirect effects of human activities, it became essential to implement a survey on marine invasive species on Saint-Pierre and Miquelon shoreline. Fukui traps and tunicates collectors implemented on different stations as well as the timely completion of observational dives , have established the following conclusions : several non native species were detected within the local marine ecosystem. This species , such as Carcinus maenas , Ciona intestinalis , Botryllus schlosseri , Caprella mutica , etc. ... threaten some local marine ecosystems and some local aquaculture activities. It seems to be essential to continue this type of annual monitoring to determine trends of marine invasive populations on the archipelago. Further works in collaboration with Canadian services should also allow the identification of human activities impacts on these populations movements. These reports will finally support a management plan for these introduced impacting organisms to limit and control biopollution impacts on marine environment and economy., Ce travail, mené en 2013, constitue un premier suivi des espèces envahissantes marines à Saint-Pierre et Miquelon. Dans un contexte global de modification des écosystèmes côtiers, accentué par l’effet direct ou indirect des activités humaines, il est apparu indispensable de faire un état des lieux concernant les espèces envahissantes marines sur les côtes de Saint-Pierre et Miquelon. La pose de casiers Fukui et de collecteurs sur différentes stations ainsi que la réalisation ponctuelle de plongées d’observations ont permis d’établir le constat suivant : plusieurs espèces jusqu’alors non recensées ont été détectées au sein de l’écosystème marin local. Ces espèces, tel que Carcinus maenas, Ciona intestinalis, Botryllus schlosseri, Caprella mutica, etc… menacent alors la stabilité des écosystèmes en place et inquiètent les professionnels de l’aquaculture. Il apparait donc nécessaire de poursuivre ce type de suivi annuel afin de déterminer l’évolution des populations d’espèces envahissantes marines sur l’archipel. Des travaux complémentaires en collaboration avec les services canadiens concernés devraient également permettre d’identifier l’influence et l’impact des activités humaines sur ces mouvements de populations. Ces actions permettront à terme d’envisager un plan de gestion de ces espèces pour limiter au mieux leur implantation ainsi que leurs impacts sur l’environnement et l’économie.

A wide range of options is available to society, especially stakeholders and managers, to move towards the goals of sustainable use, conservation, and restoration of marine biodiversity. Management approaches include protected areas to preserve ecosystem state and habitat restoration to maintain ecosystem services. A series of additional tools is being developed to enable decision-makers to (1) take ecosystem value into account in their decisions (e.g. in managing recreational uses and tourism), (2) recognise diffuse ecosystem benefits on a local scale, (3) establish property or access rights for living resources (e.g. ITQs or managed quotas) and (4) disseminate knowledge and raise public awareness about ecological footprints, life-cycle analyses, green- or eco-labelling, etc.

Human impacts have been shown to profoundly modify genetic and species diversity (Palumbi 2001) (Fig. 1.9). The main direct impacts are caused by overexploitation and habitat loss, while indirect effects may result from cascading interactions in the food web (e.g. removing competitors and predators from the system) and the effects of environmental change. Dulvy et al. (Fish Fish 4: 25–64, 2003) reviewing local, regional and global marine extinction, identified “exploitation” and “habitat loss” as being respectively responsible for 55 and 37 % of 133 reported extinctions.

The study of marine biodiversity is timely and fundamental for a number of reasons (CBD, Global Biodiversity Outlook 3, 2010). Marine biodiversity plays a key role through ecosystem services (provisioning and regulation, amongst others). They provide economic wealth and resources that range from active ingredients for pharmaceuticals and medicine to products from fisheries and aquaculture, as well as contributing to cultural well-being and supplying relevant “biological models” for both basic and applied research. The role and dynamics of biodiversity are central themes when addressing climate change, earth and universe sciences or sustainable use of natural resources. Thus the issues of application involve policy, regulations and ways to globally manage energy and food security.

Our limited knowledge of the world’s biodiversity, coupled with the limitations of the current approaches to cataloguing biodiversity, are the main driving forces behind new approaches to species identification. Estimates of the total number of existing eukaryotic species range from the most conservative of 3.6 million to over 100 million, with a figure of 10 million favoured by most analysts as the nearest order of magnitude. To date, some 1.9 million species have been deposited in museums.

In describing the triggering element of a phenomenon, the terms “drivers” and “driving forces” will be used interchangeably here.

