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Auteur van Gils, J.A.; van der Geest, M.; De Meulenaer, B.; Gillis, H.; Piersma, T.; Folmer, E.O. url  doi
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  Titre Moving on with foraging theory: incorporating movement decisions into the functional response of a gregarious shorebird Type Article scientifique
  Année 2015 Publication Revue Abrégée Journal of Animal Ecology  
  Volume 84 Numéro Pages 554-564  
  Mots-Clés competition continuous-time Markov chain cryptic interference diet distribution habitat choice intake rate movement ecology predation toxic prey SPATIAL-DISTRIBUTION RED KNOTS MODELING INTERFERENCE CRYPTIC INTERFERENCE STOCHASTIC VERSION BEHAVIORAL ECOLOGY MULTISTATE MODELS BANC-DARGUIN GROUP-SIZE PREY Ecology Zoology  
  Résumé 1. Models relating intake rate to food abundance and competitor density (generalized functional response models) can predict forager distributions and movements between patches, but we lack understanding of how distributions and small-scale movements by the foragers themselves affect intake rates. Using a state-of-the-art approach based on continuous-time Markov chain dynamics, we add realism to classic functional response models by acknowledging that the chances to encounter food and competitors are influenced by movement decisions, and, vice versa, that movement decisions are influenced by these encounters. We used a multi-state modelling framework to construct a stochastic functional response model in which foragers alternate between three behavioural states: searching, handling and moving. Using behavioural observations on a molluscivore migrant shorebird (red knot, Calidris canutus canutus), at its main wintering area (Banc d'Arguin, Mauritania), we estimated transition rates between foraging states as a function of conspecific densities and densities of the two main bivalve prey. Intake rate decreased with conspecific density. This interference effect was not due to decreased searching efficiency, but resulted from time lost to avoidance movements. Red knots showed a strong functional response to one prey (Dosinia isocardia), but a weak response to the other prey (Loripes lucinalis). This corroborates predictions from a recently developed optimal diet model that accounts for the mildly toxic effects due to consuming Loripes. Using model averaging across the most plausible multi-state models, the fully parameterized functional response model was then used to predict intake rate for an independent data set on habitat choice by red knot. Comparison of the sites selected by red knots with random sampling sites showed that the birds fed at sites with higher than average Loripes and Dosinia densities, that is sites for which we predicted higher than average intake rates. We discuss the limitations of Holling's classic functional response model which ignores movement and the limitations of contemporary movement ecological theory that ignores consumer-resource interactions. With the rapid advancement of technologies to track movements of individual foragers at fine spatial scales, the time is ripe to integrate descriptive tracking studies with stochastic movement-based functional response models.  
  Adresse [van Gils, Jan A.; van der Geest, Matthijs; De Meulenaer, Brecht; Gillis, Hanneke; Piersma, Theunis; Folmer, Eelke O.] NIOZ Royal Netherlands Inst Sea Res, Dept Marine Ecol, NL-1790 AB Den Burg, Texel, Netherlands. [van der Geest, Matthijs; Piersma, Theunis] Univ Groningen, Anim Ecol Grp, Ctr Ecol & Evolutionary Studies CEES, Chair Global Flyway Ecol, NL-9700 CC Groningen, Netherlands. van Gils, JA (reprint author), NIOZ Royal Netherlands Inst Sea Res, Dept Marine Ecol, POB 59, NL-1790 AB Den Burg, Texel, Netherlands. Jan.van.Gils@nioz.nl  
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  ISSN 0021-8790 ISBN Médium  
  Région Expédition Conférence  
  Notes ISI Document Delivery No.: CB9RB Times Cited: 0 Cited Reference Count: 61 van Gils, Jan A. van der Geest, Matthijs De Meulenaer, Brecht Gillis, Hanneke Piersma, Theunis Folmer, Eelke O. NWO WOTRO [W.01.65.221.00]; NWO [R 84-639]; NWO VIDI [864.09.002] We thank Parc National du Banc d'Arguin (PNBA) for their hospitality, the hosting of our presence and the permission to work in and from the Iwik scientific station. Lemhaba ould Yarba made the logistic arrangements. Joop van Eerbeek, Erik J. Jansen, Han Olff and El-Hacen Mohamed El-Hacen helped collecting and sorting benthos samples. Valuable comments on the manuscript were given by Allert Bijleveld, Jaap van der Meer, Ola Olsson, Thomas Oudman, Isabel M. Smallegange, an anonymous referee and by the 'literature club' of the Centre for Integrative Ecology during JAvG's sabbatical at Deakin University. Dick Visser polished the figures. This work is supported by an NWO WOTRO Integrated Programme grant (W.01.65.221.00) to TP, an NWO travel grant (R 84-639) to EOF, and an NWO VIDI grant (864.09.002) to JAvG. 0 WILEY-BLACKWELL HOBOKEN J ANIM ECOL Approuvé pas de  
  Numéro d'Appel MARBEC @ alain.herve @ 1412 collection (down) 1383  
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Auteur Suquet, M.; Cosson, J.; Donval, A.; Labbe, C.; Boulais, M.; Haffray, P.; Bernard, I.; Fauvel, C. url  doi
openurl 
  Titre Marathon vs sprint racers: an adaptation of sperm characteristics to the reproductive strategy of Pacific oyster, turbot and seabass Type Article scientifique
  Année 2012 Publication Revue Abrégée J. Appl. Ichthyol.  
