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Auteur Boyd, C.; Punt, A.E.; Weimerskirch, H.; Bertrand, S.
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 355
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Auteur Cuif, M.; Keller, F.; Chateau, O.; Kaplan, D.; Labonne, M.; Lett, C.; Vigliola, L.
Titre Evaluation of transgenerational isotope labeling of embryonic otoliths in a coral reef damselfish with single and repeated injections of enriched (137)Barium Type Article scientifique
Année 2014 Publication Revue Abrégée Journal of Experimental Marine Biology and Ecology
Volume 459 Numéro Pages 151-159
Mots-Clés Barium isotopes; Connectivity; Dascyllus aruanus; La-Icp-Ms; microchemistry; Otolith; Transgenerational marking
Résumé Quantifying the larval dispersal component of population connectivity is extremely challenging due to the many difficulties associated with directly observing larvae in their marine environment. Transgenerational isotope labeling is a recent empirical technique that addresses this challenge. It relies on the transmission of an artificially enriched stable isotope (e.g., Ba-137) from gravid females to the embryonic otoliths of their offspring, allowing for mass permanent marking of larvae. Before implementing transgenerational isotope labeling in the wild, it is essential to investigate the transmission longevity of the mark from females to larvae and to assess the potential negative effects on females and their offspring. We injected females of the Humbug damselfish, Dascyllus aruanus, with an enriched Ba-137 solution and reared the resulting progeny to test the marking success and the transmission longevity of the mark, as well as determine potential effects of transgenerational isotope labeling on spawning frequency and size of 1-day eggs and 2-day larvae. Three different single-injection dosages (0.5, 1 and 5 mu g of Ba-137 g(-1) fish weight) were tested, as well as monthly repeated injections of the lowest dosage over a whole reproductive season. We implemented a new method that allows extracting otoliths of newly hatched larvae and analyzing them using laser ablation coupled plasma mass spectrometry (ICP-MS). We showed that for D. aruanus, injection with a low dose (0.5 mu g Ba-137 g(-1), fish weight) produced consistently significantly marked larvae with a half-life for successful enriched Ba mark transmission of approximately 1 month, and that monthly repeated injections of this dose did not negatively impact spawning success or condition of eggs and larvae. Monthly repeated injections of enriched Ba isotope injections at 0.5 mu g Ba-137 g(-1) fish weight will therefore present an effective means of mass marking D. aruanus larvae throughout an entire reproductive season.
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Langue (up) Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0022-0981 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 357
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Auteur Miller, M.J.; Bonhommeau, S.; Munk, P.; Castonguay, M.; Hanel, R.; McCleave, J.D.
Titre A century of research on the larval distributions of the Atlantic eels: a re-examination of the data Type Article scientifique
Année 2014 Publication Revue Abrégée Biological Reviews
Volume Numéro Pages
Mots-Clés anguilla; freshwater eels; larval distribution; oceanic fronts.; Sargasso Sea; spawning area
Résumé The spawning areas of the Atlantic freshwater eels were discovered about a century ago by the Danish scientistJohannes Schmidt who after years of searching found newly hatched larvae of the European eel, Anguillaanguilla, and the American eel, Anguilla rostrata, in the southern Sargasso Sea. The discovery showed thatanguillid eels migrate thousands of kilometers to offshore spawning areas for reproduction, and that theirlarvae, called leptocephali, are transported equally long distances by ocean currents to their continentalrecruitment areas. The spawning sites were found to be related to oceanographic conditions several decadeslater by German and American surveys from 1979 to 1989 and by a Danish survey in 2007 and a Germansurvey in 2011. All these later surveys showed that spawning occurred within a restricted latitudinal range,between temperature fronts within the Subtropical Convergence Zone of the Sargasso Sea. New data andre-examinations of Schmidt’s data confirmed his original conclusions about the two species having someoverlap in spawning areas. Although there have been additional collections of leptocephali in various parts ofthe North Atlantic, and both otolith research and transport modelling studies have subsequently been carriedout, there is still a range of unresolved questions about the routes of larval transport and durations of migration.This paper reviews the history and basic findings of surveys for anguillid leptocephali in the North Atlantic andanalyses a new comprehensive database that includes 22612 A. anguilla and 9634 A. rostrata leptocephali, whichprovides a detailed view of the spatial and temporal distributions and size of the larvae across the Atlantic basinand in the Mediterranean Sea. The differences in distributions, maximum sizes, and growth rates of the twospecies of larvae are likely linked to the contrasting migration distances to their recruitment areas on eachside of the basin. Anguilla rostrata leptocephali originate from a more western spawning area, grow faster, andmetamorphose at smaller sizes of <70mm than the larvae of A. anguilla, which mostly are spawned further eastand can reach sizes of almost 90 mm. The larvae of A. rostrata spread west and northwest from the spawningarea as they grow larger, with some being present in the western Caribbean and eastern Gulf of Mexico. Larvaeof A. anguilla appear to be able to reach Europe by entering the Gulf Stream system or by being entrainedinto frontal countercurrents that transport them directly northeastward. The larval duration of A. anguillais suggested to be quite variable, but gaps in sampling effort prevent firm conclusions. Although knowledgeabout larval behaviour is lacking, some influences of directional swimming are implicated by the temporaldistributions of the largest larvae. Ocean–atmosphere changes have been hypothesized to affect the survivalof the larvae and cause reduced recruitment, so even after about a century following the discovery of theirspawning areas, mysteries still remain about the marine life histories of the Atlantic eels.
