Consulta: creatorFacets:"Lefebvre, Sebastien"
Registros recuperados: 38
Data/hora: 01/06/2024 06:15:09

Body size-trophic position relationship in marine fish depends on biological and spatial scales
Provedor de dados: 5
Autores: Kopp, Dorothee; Lefebvre, Sebastien; Villanueva, Ching-maria; Ernande, Bruno.
-Food web structure can be partly characterized by species' trophic level - In marine fish, trophic level appears positively correlated to individual body size at the community scale (Jennings et al 2001) -Trophic level may change across sizes but also taxa, seasons, and habitats -Very few studies have addressed how size-dependence of trophic position varies in space, i.e. according to habitat, and whether observed community-scale patterns hold at the level of species or guilds.
Tipo: Text
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00163/27396/25627.pdf

Within outlying mean indexes: refining the OMI analysis for the realized niche decomposition
Provedor de dados: 5
Autores: Karasiewicz, Stephane; Doledec, Sylvain; Lefebvre, Sebastien.
The ecological niche concept has regained interest under environmental change (e.g., climate change, eutrophication, and habitat destruction), especially to study the impacts on niche shift and conservatism. Here, we propose the within outlying mean indexes (WitOMI), which refine the outlying mean index (OMI) analysis by using its properties in combination with the K-select analysis species marginality decomposition. The purpose is to decompose the ecological niche into subniches associated with the experimental design, i.e., taking into account temporal and/or spatial subsets. WitOMI emphasize the habitat conditions that contribute (1) to the definition of species' niches using all available conditions and, at the same time, (2) to the delineation of...
Tipo: Text
Palavras-chave: Biological constraint; Niche dynamic; Marginality; Community; Spatio-temporal; Subniche; Habitat.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00389/49999/50584.pdf

Effects of blue light on the biochemical composition and photosynthetic activity of Isochrysis sp. (T-iso)
Provedor de dados: 5
Autores: Marchetti, Julie; Bougaran, Gael; Jauffrais, Thierry; Lefebvre, Sebastien; Rouxel, Catherine; Saint-jean, Bruno; Lukomska, Ewa; Robert, Rene; Cadoret, Jean-paul.
In aquaculture, particularly in bivalve hatcheries, the biochemical composition of algal diets has a strong influence on larval and post-larval development. Biochemical composition is known to be related to culture conditions, among which light represents a major source of variation. The effects of blue light on biochemical composition and photosynthetic rate of Isochrysis sp. (T-iso) CCAP 927/14 were assessed in chemostat at a single irradiance (300 μmol photons m−2 s−1) and compared with white light. Two different dilution (renewal) rates were also tested: 0.7 and 0.2 d−1. Relative carbohydrate content was lower under blue light than under white light at both dilution rates, whereas chlorophyll a and photosynthesis activity were higher. In contrast,...
Tipo: Text
Palavras-chave: Isochrysis; Blue light; Photosynthesis; Proximate composition; Chemostat.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00085/19599/17237.pdf

Forces, failles et opportunités de la recherche française en écologie trophique
Provedor de dados: 5
Autores: Perga, Marie-elodie; Danger, Michael; Dubois, Stanislas; Fritch, Clementine; Gaucherel, Cedric; Hubas, Cedric; Jabot, Franck; Lacroix, Gerard; Lefebvre, Sebastien; Marmonier, Pierre; Bec, Alexandre.
The French National Institute of Ecology and Environment (INEE) aims at fostering pluridisciplinarity in Environmental Science and, for that purpose, funds ex muros research groups (GDR) on thematic topics. Trophic ecology has been identified as a scientific field in ecology that would greatly benefit from such networking activity, as being profoundly scattered. This has motivated the seeding of a GDR, entitled “GRET”. The contours of the GRET's action, and its ability to fill these gaps within trophic ecology at the French national scale, will depend on the causes of this relative scattering. This study relied on a nationally broadcasted poll aiming at characterizing the field of trophic ecology in France. Amongst all the unique individuals that fulfilled...
Tipo: Text
Palavras-chave: Trans-ecosystem; Scientific network; Cleavage; Ecology; Population; Community.
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00442/55338/56849.pdf

Are food web structures well represented in isotopic spaces?
Provedor de dados: 5
Autores: Jabot, Franck; Giraldo, Carolina; Lefebvre, Sebastien; Dubois, Stanislas.
Isotopic analyses are increasingly used to assess the structure of food webs and a series of isotopic functional indices have been proposed in the last decade to characterize this structure. These indices are based on the foundational assumption that proximity in the isotopic space informs on trophic similarity between species. While it has been recognized for long that this simplifying assumption should be used with caution, no formal evaluation of its domain of validity has been performed to date. We here simulate a large number (15,000) of food webs with varying characteristics to assess i) whether isotopic distance is a good proxy of trophic dissimilarity; ii) whether isotopic functional indices are good proxies of trophic functional properties; and...
Tipo: Text
Palavras-chave: Connectance; Isotopic functional indices; Niche model; Omnivory; Virtual ecology.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00385/49596/50110.pdf

