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The invasive benthic foraminifera Trochammina hadai has been found for the first time in Europe along the coast of Normandy. Its native range of distribution is in Asia (Japan and Korea), and it has also been introduced along the coasts of western North America, Brazil and Australia. Morphological and molecular assessments confirm that specimens found in Le Havre and Caen-Ouistreham harbors belong to the Asiatic type. Like in Asia, T. hadai was found in transitional waters with muddy sediments. It exhibited high relative abundances (up to about 40%) confirming that T. hadai is a highly competitive species. In the present study, it was nearly absent from natural transitional waters and very abundant in heavily modified habitats like harbors, suggesting that ballast waters may likely be the vector of introduction. It was not recorded farther north along the coast of the Hauts-de-France. It is further hypothesized that the finding of a few specimens outside the harbor may facilitate the expansion of T. hadai in the English Channel by means of propagules dispersion.

International audience; Three specimens of the Northern American bivalve Yoldia limatula (Say, 1831) were retrieved from Le Havre Harbour (The English Channel, Normandy, France) for the first time in 2021. This species was initially recorded from Europe in the Netherlands in 2019, after which specimens were found in Belgium in 2020. This is the first record of this species in Normandy and France now extends the invasive range of the species from the eastern part of the English Channel to the southern part of the North Sea. This species is considered as non-indigenous in Normandy and was most likely introduced via ballast water due to intense marine shipping between North American and European harbours.

(IF 1.67; Q2); International audience; An overview is presented of the Non-Indigenous Species (NIS) of algae and invertebrates recorded in the marine and brackish coastal waters of Normandy in France. Out of the 152 NIS found, 86 have been introduced through shipping (ballast waters and fouling) and 66 through aquaculture activities. A total of 95 NIS are linked to a Pacific origin and 32 come from the northwestern region of the Atlantic. Among the 152 NIS identified, only nine show an invasive demography in Normandy waters. The first introductions occurred in the middle of the 19 th century and became frequent by the beginning of the 20 th century. However, over 50% of the NIS so far recorded were found only during the three last decades.

This study describes for the first time in the central Mediterranean Sea the effects of bottom trawling on macrobenthic fauna in tidal channels of the Kneiss Islands in the Gulf of Gabès, Tunisia. Following a BACI protocol, two control stations (protected by artificial reefs) and two trawled stations (impacted stations) were sampled during a period with the absence of bottom trawling activity (the COVID-19 pandemic lockdown period from March to May 2020) and during a trawled period. Although bottom trawling had no impact on sediment composition, this anthropogenic activity reduced the concentration of dissolved oxygen and had a noticeable effect on water column turbidity. The absence of trawling led to a significant increase in biomass, number of species, and abundance of total macrofauna. This illustrated the negative effect of trawling activity in shallow waters and the high resilience of macrobenthic communities of the tidal ecosystem of the Kneiss Islands. In the future, it would be very important to control the use of this destructive fishing gear due to its negative impact on the marine habitat and macrofauna, which represents essential prey for fishes and birds living in this protected area.

The current development of human activities at sea (e.g. land reclamation, maritime activity and marine renewable energy) is leading to a significant increase in the number of infrastructures installed in marine settings. These artificial structures provide new hard-bottom habitats for many marine organisms and can thus modify the structure and functioning of coastal ecosystems. In order to better evaluate the nature of these modifications as well as the potential benefits and/or impacts generated, it becomes essential to develop assessment methods that can be applied to a wide variety of study sites from harbours to coastal offshore environments. In this context, our study aims to review the different methods and indicators available which are used to measure the modifications of biodiversity and ecological functioning generated by such structures. Among the methods reviewed, we highlight some that were developed specifically for artificial structures, and others intended for various primary uses but which have been successfully transposed to artificial structures. Nevertheless, we also point out the lack of reliable methods concerning some biological ecosystem components impacted by artificial structures. In this context, we require the adaptation or creation of brand-new indicators to achieve a better characterisation of the ecological impacts generated by these structures. Overall, this study highlights a very high number of existing methods, which provide stakeholders with useful tools to study the impacts of artificial structures, and identifies the need to develop integrative indicators to enhance the deployment of new artificial structures.

International audience; The fauna inhabiting the brown seaweed Sargassum muticum was studied on a spatial scale along the Normandy coast from the Normand-Breton Gulf to the Bay of Seine (English Channel) in both shallow sandy and rocky tidal pools during the springs 2018 and 2019. In this paper, we test the following hypothesis: do the areas with dense populations of S. muticum represent an appropriate habitat for dense motile fauna including other Non-Indigenous Species (NIS)? The ALEX (ALien biotic indEX) is used to ascertain whether or not S. muticum favours the establishment of other NIS in this new habitat. Results show that the epifaunal assemblage associated with S. muticum differs between the five sampling sites. However, the fauna at all five sites is dominated by arthropoda, especially the amphipods and isopods. In addition, five non indigenous species are observed inhabiting the brown seaweed (four amphipods: Aoroides longimerus, Aoroides semicurvatus, Monocorophium acherusicum, Monocorophium sextonae and one decapod: Hemigrapsus sanguineus). In spite of the presence of Non-Indigenous Species (NIS) associated with the invasive Sargassum, the ALEX yields a high Ecological Quality Status for all the sites. Nevertheless, the results suggest that S. muticum is a suitable habitat for many invertebrates especially amphipods and isopods, while also representing a potential source of food for several local fish and cephalopod species.