  Volume 28 Numéro 6 Pages 956-960  
  Mots-Clés activation; crassostrea-gigas; fertilization; marine fish; motility; movement; pecten-maximus; respiration; scophthalmus-maximus; spermatozoa  
  Résumé This work assesses the present knowledge on Pacific oyster sperm biology in comparison to two marine fish species (turbot and seabass) whose sperm characteristics are well described. Sperm morphology mainly differs by the presence of an acrosome in Pacific oyster which is absent in both fish species. In turbot as in Pacific oyster, a sperm maturation process along the genital tract is observed. Sperm motility is triggered by changes in osmolality for seabass and turbot and in pH for Pacific oyster. However, complementary factors are involved to maintain sperm immotile in the genital tract. Sperm movement duration is very long in Pacific oyster (2024 h), compared to turbot (35 min) and seabass (4050 s). A high capacity of ATP regeneration is observed in Pacific oyster sperm, sustained by the limited changes in its morphology observed at the end of the swimming phase. Then, the total distance covered by spermatozoa is very different among the studied species (seabass: 2 mm, turbot: 12 mm, Pacific oyster: 1 m). Considering the main characteristics of sperm movement, the three studied species can be separated in two groups: the sprint racer group (seabass: high velocity and short distance covered) and the marathonian racer one (Pacific oyster: low velocity but covering long distances). To an intermediate extent, turbot sperm belongs to the sprint racer group. Then, the two different sperm movement strategies observed in the three species, are compensated by the behaviour of the breeders.  
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  ISSN 0175-8659 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection (down) 701  
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Auteur Coz, R.; Ouisse, V.; Artero, C.; Carpentier, A.; Crave, A.; Feunteun, E.; Olivier, J.M.; Perrin, B.; Ysnel, F. url  doi
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  Titre Development of a new standardised method for sustainable monitoring of the vulnerable pink sea fan Eunicella verrucosa Type Article scientifique
  Année 2012 Publication Revue Abrégée Marine Biology  
  Volume 159 Numéro 6 Pages 1375-1388  
  Mots-Clés atlantic canada; cavolini coelenterata octocorallia; channel; gonadal development; gorgonian paramuricea-clavata; marine invertebrate; mediterranean-sea; modular growth; movement; northeast; singularis esper; water  
  Résumé The aim of this survey was to test a standardised method to follow the demographic evolution of a dense aggregative 'forest' population of the temperate gorgonian Eunicella verrucosa (Octocorallia, Gorgoniidae) using in situ photographic recordings. Distribution, density, growth and demographic evolution of the colonies was compared along two parallel transects. Computer treatment allowed the estimation of the total branch fan surface area, and the individual growth of tagged colonies was determined by measuring the increase in this surface area, using consecutive photographs taken at two-year intervals. To integrate the potential bias of branch overlapping, we proposed a correction factor between the in situ photographic surface area and the surface area of the gorgonian calculated from ex situ photographic surface area with all branches deployed. The surface-frequency distribution of colonies was converted to estimated-age-frequency distribution using an estimated growth curve based on the net growth rate. The technique used revealed significant differences in population structure and the dynamics of gorgonian colonies, as the two transects appeared to be influenced by different environmental conditions. The recruitment also seemed to vary according to year and transect, resulting in different densities. Our work showed clear results in characterising the variations of gorgonian demographic evolution at a small spatial scale; thus, it is assumed that this method could be a sustainable tool for coastal environmental managers.  
