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6 results on '"Marie Cachera"'

1. Dynamic Coastal-Shelf Seascapes to Support Marine Policies Using Operational Coastal Oceanography: The French Example

Author

Marie Cachera, Victor Quilfen, Martial Boutet, and Emilie Tew-Kai

Subjects
0106 biological sciences, Water mass, 010504 meteorology & atmospheric sciences, Good Environmental Status, Ocean Engineering, Context (language use), 01 natural sciences, Marine Strategy Framework Directive, lcsh:Oceanography, lcsh:VM1-989, lcsh:GC1-1581, Categorical variable, Spatial planning, 0105 earth and related environmental sciences, Water Science and Technology, Civil and Structural Engineering, geography, geography.geographical_feature_category, EOVs, business.industry, 010604 marine biology & hydrobiology, marine policy, Environmental resource management, ocean partitioning, lcsh:Naval architecture. Shipbuilding. Marine engineering, operational coastal oceanography, seascapes, Seascapes, Environmental science, hydrographical patches, business, Channel (geography)
Abstract

In the context of maritime spatial planning and the implementation of spatialized Good Environmental Status indicators in the Marine Strategy Framework Directive (MSFD), the definition of a mosaic composed of coherent and standardised spatial units is necessary. We propose here a characterization of seascapes in time and space within the specific framework of the MSFD in the English Channel and the Bay of Biscay areas. A spatio-temporal classification of coastal-shelf water masses is carried out using twelve essential oceanographic and derived variables from operational coastal oceanography using the HYCOM model. Partitioning is computed using a multivariate hybrid two-step clustering process defining a time series of categorical maps representing hydrographical patch classes. Main patch occurrence is analyzed to understand their spatio-temporal dynamics and their oceanographic characteristics. Finally, patch classes are combined with MSFD marine sub-region delimitations to build seascapes, including ecosystem approach management and marine policy considerations.

Published
2020

2. Reorganization of a marine trophic network along an inshore–offshore gradient due to stronger pelagic–benthic coupling in coastal areas

Author

Sébastien Lefebvre, Bruno Ernande, Marie Cachera, Dorothée Kopp, Maria Ching Villanueva, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), and Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord])

Subjects
0106 biological sciences, geography, geography.geographical_feature_category, δ13C, Ecology, Continental shelf, 010604 marine biology & hydrobiology, Geology, Pelagic zone, δ15N, Aquatic Science, 010603 evolutionary biology, 01 natural sciences, Food web, Oceanography, [SDU]Sciences of the Universe [physics], Benthic zone, Environmental science, Submarine pipeline, 14. Life underwater, Trophic level
Abstract

International audience; Recent theoretical considerations have highlighted the importance of the pelagic-benthic coupling in marine food webs. In continental shelf seas, it was hypothesized that the trophic network structure may change along an inshore-offshore gradient due to weakening of the pelagic-benthic coupling from coastal to offshore areas. We tested this assumption empirically using the eastern English Channel (EEC) as a case study. We sampled organisms from particulate organic matter to predatory fishes and used baseline-corrected carbon and nitrogen stable isotope ratios (δ13C and δ15N) to determine their trophic position. First, hierarchical clustering on δ13C and δ15N coupled to bootstrapping and estimates of the relative contribution of pelagic and benthic carbon sources to consumers' diet showed that, at mesoscale, the EEC food web forms a continuum of four trophic levels with trophic groups spread across a pelagic and a benthic trophic pathway. Second, based on the same methods, a discrete approach examined changes in the local food web structure across three depth strata in order to investigate the inshore-offshore gradient. It showed stronger pelagic-benthic coupling in shallow coastal areas mostly due to a reorganization of the upper consumers relative to the two trophic pathways, benthic carbon sources being available to pelagic consumers and, reciprocally, pelagic sources becoming accessible to benthic species. Third a continuous approach examined changes in the mean and variance of upper consumers' δ13C and δ15N with depth. It detected a significant decrease in δ13C variance and a significant increase in δ15N variance as depth increases. A theoretical two-source mixing model showed that an inshore-offshore decrease in the pelagic-benthic coupling was a sufficient condition to produce the δ13C variance pattern, thus supporting the conclusions of the discrete approach. These results suggest that environmental gradients such as the inshore-offshore one should be accounted for to better understand marine food webs dynamics.

Published
2015
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3. Benthic and fish aggregation inside an offshore wind farm: Which effects on the trophic web functioning?