This study from January to December 2018 was the first initiative of a Port Baseline Survey (PBS) aimed at assessing the impact of biological invasions in harbours of the Gulf of Gabès (GG). A total of 12 fishing and industrial harbours were seasonally prospected during 2018. A total of 174 macrobenthos taxa were recorded, belonging to eight zoological groups, with a dominance of crustaceans (32%), molluscs (31%) and polychaetes (20%). Among these taxa, 57 were Non-Indigenous Species (NIS) for Tunisian waters, while 27 species were recorded for the first time in GG harbours and three decapods ( Dyspanopeus sayi, Hippolyte prideauxiana and Pilumnus minutus ) and one amphipod ( Hamimaera hamigera ) were newly recorded from Tunisian waters. Two main categories of harbours are distinguished according to their macrobenthic communities and environmental features (essentially edaphic factors). The industrial harbours yield higher numbers of species and abundance of NIS than the fishing ports. The ALEX metric is used to evaluate the biological invasion status of the Gulf of Gabès harbours, showing that their status ranges from unaffected in fishing harbours to extremely affected in industrial harbours. Three biotic indices (AMBI, BO2A and BENTIX) are applied to assess the ecological status of harbours, which varies from moderate to good. ALEX and the other biotic indices are significantly correlated with harbour characteristics, maritime traffic and edaphic factors (organic matter and chemical contamination). The present study gives an overview of all available benthic data, the impact of biological invasions and the ecological quality status of harbours in the Gulf of Gabès. The results could be considered as providing important baseline data for the implementation of environmental policies and management plans in the future.

International audience; The French coast of the Atlantic and English Channel (EC) is promising for the development of Marine Renewable Energy (MRE), including wind, wave, and tidal stream, due to the high velocity of currents in some parts of the area. This paper, focusing on wind and tidal energy, discusses how the implementation of MRE converters influences biodiversity, and vice versa, through biofouling and reef effects. The understanding of these interactions requires the knowledge of the hydro-sedimentary conditions and the macrofauna. The research on these topics, performed at the Continental and Coastal Morphodynamic laboratory (M2C) (UNICAEN, France), is presented through a multi-disciplinary approach by i) studying the hydrodynamic conditions and the macrofauna in Alderney Race, ii) studying the biofouling effects on tidal turbines and their influence on the turbulent wake, iii) assessing the hydro-sedimentary impacts induced by the offshore wind farm, like scouring, and iv) taking an ecosystem approach on MRE, such as the reef effect. From an ecological perspective, the reef effect can be responsible for changes in the structure and function of the ecosystem. Although several studies have analyzed this effect at the species-or community-scale, the propagation of the reef effect at the ecosystem-scale remains unclear. Thus, understanding these ecosystem-scale effects is urgent for future research. From an engineering perspective, biofouling changes the structural characteristics (i.e., supplementary mass) of the converters and thus, affects their performance.

International audience; A yearlong seasonal survey was carried out during 2016–2017 at 26 stations representing four tidal channels of the north-western part of the Gulf of Gabès (Tunisia). The area studied (characterized by a maximum tidal range of 2.3 m) was subjected to diverse anthropogenic pressures: from the phosphate industry and its metallic pollution, unauthorized bottom trawling in shallow water (known locally as ‘Kiss’), and organic pollution from the nearby urbanized areas. A total of 23,506 invertebrates representing 311 taxa were collected. Dominant taxa were the polychaetes with 51.4% of the individuals collected and 39.3% of the taxa, the amphipods (18.6% and 15.5%), the tanaids (12.3% and 2.6%), and the molluscs (11.5% and 18.3%). The mean annual abundances varied widely from one channel to another: from 300 to 3700 ind·m−2. The stations located in deeper waters exhibited greater variability. Measurements of abundance revealed seasonal changes with maximum values in winter, spring, and lower numbers in summer. Each tidal channel was characterized by specific features in the fauna. The macrofauna were dominated by the polychaete Cirratulus cirratus (mainly in spring) and the amphipod Microdeutopus anomalus (mainly in winter), whilst both of the tanaids, Apseudopsis gabesi (the first sighting reported for the area) and A. mediterraneus, were found to be abundant in winter in at least one of the four channels. Species are mainly deposit feeders, herbivorous and omnivorous. The analyses on spatial and temporal changes of the macrofauna population revealed variations according to the composition of the fauna increasing or falling along the channels and as a function of seasonal changes. In spite of a high level of anthropogenic activities, the Ecological Status (ES) assessment (applying the AMBI and M-AMBI indices) attributed High or Good ES for 10 stations, Moderate ES for 11 stations and five stations showed a poor ES at least during one season. Sampling subtidal stations in the future to survey long-term degradation of such ecosystems of the coastal environment of the Gulf of Gabès in Tunisia is proposed.