Oyster greening was first described in the seventeenth century as a natural phenomenon. However, it has recently been discovered that the diatom Haslea ostrearia Simonsen causes greening by synthesis of a blue pigment designated as ‘marennine’. This phenomenon, which involves massive proliferation of H. ostrearia in oyster ponds, was not understood or controlled by oyster farmers in the

Feeding competition between the Pacific cupped oyster Crassostrea gigas and the polychaete Lanice conchilega was studied by assessing the polychaete suspension feeding activity. Retention efficiency was estimated by comparing particle size distributions at the output of experimental chambers containing the species and controls. Although particles ranging from 4 to 12 μm were collected by L. conchilega , no upper threshold or maximum retention rate was reached within this range. In contrast, C. gigas showed retention starting at 2 μm, and reaching an upper threshold at 6 to 8 μm. Based on our results, feeding competition is likely to occur between C. gigas and L. conchilega . Standardised filtration rates reached 0.225 l h −1 g dmw −1 (±0.08) for L. conchilega and 2.43 l h −1 g dmw −1 C. gigas for animals of 1 g dry meat weight (dmw). Assimilation rates, 0.44 for L. conchilega and 0.49 for C. gigas , were similar for the two species. Respiration rates were estimated at 0.113 and 0.68 ml O 2 h −1 for L. conchilega (Allometric coefficient=0.534) and C. gigas respectively. Therefore polychaete scope for growth (SFG) (4.01 J h −1 g dmw −1 ) was significantly lower when compared with C. gigas SFG (61.96 J h −1 g dmw −1 ). The impact of the L. conchilega population on that of cultivated oysters was evaluated from these results and field population assessment of both species. Based on field population estimates, L. conchilega was responsible for a 19% decrease in the carrying capacity and 30% of the oxygen depletion from the total activity of both species. However, L. conchilega SFG was only 16% of that of the C. gigas population. Several hypotheses regarding population interactions are discussed.

Bioassays were carried out with the 'blue diatom' Haslea ostrearia Simonsen, which is responsible for oyster greening during the fattening period of Crassostrea gigas Thunberg in oyster ponds. Samples of seawater were taken from two oyster ponds: one without oysters and the other with 20 oysters per m_, maximal density allowed by the French AFNOR norm for 'refinement'. The aims were to clarify the nutrient requirements of this diatom, also to elucidate the eventual influence of C. gigas at this density on the seawater fertility and to envisage the mass production of this diatom by pond fertilization. Examination of cell numeric densities at the end of bioassays allows us to conclude that silicate was the first limiting nutrient, closely followed by phosphate. Chlorophyll a concentrations led to different conclusions: phosphate was the first limiting factor, but after the seawater storage period in ponds, seawater quality evolved to a deficiency of nitrogen. Silicate addition increased cell division rate, and silicate depletion increased chl a synthesis for this species. Examination of nutrient assimilation ratios confirms that H. ostrearia requires a large amount of silicon. From these results, it was possible to prepar eaN+P + Si simplified medium which has been tested in laboratory and field mesocosm conditions. In both conditions, similar results were observed: a significant increase in H. ostrearia cell concentrations and consequently an evolution up to the greening stage. Applications of this work are numerous; the principal permits us to envisage the production of this species in 25-m 3 ponds, with the aim of allowing constant production of the greening phenomenon. © 1999 Ifremer/Cnrs/Inra/Ird/Cemagref/Editions scientifiques et medicales Elsevier SAS Limiting nutrients / Bacillariophyceae / Haslea ostrearia / bioassay / mesocosm experiment / oyster ponds