The stony road to understand isotopic enrichment and turnover rates: insight into the metabolic part
Provedor de dados: 5
Autores: Lefebvre, Sebastien; Dubois, Stanislas.
Trophic enrichment factors (TEF) are essential to properly and fruitfully explore stable isotope analysis in ecology. And so is the time window of food source integration, usually estimated with the turnover rates (lambda) of isotopic incorporation. On the road to provide ecologists with a general and reliable method to obtain TEF and turnover rates for diet reconstruction, isotopists start realizing that those two parameters are ultimately linked with the physiological state of organisms and that metabolic pathways are of primary importance to understand the large ranges in TEF values. In this study, we used a diet-switching experiment for seven small marine invertebrates. Changes in isotopic compositions were fitted to an exponential decay model to...
Tipo: Text
Palavras-chave: Stable isotopes; Growth rates; Diet-tissue discrimination; Dynamic energy budget; Trophic fractionation; Catabolism.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00387/49856/52266.pdf

Modelling isotopes dynamics in soft tissues of Crassostrea gigas in the context of DEB theory to study the trophic ecology of oysters at large spatial scale
Provedor de dados: 5
Autores: Emmery, Antoine; Lefebvre, Sebastien; Alunno-bruscia, Marianne; Kooijman, S. A. L. M.
Biological performances (growth and reproduction) of intertidal bivalves mainly rely on environmental factors such as water temperature and food sources. Both quality and quantity of bivalve food sources, however, are not easy to determine because of complex features of coastal ecosystem functioning, such as high spatial heterogeneity. This is particularly critical for oyster (Crassostrea gigas) culture in France when quantifying and explaining the variability in growth performances of oysters among culture sites at a large spatial scale. In this context, insights for new operational tools to characterise trophic features of coastal ecosystems are needed. The aim of the present study is to couple natural isotope tracers and DEB modeling to describe and...
Tipo: Text
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00032/14370/11659.pdf

On the interest of using field primary production data to calibrate phytoplankton rate processes in ecosystem models
Provedor de dados: 5
Autores: Grangere, Karine; Lefebvre, Sebastien; Menesguen, Alain; Jouenne, Fabien.
In many ecosystem models based on empirical formulations, parameters generally are calibrated in order to achieve the best fit between measured and simulated chlorophyll a standing stocks. An accurate calibration of rate processes as primary production rarely is taken into account. In this paper, we test the usefulness of calibration of phytoplankton photosynthetic processes in an ecosystem model using field primary production data. We used 18 months of photosynthetic process data from the Baie des Veys ecosystem (Normandy, France). Five empirical formulations of photosynthesis-irradiance curve models amongst the most widely used were tested. In each formulation, the variability of photosynthetic parameters (i.e. the light-saturated rate of photosynthesis...
Tipo: Text
Palavras-chave: Baie des Veys; Normandy; France; Diatoms; Chlorophyll a to carbon ratio; Parameter optimisation; Mechanistic formulations; Empirical formulations; Photosynthesis irradiance curve.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6810.pdf

How does shape affect predator- prey interactions in fish? Implications for marine food web structure and dynamics
Provedor de dados: 5
Autores: Cachera, Marie; Villanueva, Ching-maria; Ernande, Bruno; Baheux, Mickael; Rouquette, Manuel; Chambord, Sophie; Lefebvre, Sebastien.
Each species pertains to a given functional niche, depending on its relationships with others species and its interactions with the abiotic environment. Understanding inter-specific interactions is critical to know and predict ecosystems' structure, functioning and dynamics, but also their response to anthropogenic impacts. Predator-prey relationship is one of the main biotic interactions as it both determines the survival of the prey and the predator and is the keystone of food webs. Unraveling the determinants of predator-prey relationships or, in other terms, the reason why a given predator catches a given prey is therefore of primary importance. Fishes are characterized by a remarkable diversity of shapes which can be associated by their feeding and...
Tipo: Text
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00161/27215/25414.pdf

There's no harm in having too much: A comprehensive toolbox of methods in trophic ecology
Provedor de dados: 5
Autores: Majdi, Nabil; Hette-tronquart, Nicolas; Auclair, Etienne; Bec, Alexandre; Chouvelon, Tiphaine; Cognie, Bruno; Danger, Michael; Decottignies, Priscilla; Dessier, Aurélie; Desvilettes, Christian; Dubois, Stanislas; Dupuy, Christine; Fritsch, Clémentine; Gaucherel, Cédric; Hedde, Mickaël; Jabot, Franck; Lefebvre, Sebastien; Marzloff, Martin; Pey, Benjamin; Peyrard, Nathalie; Powolny, Thibaut; Sabbadin, Régis; Thébault, Elisa; Perga, Marie-elodie.
Trophic ecology is the study of feeding interactions and food acquisition by organisms. It includes the causes and consequences of those behaviours at all levels of biological organisation. As a field of research, it crosses many disciplinary boundaries and provides knowledge that is pertinent to many other areas of ecology. Here we list and categorise the methods available to trophic ecologists whose toolbox has broadened considerably in recent years. They encompass empirical and numerical approaches with focus ranging from molecules to ecosystems. We further examine the relationship of each method to features such as the scale of observation (from microbes to largest organisms) and organisational level (from individuals to ecosystems) as well as the...
Tipo: Text
Palavras-chave: Food web; Feeding interactions; Flux of energy; Computer simulations; Trophic models.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00487/59834/65986.pdf