(IF 4.95; Q1); International audience; The “Rade de Cherbourg” (RdC, Cotentin) hosts the only marine salmon fish farm along the French coasts. High hydrodynamic regime would limit, there, organic matter (OM) accumulation directly under the cages, and enhance the transport of OM in the surrounding of the cages. This study was aiming at (1) monitoring the impact of a salmon fish farm on ecological quality statuses (EcoQs) of the RdC based on a benthic foraminiferal biotic index, (2) comparing EcoQs assessment results between foraminifera and macrofauna, and (3) in fine assessing the potential for benthic foraminifera to become an alternate biological quality element. In 2014 and 2015, bottom sediments of the RdC were sampled at 13 stations under and outside the farm for sedimentary (grain size and OM), and living foraminiferal and macrofaunal analyses. For benthic foraminifera, Exp(H’bc) was used to determine EcoQs, while H’, AMBI and BO2A indices were used for benthic macrofauna. Rank-frequency distributions (RFDs) were calculated for both groups. Ecological quality statuses based on foraminifera and macrofauna indicated a moderate degradation of the environmental conditions, shifting from excellent outside the farm to poor under the cages for foraminifera and from excellent to moderate for macrofauna. This study showed that benthic foraminifera are as reliable as macrofauna to assess EcoQs in the RdC. It offers interesting perspectives to monitor the health of marine systems based on benthic foraminifera. Furthermore, results obtained with RFDs suggested that this approach should be considered in the assessment of the good environmental status within the European marine strategic framework directive. Finally, diversity proved to be efficient in monitoring the health of the RdC, suggesting that it should not be set aside for the benefit of sensitivity-based indices.

International audience; From collected data analyzed to produce an inventory of all polychaetes in Algerian waters, the diversity of this group was estimated as 534 species. The largest families are Syllidae (66 species), Spionidae (37 species) and Terebellidae (27 species). The presence of those listed species along the Algerian coast was compared with their occurrence in nine other areas of the Mediter-ranean Sea, in the Black Sea and in four other more distant seas around the world. Comparisons are also made with respect to the biogeographical origin for each species. The polychaete fauna of the Algerian coast is among the richest of the Mediterranean Sea and comparable to the diversity reported for the French Mediterranean continental shelf and that in the Aegean Sea, but higher that that found in the nearby coastlines of Morocco and Tunisia. Most of the species found have an Atlantic origin and are present in the western Mediterranean Sea. This current inventory includes eight non-indigenous polychaete species found in the Algerian waters.

(IF 2.93; Q1); International audience; As part of the energy transition, the French government is planning Offshore Wind Farm (OWF) constructions in the next decades. An integrated ecosystem approach of two future OWF sites of the Eastern English Channel (Courseulles-sur-mer and Dieppe-Le Tréport) was developed to model the marine ecosystems before the OWF implementation. Such ecosystem models allow simulating the possible reef and reserve effects associated to the presence of the farm, and to character the overall changes in the food-web functioning. This holistic view of OWF effects could be replicated on other sites and form the basis of an ecosystem based management of marine renewable energies. However, to use these models for management purpose, they need to be validated. In order to do so, stable isotope ratios of nitrogen were used for determining the accuracy of the effective trophic levels computed in these two models. Results showed that trophic levels estimated by the two models were consistent with the trophic levels estimated by the independent isotopic data. In the context of OWF development and cumulative impacts analysis, this step of validation of the models is essential for developing their use by management actors and policy makers. © 2020 Elsevier Ltd

The Bay of Seine (Normandy coast of the English Channel) is a highly impacted ecosystem concerned by numerous human activities. It is subjected to heavy historic anthropogenic pressures and the emergence of new human activities: fishing, harbour extension, aggregate extraction, deposition of dredged sediment, and offshore wind farms. By contrast, this area shows a high level of protection of its natural heritage, mainly owing to the Natural Reserve and Natura 2000 sites. Moreover, an accumulation of research projects has ensured the acquisition of a high level of scientific knowledge and high-quality ecological data in this area. However, there is a lack of a systematic approach taking into account the available data. By building maps of benthic habitats, food-web modelling and calculating ecological indicators, we are able to take the first steps towards an ecosystem-based management. These integrative approaches allow us to assess the ecological quality status of the Bay of Seine and the Seine estuary. Trophic models based on the quantification of energy and matter fluxes in ecosystems, as well as indices derived from ecological network analysis, are used to describe the interaction between species across all trophic levels. When applied to spatial models, ecological functioning and ecosystem health can be assessed in different areas of the ecosystem. In the Bay of Seine, benthic habitats display high resilience while pelagic, fish and bird compartments have been shown to be highly modified, due to hydrological and climatic changes. The North Channel and the Navigation Channel of the Seine estuary appear to be far more intensely stressed, while the South Channel and marine areas of the Bay show a more mature functioning. Our conclusions reveal the need to consider the influence of human pressures on the functioning of complex ecosystems, thus providing an integrated approach that can be used to study a social-ecological system affected by global changes and investigate the cumulative impacts of human activities.