Respiration rates of various geographical strains of Crassostrea gigas were compared to assess the respiratory expenditure as a physiological indicator of catabolism (cost of maintenance). Parental oysters, sampled in France (Marennes-Oleron), Japan (Hiroshima), Taiwan (Tunkang) and Spain (Cadix), were differentiated by both their geographic origin and by mitochondrial DNA markers, allowing the distinction between the two closely related taxa Crassostrea gigas and Crassostrea angulata. After reproduction of these parental oysters, respiration rates of spat of each strain, reared under common controlled conditions, were individually estimated at 20 degrees C by using a volumetric microrespirometer. Our results demonstrated that physiological variability existed among the Crassostrea gigas strains and is likely to be related to physiological differences between geographical regions and/or genetic adaptations. The French strain showed the highest rates (0.71 mu L.h(-1)), while the Japanese, Taiwanese and the hybrid between Spanish and French strains consumed less, 0.53, 0.43 and 0.40 mu L.h(-1) respectively. Our results confirmed the discrepancies previously suggested between Crassostrea gigas and Crassostrea angulata. Comprehensive physiological assessments should be carried out over a wide temperature range to confirm our results and to further evaluate growth potential. Appropriate decision making based on these studies will help future shellfish management in shellfish rearing areas such as the overstocked Marennes-Oleron Bay., Les taux de respiration de différentes souches géographiques de l'huître creuse japonaise Crassostrea gigas ont été comparés afin d'évaluer, en tant qu'indicateur physiologique, le coût énergétique de maintenance résultant du catabolisme (pertes énergétiques). Les géniteurs échantillonnés en France (Marennes-Oléron), au Japon (Hiroshima), à Taiwan (Tunkang) et en Espagne (Cadix) ont été différenciés à la fois par leur origine géographique et par l'utilisation de marqueurs ADN mitochondriaux, permettant ainsi la distinction entre deux taxa très proches Crassostrea gigas et Crassostrea angulata. Après reproduction de ces géniteurs, les taux de respiration du naissain de chaque souche, élevé dans des conditions contrôlées similaires, ont été mesurés individuellement à 20°C au moyen d'un microrespiromètre volumétrique. Nos résultats démontrent qu'il existe une variabilité physiologique entre les différentes souches, due probablement à une adaptation physiologique locale et/ou à des adaptations génétiques. Les huîtres de souche française ont montré les taux de respiration les plus élevés (0,71 μL·h−1), comparés aux taux de consommation de 0,53, 0,43 and 0,40 μL·h−1 respectivement pour les souches japonaise, taiwanaise et les hybrides entre la souche espagnole et française. Ces résultats confirment les différences déjà suggérées entre les souches Crassostrea angulata et Crassostrea gigas. Des évaluations complètes des fonctions physiologiques doivent être réalisées en fonction d'une gamme de température pour confirmer ces résultats et estimer le potentiel de croissance des différentes souches. Ces études doivent faciliter les futures décisions en matière d'aménagement des cultures marines dans les bassins de production français, en particulier dans des zones d'élevage surchargées comme le bassin de Marennes-Oléron.

Manila clam (Tapes philippinarum) culture and sediment interactions were tested by comparing two rearing areas, including an oceanic (‘Le-Ferret’) and a more estuarine (‘Les-Jacquets’) sites in the bay of Arcachon (France). The growth of a calibrated clam population (10-mm spat) was monitored in these two areas with a concomitant sediment-water interface survey over a 1.5-year period. Two sites per area, including control and rearing plots, were sampled on a monthly basis. The potential clam farming impacts by bioturbation and interactions were examined at three sediment depths: 0–1, 1–2 and 2–10 cm. Moreover, the main hydrobiological parameters were measured on a weekly basis to establish a relationship between these parameters and sediment-water interface characteristics. The existence of a gradient between the three depths was revealed for most of the parameters examined, with the exception of silt and organic carbon levels, and this regardless of the area examined. Clam growth showed a rate improvement in the oceanic area, which is characterized by a lower silt content. The clam effect was minimal and the activity identified at the ‘Ferret’ site was in fact due to the presence of a net which acted as a particle trap. No significant relationship was established between water column parameters and those of the sediment-water interface at the two geographical sites examined. These results demonstrate that clam rearing had only a limited effect on the environmental sediment parameters (i.e. water percentage, and phaeopigments and silt levels) from a spatio-temporal point of view. Therefore, a return to environmental conditions existing before the implementation of clam fanning is likely to occur upon cessation of this activity.

A hydrobiological monitoring network has been in place since 1977 in the Bay of Marennes Oleron (France). Data collected for physical variables (seawater temperature, salinity, oxygen concentration), nutrients (ammonium, nitrates, phosphates and silicates) and chlorophyll a and pheophytin, from 5 representative stations in the bay, were examined by time-series analysis (Census II method) to study seasonal variability and trends. The seasonal changes were similar over the entire Marennes Oleron Bay for all variables and were chiefly influenced by fluxes in the Charente river. The seasonal range reached 180 units for nitrates and 70 and 100 units respectively for phosphates and silicates. These values were similarly mostly correlated with the Charente River fluxes. With regard to long-term trends, seawater temperature has shown a significantly increasing trend close to 2 °C over 18 years. At the same time, a 1 °C gradient was demonstrated from the northern to the southern part of the Bay. The salinity trend varied between 30 and 34‰for all stations. The trend for oxygen concentration, ranged from 90 to 100% but during a specific two year period (1980–1982) saturation decreased to 76% in the northern part of the Bay. The trend analysis for nitrates showed a significant relationship with the water output level of the Charente. Phosphate inputs have been irregular during the two last decades which has affected primary productivity along the coastline (e.g., spring 1979–1983; 1990; 1993–1995). Since 1988, a significant increasing trend for ammonium was observed at the mouth of the Seudre river (4 μmoles l−1 ) while other stations were well below this, ranging from 1 to 3 μmoles l−1 . This should be considered as an indicator of seawater deterioration within the southern part of the Marennes Oleron Bay.

