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Auteur Dueri, S.; Bopp, L.; Maury, O.
Titre Projecting the impacts of climate change on skipjack tuna abundance and spatial distribution Type Article scientifique
Année 2014 Publication Revue Abrégée Global Change Biology
Volume 20 Numéro 3 Pages 742-753
Mots-Clés Apecosm-E; Atlantic Ocean; global warming; Indian Ocean; Katsuwonus pelamis; Pacific Ocean; scenario; Tropical tuna
Résumé Climate-induced changes in the physical, chemical, and biological environment are expected to increasingly stress marine ecosystems, with important consequences for fisheries exploitation. Here, we use the APECOSM-E numerical model (Apex Predator ECOSystem Model – Estimation) to evaluate the future impacts of climate change on the physiology, spatial distribution, and abundance of skipjack tuna, the worldwide most fished species of tropical tuna. The main novelties of our approach lie in the mechanistic link between environmental factors, metabolic rates, and behavioral responses and in the fully three dimensional representation of habitat and population abundance. Physical and biogeochemical fields used to force the model are provided by the last generation of the IPSL-CM5 Earth System Model run from 1990 to 2100 under a &8216;business-as-usual&8217; scenario (RCP8.5). Our simulations show significant changes in the spatial distribution of skipjack tuna suitable habitat, as well as in their population abundance. The model projects deterioration of skipjack habitat in most tropical waters and an improvement of habitat at higher latitudes. The primary driver of habitat changes is ocean warming, followed by food density changes. Our projections show an increase of global skipjack biomass between 2010 and 2050 followed by a marked decrease between 2050 and 2095. Spawning rates are consistent with population trends, showing that spawning depends primarily on the adult biomass. On the other hand, growth rates display very smooth temporal changes, suggesting that the ability of skipjack to keep high metabolic rates in the changing environment is generally effective. Uncertainties related to our model spatial resolution, to the lack or simplification of key processes and to the climate forcings are discussed.
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Volume de collection Numéro de collection (up) Edition
ISSN 1354-1013 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 327
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Auteur Chu, Y.; Tournoud, M.G.; Salles, C.; Got, P.; Perrin, J.L.; Rodier, C.; Caro, A.; Troussellier, M.
Titre Spatial and temporal dynamics of bacterial contamination in South France coastal rivers: focus on in-stream processes during low flows and floods Type Article scientifique
Année 2014 Publication Revue Abrégée Hydrological Processes
Volume 28 Numéro 8 Pages 3300-3313
Mots-Clés Coliforms and streptococci; Mediterranean rivers; faecal indicator loads; flush effect; point sources; riverbed sediment abundance
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Langue Langue du Résumé Titre Original
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Volume de collection Numéro de collection (up) Edition
ISSN 0885-6087 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 839
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Auteur Fablet, R.; Chaigneau, A.; Bertrand, S.
Titre Multiscale analysis of geometric planar deformations : application to wild animal electronic tracking and satellite ocean observation data Type Article scientifique
Année 2014 Publication Revue Abrégée Ieee Transactions on Geoscience and Remote Sensing
Volume 52 Numéro 6 Pages 3627-3636
Mots-Clés Animal movements; geophysical fields; multiscale geometry; planar curve; trajectory analysis; wavelet analysis
Résumé The development of animal tracking technologies (including GPS and ARGOS satellite systems) and the increasing resolution of remote-sensing observations call for tools extracting and describing the geometric patterns along a track or within an image over a wide range of spatial scales. Whereas shape analysis has largely been addressed over the last decades, the multiscale analysis of the geometry of opened planar curves has received little attention. We here show that classical multiscale techniques cannot properly address this issue and propose an original wavelet-based scheme. To highlight the generic nature of our multiscale wavelet technique, we report applications to two different observation data sets, namely, wild animal movement paths recorded by electronic tags and satellite observations of sea-surface geophysical fields.
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Langue Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection (up) Edition
ISSN 0196-2892 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 328
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Auteur Gutowsky, S.E.; Tremblay, Y.; Kappes, M.A.; Flint, E.N.; Klavitter, J.; Laniawe, L.; Costa, D.P.; Naughton, M.B.; Romano, M.D.; Shaffer, S.A.