(IF 0.68; Q3); International audience; Among the Erymidae Van Straelen, 1925, known as early as the Late Permian (Changhsingian) and widespread in the Jurassic, the genus Enoploclytia M’Coy, 1849 seems to have a late appearance because of its lack before the Cretaceous. Until now, the oldest representative was E. augustobonae Devillez, Charbonnier, Hyžný and Leroy, 2016 from the Early Cretaceous (Barremian) of the eastern Paris basin (France). However, a new fossil collected in Normandy (France), showing the typical carapace groove pattern of Enoploclytia, attests the presence of the genus in the Late Jurassic (Oxfordian).; Parmi les Erymidae Van Straelen, 1925, connus dès le Permien supérieur (Changhsingien) et répandus au Jurassique, le genre Enoploclytia M’Coy, 1849 passe pour être apparu tardivement en raison de son absence avant le Crétacé. Jusqu’à présent, le plus ancien représentant était E. augustobonae Devillez, Charbonnier, Hyžný et Leroy, 2016 du Crétacé inférieur (Barrémien) de l’est du bassin de Paris (France). Cependant, un nouveau fossile récolté en Normandie (France), présentant une architecture des sillons de la carapace typique d’Enoploclytia, atteste de la présence du genre dès le Jurassique supérieur (Oxfordien).

An experimental artificial structure was deployed in March 2014 on the intertidal zone of the Bay of Seine (eastern part of the English Channel), at intervals of one year until April 2018, i.e., from February 2015 onwards, two blocks were collected in April each year. This study provides an inventory of sessile and motile invertebrates living on the artificial hard-bottom and describes the stages of colonization and succession during the four-year study. A total of 84 taxa were identified including 13 sessile and 71 motile taxa. For the sessile fauna, only two taxa Balanus crenatus and Mytilus edulis had colonised the blocks in 2014, and the Taxonomic Richness (TR) was relatively stable during the next three years (between 8 and 10 taxa). The TR of the motile fauna showed an increase between 2014 (5 taxa) and 2015 (34 taxa), and then decreased from 54 taxa in 2017 to 29 taxa in 2018. The abundance of the sessile fauna was very high in 2014 due to the rapid settlement of the barnacle Balanus crenatus, which remained the dominant species throughout the study. Another barnacle Perforatus perforatus, the blue mussel Mytilus edulis and three ascidians including two non-indigenous species Perophora japonica and Corella eumyota, and Molgula sp. were also among the dominant taxa of the sessile fauna. In April 2014, the dominant motile taxa was the decapod Carcinus maenas juvenile, then in 2015 the fauna became dominated by pioneer taxa such as the amphipod of the genus Monocorophium and the tanaid Zeuxo holdichi. A reduction of mean abundance was observed in the last three years of the study, combined with diversification of the dominant species especially those of small size such as Peracarida. The study shows that the colonization of such blocks deployed on oyster tables in the intertidal zone is efficient to test the ability of building material to be colonized in this transition zone.

Marine renewable energy developments (MREDs) are rapidly expanding in size and number as society strives to maintain electricity generation whilst simultaneously reducing climate-change linked CO2 emissions. MREDs are part of an ongoing large-scale modification of coastal waters that also includes activities such as commercial fishing, shipping, aggregate extraction, aquaculture, dredging, spoil-dumping and oil and gas exploitation. It is increasingly accepted that developments, of any kind, should only proceed if they are ecologically sustainable and will not reduce current or future delivery of ecosystem services. The benthos underpins crucial marine ecosystem services yet, in relation to MREDs, is currently poorly monitored: current monitoring programmes are extensive and costly yet provide little useful data in relation to ecosystem-scale-related changes, a situation called ‘data-rich, information-poor’ (DRIP). MRED –benthic interactions may cause changes that are of a sufficient scale to change ecosystem services provision, particularly in terms of fisheries and biodiversity and, via trophic linkages, change the distribution of fish, birds and mammals. The production of DRIPy data should be eliminated and the resources used instead to address relevant questions that are logically bounded in time and space. Efforts should target identifying metrics of change that can be linked to ecosystem function or service provision, particularly where those metrics show strongly non-linear effects in relation to the stressor. Future monitoring should also be designed to contribute towards predictive ecosystem models and be sufficiently robust and understandable to facilitate transparent, auditable and timely decision-making.