Body size and temperature effects on standard metabolic rate for determining metabolic scope for activity of the polychaete     Hediste (Nereis) diversicolor
Provedor de dados: 5
Autores: Lopes Galasso, Helena; Richard, Marion; Lefebvre, Sebastien; Aliaume, Catherine; Callier, Myriam.
Considering the ecological importance and potential value of Hediste diversicolor, a better understanding of its metabolic rate and potential growth rates is required. The aims of this study are: (i) to describe key biometric relationships; (ii) to test the effects of temperature and body size on standard metabolic rate (as measure by oxygen consumption) to determine critical parameters, namely Arrhenius temperature (TA), allometric coefficient (b) and reaction rate; and (iii) to determine the metabolic scope for activity (MSA) of H. diversicolor for further comparison with published specific growth rates. Individuals were collected in a Mediterranean lagoon (France). After 10 days of acclimatization, 7 days at a fixed temperature and 24 h of fasting,...
Tipo: Text
Palavras-chave: Annelida; Deposit-feeder; Oxygen consumption; Allometric coefficient; Arrhenius temperature; Aerobic scope; Growth.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00465/57682/59885.pdf

Individual diet variation in a marine fish assemblage: Optimal Foraging Theory, Niche Variation Hypothesis and functional identity
Provedor de dados: 5
Autores: Cachera, Marie; Ernande, Bruno; Villanueva, Ching-maria; Lefebvre, Sebastien.
Individual diet variation (i.e. diet variation among individuals) impacts intra- and inter-specific interactions. Investigating its sources and relationship with species trophic niche organization is important for understanding community structure and dynamics. Individual diet variation may increase with intra-specific phenotypic (or “individual state”) variation and habitat variability, according to Optimal Foraging Theory (OFT), and with species trophic niche width, according to the Niche Variation Hypothesis (NVH). OFT proposes “proximate sources” of individual diet variation such as variations in habitat or size whereas NVH relies on “ultimate sources” related to the competitive balance between intra- and inter-specific competitions. The latter implies...
Tipo: Text
Palavras-chave: Specialization; Trophic similarity; Size-dependent diet variation; English Channel; Semi-enclosed sea.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00349/45986/46031.pdf

Application of a dynamic energy budget model to the Pacific oyster, Crassostrea gigas, reared under various environmental conditions
Provedor de dados: 5
Autores: Pouvreau, Stephane; Bourles, Yves; Lefebvre, Sebastien; Gangnery, Aline; Alunno-bruscia, Marianne.
The Dynamic Energy Budget (DEB) model (Kooijman, S.A.L.M., 1986. Energy budgets can explain body size relations. J. Theor. Biol. 121, 269¿282; Kooijman, S.A.L.M., 2000. Dynamic Energy and Mass Budgets in Biological Systems. Cambridge University Press, Cambridge, 424 pp.) has been adapted to describe the dynamics of growth and reproduction of the Pacific oyster (Crassostrea gigas) reared in different areas under conditions ranging from controlled to natural. The values of the model parameters were estimated from available physiological data and from published information. The sets of data used to validate the model came from three long-term growth experiments (&gt; 5 months) performed on Pacific oysters reared under different conditions of food and...
Tipo: Text
Palavras-chave: Reproductive effort; Reproduction; Growth; Ecophysiology; Dynamic energy budget; Crassostrea gigas.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-1817.pdf

Trophic relationships in the eastern English Channel: how to simplify food web structure description for trophic niche determination?
Provedor de dados: 5
Autores: Kopp, Dorothee; Lefebvre, Sebastien; Villanueva, Ching-maria; Ernande, Bruno.
Determining the organisation of natural communities as well as their ability to face environmental changes are at the core of many ecological studies. In that aim, many studies tried to describe trophic interactions between species and quantify their strength in ecological networks, the multiplicity of trophic links being assumed to promote the stability and persistence of communities. In marine ecosystems, the study of trophic relationships has extensively benefited from the development of analytical tools like stable isotopes analysis (SIA) as dietary tracers. Particularly, δ15N values are useful in estimating intra- and inter-specific trophic level variations while δ13C values will indicate variation in the source of organic matter. Here, we proposed to...
Tipo: Text
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00163/27394/25624.pdf

Rapid light curves (RLC) or non-sequential steady-state light curves (N-SSLC): which fluorescence-based light response curve methodology robustly characterizes phytoplankton photosynthetic activity and acclimation status?
Provedor de dados: 5
Autores: Houliez, Emilie; Lefebvre, Sebastien; Lizon, Fabrice; Schmitt, Francois G.
This study is the first in situ work comparing rapid light curves (RLC) and non-sequential steady-state light curves (N-SSLC) in their efficiency to characterize phytoplankton photosynthetic activity and acclimation status. Measurements were carried out at two time scales (daily and annual) using the Pulse Amplitude Modulated fluorometry on samples taken in the coastal waters of a macrotidal ecosystem (the Strait of Dover, eastern English Channel). RLC and N-SSLC were compared under a wide range of environmental conditions and phytoplankton composition in order to define the best methodology to accurately capture short and long-term adjustments in the functioning of the photosynthetic apparatus. The relationships between the photosynthetic parameters...
Tipo: Text
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00395/50596/51484.pdf