Author

Aurore Raoux, Géraldine Lassalle, François Le Loc'h, Camille Le Guen, Nathalie Niquil, Jean-Philippe Pezy, Dan Wilhelmsson, Steven Degraer, Jean-Claude Dauvin, Karine Grangeré, Matilda Haraldsson, Bruno Ernande, Samuele Tecchio, Marie Cachera, Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Sorbonne Université (SU)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut de Recherche pour le Développement (IRD), Morphodynamique Continentale et Côtière (M2C), Centre National de la Recherche Scientifique (CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Ecosystèmes aquatiques et changements globaux (UR EABX), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Royal Belgian Institute of Natural Sciences (RBINS), The Royal Swedish Academy of Sciences, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), IFREMER Laboratoire Ressources Halieutiques (IFREMER Laboratoire Ressources Halieutiques), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ressources halieutiques Manche Mer du nord, IFREMER Centre Manche Mer du Nord, (HMMN), Institut de Recherche pour le Développement (IRD), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ressources halieutiques Boulogne sur mer (LRHBL), Halieutique Manche Mer du Nord (HMMN), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Biologie des Organismes et Ecosystèmes Aquatiques ( BOREA ), Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Muséum National d'Histoire Naturelle ( MNHN ) -Institut de Recherche pour le Développement ( IRD ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université des Antilles ( UA ), Morphodynamique Continentale et Côtière ( M2C ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Rouen Normandie ( UNIROUEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ), Ecosystèmes aquatiques et changements globaux ( UR EABX ), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture ( IRSTEA ), Royal Belgian Institute of Natural Sciences ( RBINS ), Laboratoire des Sciences de l'Environnement Marin (LEMAR) ( LEMAR ), Institut de Recherche pour le Développement ( IRD ) -Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ) -Université de Brest ( UBO ) -Institut Universitaire Européen de la Mer ( IUEM ), Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ), IFREMER Laboratoire Ressources Halieutiques ( IFREMER Laboratoire Ressources Halieutiques ), Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ), Institut Universitaire Européen de la Mer (IUEM), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)

Subjects
0106 biological sciences, Reef effect, 010504 meteorology & atmospheric sciences, General Decision Sciences, 01 natural sciences, [ SDE.IE ] Environmental Sciences/Environmental Engineering, Wind farm, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, Ecosystem model, Ecosystem-based approach, EcoSim, Ecosystem, 14. Life underwater, Ecology, Evolution, Behavior and Systematics, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Trophic level, Biomass (ecology), [ SDU.STU.OC ] Sciences of the Universe [physics]/Earth Sciences/Oceanography, Ecology, [SDE.IE]Environmental Sciences/Environmental Engineering, 010604 marine biology & hydrobiology, ACL, 15. Life on land, Marine renewable energies, Food web, [ SDV.EE.ECO ] Life Sciences [q-bio]/Ecology, environment/Ecosystems, Fishery, Offshore wind power, 13. Climate action, Benthic zone, Ecopath with Ecosim, Environmental science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract

International audience; As part of the energy transition, the French government is planning the construction of three offshore wind farms in Normandy (Bay of Seine and eastern part of the English Channel, northwestern France) in the next years. These offshore wind farms will be integrated into an ecosystem already facing multiple anthropogenic disturbances such as maritime transport, fisheries, oyster and mussel farming, and sediment dredging. Currently no integrated, ecosystem-based study on the effects of the construction and exploitation of offshore wind farms exists, where biological approaches generally focused on the conservation of some valuable species or groups of species. Complementary trophic web modelling tools were applied to the Bay of Seine ecosystem (to the 50 km 2 area covered by the wind farm) to analyse the potential impacts of benthos and fish aggregation caused by the introduction of additional hard substrates from the piles and the turbine scour protections. An Ecopath ecosystem model composed of 37 compartments, from phytoplankton to seabirds, was built to describe the situation " before " the construction of the wind farm. Then, an Ecosim projection over 30 years was performed after increasing the biomass of targeted benthic and fish compartments. Ecological Network Analysis (ENA) indices were calculated for the two periods, " before " and " after " , to compare network functioning and the overall structural properties of the food web. Our main results showed (1) that the total ecosystem activity, the overall system omnivory (proportion of generalist feeders), and the recycling increased after the construction of the wind farm; (2) that higher trophic levels such as piscivorous fish species, marine mammals, and seabirds responded positively to the aggregation of biomass on piles and turbine scour protections; and (3) a change in key-stone groups after the construction towards more structuring and dominant compartments. Nonetheless, these changes could be considered as limited impacts of the wind farm installation on this coastal trophic web structure and functioning.

