Consulta: creatorFacets:"Guinet, Christophe"
Registros recuperados: 19
Data/hora: 16/06/2024 17:41:54

Spatial distribution of foraging in female Antarctic fur seals Arctocephalus gazella in relation to oceanographic variables: a scale-dependent approach using geographic information systems
Provedor de dados: 5
Autores: Guinet, Christophe; Dubroca, L; Lea, Ma; Goldsworthy, S; Cherel, Yan; Duhamel, Guy; Bonadonna, F; Donnay, Jp.
The distribution of foraging activity for female Antarctic fur seals was investigated at Cap Noir (49 degrees 07 'S, 70 degrees 45 'E), Kerguelen Island in February 1998. Eleven females were fitted with a satellite transmitter and time-depth recorder. The 2 data sets were combined in order to locate diving activity of the seals. The occurrence of fish in the diet of the seals was investigated by the identification of otoliths in 55 scats collected at the breeding colony during the study period. Oceanographic variables were measured simultaneously by direct sampling and satellite remote sensing. The mesopelagic fish community was sampled at 20 stations along 4 transects, where epipelagic trawls were conducted at night at 50 ni depth. We then investigated,...
Tipo: Text
Palavras-chave: Antarctic fur seal; Diet; Oceanographic conditions; Foraging; Geographic information system.
Ano: 2001
URL: https://archimer.ifremer.fr/doc/00247/35843/34354.pdf

Calibration procedures and first dataset of Southern Ocean chlorophyll a profiles collected by elephant seals equipped with a newly developed CTD-fluorescence tags
Provedor de dados: 5
Autores: Guinet, Christophe; Xing, X.; Walker, E; Monestiez, P; Marchand, S.; Picard, Baptiste; Jaud, T.; Authier, Matthieu; Cotte, Cedric; Dragon, Ac; Diamond, E; Antoine, David; Lovell, P.; Blain, Stephane; D'Ortenzio, Fabrizio; Claustre, Herve.
In situ observation of the marine environment has traditionally relied on ship-based platforms. The obvious consequence is that physical and biogeochemical properties have been dramatically undersampled, especially in the remote Southern Ocean (SO). The difficulty in obtaining in situ data represents the major limitations to our understanding, and interpretation of the coupling between physical forcing and the biogeochemical response. Southern elephant seals (Mirounga leonina) equipped with a new generation of oceanographic sensors can measure ocean structure in regions and seasons rarely observed with traditional oceanographic platforms. Over the last few years, seals have allowed for a considerable increase in temperature and salinity profiles from the...
Tipo: Text
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00185/29663/28034.pdf

CORIOLIS. Rapport d’activités 2016
Provedor de dados: 5
Autores: Pouliquen, Sylvie; Maze, Guillaume; Lebreton, Nathanaele; D'Ortenzio, Fabrizio; Alory, Gaël; Delcroix, Thierry; Bourles, Bernard; Blouch, Pierre; Guinet, Christophe; Gouriou, Yves; Gaillard, Fabienne; Heyndrickx, Céline; Le Menn, Marc; Testor, Pierre; Donato, Vincent; Charria, Guillaume; Carval, Thierry; Reverdin, Gilles; Emzivat, Gilbert.
Rapport d'activité Coriolis pour l'année 2016 dans le cadre de la convention cadre Coriolis 2014-2020
Tipo: Text
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00388/49970/50562.pdf

High mortality rates in a juvenile free‐ranging marine predator and links to dive and forage ability
Provedor de dados: 5
Autores: Cox, Samantha; Authier, Matthieu; Orgeret, Florian; Weimerskirch, Henri; Guinet, Christophe.
High juvenile mortality rates are typical of many long‐lived marine vertebrate predators. Insufficient development in dive and forage ability is considered a key driver of this. However, direct links to survival outcome are sparse, particularly in free‐ranging marine animals that may not return to land. In this study, we conduct exploratory investigations toward early mortality in juvenile southern elephant seals Mirounga leonina. Twenty postweaning pups were equipped with (a) a new‐generation satellite relay data tag, capable of remotely transmitting fine‐scale behavioral movements from accelerometers, and (b) a location transmitting only tag (so that mortality events could be distinguished from device failures). Individuals were followed during their...
Tipo: Text
Palavras-chave: Bio-logging; Early life; Foraging ecology; Juvenile mortality; Mirounga leonina; Southern elephant seal; Survival analyses.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00598/71016/69289.pdf