Dynamics of particulate organic matter composition in coastal systems: a spatio-temporal study at multi-systems scale
Provedor de dados: 5
Autores: Lienart, Camilla; Savoye, Nicolas; Bozec, Yann; Breton, Elsa; Conan, Pascal; David, Valerie; Feunteun, Eric; Grangere, Karine; Kerherve, Philippe; Lebreton, Benoit; Lefebvre, Sebastien; L'Helguen, Stephane; Mousseau, Laure; Raimbault, Patrick; Richard, Pierre; Riera, Pascal; Sauriau, Pierre-guy; Schaal, Gauthier; Aubert, Fabien; Aubin, Sebastien; Bichon, Sabrina; Boinet, Christophe; Bourasseau, Line; Breret, Martine; Caparros, Jocelyne; Cariou, Thierry; Charlier, Karine; Claquin, Pascal; Cornille, Vincent; Corre, Anne-marie; Costes, Laurence; Crispi, Olivier; Crouvoisier, Muriel; Czamanski, Marie; Del Amo, Yolanda; Derriennic, Herve; Dindinaud, Francois; Durozieri, Maia; Hanquiez, Vincent; Nowaczyk, Antoine; Devesa, Jeremy; Ferreira, Sophie; Fornier, Michel; Garcia, Fabrice; Garcia, Nicole; Geslin, Sandrine; Grossteffan, Emilie; Gueux, Aurore; Guillaudeau, Julien; Guillou, Gael; Joly, Orianne; Lachaussee, Nicolas; Lafont, Michel; Lamoureux, Jezabel; Lecuyer, Eric; Lehodey, Jean-paul; Lemeille, David; Leroux, Cedric; Mace, Eric; Maria, Eric; Pineau, Philippe; Petit, Franck; Pujo-pay, Mireille; Rimelin-maury, Peggy; Sultan, Emmanuelle.
In coastal systems, the multiplicity of sources fueling the pool of particulate organic matter (POM) leads to divergent estimations of POM composition. Eleven systems (two littoral systems, eight embayments and semi-enclosed systems and one estuary) distributed along the three maritime façades of France were studied for two to eight years in order to quantify the relative contribution of organic matter sources to the surface-water POM pool in coastal systems. This study was based on carbon and nitrogen elemental and isotopic ratios, used for running mixing models.  The POM of the estuary is dominated by terrestrial material (93% on average), whereas the POM of the other systems is dominated by phytoplankton (84% on average). Nevertheless, for the latter...
Tipo: Text
Palavras-chave: Particulate organic matter; Coastal systems; C and N stable isotopes; C:N ratio; Mixing model.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00374/48550/48871.pdf

Benthic-pelagic couplings as key determinants of food web structure along environmental gradients
Provedor de dados: 5
Autores: Lefebvre, Sebastien; Giraldo, Carolina; Kopp, Dorothee; Cresson, Pierre; Travers-trolet, Morgane; Ernande, Bruno.
Trophic relationships play a crucial role in shaping community structure and ecological functions in marine ecosystems. Studying food-web variation along environmental gradients is still in its infancy and provides new insights in understanding how abiotic variables shape species interactions. In epicontinental seas, benthic-pelagic couplings modify predator-prey relationships and lead to entangled trophic networks. Here, we  assumed that depth affects benthic-pelagic couplings’ strength and we investigated depth-related changes in the feeding patterns of fish in the whole English Channel (EC) used as a case study. Gut content and stable carbon and nitrogen isotopes of 33 fish species were collected between 5-100 m depth in 2009 and in 2014. Samples from...
Tipo: Text
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00455/56634/58370.pdf

Spatial and temporal variations in food web structure from newly-opened habitat at hydrothermal vents
Provedor de dados: 5
Autores: Gaudron, Sylvie Marylene; Lefebvre, Sebastien; Jorge, Amandine Nunes; Gaill, Francoise; Pradillon, Florence.
To highlight the spatio-temporal variability of the food web structure of hydrothermal vent fauna from newly-opened habitat, a series of Titanium Ring for Alvinellid Colonization devices (TRACs) was deployed at TICA site on the East Pacific Rise in 2006. This experiment was conducted for periods of 4 days, 13 days and one month and deployments were aligned along a gradient from the basaltic bottom to the vent openings. delta C-13 values of colonists revealed a narrower range of carbon sources in proximity to vent openings in Alvinella pompejana habitat than in Tevnia jerichonana habitat, separated by a distance of four meters. This was possibly due to a spatial change in available food sources with a possible higher contribution of particulate organic...
Tipo: Text
Palavras-chave: Trophic relationships; Food web structure; Hydrothermal vent; East Pacific Rise; Stable isotopes; Colonization experiment; TRACs; Alvinella pompejana; Epibiosis.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00085/19580/19581.pdf

