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Auteur (down) Zudaire, I.; Murua, H.; Grande, M.; Goñi, N.; Potier, M.; Ménard, F.; Chassot, E.; Bodin, N.
Titre Variations in the diet and stable isotope ratios during the ovarian development of female yellowfin tuna (Thunnus albacares) in the Western Indian Ocean Type Article scientifique
Année 2015 Publication Revue Abrégée Mar Biol
Volume 162 Numéro 12 Pages 2363-2377
Mots-Clés Freshwater & Marine Ecology; Marine & Freshwater Sciences; Microbiology; Oceanography; Zoology
Résumé The feeding strategy of female yellowfin tuna (Thunnus albacares) during their reproductive cycle was investigated using a combination of different trophic tracers, i.e., stomach contents and dual stable isotope analysis, along with an assessment of ovarian development based on a histological analysis. To complete these analyses, we collected 215 female yellowfin from the Western Indian Ocean in 2009 and 2010. From these fish, we noted the ovarian development and analyzed the contents of 166 non-empty stomachs and 104 liver and muscle tissue samples. Stomach content analysis identified a large variety of prey species (45 prey families), key groups including crustaceans dominated by the swimming crab Charybdis smithii and crustacean larvae; fish dominated by the cigarfish Cubiceps pauciradiatus; and cephalopods dominated by ommastrephids Sthenoteuthis oualaniensis and Ornithoteuthis volatilis. Individuals capable of spawning appeared to feed intensively, particularly on cigarfish, during the reproductive period. From the mean reconstituted weight values of the preys, our results indicated that this intensive feeding led to increased amounts of acquired energy. The results of the stable isotope analyses, carried out on the muscle and liver tissues, indicated a clear decrease in values from north to south. These analyses also showed that liver δ15N values in spawning females were significantly lower than those in immature and developing individuals. This latter observation highlights the differences in metabolic processes that occur between tissues during ovarian development and underlines the importance of the liver in energy acquisition and mobilization in female yellowfin tuna during reproduction.
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ISSN 0025-3162, 1432-1793 ISBN Médium
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Auteur (down) Young, J.W.; Olson, R.J.; Ménard, F.; Kuhnert, P.M.; Duffy, L.M.; Allain, V.; Logan, J.M.; Lorrain, A.; Somes, C.J.; Graham, B.; Goñi, N.; Pethybridge, H.; Simier, M.; Potier, M.; Romanov, E.; Pagendam, D.; Hannides, C.; Choy, C.A.
Titre Setting the stage for a global-scale trophic analysis of marine top predators: a multi-workshop review Type Article scientifique
Année 2015 Publication Revue Abrégée Rev Fish Biol Fisheries
Volume 25 Numéro 1 Pages 261-272
Mots-Clés climate change; Freshwater & Marine Ecology; Global diet data; Global nitrogen model; Global stable isotope data; Predictive analyses; top predators; Tuna trophic ecology; Zoology
Résumé Global-scale studies of marine food webs are rare, despite their necessity for examining and understanding ecosystem level effects of climate variability. Here we review the progress of an international collaboration that compiled regional diet datasets of multiple top predator fishes from the Indian, Pacific and Atlantic Oceans and developed new statistical methods that can be used to obtain a comprehensive ocean-scale understanding of food webs and climate impacts on marine top predators. We loosely define top predators not as species at the apex of the food web, but rather a guild of large predators near the top of the food web. Specifically, we present a framework for world-wide compilation and analysis of global stomach-contents and stable-isotope data of tunas and other large pelagic predatory fishes. To illustrate the utility of the statistical methods, we show an example using yellowfin tuna in a “test” area in the Pacific Ocean. Stomach-contents data were analyzed using a modified (bagged) classification tree approach, which is being prepared as an R statistical software package. Bulk δ15N values of yellowfin tuna muscle tissue were examined using a Generalized Additive Model, after adjusting for spatial differences in the δ15N values of the baseline primary producers predicted by a global coupled ocean circulation-biogeochemical-isotope model. Both techniques in tandem demonstrated the capacity of this approach to elucidate spatial patterns of variations in both forage species and predator trophic positions and have the potential to predict responses to climate change. We believe this methodology could be extended to all marine top predators. Our results emphasize the necessity for quantitative investigations of global-scale datasets when evaluating changes to the food webs underpinning top ocean predators under long-term climatic variability.
