The Estuarine Quality Paradox: is it possible to define an Ecological Quality Status for specific modified and naturally stressed estuarine ecosystems?

International audienceThe implementation of the European Water Framework Directive has provoked enthusiastic debate between scientists and stakeholders, as they try to define the ecological quality status (EcoQS) of all water bodies, including estuaries (i.e., transitional waters). The issue is complex because estuarine environments are variable, due to fresh and marine water input and anthropogenic impacts. Benthic species and communities have adapted to tolerate temporal physico-chemical changes (e.g., salinity, substrata, depth, fine particles and a Maximum Turbidity Zone that is rich in organic matter). However, anthropogenization affects not only the water quality, but also estuarine surface size and navigation channel management. Though numerous bio-indicators and indices are used to define estuarine system EcoQS, very few of them were developed specifically for such variable anthropogenized systems comprising a variety of conditions. The critical question is: 'Is it possible to define an EcoQS for such specific modified and naturally stressed ecosystems?' Indicators must be chosen pragmatically so that they will be environmentally sustainable, economically viable, technologically feasible, socially desirable/tolerable, legally permissible and politically expedient. This contribution proposes an adaptation of the BOPA index, the Benthic Opportunistic Annelida Amphipod index (BO2 A), for use in the freshwater zones of transitional waters (i.e., up to the upper limit of tidal range). Several possibilities are discussed in light of the diverse disturbances and the heterogeneity of such stressed zones

Surveillance Écologique et Halieutique Site de Gravelines. Novembre 2013 - Octobre 2014

This is the 37th annual surveillance report concerning the nuclear power plant of Gravelines. Its very high power level results from six plant units located on the shore and is characterised by a cooling system with a coastal surface input and output. The production of electricity began in 1980 and reached maximum in 1986. Surveys concern monitoring of pelagic system (hydrology, microbiology, phytoplankton, and zooplankton), fish populations (larvae and eggs of Sole and Sprat) or crustaceans (shrimps), and benthic macrofauna (intertidal and subtidal). This survey deals with spatial and temporal approaches (i) study of the direct impact by comparison of the input and output seawater stations, (ii) study of medium and long term evolution of the area by comparison with a reference station.Ce travail constitue le 37e rapport de surveillance du site électronucléaire de Gravelines dont la grande puissance énergétique est assurée par le fonctionnement de 6 tranches. Ce site, implanté sur le littoral, présente une prise d’eau de mer assurant le refroidissement du système et un rejet côtier d’eau chaude en surface. Le fonctionnement de la centrale a débuté en 1980 et elle a atteint la puissance maximale en 1986. La surveillance concerne les domaines pélagique (hydrologie, microbiologie, phytoplancton, zooplancton), halieutique (larves et œufs de Sole, de Sprat et crevettes grises), et benthique (intertidal et subtidal). La stratégie de surveillance est basée sur une approche spatiale et temporelle (i) Etude de l’impact immédiat par comparaison de la station « Prise d’eau » et de la station « Canal de rejet » sur une surface limitée (ii) Etude de l’évolution à moyen ou à long terme du milieu marin par rapport à une situation de référence (échelle locale)

Surveillance Écologique et Halieutique Site de Gravelines. Novembre 2014 - Octobre 2015

This is the 38th annual surveillance report concerning the nuclear power plant of Gravelines. Its very high power level results from six plant units located on the shore and is characterised by a cooling system with a coastal surface input and output. The production of electricity began in 1980 and reached maximum in 1986. Surveys concern monitoring of pelagic system (hydrology, microbiology, phytoplankton, and zooplankton), fish populations (larvae and eggs of Sole and Sprat) or crustaceans (shrimps), and benthic macrofauna (intertidal and subtidal). This survey deals with spatial and temporal approaches (i) study of the direct impact by comparison of the input and output seawater stations, (ii) study of medium and long term evolution of the area by comparison with a reference station.Ce travail constitue le 38e rapport de surveillance du site électronucléaire de Gravelines dont la grande puissance énergétique est assurée par le fonctionnement de 6 tranches. Ce site, implanté sur le littoral, présente une prise d’eau de mer assurant le refroidissement du système et un rejet côtier d’eau chaude en surface. Le fonctionnement de la centrale a débuté en 1980 et elle a atteint la puissance maximale en 1986. La surveillance concerne les domaines pélagique (hydrologie, microbiologie, phytoplancton, zooplancton), halieutique (larves et œufs de Sole, de Sprat et crevettes grises), et benthique (intertidal et subtidal). La stratégie de surveillance est basée sur une approche spatiale et temporelle (i) Étude de l’impact immédiat par comparaison de la station « Prise d’eau » et de la station « Canal de rejet » sur une surface limitée (ii) Étude de l’évolution à moyen ou à long terme du milieu marin par rapport à une situation de référence (échelle locale)

Surveillance Écologique et Halieutique. Site de Gravelines. Novembre 2015 - Octobre 2016