Impact of environmental variability on Pinctada margaritifera life-history traits: A full life cycle deb modeling approach
Provedor de dados: 5
Autores: Sangare, Nathanael; Lo-yat, Alain; Le Moullac, Gilles; Pecquerie, Laure; Thomas, Yoann; Lefebvre, Sebastien; Le Gendre, Romain; Beliaeff, Benoit; Andréfouët, Serge.
The black-lipped pearl oyster (Pinctada margaritifera) is extensively farmed in French Polynesia to produce black pearls. For a sustainable management of marine resources, studying interactions between organisms and environment, and the associated factors and processes that will impact their life cycle and thus modulate population dynamics is a major research priority. Here, we describe black-lipped pearl oyster energy acquisition and use, and its control by temperature and food concentration within the Dynamic Energy Budget (DEB) theory framework. The model parametrization was based on literature data and a specific laboratory experiment. Model validation was carried out thanks to historical in-situ datasets and a dedicated field survey. Three theoretical...
Tipo: Text
Palavras-chave: Bivalve; Physiology; Bioenergetics; Dynamic energy budget theory; Environmental change; Pearl farming.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00613/72469/71614.pdf

Realized niche analysis of phytoplankton communities involving HAB: Phaeocystis spp. as a case study
Provedor de dados: 5
Autores: Karasiewicz, Stephane; Breton, Elsa; Lefebvre, Alain; Hernandez Farinas, Tania; Lefebvre, Sebastien.
The link between harmful algal blooms, phytoplankton community dynamics and global environmental change is not well understood. To tackle this challenging question, a new method was used to reveal how phytoplankton communities responded to environmental change with the occurrence of an harmful algae, using the coastal waters of the eastern English Channel as a case study. The great interannual variability in the magnitude and intensity of Phaeocystis spp. blooms, along with diatoms, compared to the ongoing gradual decrease in anthropogenic nutrient concentration and rebalancing of nutrient ratios; suggests that other factors, such as competition for resources, may also play an important role. A realized niche approach was used with the Outlying Mean Index...
Tipo: Text
Palavras-chave: Harmful algae bloom; WitOMI; Subniche; Diatoms; Biotic interaction; Eastern English Channel.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00416/52786/56650.pdf

Depth gradient on the resource use of a fish community from a semi-enclosed sea
Provedor de dados: 5
Autores: Giraldo, Carolina; Ernande, Bruno; Cresson, Pierre; Kopp, Dorothee; Cachera, Marie; Travers-trolet, Morgane; Lefebvre, Sebastien.
Depth is one of the environmental variables influencing the structure of marine food webs by directly or indirectly influencing benthic-pelagic coupling and predator-prey relationships. In shallow waters, the high degree of connectivity between pelagic and benthic networks results in complex systems with multiple interactions. Digestive tract (DT) and stable isotope (SI) analyses were used to investigate depth-related changes in feeding patterns for 33 fish species (eastern English Channel [EEC]) collected between 5 m and 80 m depth. Fish species were first arranged into functional groups based upon trophic and habitat similarities. DTs were used to determine the general topology of the food web and SIs were used to estimate the contributions of different...
Tipo: Text
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00386/49711/52255.pdf

FISH : shapes and swimming styles
Provedor de dados: 5
Autores: Cachera, Marie; Ernande, Bruno; Villanueva, Ching-maria; Baheux, Mickael; Lefebvre, Sebastien.
By covering 80% of Earth, the global ocean is the most spread ecosystem in the world. Human activities (pollution, fisheries…) have huge impacts on both oceans and marine life. Despites overfishing and intense maritime transport, many fish species remain in the English Channel. A major challenge in biological research is to comprehend and facilitate the emergence of body shape in fishes for understanding how these organisms may respond and persist in complex and multiple environments with predictable and unpredictable perturbations. Body shape in fish is conditioned by several developmental paths and functions depending on multitude behaviours. Fishes body morphology varies in every species and in some cases had been shown to influence their occurrence,...
Tipo: Text
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00161/27217/25416.pdf

Le risque trophique : caractéristiques trophique et hétérogénéité des ressources alimentaires en lien avec les mortalités ostréicoles
Provedor de dados: 5
Autores: Ropert, Michel; Lefebvre, Sebastien; Soletchnik, Patrick; Blin, J. L.; Faury, Nicole; Struski, Caroline.
The "trophic risk" has been demonstrated in the bioenergetic model developed in vivo and based on various diet conditions similar to those of different types of oyster culture basins (eutrophic, heterotrophic and oligotrophic) [22, 23]. The trophic resource – mortality relationship differs from one basin to another, according to the quantity of this resource. Multy-varied analysis (ACP) conducted on a total of 11 oyster culture sites and handled in a database matching mortality and environmental data, show that the trophic indicator "chlorophyll a" (often coupled with temperature) is involved in a positive correlation with the mortality of both age classes (1 and 2 years old). The stock transfer from the Bay of Veys to the west coast of Cotentin in spring...
Tipo: Text
Palavras-chave: MOREST; Crassostrea gigas; Physiologie; Phéopigments; Ressources trophiques; Modèle bioénergétique; Mortalités; Huîtres.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/2004/acte-3410.pdf