Published
2017
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4. Assessing risk of underwater noise impact on marine mammals throughout a new methodology

Author

Florent Le Courtois, Marie Cachera, Marie Mauran, Yann Stephan, Jérôme Spitz, and G. Bazile Kinda

Subjects
Underwater noise, education.field_of_study, Acoustics and Ultrasonics, biology, Whale, business.industry, Population, Environmental resource management, Anthropogenic pressure, Noise, Trend analysis, Arts and Humanities (miscellaneous), Statistical analyses, biology.animal, Environmental science, Underwater, education, business
Abstract

Shipping noise has been identified as a threat on underwater ecosystems. In particular, several impacts have been documented on cetaceans, e.g., communication’s masking and stress increasing. To assess the risk related to such anthropogenic noise requires both quantifying the noise levels and estimating the distribution of the cetaceans’ population. However, current methods evaluating the risks related to anthropogenic pressures generally rely on strong expert priors, which may be difficult to define. This presentation aims at introducing a new framework for the comparison of anthropogenic pressure levels maps and cetaceans’ distribution in order to infer the risk of impact and provide management solutions. The methodology, combining simple statistical analyses and a theoretical representation tool was applied to the Bay of Biscay using shipping noise model and fin whale observation from regular surveys for the years 2012 and 2016. Relationships between cetaceans’ distribution and noise levels were investigated and linked to mammals theoretical responses to pressure. A trend analysis between 2012 and 2016 was also proposed to identify the noise hotspots. The results were interpreted in both terms of ecological meaning for fin whale and conservation measures for shipping noise, according to marine policies requirements.

Published
2018
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5. Evaluating ecosystem-level anthropogenic impacts in a stressed transitional environment: The case of the Seine estuary

Author

Marie Cachera, Nathalie Niquil, Justine Lequesne, Valérie Girardin, Jean-Claude Dauvin, Armonie Tous Rius, Aurore Raoux, Géraldine Lassalle, Samuele Tecchio, Philippe Riou, Jérémy Lobry, Aurélie Chaalali, Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Sorbonne Université (SU)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut de Recherche pour le Développement (IRD), Morphodynamique Continentale et Côtière (M2C), Centre National de la Recherche Scientifique (CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Laboratoire de Mathématiques Nicolas Oresme (LMNO), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Environnement et Ressources de Normandie, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Institut Français de Recherche pour l'Exploitation de la Mer - Atlantique (IFREMER Atlantique), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Ecosystèmes aquatiques et changements globaux (UR EABX), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Environnement Ressources de Normandie (LERN), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Biologie des Organismes et Ecosystèmes Aquatiques ( BOREA ), Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Muséum National d'Histoire Naturelle ( MNHN ) -Institut de Recherche pour le Développement ( IRD ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université des Antilles ( UA ), Morphodynamique Continentale et Côtière ( M2C ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Rouen Normandie ( UNIROUEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ), Laboratoire de Mathématiques Nicolas Oresme ( LMNO ), Normandie Université ( NU ) -Normandie Université ( NU ) -Centre National de la Recherche Scientifique ( CNRS ), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture ( IRSTEA ), Laboratoire des Sciences de l'Environnement Marin (LEMAR) ( LEMAR ), Institut de Recherche pour le Développement ( IRD ) -Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ) -Université de Brest ( UBO ) -Institut Universitaire Européen de la Mer ( IUEM ), Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ), and Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER )

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, Seine estuary, General Decision Sciences, Estuarine ecosystem, Ecological succession, Linear inverse model, 01 natural sciences, E3, media_common.cataloged_instance, Ecosystem, 14. Life underwater, European union, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, media_common, Trophic level, geography, Biomass (ecology), Ecosystem health, [ SDE.BE ] Environmental Sciences/Biodiversity and Ecology, English Channel, geography.geographical_feature_category, Ecology, 010604 marine biology & hydrobiology, ACL, Estuary, 15. Life on land, Food web, 13. Climate action, Environmental science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract

00000; International audience; During 2002–2005, a new container terminal in the commercial harbour of Le Havre, named “Port2000”, was built on the northern flank of the Seine estuary, northern France. This extension is already known to have modified the estuary current and sediment dynamics, as well as reducing biomass of the suprabenthos assemblage, for the whole downstream part of the system. However, studies on other biotic communities were largely inconclusive, and an ecosystem-wide analysis was still lacking. Here, we performed a before/after study of ecosystem dynamics of the different habitats of the Seine estuary, using a Linear Inverse Modelling technique (LIM-MCMC) to estimate all flows occurring in the food web. Ecological Network Analysis indices were calculated, summarising ecosystem functioning traits and giving indications about the habitat health status. Results showed that the southern flank (FS, Fosse Sud) exhibits all characteristics to be considered as the least stressed habitat of the estuary: system activity and functional specialisation of flows were stable between periods, ecosystem recycling processes and detrital dynamics were also stable; an increase in trophic specialisation (decrease in system omnivory) was the only change confirming a general ecological succession. The northern flank (FN, Fosse Nord), where the actual terminal was built, showed a food web with increased importance of lower trophic levels (increased detritivory and carbon recycling), increased stability and flow efficiency, but possibly regressed to a previous step in ecological succession. In the central navigation channel (CH), patterns of network indices were overall inconclusive and the general image is one of a constantly shifting food web, a condition possibly caused by the year-round dredging activities. The functioning of the Seine estuary – especially of FN and FS – seems to have been modified by the combination of harbour construction and the related mitigation measures. Network indices partially captured this combination of changes and, although not fully operational yet, they are promising tools to comply with the European Union mandate of defining ecosystem health status.

Published
2016
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6. The mosaic of habitats of the Seine estuary: Insights from food-web modelling and network analysis

Author

Samuele Tecchio, Aurélie Chaalali, Jérémy Lobry, Jean-Claude Dauvin, Nathalie Niquil, Marie Cachera, Géraldine Lassalle, Nicolas Bacq, Armonie Tous Rius, Jocelyne Morin, Maria Ching Villanueva, Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Morphodynamique Continentale et Côtière (M2C), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Écologie et Modèles pour l'Halieutique (IFREMER EMH), Institut Français de Recherche pour l'Exploitation de la Mer - Atlantique (IFREMER Atlantique), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Groupement d’Intérêt Public Seine-Aval (GIP-Seine-Aval), Université de Bordeaux (UB), Environnements et Paléoenvironnements OCéaniques (EPOC), Centre National de la Recherche Scientifique (CNRS), and Normandie Université (NU)

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Ecological network analysis, Trophic network, 01 natural sciences, EcoSim, Ecosystem, 14. Life underwater, 0105 earth and related environmental sciences, Trophic level, geography, Biomass (ecology), geography.geographical_feature_category, Primary producers, Ecology, 010604 marine biology & hydrobiology, Ecological Modeling, Estuary, Marine habitats, Food web, 15. Life on land, [SDE.ES]Environmental Sciences/Environmental and Society, 13. Climate action, Ecopath with Ecosim, Ecosystem health indicators, [SDE]Environmental Sciences, Environmental science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract

International audience; Ecological network analysis was applied in the Seine estuary ecosystem, northern France, integrating ecological data from the years 1996 to 2002. The Ecopath with Ecosim (EwE) approach was used to model the trophic flows in 6 spatial compartments leading to 6 distinct EwE models: the navigation channel and the two channel flanks in the estuary proper, and 3 marine habitats in the eastern Seine Bay. Each model included 12 consumer groups, 2 primary producers, and one detritus group. Ecological network analysis was performed, including a set of indices, keystoneness, and trophic spectrum analysis to describe the contribution of the 6 habitats to the Seine estuary ecosystem functioning. Results showed that the two habitats with a functioning most related to a stressed state were the northern and central navigation channels, where building works and constant maritime traffic are considered major anthropogenic stressors. The strong top-down control highlighted in the other 4 habitats was not present in the central channel, showing instead (i) a change in keystone roles in the ecosystem towards sediment-based, lower trophic levels, and (ii) a higher system omnivory. The southern channel evidenced the highest system activity (total system throughput), the higher trophic specialisation (low system omnivory), and the lowest indication of stress (low cycling and relative redundancy). Marine habitats showed higher fish biomass proportions and higher transfer efficiencies per trophic levels than the estuarine habitats, with a transition area between the two that presented intermediate ecosystem structure. The modelling of separate habitats permitted disclosing each one's response to the different pressures, based on their a priori knowledge. Network indices, although non-monotonously, responded to these differences and seem a promising operational tool to define the ecological status of transitional water ecosystems.

Published
2015
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