L'actuelle demande alimentaire croissante sur les produits de la mer met l'aquaculture en situation de développement; les stratégies de développement mises en place incluent des questions de durabilité économique, sociale et environnementale. Au cœur de celles-ci, l'accès à l'espace (sélection de sites, conflits d'usage, etc…) place cette dimension au premier plan. La planification spatiale du développement des projets aquacoles est donc un élément essentiel, incluse dans une démarche de gestion intégrée de la bande côtière. C'est un élément considéré comme une étape cruciale tant par les scientifiques dans le cadre d'une approche ecosystémique, que par les diverses nations et organismes Européens via le développement d’une réglementation ad-hoc. Dans ce contexte, les Systèmes d'Information Géographiques (SIG) sont des outils d'analyse spatiale et d'aide à la décision relativement incontournables. Leur capacité à agréger, présenter, et analyser des données de sources très variables (satellites, photos, réglementation, résultats de modélisation…) permet une meilleure accessibilité et un meilleur partage de l'information spatialisée. L'Ifremer utilise et structure les données marines et côtières dans ce type de système depuis les années 1990. Ce document présente une revue de différents types d'applications dans le domaine aquacole utilisant les SIG en fonctionnement dans le cadre des missions de soutien aux administrations et utilisateurs des espaces littoraux des laboratoires côtiers de l'Ifremer. Sont présentées les données et analyses géostatistiques multicritères pour la sélection de sites, les différentes évaluations de stocks de mollusques ou d'échantillonnage environnemental spatialisé. Des études utilisant la modélisation (hydrodynamique, écophysiologie) afin de qualifier les espaces littoraux sont également abordées. Une synthèse bibliographique à jour est également fournie en annexe, passant en revue les diverses applications et catégories d'usages SIG & Aquaculture.

International audience

208 pages; National audience

Adverse effects of invasive alien species, or biological pollution, is an increasing problem in marine coastal waters, which remain high on the environmental management agenda. All maritime countries need to assess the size of this problem and consider effective mechanisms to prevent introductions, and if necessary and where possible to monitor, contain, control or eradicate the introduced impacting organisms. Despite this, and in contrast to more enclosed water bodies, the openness of marine systems indicates that once species are in an area then eradication is usually impossible. Most institutions in countries are aware of the problem and have sufficient governance in place for management. However, there is still a general lack of commitment and concerted action plans are needed to address this problem. This paper provides recommendations resulting from an international workshop based upon a large amount of experience relating to the assessment and control of biopollution., JRC.H.1-Water Resources

The Millenium Ecosystem Assessment (2005) demonstrated that the biodiversity is the keystone for the sustainaibility of present and future ecosystems services. In spite of the highly significant effort carried out by the Census of Marine Life over the last ten years, and an increasing research effort, marine biodiversity and precise ecosystem functioning remain largely unknown and failure to reach the CBD 2010 objectives is obvious. Meanwhile, the concept of ‘ecosystem approach’ is progressing, translated into new policies such as the revised European Common Fisheries Policy (CFP). We might question if the scientific community is ready enough to built scenarios for the future and provide integrated advice to the policy makers for biodiversity conservation considering the previous uncertainties ? Key issues in term of data availability and research priorities will be discussed concomitantly to the policy agenda at the European and French levels.

Considering the filtration capacity of mussels to qualitative particle selection, our study focused directly on ingested species by assessing mussel stomach content of various size classes (1-5 cm) over a year (August 97-June 98) rather than monitoring seawater samples. Different size of mussels (1, 2, 3, 4, 5 cm in length) was sampled monthly from the sides of fish cage floats in Urla-Izmir. Stomach contents were analyzed under microscope and different plankton species were grouped taxonomically. Bacillariophycea, Dinophyceae, Oxyphceae, Euglenophyceae as phytoplanktonic species were observed in the stomach contents of mussels as well as zooplanktonic species including Ciliata, Cladocera, Copepod, bivalve and gastropod larvae. Over the sampling period, according to the Bray-Curtis similarity test mussels’ stomach for all sizes was of similar content except in August and October.