La forme du poisson: Permet-elle de déduire les guildes trophiques
Provedor de dados: 5
Autores: Chambord, Sophie; Villanueva, Ching-maria; Ernande, Bruno; Lefebvre, Sebastien.
Les réseaux trophiques engendrent tous les transferts d’énergies et de matières au sein d’un écosystème, ce qui expliquent l’intérêt de leur compréhension. Ces réseaux dépendent essentiellement des relations proies-prédateurs, il est donc important de connaître les processus les déterminants. La morphométrie peut être un processus déterminants les relations proies-prédateurs. Ces travaux ont permis d’identifier les relations entre les caractéristiques morphologiques des individus et leur régime alimentaire chez deux espèces relativement contrastée en termes de guilde trophique, à savoir Pleuronectes platessa (plie, Linné 1758) et Dicentrarchus labrax (bar commun, Linné 1758).
Tipo: Text
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00143/25417/23568.pdf

Modelling the spatial heterogeneity of ecological processes in an intertidal estuarine bay: dynamic interactions between bivalves and phytoplankton
Provedor de dados: 5
Autores: Grangere, Karine; Lefebvre, Sebastien; Bacher, Cedric; Cugier, Philippe; Menesguen, Alain.
Spatial patterns in ecological communities result from a combination of physical and biological factors. In an estuarine intertidal bay, spatial differences have been found in the structure of phytoplanktonic communities and in the biological performance of cultivated oysters. It has been hypothesised that trophic heterogeneity exists, although the mechanisms controlling it remain undefined. Spatial and temporal interactions in the structure of phytoplanktonic biomass and in the biological performance of cultivated oysters were highlighted in this estuarine intertidal bay using a 2-dimensional hydrodynamic model coupled to a nutrient-phytoplankton-zooplankton bivalve food web model. The coupled models allowed a reproduction in space and time of variations...
Tipo: Text
Palavras-chave: Spatial heterogeneity; Hydrodynamics; Ecosystem model; Food supply; Bivalves; Dynamic energy budget model; Physiological status; Baie des Veys.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00017/12854/9819.pdf

Effluents from land based marine farms: nature, treatment, valorisation, modelisation. Applications to fish and shrimp rearing
Provedor de dados: 5
Autores: Hussenot, Jerome; Lefebvre, Sebastien; Martin, Jean-louis.
Fish culture (seabass, turbot...) on the French metropolitan coast, and shrimp culture in the overseas territories (essentially New Caledonia and Tahiti) are subject to a regular development through land based farms. Three thematic of research on aquaculture ponds are carried out in CREMA-L’Houmeau, in collaboration with producers. The aim of the first one is to determine the optimal rearing conditions (stocking density, water renewal rate, input of oxygen, rate of feeding...) which allow to minimise the quantity of wastes for a similar final biomass. The second part aims to reduce the nutrient loading in the effluent, through open-air treatments: sedimentation ponds, foam fractionation, mass production of phytoplankton, and rearing of molluscs on the...
Tipo: Text
Palavras-chave: Fish; Shrimp; Pond management; Effluents; Treatment.
Ano: 2000
URL: http://archimer.ifremer.fr/doc/00016/12728/9650.pdf

Shift in benthic assemblages and organisms’ diet at salmon farms: community structure and stable isotope analyses
Provedor de dados: 5
Autores: Callier, Myriam; Lefebvre, Sebastien; Dunagan, Mary K.; Bataille, Marie-paule; Coughlan, Jennifer; Crowe, Tasman P.
The extent of the influence of salmon farming on the environment and on the uptake of particulate and dissolved effluents by benthic organisms was assessed using community structure and stable isotope analyses. Sediment cores were collected in 2 directions: perpendicular and parallel to the main residual current, 0, 25 and 200 m from 2 salmon farms (Millstone and Cranford) located in Mulroy Bay, Ireland. In addition, artificial substrates were placed for 2 mo at 1 m depth 0, 25 and 200 m from one farm to trace the uptake of farm-related nutrients by fouling organisms. The extent of measurable change in benthic communities (abundance, diversity, structure, trophic composition) depended on residual current direction. Intraspecific variation in isotopic...
Tipo: Text
Palavras-chave: Aquaculture; Organic matter; Stable isotope; Community structure; Diet shift; Trophic structure.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00144/25481/23634.pdf

Linking life-history traits, spatial distribution and abundance of two species of lugworms to bait collection: A case study for sustainable management plan
Provedor de dados: 5
Autores: De Cubber, Lola; Lefebvre, Sebastien; Fisseau, Charline; Cornille, Vincent; Gaudron, Sylvie Marylene.
Arenicola spp. are marine benthic polychaetes dug for bait by anglers. Without regulation, this activity can lead to the decrease of lugworms' population meanwhile affecting the physical characteristics of the beach and the biodiversity. Here, we identified through morphology and genetics two species of lugworms, Arenicola marina and A. defodiens, within a Marine Protected Area of the Eastern English Channel (France). For each species, abundance and spatial distribution were assessed using a stratified random sampling and interpolation at four studied sites, as well as some life-history traits. These data were compared to lugworms' collection data to estimate its sustainability and to provide potential management measures. At one site, A. marina was...
Tipo: Text
Palavras-chave: Arenicola marina; Arenicola defodiens; Spawning; Population structure; Size at first maturity; Recreational fisheries; Conservation; English channel.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00451/56284/60474.pdf

