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Auteur Fred Jean
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Building functional groups of marine benthic macroinvertebrates on the basis of general community assembly mechanisms
article dans des revues - 2017-03
Alexandridis, Nikolaos, et al.
Titre Building functional groups of marine benthic macroinvertebrates on the basis of general community assembly mechanisms Type d'Ã©tude article dans des revues Auteurs personnes Alexandridis Nikolaos Auteur Bacher CÃ©dric Auteur Desroy Nicolas Auteur Jean Fred Auteur Date de publication 2017-03 Editeur(s) [S.l.] : Elsevier Journal of Sea Research, ISSN 1385-1101 vol.121 RÃ©sumÃ© The accurate reproduction of the spatial and temporal dynamics of marine benthic biodiversity requires the development of mechanistic models, based on the processes that shape macroinvertebrate communities. The modelled entities should, accordingly, be able to adequately represent the many functional roles that are performed by benthic organisms. With this goal in mind, we applied the emergent group hypothesis (EGH), which assumes functional equivalence within and functional divergence between groups of species. The first step of the grouping involved the selection of 14 biological traits that describe the role of benthic macroinvertebrates in 7 important community assembly mechanisms. A matrix of trait values for the 240 species that occurred in the Rance estuary (Brittany, France) in 1995 formed the basis for a hierarchical classification that generated 20 functional groups, each with its own trait values. The functional groups were first evaluated based on their ability to represent observed patterns of biodiversity. The two main assumptions of the EGH were then tested, by assessing the preservation of niche attributes among the groups and the neutrality of functional differences within them. The generally positive results give us confidence in the ability of the grouping to recreate functional diversity in the Rance estuary. A first look at the emergent groups provides insights into the potential role of community assembly mechanisms in shaping biodiversity patterns. Our next steps include the derivation of general rules of interaction and their incorporation, along with the functional groups, into mechanistic models of benthic biodiversity. CatÃ©gories thÃ©matiques benthosÃ©cosystÃ¨me benthiquedomaine benthiquemodÃ¨le de comportementestuairediversitÃ© biologique Mots-clÃ©s libres Assembly mechanisms/Benthic communities/Biological traits/Emergent groups/estuaire de la Rance/estuary/flore benthique/Functional diversity/Functional redundancy Echelle de territoire bassins versants Bassin(s) versant(s) Rance - Faluns Note DOI = 10.1016/j.seares.2017.01.007 Langue(s) Anglais Format p59 Ã p70 Document en ligne https://www.sciencedirect.com/science/article/pii/S1385110116300508 NÂ° d'Ã©dition (ISBN, DOI,...) 10.1016/j.seares.2017.01.007 Permalink http://etudes.bretagne-environnement.org/index.php?lvl=notice_display&id=159810A theoretical individual-based model of Brown Ring Disease in Manila clams, Venerupis philippinarum
article scientifique - 2014-08
Paillard, Christine, et al.
Titre A theoretical individual-based model of Brown Ring Disease in Manila clams, Venerupis philippinarum Type d'Ã©tude article scientifique Auteurs personnes Paillard Christine Auteur Jean Fred Auteur Ford Susan E. Auteur Powell Eric N. Auteur Klinck John M. Auteur Hofmann Eileen E. Auteur Flye-Sainte-Marie Jonathan Auteur Date de publication 2014-08 Editeur(s) [S.l.] : Elsevier Revue scientifique Journal of Sea Research, ISSN 1385-1101 Volume 91, Pages 15â€“34 RÃ©sumÃ© An individual-based mathematical model was developed to investigate the biological and environmental interactions that influence the prevalence and intensity of Brown Ring Disease (BRD), a disease, caused by the bacterial pathogen, Vibrio tapetis, in the Manila clam (Venerupis (= Tapes, = Ruditapes) philippinarum). V. tapetis acts as an external microparasite, adhering at the surface of the mantle edge and its secretion, the periostracal lamina, causing the symptomatic brown deposit. Brown Ring Disease is atypical in that it leaves a shell scar that provides a unique tool for diagnosis of either live or dead clams. The model was formulated using laboratory and field measurements of BRD development in Manila clams, physiological responses of the clam to the pathogen, and the physiology of V. tapetis, as well as theoretical understanding of bacterial disease progression in marine shellfish. The simulation results obtained for an individual Manila clam were expanded to cohorts and populations using a probability distribution that prescribed a range of variability for parameters in a three dimensional framework; assimilation rate, clam hemocyte activity rate (the number of bacteria ingested per hemocyte per day), and clam calcification rate (a measure of the ability to recover by covering over the symptomatic brown ring deposit), which sensitivity studies indicated to be processes important in determining BRD prevalence and intensity. This approach allows concurrent simulation of individuals with a variety of different physiological capabilities (phenotypes) and hence by implication differing genotypic composition. Different combinations of the three variables provide robust estimates for the fate of individuals with particular characteristics in a population that consists of mixtures of all possible combinations. The BRD model was implemented using environmental observations from sites in Brittany, France, where Manila clams routinely exhibit BRD signs. The simulated annual cycle of BRD prevalence and intensity agrees with observed disease cycles in cultured clam populations from this region, with maximum disease prevalence and intensity occurring from December to April. Sensitivity analyses of modeled physiological processes showed that the level of hemocyte activity is the primary intrinsic determinant of recovery of infected clams. Simulations designed to investigate environmental effects on BRD suggested that the outcome of the host-parasite interaction is dependent on food supply (high values being favourable for the host) and temperature. Results of simulations illustrate the complex interaction of temperature effects on propagation and viability of the bacterium, on the phagocytic activity of the hemocytes, and on other physiological processes of the host clam. Simulations using 1o C and 2o C increases in temperature generally favored disease development, indicating that climate warming might favor the spread of BRD. CatÃ©gories thÃ©matiques mollusquesantÃ© publiquesurveillance Mots-clÃ©s libres bacteria/BRD/host-parasite-environment/Manila clam/numerical model/Vibrio tapetis Echelle de territoire rÃ©gion (ou supra) Langue(s) Anglais Document en ligne http://dx.doi.org/10.1016/j.seares.2014.03.005 NÂ° d'Ã©dition (ISBN, DOI,...) 10.1016/j.seares.2014.03.005 Permalink http://etudes.bretagne-environnement.org/index.php?lvl=notice_display&id=19289