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ISSN 0960-3166, 1573-5184 ISBN Médium
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Auteur (down) Wang, T.; Lefevre, S.; Iversen, N.K.; Findorf, I.; Buchanan, R.; McKenzie, D.J.
Titre Anaemia only causes a small reduction in the upper critical temperature of sea bass: is oxygen delivery the limiting factor for tolerance of acute warming in fishes? Type Article scientifique
Année 2014 Publication Revue Abrégée Journal of Experimental Biology
Volume 217 Numéro 24 Pages 4275-4278
Mots-Clés aerobic scope; cardiac-performance; Cardiovascular; climate-change; dicentrarchus-labrax; ecology; exp. biol. 216; fish; Haematocrit; metabolism; Oxygen transport; phenylhydrazine-induced anemia; thermal tolerance; trout
Résumé To address how the capacity for oxygen transport influences tolerance of acute warming in fishes, we investigated whether a reduction in haematocrit, by means of intra-peritoneal injection of the haemolytic agent phenylhydrazine, lowered the upper critical temperature of sea bass. A reduction in haematocrit from 42 +/- 2% to 20 +/- 3% (mean +/- s.e.m.) caused a significant but minor reduction in upper critical temperature, from 35.8 +/- 0.1 to 35.1 +/- 0.2 degrees C, with no correlation between individual values for haematocrit and upper thermal limit. Anaemia did not influence the rise in oxygen uptake between 25 and 33 degrees C, because the anaemic fish were able to compensate for reduced blood oxygen carrying capacity with a significant increase in cardiac output. Therefore, in sea bass the upper critical temperature, at which they lost equilibrium, was not determined by an inability of the cardio-respiratory system to meet the thermal acceleration of metabolic demands.
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ISSN 0022-0949 ISBN Médium
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Notes <p>ISI Document Delivery No.: AW7BT<br/>Times Cited: 1<br/>Cited Reference Count: 44<br/>Wang, Tobias Lefevre, Sjannie Iversen, Nina K. Findorf, Inge Buchanan, Rasmus McKenzie, David J.<br/>Centre National de la Recherche Scientifique (CNRS); Danish Research Council; Region Languedoc-Roussillon (RLR); Ambassade de France in Copenhagen; Universite Montpellier 2<br/>This research was supported by the Centre National de la Recherche Scientifique (CNRS), the Danish Research Council, The Ambassade de France in Copenhagen and Universite Montpellier 2. T.W. was supported by a fellowship from Region Languedoc-Roussillon (RLR) as a visiting professor at Universite Montpellier 2. I.F. and N.K.I. were supported by a student grant from The Ambassade de France in Copenhagen.<br/>Company of biologists ltd<br/>Cambridge</p> Approuvé pas de
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Auteur (down) Violle, C.; Thuiller, W.; Mouquet, N.; Munoz, F.; Kraft, N.J.B.; Cadotte, M.W.; Livingstone, S.W.; Mouillot, D.
Titre Functional Rarity: The Ecology of Outliers Type Article scientifique
Année 2017 Publication Revue Abrégée Trends Ecol. Evol.
Volume 32 Numéro 5 Pages 356-367
Mots-Clés biodiversity; community ecology; Conservation; ecosystem function; intraspecific variability; niche; phylogenetic diversity; plant-communities; spatial mismatch; trait
Résumé Rarity has been a central topic for conservation and evolutionary biologists aiming to determine the species characteristics that cause extinction risk. More recently, beyond the rarity of species, the rarity of functions or functional traits, called functional rarity, has gained momentum in helping to understand the impact of biodiversity decline on ecosystem functioning. However, a conceptual framework for defining and quantifying functional rarity is still lacking. We introduce 12 different forms of functional rarity along gradients of species scarcity and trait distinctiveness. We then highlight the potential key role of functional rarity in the long-term and large-scale maintenance of ecosystem processes, as well as the necessary linkage between functional and evolutionary rarity.
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ISSN 0169-5347 ISBN Médium
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Auteur (down) van Gils, J.A.; van der Geest, M.; De Meulenaer, B.; Gillis, H.; Piersma, T.; Folmer, E.O.
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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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
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