Does the positive body-size-trophic level relationship hold at the species level?
Provedor de dados: 5
Autores: Kopp, Dorothee; Lefebvre, Sebastien; Villanueva, Ching-maria; Ernande, Bruno.
The structure, dynamics and productivity of marine ecosystems depend mainly on their underlying food webs. In temperate marine ecosystems, specifically in the English Channel, strong seasonality, habitat diversity and variability in the sources of available organic matters are controlling factors affecting the trophodynamics of these networks. Exploitation through fisheries may also alter these food webs. During the last decade, the study of trophic ecology has greatly benefited from the use of stable isotope analysis (SIA) that integrates diet information over long time periods and complements gut content analysis. Applied in complex ecosystems, such as the English Channel, SIA may help to detect nutrient pathways and trophic links. Stable isotopic...
Tipo: Text
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00161/27213/25412.pdf

Modelling the effects of macrofauna on sediment transport and bed elevation: Application over a cross-shore mudflat profile and model validation
Provedor de dados: 5
Autores: Orvain, Francis; Le Hir, Pierre; Sauriau, Pierre-guy; Lefebvre, Sebastien.
Tipo: Text
Palavras-chave: Modelling; Sediment dynamics; Erodability; Bioturbation; Macrofauna; Biota; Sediment stability.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00079/19055/18610.pdf

Trophic ecology of European sardine Sardina pilchardus and European anchovy Engraulis encrasicolus in the Bay of Biscay (north-east Atlantic) inferred from delta C-13 and delta N-15 values of fish and identified mesozooplanktonic organisms
Provedor de dados: 5
Autores: Chouvelon, Tiphaine; Chappuis, A.; Bustamante, Paco; Lefebvre, Sebastien; Mornet, Francoise; Guillou, G.; Violamer, L.; Dupuy, Christine.
European sardine (Sardina pilchardus) and European anchovy (Engraulis encrasicolus) are two species of economical and ecological significance in the Bay of Biscay (north-east Atlantic). However, the trophic ecology of both species is still poorly known in the area, and more generally, few studies have considered the potential trophic overlap between sardines and anchovies worldwide. This study aims to highlight the trophic links between the mesozooplankton and adults of these two pelagic fish in the Bay of Biscay, through carbon and nitrogen stable isotope analysis (SIA). Mesozooplankton and individuals of sardines and anchovies were collected during one season (spring 2010), over spatially contrasted stations within the study area. First, the potential...
Tipo: Text
Palavras-chave: Plankton preservation; Plankton delipidation; Pelagic fish; Trophic interactions; Spatial variability; Isotopic mixing model.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00176/28741/27280.pdf

Storage of Pacific oysters Crassostrea gigas in recirculating tank: ammonia excretion and potential nitrification rates
Provedor de dados: 5
Autores: Buzin, Florence; Dupuy, Beatrice; Lefebvre, Sebastien; Barille, Laurent; Haure, Joel.
In response to the closure of shellfish production sites due to increasing occurrence of toxic algal blooms, land-based recirculating aquaculture systems (RAS) could be used by producers to store a proportion of their stock temporarily. An RAS prototype was tested in this study to store Pacific oyster Crassostrea gigas over a range of temperatures. In such systems, the water temperature is a variable that could influence the bivalve excretion rate of ammonia, the concentration of which may become critical for the water quality. In this study, we first estimated the total ammonia nitrogen (TAN, N-NH4+ + N-NH3) excretion of the Pacific oyster and then investigated whether the bacterial population associated with the oysters could act as a natural biofilter...
Tipo: Text
Palavras-chave: Crassostrea gigas; Ammonia excretion; Nitrification rate; Recirculating system; Temperature.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00248/35889/34409.pdf

Understanding the dynamics of δ13C and δ15N in soft tissues of the bivalve Crassostrea gigas facing environmental fluctuations in the context of Dynamic Energy Budgets (DEB)
Provedor de dados: 5
Autores: Emmery, Antoine; Lefebvre, Sebastien; Alunno-bruscia, Marianne; Kooijman, S. A. L. M.
We studied the dynamics of stable isotopes δ13C and δ15N of an opportunistic suspension feeder the Pacific oyster (Crassostrea gigas) to better understand the factors that influence the trophic enrichment (trophic-shift, Δ) between primary producers and consumers. Most of the previous studies on this topic do not quantify mass fluxes or isotopic discrimination phenomena in the organism, which are two pillars in isotope ecology. We used a dynamic energy budget (DEB) approach (Kooijman, 2010) to quantify i) the fluxes of elements and isotopes in C. gigas soft tissues and ii) the impact of the scaled feeding level, the organism mass and the isotopic ratio of food on the "trophic-shift" Δ, and isotope turnover in tissues. Calibration and parametrization...
Tipo: Text
Palavras-chave: Oyster; Isotopic ratio; Discrimination; Trophic-shift; Diet; DEB theory.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00043/15434/12784.pdf