Titre Divergent post-breeding distribution and habitat associations of fledgling and adult black-footed Albatrosses Phoebastria nigripes in the North Pacific Type Article scientifique
Année 2014 Publication Revue Abrégée Ibis
Volume 156 Numéro 1 Pages 60-72
Mots-Clés dispersal; geolocators; habitat use; Juvenile; Procellariiform; satellite telemetry; seabird
Résumé Past tracking studies of marine animals have primarily targeted adults, biasing our understanding of at-sea habitat use toward older life stages. Anthropogenic threats persist throughout the at-sea ranges of all life stages and it is therefore of interest to population ecologists and managers alike to understand spatiotemporal distributions and possible niche differentiation between age-classes. In albatrosses, particularly little is known about the juvenile life stage when fledglings depart the colonies and venture to sea with no prior experience or parental guidance. We compared the dispersal of 22 fledgling Black-footed Albatross Phoebastria nigripes between 2006 and 2008 using satellite telemetry and 16 adults between 2008 and 2009 using geolocaters from Midway Atoll National Wildlife Refuge, Northwest Hawaiian Islands. Following tag deployment, all fledglings spent several days within the calm atoll waters, then travelled northward until reaching 750-900km from the colony. At this point, fledgling distributions approached the productive North Pacific Transition Zone (NPTZ). Rather than reaching the high chlorophyll a densities on the leading edge of this zone, however, fledglings remained in areas of low productivity in the subtropical gyre. In contrast, adult albatrosses from the same breeding colony did not utilize the NPTZ at this time of year but rather ranged throughout the highly productive northern periphery of the Pacific Ocean Basin among the shelf regions off Japan and the Aleutian Islands. The dichotomy in habitat use between fledglings and adults from Midway Atoll results in complete spatial segregation between age-classes and suggests ontogenetic niche separation in this species. This research fills a large knowledge gap in at-sea habitat use during a little known yet critical life stage of albatrosses, and contributes to a more comprehensive understanding of differential mortality pressure between age-classes and overall conservation status for the vulnerable Black-footed Albatross.
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Volume de collection Numéro de collection (up) Edition
ISSN 0019-1019 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 329
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Auteur Neira, S.; Moloney, C.; Christensen, V.; Cury, P.; Shannon, L.; Arancibia, H.
Titre Analysing changes in the southern Humboldt ecosystem for the period 1970-2004 by means of dynamic food web modelling Type Article scientifique
Année 2014 Publication Revue Abrégée Ecological Modelling
Volume 274 Numéro Pages 41-49
Mots-Clés Ecopath with Ecosim; Fishing patterns; Physical forcing; Regime shifts; Southern Humboldt; Trophic controls
Résumé A 22-group Ecopath model representing the southern Humboldt (SH) upwelling system in the year 1970 is constructed. The model is projected forward in time and fitted to available time series of relative biomass, catch and fishing mortality for the main fishery resources. The time series cover the period 1970 to 2004 and the fitting is conducted using the Ecopath with Ecosim (EwE) software version 5.1. The aim is to explore the relative importance of internal (trophic control) and external (fishing, physical variability) forcing on the dynamics of commercial stocks and the Southern Chilean food web. Wide decadal oscillations are observed in the biomass of commercial stocks during the analyzed period. Fishing mortality explains 21% of the variability in the time series, whereas vulnerability (v) parameters estimated using EwE explain an additional 20%. When a function affecting primary production (PP) is calculated by Ecosim to minimize the sum of squares of the time series, a further 28% of variability is explained. The best fit is obtained by using the fishing mortality time series and by searching for the best combination of v parameters and the PP function simultaneously, accounting for 69% of total variability in the time series. The PP function obtained from the best fit significantly correlates with independent time series of an upwelling index (UI; rho = 0.47, p<0.05) and sea surface temperature (SST; rho = -0.45, p<0.05), representing environmental conditions in the study area during the same period of time. These results suggest that the SH ecosystem experienced at least two different environmentally distinct periods in the last three decades: (i) from 1970 to 1985 a relatively warm period with low levels of upwelling and PP, and (ii) from 1985 to 2004 a relatively cold period with increased upwelling and PP. This environmental variability can explain some of the changes in the food webs. Fishing (catch rate) and the environment (bottom-up anomaly in PP) appear to have affected the SH both at the stock and at the food web level between 1970 and 2004. The vulnerability setting indicates that the effects of external forcing factors may have been mediated by trophic controls operating in the food web.
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Editeur Lieu de Publication Éditeur
Langue Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection (up) Edition
ISSN 0304-3800 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 330
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