The establishment of benthic marine habitat maps plays an important role in the conservation and management of coastal ecosystems faced with the increasing impacts of human activities. The Bay of Seine, bordering the eastern part of the English Channel, is an area undergoing considerable cumulative impacts, and which consequently requires a synthesis of our knowledge of the ecological status of its benthic habitats. Fortunately, numerous benthic sampling campaigns have been carried out over the last two decades, mainly in the eastern and western shallow parts of the bay. These campaigns have led to the construction of a database, allowing statistical analyses at the scale of the whole area which are then used to produce maps. Nevertheless, it appears that maps constructed using existing Natura 2000, EUNIS (European Nature Information System), and French MNHN (Museum National d’Histoire Naturelle) typologies are not enough detailed to distinguish the mosaic of habitats of the Seine estuary. It is indispensable to add expert judgements concerning local areas to updated maps of the benthic communities in the Bay of Seine. Several Natural Zones of Interest for Ecology in terms of Flora and Fauna named ‘ZNIEFF-Marine’ areas have been identified, which could be useful in the future in the context of marine Natura 2000 sites for the management and conservation of endangered marine habitats in this maritime zone subject to highly conflicting interests.

(IF 5.71 [2018]; Q1); International audience; Anthropogenic activities including coastal industries, urbanization, extensive agriculture and aquaculture as well as their cumulative impacts represent major sources of perturbation of marine coastal systems. Macrobenthic communities are useful ecological indicators for monitoring the health status of marine environments (or polluted environments). The present study reports, for the first time, the response of benthic macrofauna sampled during two years survey (2015–2016) to multiple anthropogenic pressures on the coastal zone south of Sfax (Tunisia). A total of 12 stations were monitored seasonally at locations downstream from the main potential sources of disturbance. 106 macrobenthos taxa, belonging to six animal phyla and 70 families, were identified with a dominance of polychaetes (42%), crustaceans (35%) and molluscs (18%). We used an ANOVA test and cluster analysis to identify spatial gradient linked to environmental and anthropogenic factors, including depth, sedimentary texture and anthropogenic activities (i.e. phosphogypsum discharges).The macrofauna present lowest species number and abundance on stations undergoing anthropogenic inputs, which are extremely polluted by heavy metals (Cd, Cu, F and N) and excess of organic matter. Univariate parameters reveal a general trend of increasing species diversity with increasing distance from the pollution source. The polluted stations are strongly dominated by carnivores, and selective deposit feeders, and more closely linked to the availability of trophic resources than to anthropogenic constraints. The seasonal changes in macrobenthic abundance, diversity indices and community structure are mainly linked to the biological cycle (e.g. recruitment events) of the dominant species. Biotic indices (AMBI and BO2A) classified the coastal zone south of Sfax as moderate and good ecological status. This study suggests that initiating a long-term monitoring programme would improve our understanding of the temporal changes of macrobenthic communities of this ecosystem, contributing to the assessment of effective management and conservation measures in this disturbed area.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]QUASARE [ADD1_IRSTEA]Dynamique et fonctionnement des écosystèmes(IF 4.49 [2018]; Q1); International audience; A combination of modelling tools was applied to simulate the impacts of the future Courseulles-sur-mer offshore wind farm (OWF) construction (Bay of Seine, English Channel) on the ecosystem structure and functioning. To do so, food-web models of the ecosystem under three scenarios were constructed to investigate the effect caused by the OWF of added substrate (reef effect), fishing restriction (reserve effect), and their combined effect. Further, Ecological Network Analysis indices and Mean Trophic Level were derived to investigate their suitability for detecting changes in the ecosystem state. Our analysis suggests changes in the ecosystem structure and functioning after the OWF construction, the ecosystem maturity was predicted to increase, but no alterations in its overall resilience capacity.

(IF 0.78 [2018]; Q3); International audience; Two galatheoid anomurans, Gastrosacus raboeufi n. sp. and G. sp., the earliest members of the genus Gastrosacus von Meyer, 1851 known to date, are recorded from upper Bathonian strata in Calvados (Normandy, France). In this respect, we consider the enigmatic Palaeomunidopsis moutieri Van Straelen, 1925 from the middle Bathonian of Giberville (Normandy) to be a nomen dubium. As far as carapace morphology of G. raboeufi n. sp. is concerned, we note that it reveals a number of primitive characters that are indicative of a close relationship with the Gastrodoridae amongst paguroid anomurans.

(IF 1.74 [2018]; Q2); International audience; The mysid Neomysis americana (S.I. Smith, 1873), which originates from North-American estuaries, was reported for the first time in 2017 in the Seine estuary (English Channel, France). This sighting represents the second reported occurrence of this species in Europe, following the record of two individuals in 2010 in the Wadden Sea (Netherlands). Its appearance seems recent since no individuals were recorded in previous intensive sampling carried out in the navigational channel and North Channel of the Seine estuary since the middle of the 1990s. In 2017, a total of 2674 individuals of N. americana were sampled, showing the rapid establishment of a reproductive population which was favorised by the decline of the autochthonous population of Neomysis integer (Leach, 1814).