This is the 39th annual surveillance report concerning the nuclear power plant of Gravelines. Its very high power level results from six plant units located on the shore and is characterised by a cooling system with a coastal surface input and output. The production of electricity began in 1980 and reached a maximum in 1986. Surveys concern monitoring of pelagic system (hydrology, microbiology, phytoplankton, and zooplankton), fish populations (larvae and eggs of Sole and Sprat) or crustaceans (shrimps), and benthic macrofauna (intertidal and subtidal). This survey deals with spatial and temporal approaches (i) study of the direct impact by comparison of the input and output seawater stations, (ii) study of medium and long term evolution of the area by comparison with a reference station.Ce travail constitue le 39e rapport de surveillance du site électronucléaire de Gravelines dont la grande puissance énergétique est assurée par le fonctionnement de 6 tranches. Ce site, implanté sur le littoral, présente une prise d’eau de mer assurant le refroidissement du système et un rejet côtier d’eau réchauffée en surface. Le fonctionnement de la centrale a débuté en 1980 et elle a atteint la puissance maximale en 1986. La surveillance concerne les domaines pélagique (hydrologie, microbiologie, phytoplancton, zooplancton), halieutique (larves et œufs de Sole, de Sprat et crevettes grises), et benthique (intertidal et subtidal). La stratégie de surveillance est basée sur une approche spatiale et temporelle (i) Étude de l’impact immédiat par comparaison de la station « Prise d’eau » et de la station « Canal de rejet » sur une surface limitée (ii) Étude de l’évolution à moyen ou à long terme du milieu marin par rapport à une situation de référence (échelle locale)

Benthic indicators and index approaches in the three main estuaries along the French Atlantic coast (Seine, Loire and Gironde)

The three main estuaries in the French Atlantic coast – the Seine, Loire and Gironde, all with high tidal regimes – are interfaces between the continental and the coastal ecosystems. The Seine and Gironde are highly contaminated, whereas the Loire remains in a more natural state. Both the Seine and Gironde have suffered from harbour construction, and as a result, their biological units are extremely compartmentalized. Benthic species and communities have adapted to tolerate temporal physical and chemical changes (e.g. salinity, substrata, depth, and levels of fine particles and oxygen) and human activities (e.g. dredging, shipping traffic, and habitat reduction). Although numerous bio-indicators and indices are used to define the ecological quality status (EcoQS) of coastal waters, very few of them were developed specifically for environments with a mosaic of conditions and salinity levels, including freshwater. The main problem appears to be that all the indices for determining anthropogenic stress examine the abundances of stress-tolerant species, which may also be able to tolerate natural stressors such as those occurring in estuaries. This paper takes a look at the development status of the benthic indicators and index approaches used in the three main estuaries along the French Atlantic coast. In addition, it examines the adaptation of the different benthic indicators to the taxonomic sufficiency principle, and the adaptation of the Benthic Opportunistic Polychaetes Amphipods index (BOPA) and the Benthic Opportunistic Annelida Amphipod index (BO2A) for use in the freshwater zones of transitional waters (i.e. up to the upper limit of the tidal range). Several perspectives are discussed in light of the diverse disturbances and the heterogeneity of such stressed zones, such as the use of multimetric and scoring approaches

Contrôle de surveillance benthique de la Directive Cadre sur l’Eau (2000/60/CE). Année 2019. District Artois-Picardie

This report deals with results of monitoring carried out in 2019 for the area concerned by the Artois-Picardie water district.Ce rapport présente les résultats des opérations menées en 2019, sur l’ensemble des masses d’eau côtières et de transition rattachées au district Artois-Picardie

Range extension of the tanaidid Zeuxo holdichi (Bamber, 1990) along the northern coasts of France?

The tanaidacean crustacean, Zeuxo holdichi was first described from Arcachon Bay, France, by Bamber in 1990. Since then, this species has been recorded several times in Europe, from Iberian Peninsula to Germany. In this present study, we report new records of this species along the northern coasts of France bordering the English Channel. It is hypothesized that Z. holdichi is being spread because of aquaculture activities.Extension géographique du tanaidid Zeuxo holdichi (Bamber, 1990), le long des côtes du nord de la France ? Les premières descriptions du tanaïdacé Zeuxo holdichi proviennent du bassin d'Arcachon, France, par Bamber en 1990. Depuis, cette espèce a été signalée dans plusieurs autres sites européens depuis la péninsule ibérique jusqu'aux côtes alle- mandes. Dans cette étude sont rapportés de nouveaux signalements de cette espèce le long des côtes septentrionales de la Manche (côté français). Z. holdichi pourrait être dispersé par les pratiques aquacoles

Use of Biotic Indices in semi-enclosed coastal ecosystems and transitional waters habitats - Implications for the implementation of the European Water Framework Directive

International audienceThis study deals with the application of macrozoobenthos-based biotic indices (BI) within the frame of the implementation of the European Water Framework Directive. More precisely, this study aimed at assessing the performance of five recently developed methodologies (BI) for the assessment of ecological quality status (EcoQ) in two semi-enclosed, sheltered coastal ecosystems and in one transitional water body situated along the Western French coast, namely Marennes-Oléron Bay, Arcachon Bay, and the Seine Estuary. This study showed that these five indices rarely agreed with each other, describing very different pictures of the overall EcoQ of the three study sites. This work also clearly underlined the limitations of these approaches, notably the dependency of most of these BI and the resulting EcoQ classifications on habitat characteristics, more particularly to natural levels of sediment silt–clay content and the location of stations in the subtidal or the intertidal. The implication of our observations concerning the use of these BI for implementation of the WFD is discussed in terms of definition of habitat-specific reference conditions and necessity to adjust thresholds to the particular habitat occurring in semi-enclosed ecosystems. Meanwhile, the unmodified use of these BI severely impaired accurate assessment of EcoQ and decision-making on the managers’ point of view