How do fishing practices influence sperm whale (Physeter macrocephalus) depredation on demersal longline fisheries?
Provedor de dados: 5
Autores: Janc, Anais; Richard, Gaetan; Guinet, Christophe; Arnould, John P. Y.; Villanueva, Ching-maria; Duhamel, Guy; Gasco, Nicolas; Tixier, Paul.
Marine mammal depredation on fisheries (animals removing fish caught on fishing gear) is a worldwide issue involving socio-economic and ecological consequences. Longline fisheries are the most impacted by odontocete (toothed whales) depredation. While technological means have provided limited efficacy in reducing depredation, this study examined the fishing practices influencing both the proportion of depredated longline sets and the amount of fish removed by whales. We used an 8-year dataset from the Patagonian toothfish (Dissostichus eleginoides) longline fisheries operating in Crozet and Kerguelen Economic Exclusive Zones (EEZs) (South Indian Ocean) and GLMMs to investigate sperm whale (Physeter macrocephalus) depredation. Sperm whale depredation...
Tipo: Text
Palavras-chave: Depredation; Demersal longline; Sperm whale; Patagonian toothfish; Fishing practices.
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00439/55070/56795.pdf

A Correction for the Thermal Mass-Induced Errors of CTD Tags Mounted on Marine Mammals
Provedor de dados: 5
Autores: Mensah, Vigan; Roquet, Fabien; Siegelman-charbit, Lia; Picard, Baptiste; Pauthenet, Etienne; Guinet, Christophe.
The effect of thermal mass on the salinity estimate from conductivity-temperature-depth (CTD) tags sensor mounted on marine mammals is documented, and a correction scheme is proposed to mitigate its impact. The algorithm developed here allows for a direct correction of the salinity data, rather than a correction of the sample's conductivity and temperature. The amplitude of the thermal mass-induced error on salinity and its correction are evaluated via comparison between data from CTD tags and from Sea-Bird Scientific CTD used as a reference. Thermal mass error on salinity appears to be generally O(10(-2)) g kg(-1), it may reach O(10(-1)) g kg(-1), and it tends to increase together with the magnitude of the cumulated temperature gradient (T-HP) within the...
Tipo: Text
Palavras-chave: Data processing; In situ oceanic observations; Instrumentation; Sensors; Profilers; Oceanic.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00585/69697/67577.pdf

Quenching correction for in vivo chlorophyll fluorescence acquired by autonomous platforms: A case study with instrumented elephant seals in the Kerguelen region (Southern Ocean)
Provedor de dados: 5
Autores: Xing, Xiaogang; Claustre, Herve; Blain, Stephane; D'Ortenzio, Fabrizio; Antoine, David; Ras, Josephine; Guinet, Christophe.
As the proxy for Chlorophyll a (Chl a) concentration, thousands of fluorescence profiles were measured by instrumented elephant seals in the Kerguelen region (Southern Ocean). For accurate retrieval of Chl a concentrations acquired by in vivo fluorometer, a two-step procedure is applied: 1) A predeployment intercalibration with accurate determination by high performance liquid chromatography (HPLC) analysis, which not only calibrates fluorescence in appropriate Chl a concentration units, but also strongly reduces variability between fluorometers, and 2) a profile-by-profile quenching correction analysis, which effectively eliminates the fluorescence quenching issue at surface around noon, and results in consistent profiles between day and night. The...
Tipo: Text
Ano: 2012
URL: https://archimer.ifremer.fr/doc/00248/35965/36927.pdf