International audience; Since the beginning of the 2000’, the French government ambition was to have an offshore wind production formed 40% of the renewable electricity in 2030. Three calls tenders of Offshore Wind Farms (OWFs) construction have been pronounced since 2011. However, no offshore wind farm (OWF) had been constructed at the end of 2017 due to long administrative procedures and numerous appeals in justice, at French and European levels. Nevertheless, several studies have been enterprised to identify the environmental conditions and ecosystem functioning in selected sites before OWF implantations. However, these studies are generally focused on the conservation of some species or groups of species, and there is no holistic study on the effects of the construction and operation of OWF on an ecosystem taken as a whole. In 2017, a complete and integrated view of the ecosystem of two future OWF sites of the eastern English Channel (Courseulles-sur-Mer and Dieppe-Le Tréport) was developed to model the marine ecosystems before OWF implementation and to simulate reef effects due to new spatial occupation of maritime territory. Results contribute to a better knowledge of the impacts of the OWFs on the functioning of marine ecosystems. They also allow to define recommendations for environmental managers and industry in terms of monitoring the effects of marine renewable energy (MRE), not only locally but also on other sites, at national and European levels.

(IF 1.20 [2018]; Q2); International audience; Here we report the first record of the red mouthed rock shell Stramonita haemastoma (Linnaeus, 1767) (Gastropoda, Muricidae) a predatory gastropod newly introduced to the English Channel. This species originally lives in the western Atlantic, eastern Pacific and Mediterranean Sea. Three specimens were collected on Pecten maximus at St-Martin-de-Bréhal, Normandy, France, on 2 February 2018. We present some hypotheses about the mode of introduction of S. haemastoma and its potential impact on the ecosystem in the English Channel.

The impact of 70 years of dumping harbour dredged material on ecosystem functioning was compared to a control site (non-impacted zone). A combination of indices (Shannon-Wiener diversity, Pielou evenness, BO2A, AMBI benthic indices) and modelling (Ecopath models) generated Ecological Network Analysis indices were used to detect the dumping operations effects. ENA indices showed that dumping operations appear to have a relatively limited impact on the structure and flow pattern of the local food web. In fact, only small variations between the two sites are revealed by a comparison of ENA indices between the impacted and non-impacted zone. This result could be explained by the fact that the Bay of Seine is historically characterized by a high level of human activities, which have led to an increase in resilience through time to face these multiple pressures. AMBI and BO2A indices (of the sediment fauna) did not allow a clear distinction between impacted and non-impacted zone while species richness, abundance, biomass and Shannon-Wiener diversity index values were significantly higher in the non-impacted zone which is in accordance with the small variations of ENA indices between the two zones and revealed a local and limited impact. Our results suggested that a combination of several tools should be used to detect the true impacts and to conduct diagnosis of the ecological status of dumping deposit in a coastal area permanently stressed under natural and anthropogenic forcing.

Responding to pressure to combat climate change by cutting greenhouse gasses emission, Offshore Wind Farm (OWF) is currently the most developed of all the renewable energy options that are based in the marine environment. However, despite its perceived benefits, OWF construction will also lead to direct and indirect impacts on the ecosystem. Nonetheless, surprisingly few studies have sought to combine trophic web modelling tools with the framework of OWF impact assessment. The objective of this study was to develop a holistic and integrated ecosystem approach as a complementary methodology to the traditional OWF environmental impact assessment. To that end, trophic web models coupled with Ecological Network Analysis indices were used to study the structure and functioning of three sedimentary types (sandy gravel, gravelly sand, and medium sand), identified on the proposed site for a new offshore wind farm at Dieppe-Le Treport (Normandy coast). The results from this study demonstrated that the trophic structures are strongly linked to the sedimentary types. The results also highlighted the existence of a maturity gradient moving between the three types of sediment identified. This study underlined the challenge and the need to have detailed biomass data on a maximum of biological compartments to enable an effective OWF impact assessment. We strongly consider that our approach will provide useful and practical information for environmental decision-makers and stakeholders. The same approach can be applied to other new OWF constructions in European or international waters.

International audience; At present, there are few operational indexes to assess the impact of a given human pressure taken alone. Nevertheless, the current challenge in the management of coastal marine environments in the framework of cumulative impacts and climatic change is to identify the relative contribution of each activity on ecosystem functioning. The objective of the present study is to propose an integrative approach to assess the environmental impacts of dumping operations, via the development of a new index, the Dredge Disposal Sediment Index (D2SI). From the selection of two types of station: impacted and unimpacted, D2SI integrates six sub-indices considering the biological and physical changes generated by dredge disposal on the seabed. A final score is proposed, according to the five classes of the European Water Framework Directive. The initial development of D2SI was conducted on the experimental dumping site of Machu (Bay of Seine), by applying a BACI (Before-After-Control-Impact) approach. An additional implementation (D2SI2) is used in the case of absence of data on ichthyofaunal or biological traits of life of macrobenthic fauna, which yields a comparable assessment of dumping pressure.In the future, the D2SI or D2SI2 indexes should be tested on other dumping sites with a view to comparing the assessment of this dumping activity.