Sampling efficiency of two oyster fishing gears, patent tongs and an oyster dredge, were compared in reference to diver-harvested quadrats in Chesapeake Bay, which supports important harvests of eastern oyster Crassostrea virginica. Mean densities of spat (≤35 mm), small oysters (>35 mm to 75 mm), marketable oysters (>75 mm), and all oysters (three size-groups combined) estimated from patent tong samples were not significantly different from those derived from diver-harvested quadrat samples. In contrast, the densities estimated from dredge samples were low, only 2–32% of the diver estimates. Accordingly, patent tongs are recommended as the sampling gear for estimating eastern oyster stock abundance in the Maryland portion of Chesapeake Bay.

The Pacific oyster (Crassostrea gigas, Thunberg, 1793) is one of 20 species in the genus Crassostrea. Although native to the Japan/Korea region, C. gigas is a hardy species that has been introduced to a number of countries worldwide, including the US, Canada, the UK, France, Korea, China, New Zealand, Australia, South Africa, and South America, mainly for aquaculture purposes (Mann et al., 1991; Orensanz et al., 2002). As a result, C. gigas has become the leading species in world shellfish culture, with an estimated production of 4.6 million t in 2006 (FAO, 2008). Because C. gigas does not require additional food to sustain its growth, this species is relatively inexpensive and easy to produce. Its capacity to adapt to various environmental conditions and temperature fluctuations, coupled with its rapid growth and resistance to highly turbid areas, contributes to its success.

Species invasion is considered as a main factor impacting the marine biodiversity (CBD, 2008). A comprehensive review of species invasion along the French Atlantic coastline is carried out to assess the present status and side effects resulting from those invasions. Vectors of introduction concerning voluntarily and involuntarily, legal & illegal case studies are reviewed to provide baseline information relating invasion success and potential control. Historical case studies regarding shellfish aquaculture-fisheries development and impacts of exotic diseases (e.g., Bonamia ostreae) as well as hitchhikers (e.g., Rapana venosa) are discussed. Among at least 150 reported exotic species, around 10 species have highly significant side-effects on the ecosystem functioning and on human commercial and recreational activities. In contrast, several economic activities including shellfish farming and fisheries are mainly based upon the use of exotic species (e.g. Pacific cupped oyster Crassostrea gigas, Manila clam Ruditapes philippinarum), therefore providing business opportunities to farmers and fishermen in rural areas. Several species, including the slipper limpet Crepidula fornicata, the Pacific cupped oyster Crassostrea gigas have prompted the decision makers and the private sector to develop management practices to address invasion and sustainable development issues. Several technical options have been tested including manual hand picking, mechanical harvest and destruction, with more or less success and potential additional side effects. Their efficiency is also highly dependant on the invasion timing and species distribution. Appropriate spatial and temporal planning is a keystone for efficiency and success to limit invasion side effects, whereas the species eradication is not an option. Various options have been developed to assess potential added value from byproducts and refuse with limited success. Moreover, the final treatment of the refuse remains a key issue from a technical and policy point of view. Management options should be evaluated in terms of cost-efficiency, ecosystem resilience as well as public acceptability. Besides practical management, new approaches should be also evaluated including 1. cross-cutting and trans-sectorial new regulations to prevent involuntarily introduction, and 2. compensation systems within the on-going debate on economic biodiversity evaluation (TEEB, 2008 ; CDC Biodiversité, 2008) to sustain on-going management. Moreover, ICES code of practice (1994), international guidelines (Code of conduct for responsible fisheries (FAO, 1997), IMO regulation on ballast waters (2004) and recent EU regulation regarding the use of exotic species in aquaculture (Council regulation N°708/2007) as well as international research projects (IMPASSE, DAISIE) provide tool-box for managers to limit side-effects and increase awareness of the scientific community as well as the public to species invasions. Eventually, the issue of species invasion has now to be considered within the EU Marine Strategy Framework Directive (MFSD) as one of the 11 descriptors which requires the development and implementation of suitable monitoring programs to assess and further reach the 'good ecological status' ( GEE) of marine waters.