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| Registros recuperados: 38 | |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00032/14370/11659.pdf |
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| 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 |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00161/27215/25414.pdf |
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| 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 |
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| 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 |
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| 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 (> 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 |
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| 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 |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00163/27394/25624.pdf |
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| 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 |
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| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00395/50596/51484.pdf |
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| 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 |
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| 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 |
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| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00455/56634/58370.pdf |
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| 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 |
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| 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 |
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| Registros recuperados: 38 | |
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