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Auteur Maloufi, S.; Catherine, A.; Mouillot, D.; Louvard, C.; Couté, A.; Bernard, C.; Troussellier, M.
Titre Environmental heterogeneity among lakes promotes hyper β-diversity across phytoplankton communities Type Article scientifique
Année 2016 Publication Revue Abrégée Freshw Biol
Volume 61 Numéro 5 Pages 633-645
Mots-Clés environmental heterogeneity; meta-community ecology; Phytoplankton; species sorting; turnover
Résumé * The extent to which stochastic and deterministic processes influence variations in species communities across space and time remains a central question in theoretical and applied ecology. Despite their high dispersal ability, the composition of phytoplankton communities displays striking spatial variations among lakes even at small spatial scale. * To investigate the mechanisms underlying the distribution of phytoplankton species, we evaluate the contribution of stochastic, spatial and environmental processes in determining β-diversity patterns of phytoplankton at a regional scale. Phytoplankton communities were surveyed in 50 different lakes from north-central France, a region characterised by strong environmental heterogeneity. * The regional species pool was characterised by extremely high β-diversity levels, which were mainly explained by species replacement (i.e. turnover) rather than by differences in species richness (i.e. nestedness). Null models of random species distribution and spatial processes failed to explain observed β-diversity patterns. At the opposite, local environmental conditions strongly influenced the degree of uniqueness of local phytoplankton communities, with the most contrasted environments, including human-dominated areas, promoting highly distinct phytoplankton communities. * Our results suggest that species-sorting mechanisms that arise from variations in local environmental conditions drive high species turnover at the region scale. Thus, in a landscape strongly impacted by cultural eutrophication, further anthropogenic impacts on aquatic ecosystems would likely induce regional homogenisation of phytoplankton communities. Overall, our study supports the fact that the management of lakes and reservoirs in anthropic landscapes should aim at maintaining environmental heterogeneity while preventing further eutrophication in order to favour the maintenance of high phytoplankton β- and γ-diversity.
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Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue en Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 1365-2427 ISBN Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1569
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Auteur van der Geest, M.; van der Lely, J.A.C.; van Gils, J.A.; Piersma, T.; Lok, T.
Titre Density-dependent growth of bivalves dominating the intertidal zone of Banc d’Arguin, Mauritania: importance of feeding mode, habitat and season Type Article scientifique
Année 2019 Publication Revue Abrégée Marine Ecology Progress Series
Volume 610 Numéro Pages 51-63
Mots-Clés Carrying capacity; Chemosymbiosis; Density dependence; Environmental heterogeneity; Feeding guild; Seagrass; Soft-sediment habitat
Résumé Accurate predictions of population dynamics require an understanding of the ways by which environmental conditions and species-specific traits affect the magnitude of density dependence. Here, we evaluated the potential impact of season and habitat (characterized by sediment grain size and seagrass biomass) on the magnitude of density dependence in shell growth of 3 infaunal bivalve species dominating the tropical intertidal benthic communities of Banc d’Arguin, Mauritania. Two of our focal species were filter feeders (Senilia senilis and Pelecyora isocardia) and one was a facultative mixotroph (Loripes orbiculatus), mainly relying on organic carbon provided by sulphide-oxidizing endosymbiotic gill-bacteria (i.e. chemosymbiotic). Distinguishing 2 seasons, winter and summer, we manipulated local bivalve densities across habitats (from bare sandy sediments to seagrass-covered mud). In situ growth of individually tagged and relocated clams was measured and compared with those of tagged clams that were allocated to adjacent sites where local bivalve densities were doubled. Growth was negatively density-dependent in both winter and summer in P. isocardia and L. orbiculatus, the 2 species that mainly inhabit seagrass sediments, but not in S. senilis, usually found in bare sediments. As reproduction and survival rates are generally size-dependent in bivalves, our results suggest that in our tropical study system, the bivalve community of seagrass-covered sediments is more strongly regulated than that of adjacent bare sediments, regardless of species-specific feeding mode or season. We suggest that ecosystem engineering by seagrasses enhances environmental stability, which allows bivalve populations within tropical seagrass beds to stay close to carrying capacity.
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Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue en Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0171-8630, 1616-1599 ISBN Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2488
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Auteur van der Geest, M.; van der Lely, J.A.C.; van Gils, J.A.; Piersma, T.; Lok, T.
Titre Density-dependent growth of bivalves dominating the intertidal zone of Banc d'Arguin, Mauritania: importance of feeding mode, habitat and season Type Article scientifique
Année 2019 Publication Revue Abrégée Mar. Ecol.-Prog. Ser.
Volume 610 Numéro Pages 51-63
Mots-Clés biomass; Carrying capacity; Chemosymbiosis; competition; Density dependence; dynamics; ecosystem; Environmental heterogeneity; Feeding guild; flats; populations; seagrass; Seagrass; sediment; site; Soft-sediment habitat; variability
Résumé Accurate predictions of population dynamics require an understanding of the ways by which environmental conditions and species-specific traits affect the magnitude of density dependence. Here, we evaluated the potential impact of season and habitat (characterized by sediment grain size and seagrass biomass) on the magnitude of density dependence in shell growth of 3 infaunal bivalve species dominating the tropical intertidal benthic communities of Banc d'Arguin, Mauritania. Two of our focal species were filter feeders (Senilia senilis and Pelecyora isocardia) and one was a facultative mixotroph (Loripes orbiculatus), mainly relying on organic carbon provided by sulphide-oxidizing endosymbiotic gill-bacteria (i.e. chemosymbiotic). Distinguishing 2 seasons, winter and summer, we manipulated local bivalve densities across habitats (from bare sandy sediments to seagrass-covered mud). In situ growth of individually tagged and relocated clams was measured and compared with those of tagged clams that were allocated to adjacent sites where local bivalve densities were doubled. Growth was negatively density-dependent in both winter and summer in P. isocardia and L. orbiculatus, the 2 species that mainly inhabit seagrass sediments, but not in S. senilis, usually found in bare sediments. As reproduction and survival rates are generally size-dependent in bivalves, our results suggest that in our tropical study system, the bivalve community of seagrass-covered sediments is more strongly regulated than that of adjacent bare sediments, regardless of species-specific feeding mode or season. We suggest that ecosystem engineering by seagrasses enhances environmental stability, which allows bivalve populations within tropical seagrass beds to stay close to carrying capacity.
Adresse
Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue English Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0171-8630 ISBN Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2593
Lien permanent pour cet enregistrement