(IF 3.02 [2018]; Q1); International audience; The Rade de Cherbourg (RdC), in the North Cotentin (Normandy, English Channel) is the only French coastal zone where an offshore salmon farm has been in operation over the past three decades. Our study leads to the identification of the Ecological Quality status of benthic habitats based on a one-year survey (2013–2014) underneath and near the cages as well as in non-impacted areas lying outside the influence of salmon farming. The semi-diurnal high tide regime of the Rade de Cherbourg (5 to 8 m tidal range from neap to spring tide) should prevent any significant accumulation of Organic Matter (OM) under the cages. Nevertheless, higher Total Organic Carbon (TOC) and the presence of opportunistic species at sampling stations under and near the cages indicate an impact of salmon farming on the benthic habitats. Three benthic assemblages are identified, corresponding to three sediment types with different levels of OM enrichment. The presence of several indicator species, such as the polychaete worm Capitella minima belonging to the Capitellidae, reflects the local impact of fish farming without long-term accumulation of OM in the shallow waters of the RdC. Moreover, one of the main characteristics of the macrofauna of the RdC and neighbouring zones is the current very high abundance and dominance of the tanaid Apseudopsis latreillii in diverse sediment types. Benthic indices (AMBI, M-AMBI, and BO2A) were also able to distinguish three main zones in relation to the distance to salmon cages.

(IF 4.49; Q1); International audience; A one-year experimental study was conducted in 2012–2013 to assess the physical and biological impacts of dumping dredge spoil composed of muddy fine sand (1 million m3) in a benthic zone with medium-grained sands in the eastern part of the Bay of Seine. Previous study showed that the impact is local and the benthic habitats show a high degree of resilience after a short dumping phase and the recovery of the community is observed just after cessation of the disturbance. Moreover, during the deposition phase, Impacted and Influenced zones can be distinguished from a Non-impacted zone. A combination of indices (BO2A, AMBI benthic indices) and modelling tools were applied to study the dumping dredge spoil impact. Results highlighted that these different indices allowed detecting the dumping operations effects. In addition, results from the AMBI et BO2A indices revealed that the system showed a high resilience after a short dumping phase. Lastly, the macrofauna and demersal fishes appear to be stimulated in the Influenced zone during the dumping phase, thus supporting the Intermediate Disturbance Hypothesis.

(IF 2.07; Q1); International audience; The spatial and temporal species richness, abundance and assemblage structure of amphipods from four tidal channel of the Gulf of Gabès were studied at 26 stations and during four seasons from March 2016 to January 2017. This led to the identification of 4,378 individuals, 45 species and 21 families. The four mostly diversified families are the Ampeliscidae (6 species), the Caprellidae (5) and the Aoridae and Maeridae (4 species both), while three families account for ~ 75% of the individuals: Aoridae (45.5 %), Corophiidae (20.5%) and Dexaminidae (7.2%). The species richness and abundance are higher in winter than at other seasons. The fauna is dominated by a small number of species characteristic of areas with detritus accumulation and seagrass meadows, including Microdeutopus anomalus, Monocorophium acherusicum, Dexamine spinosa, Microdeutopus gryllotalpa, Cymadusa filosa and Elasmopus rapax, which are commonly recorded in lagoons and coastal shallow waters of the Mediterranean Sea. The amphipod structure is linked to the location of tidal channels in the Gulf of Gabès. Abundances are low in the Kerkennah channel compared with other channels, especially the Maltine channel with high winter accumulation of organic matter. There are also low abundances in high-energy hydrodynamic zones with gravel sediment; conversely, the presence of macrophytes, mainly in the seagrass meadows, increases amphipod diversity. As a result of this study, five new species can be added to the inventory of the Tunisian marine amphipod fauna, including a non-native species for the Mediterranean Sea, Paracaprella pusilla.

The European seas are known to be the recipient of several hundreds of Non-Native Species (NNS) due two main origins: shipping and aquaculture. More than 160 NNS had been recorded along the Normandy coast, which remains low in comparison with the number of marine invertebrate species known in the English Channel (> 3,000). The main sites of introduction are the harbours, especially Le Havre and the oyster cultivation zones. Among these NNS, 56 are present in Normandy and considered invasive along the European coasts, but only ten (one macro-algae and nine invertebrates) are invasive in Normandy. Six examples are illustrate, the molluscs Magallana gigas, Crepidula fornicata, Ensis leei, and Ruditapes philippinarum, the polychaete Ficopomatus enigmaticus and the crab Hemigrapsus sanguineus. The two first species have changed the dynamics and functioning of the coastal ecosystems, while the others have lower impact. In fact, the oyster and the manila clam are now key species for the French economy, while the rapid expansion of the other species change biodiversity in the more colonised sites. The ALEX (ALien Biotic IndEX) proposed by Cinar and Bakir in 2014 for the Mediterranean Sea is used for the first time in Atlantic waters.