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  ISSN 0025-3162 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection (down) 539  
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Auteur Sturrock, A.M.; Trueman, C.N.; Darnaude, A.M.; Hunter, E. url  doi
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  Titre Can otolith elemental chemistry retrospectively track migrations in fully marine fishes? Type Article scientifique
  Année 2012 Publication Revue Abrégée J. Fish Biol.  
  Volume 81 Numéro 2 Pages 766-795  
  Mots-Clés chemical fingerprint; geolocation; microchemistry; movement; natural; tag; trace metals  
  Résumé Otolith microchemistry can provide valuable information about stock structure and mixing patterns when the magnitude of environmental differences among areas is greater than the cumulative influence of any vital effects. Here, the current understanding of the underlying mechanisms governing element incorporation into the otolith is reviewed. Hard and soft acid and base (HSAB) theory is employed to explore the differences in chemical behaviours, distributions and affinities between elements. Hard acid cations (e.g. Mg2+, Li+ and Ba2+) tend to be less physiologically influenced and accepted more readily into the otolith crystal lattice but are relatively homogeneous in seawater. Soft acid cations (e.g. Zn2+ and Cu2+) on the other hand, exhibit more varied distributions in seawater, but are more likely to be bound to blood proteins and less available for uptake into the otolith. The factors influencing the geographical distribution of elements in the sea, and their incorporation into the otoliths of marine fishes are reviewed. Particular emphasis is placed on examining physiological processes, including gonad development, on the uptake of elements commonly used in population studies, notably Sr. Finally, case studies are presented that either directly or indirectly compare population structuring or movements inferred by otolith elemental fingerprints with the patterns indicated by additional, alternative proxies. The main obstacle currently limiting the application of otolith elemental microchemistry to infer movements of marine fishes appears to lie in the largely homogeneous distribution of those elements most reliably measured in the otolith. Evolving technologies will improve the discriminatory power of otolith chemistry by allowing measurement of spatially explicit, low level elements; however, for the time being, the combination of otolith minor and trace element fingerprints with alternative proxies and stable isotopic ratios can greatly extend the scope of migration studies. Among the otolith elements that routinely occur above instrument detection limits, Ba, Mn and Li were deemed the most likely to prove reliable geographic markers in marine species.  
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  ISSN 0022-1112 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection (down) 462  
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Auteur Boyd, C.; Punt, A.E.; Weimerskirch, H.; Bertrand, S. url  doi
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  Titre Movement models provide insights into variation in the foraging effort of central place foragers Type Article scientifique
  Année 2014 Publication Revue Abrégée Ecological Modelling  
  Volume 286 Numéro Pages 13-25  
  Mots-Clés Animal movement; Foraging ecology; Hidden Markov model; Provisioning theory; Seabirds; Sula variegata  
  Résumé Ecology and conservation depend on an understanding of how animals adjust their behaviour patterns in response to changes in their environment. Central place foragers (CPFs) are well-suited for developing ecological models of adaptive processes because their objective functions and operational constraints can be reasonably inferred. Central place foraging and provisioning theory provide the theoretical framework for this analysis. Analysis of CPF time allocation and energy budgets can provide insights into their strategies for responding to environmental variation. However, until recently, suitable high-resolution data on the behaviour of seabirds and other CPFs at sea have not been available. Previous studies of breeding seabirds have investigated variation in foraging trip duration and colony attendance, but few studies have analyzed variation in time allocation within foraging trips. Here, we develop a conceptual energy-based model for analysing variation in the time allocation of CPFs during foraging trips, and apply it to the movement patterns of Peruvian boobies (Sula variegata). Foraging trips of Peruvian boobies, recorded using high-resolution global positioning systems (GPS), were first partitioned into movement modes consistent with travel and foraging behaviours using a hidden Markov model (HMM) adapted to account for gaps in the GPS tracks associated with diving behaviour. Analysis of the HMM results based on the conceptual model indicated that differences in foraging effort between two treatments were best explained by a combination of differences in travel time and in time spent searching for prey. The conceptual model provides the basis for an integrated approach to analysis of variation in foraging strategies in which identification of various behaviours is coupled with assessments of time and energy budgets. This integrated approach can contribute to greater understanding of the processes determining foraging strategies and the limits to these strategies in the context of competition for resources and global climate change.  
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  ISSN 0304-3800 ISBN Médium  
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  Numéro d'Appel LL @ pixluser @ collection (down) 355  
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