Conception et réalisation de bancs automatisés pour les mesures écophysiologiques des mollusques filtreurs en condition contrôlée à La Station Expérimentale d'Argenton
Provedor de dados: 5
Autores: Fagon, N.; Le Souchu, Pierrick; Lefebvre, Sebastien; Pouvreau, Stephane.
Force est de constater que, malgré un intérêt croissant depuis les 20 dernières années en matière d'écophysiologie des mollusques, il n'existe, à notre connaissance, aucun système réellement adapté à la mesure en continu et de façon concomitante des principales fonctions écophysiologies des mollusques filtreurs (notamment consommation et filtration). Faisant suite à la réalisation d'un cahier des charges et d'une version préliminaire d'un système, le but du présent projet est de doter la Station Expérimentale d'Argenton (entité expérimentale de l'UMR « Physiologie et Ecophysiologie des Mollusques Marins) de deux systèmes automatisés et opérationnels de mesures de l'écophysiologie des mollusques filtreurs. Après un bref rappel des principes de mesures des...
Tipo: Text
Ano: 2000
URL: http://archimer.ifremer.fr/doc/00306/41769/40982.pdf

Spatial and temporal interaction between sediment and microphytobenthos in a temperate estuarine macro-intertidal bay
Provedor de dados: 5
Autores: Orvain, Francis; Lefebvre, Sebastien; Montepini, J.; Sebire, M.; Gangnery, Aline; Sylvand, B.
Intertidal flats of the estuarine macro-intertidal Baie des Veys (France) were investigated to identify spatial features of sediment and microphytobenthos (MPB) in April 2003. Gradients occurred within the domain, and patches were identified close to vegetated areas or within the oyster-farming areas where calm physical conditions and biodeposition altered the sediment and MPB landscapes. Spatial patterns of chl a content were explained primarily by the influence of sediment features, while bed elevation and compaction brought only minor insights into MPB distribution regulation. The smaller size of MPB patches compared to silt patches revealed the interplay between physical structure defining the sediment landscape, the biotic patches that they contain,...
Tipo: Text
Palavras-chave: Benthic diatoms; Benthos; Coastal ecosystems; Intertidal flats; Baie des Veys; Normandie; Spatial pattern; Geostatistics; Kriging.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00088/19945/17598.pdf

Underestimation of chemical contamination in marine fish muscle tissue can be reduced by considering variable wet:dry weight ratios
Provedor de dados: 5
Autores: Cresson, Pierre; Travers-trolet, Morgane; Rouquette, Manuel; Timmerman, Charles-andre; Giraldo, Carolina; Lefebvre, Sebastien; Ernande, Bruno.
Whether considered as a risk for human health or as ecological tracers, contaminants' concentrations measured in fish muscles are commonly expressed relative to wet or dry mass. Comparison of results required conversion factors (CF) but accurate values are scarce and case-specific. The present paper is aimed at investigating errors linked with the use of the theoretical value. Muscles dry and wet masses were measured in 15 fish species to determine the actual CF. Most CF were lower than the theoretical wet:dry ratio of 5 classically used, with variations at individual and species level. Muscle lipid content (inferred by C/N ratios) was a crucial factor explaining discrepancies, claiming for caution when working with lipid-rich species. The observed...
Tipo: Text
Palavras-chave: Wet:dry ratio; Conversion factor; Contaminant concentration; Marine fish; Percentage of humidity.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00396/50736/51456.pdf

Reorganization of a marine trophic network along an inshore-offshore gradient due to stronger pelagic-benthic coupling in coastal areas
Provedor de dados: 5
Autores: Kopp, Dorothee; Lefebvre, Sebastien; Cachera, Marie; Villanueva, Maria Ching; Ernande, Bruno.
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...
Tipo: Text
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00226/33765/32191.pdf

Spatial Variability of Benthic-Pelagic Coupling in an Estuary Ecosystem: Consequences for Microphytobenthos Resuspension Phenomenon
Provedor de dados: 5
Autores: Ubertini, Martin; Lefebvre, Sebastien; Gangnery, Aline; Grangere, Karine; Le Gendre, Romain; Orvain, Francis.
The high degree of physical factors in intertidal estuarine ecosystem increases material processing between benthic and pelagic compartments. In these ecosystems, microphytobenthos resuspension is a major phenomenon since its contribution to higher trophic levels can be highly significant. Understanding the sediment and associated microphytobenthos resuspension and its fate in the water column is indispensable for measuring the food available to benthic and pelagic food webs. To identify and hierarchize the physical/biological factors potentially involved in MPB resuspension, the entire intertidal area and surrounding water column of an estuarine ecosystem, the Bay des Veys, was sampled during ebb tide. A wide range of physical parameters (hydrodynamic...
Tipo: Text
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00090/20126/17775.pdf