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Langue (up) Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 1464-7931 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1125
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Auteur Espinoza, P.; Bertrand, A.
Titre Ontogenetic and spatiotemporal variability in anchoveta Engraulis ringens diet off Peru Type Article scientifique
Année 2014 Publication Revue Abrégée Journal of Fish Biology
Volume 84 Numéro 2 Pages 422-435
Mots-Clés euphausiids; Humboldt Current system; oxygen; Peruvian anchovy; spatiotemporal variability; trophic ecology
Résumé In this study, historical data available since 1954 were used to get new insight to ontogenetic and spatiotemporal variability in Peruvian anchovy or anchoveta Engraulis ringens diet. Whatever the period, E. ringens foraged mainly on macrozooplankton and the importance of euphausiids in E. ringens diet appears directly related to euphausiids abundance. This bottom-up effect is also observed at smaller scale because the euphausiids fraction increased with E. ringens total length and euphausiids accessibility. Selecting the largest prey, the euphausiids, provides an energetic advantage for E. ringens in its ecosystem where oxygen depletion imposes strong metabolic constraints on pelagic fishes. This study illustrates the plasticity of E. ringens that allows it to cope with its highly variable environment.
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Langue (up) Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0022-1112 ISBN Médium
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Notes Approuvé pas de
Numéro d'Appel LL @ pixluser @ collection 358
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Auteur BORDIER, C.; SARAUX, C.; VIBLANC, V.A.; GACHOT-NEVEU, H.; BEAUGEY, M.; LE MAHO, Y.; LE BOHEC, C.
Titre Inter-Annual Variability of Fledgling Sex Ratio in King Penguins Type Article scientifique
Année 2014 Publication Revue Abrégée Plos One
Volume 9 Numéro 12 Pages 1-17
Mots-Clés
Résumé As the number of breeding pairs depends on the adult sex ratio in a monogamous species with biparental care, investigating sex-ratio variability in natural populations is essential to understand population dynamics. Using 10 years of data (20002009) in a seasonally monogamous seabird, the king penguin (Aptenodytes patagonicus), we investigated the annual sex ratio at fledging, and the potential environmental causes for its variation. Over more than 4000 birds, the annual sex ratio at fledging was highly variable (ranging from 44.4% to 58.3% of males), and on average slightly biased towards males (51.6%). Yearly variation in sex-ratio bias was neither related to density within the colony, nor to global or local oceanographic conditions known to affect both the productivity and accessibility of penguin foraging areas. However, rising sea surface temperature coincided with an increase in fledging sex-ratio variability. Fledging sex ratio was also correlated with difference in body condition between male and female fledglings. When more males were produced in a given year, their body condition was higher (and reciprocally), suggesting that parents might adopt a sex-biased allocation strategy depending on yearly environmental conditions and/or that the effect of environmental parameters on chick condition and survival may be sex-dependent. The initial bias in sex ratio observed at the juvenile stage tended to return to 1:1 equilibrium upon first breeding attempts, as would be expected from Fisher's classic theory of offspring sex-ratio variation.
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Langue (up) Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 1932-6203 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1126
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