The polychaete Chaetopterus variopedatus lives in large, leathery U-shaped tubes in subtidal sands or gravel. The species is scarcely distributed in the English Channel and thus not easy to find. The studied animals and their associated fauna originate from beam trawls or were washed up on beaches in Normandy. In the upper part of the tube, near the prostomium of C. variopedatus, we found the following commensal species: the crab Asthenognathus atlanticus and the polychaetes Harmothoe glabra and Gattyana cirrhosa. For the tropical-temperate crab A. atlanticus our findings represent an extension of its geographical range. Moreover, at the tube’s extremity several epifaunal species were present, among them the ascidian Styela clava, an introduced species from Japan. Undoubtedly, tubes of C. variopedatus provide an excellent habitat for associated species and further studies involving the interaction of the host and its commensals could prove very interesting. Our results suggest also that these tubes represent a stepping-stone habitat for the introduction of non-native species and the geographical extension of tropical-temperate species in the English Channel.

The Gulf of Gabès on the southern coasts of Tunisia in the central part of the Mediterranean is a very shallow basin, characterized by semidiurnal tides, attaining a range of 2.3 m during spring tides. The intertidal zone was covered by extended Zostera (Zosterella) noltei Hornemann, 1832 beds mainly developed around the Kneiss Islands while tidal channels ensured the water circulation in this sub-tropical environment with very low freshwater input and high summer temperature. In spite of protected conventions, the area remained under high human pressures: overfishing, and the impact of the pollution of the phosphate industry. Intensive sampling in both intertidal and shallow subtidal zones during annual cycles permitted to identify a rich macrofauna which increase considerably the species known in this eastern part of the Mediterranean Sea. More than 50 species are added for the Tunisian fauna. Moreover, patterns of diversity are analysed with the sediment types, presence or absence of Zostera noltei seagrass bed, and human pressures. The list of the collected species are compared with those of surrounding areas in both Western and Eastern Mediterranean Sea.

International audience; The eastern part of the English Channel (north-eastern Atlantic) in a megatidal environment is one of the most impacted area in the world wide ocean. To the traditional fish activities and maritime transports with dredging and deposit spoil sediment which impact the ecosystem, aggregate extractions and implementation of offshore wind farms increase the pressures in this shallow epicontinental sea. The soft-bottom sea bed was mainly covered by sandy gravels and gravelly sand located offshore under high tidal currents while medium sand and muddy fine sand were deposit along the coast in area with weak currents. A large number of benthic indices had been recently developed mainly to the implementation of the European Water Framework Directive, but to structural assessment, development of more integrate method such as Ecological Network Analysis with the Ecopath model permit to furnish a functional assessment of the benthic habitats. Several studies in diverse sediment type under human pressures or future activities with reef and protected scenarios within an offshore windfarm permit to evaluate the suitability of structural and functional indices to reveal spatio-temporal statutes and changes of the Ecological Status of the benthic ecosystems.

(IF 3.78; Q1); International audience

(IF 2.87; Q1); International audience; As part of the energy transition, the French government is planning the construction of Offshore Wind Farms (OWFs) in Normandy. These OWFs will be integrated into an ecosystem already facing multiple anthropogenic disturbances. A holistic view of cumulated impacts (OWF construction, global warming and fisheries) were developed on the Courseulles-sur-Mer’ ecosystem through the use of a qualitative mathematical modelling approach. This modelling approach provides the mean to consider alternative hypotheses about how the ecosystem structure and function affects its dynamics. Alternative models were constructed to address the different hypotheses regarding the behaviour of top predator (whether the top predators will be scared away by the OWF or attracted by the reef effect), impacts of global warming and changes in fisheries activities. Key findings from these analyses are that the OWF construction could lead to an increase in benthos species and fish benthos feeders whatever the perturbation scenario, while the predicted response of top predators was ambiguous across all perturbation scenario. Qualitative modelling results can play a vital role in decision making by improving long term planning for the marine environment but also as a tool for communication with the public and so contribute to a better acceptability of the Marine Renewable Energy (MRE) project.

The French government is planning the construction of offshore wind farms (OWF) in the next decade (around 2900 MW). Following the European Environmental Impact Assessment Directive 85/337/EEC, several studies have been undertaken to identify the environmental conditions and ecosystem functioning at selected sites prior to OWF construction. However, these studies are generally focused on the conservation of some species and there is no holistic approach for analysing the effects arising from OWF construction and operation. The objective of this article is to promote a sampling strategy to collect data on the different ecosystem compartments of the future Dieppe-Le Tréport (DLT) wind farm site, adopting an ecosystem approach, which could be applied to other OWFs for the implementation of a trophic network analysis. For that purpose, an Ecopath model is used here to derive indices from Ecological Network Analysis (ENA) to investigate the ecosystem structure and functioning. The results show that the ecosystem is most likely detritus-based, associated with a biomass dominated by bivalves, which could act as a dead end for a classic trophic food web since their consumption by top predators is low in comparison to their biomass. The systemic approach developed for DLT OWF site should be applied for other French and European installations of Offshore Wind Farm.