Seasonal and Geographic Variation of Southern Blue Whale Subspecies in the Indian Ocean
Provedor de dados: 5
Autores: Samaran, Flore; Stafford, Kathleen M.; Branch, Trevor A.; Gedamke, Jason; Royer, Jean-yves; Dziak, Robert P.; Guinet, Christophe.
Understanding the seasonal movements and distribution patterns of migratory species over ocean basin scales is vital for appropriate conservation and management measures. However, assessing populations over remote regions is challenging, particularly if they are rare. Blue whales (Balaenoptera musculus spp) are an endangered species found in the Southern and Indian Oceans. Here two recognized subspecies of blue whales and, based on passive acoustic monitoring, four "acoustic populations" occur. Three of these are pygmy blue whale (B. m. brevicauda) populations while the fourth is the Antarctic blue whale (B. m. intermedia). Past whaling catches have dramatically reduced their numbers but recent acoustic recordings show that these oceans are still important...
Tipo: Text
Ano: 2013
URL: https://archimer.ifremer.fr/doc/00274/38490/36960.pdf

Variations de la répartition des cachalots sur le plateau de Kerguelen suggérée par les données d’interaction avec les pêcheries
Provedor de dados: 5
Autores: Tixier, Paul; Welsford, Dirk; Lea, Mary-anne; Hindell, Mark; Guinet, Christophe; Janc, Anaïs; Richard, Gaetan; Gasco, Nicolas; Duhamel, Guy; Arangio, Rhys; Villanueva, Ching-maria; Suberg, Lavinia; Arnould, John.
The emergence of longline fishing for Patagonian toothfish (Dissostichus eleginoides) on the Kerguelen Plateau over the past two decades is concomitant with the development of depredation-type interactions by sperm whales (Physeter macrocephalus). Through a unique collaboration between the French and the Australian fisheries operating respectively around Kerguelen, and Heard Island and McDonald Islands (HIMI), this study preliminarily investigated the spatio–temporal variations of the rate of occurrence of sperm whale depredation on the Kerguelen Plateau. Between 2011 and 2016, sperm whales depredated toothfish on 29.1% of all longline sets and over 49.4% of the fished area. The probability of vessels to experience depredation decreased with the latitude...
Tipo: Text
Palavras-chave: Fisheries interactions; Sperm whale; Patagonian toothfish; Kerguelen; Depredation.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00502/61411/65094.pdf

Estimates of the Southern Ocean general circulation improved by animal-borne instruments
Provedor de dados: 5
Autores: Roquet, Fabien; Wunsch, Carl; Forget, Gael; Heimbach, Patrick; Guinet, Christophe; Reverdin, Gilles; Charrassin, Jean-benoit; Bailleul, Frederic; Costa, Daniel P.; Huckstadt, Luis A.; Goetz, Kimberly T.; Kovacs, Kit M.; Lydersen, Christian; Biuw, Martin; Nost, Ole A.; Bornemann, Horst; Ploetz, Joachim; Bester, Marthan N.; Mcintyre, Trevor; Muelbert, Monica C.; Hindell, Mark A.; Mcmahon, Clive R.; Williams, Guy; Harcourt, Robert; Field, Iain C.; Chafik, Leon; Nicholls, Keith W.; Boehme, Lars; Fedak, Mike A.
Over the last decade, several hundred seals have been equipped with conductivity-temperature-depth sensors in the Southern Ocean for both biological and physical oceanographic studies. A calibrated collection of seal-derived hydrographic data is now available, consisting of more than 165,000 profiles. The value of these hydrographic data within the existing Southern Ocean observing system is demonstrated herein by conducting two state estimation experiments, differing only in the use or not of seal data to constrain the system. Including seal-derived data substantially modifies the estimated surface mixed-layer properties and circulation patterns within and south of the Antarctic Circumpolar Current. Agreement with independent satellite observations of sea...
Tipo: Text
Palavras-chave: Animal-borne sampling; Southern Ocean; State estimation; Hydrography.
Ano: 2013
URL: https://archimer.ifremer.fr/doc/00241/35252/33765.pdf

Southern elephant seals from Kerguelen Islands confronted by Antarctic Sea ice. Changes in movements and in diving behaviour
Provedor de dados: 5
Autores: Bailleul, Frédéric; Charrassin, Jean-benoit; Ezraty, Robert; Ardhuin, Fanny; Mcmahon, Clive R.; Field, Iain C.; Guinet, Christophe.
The behaviour of southern elephant seals from Kerguelen Island (4950&amp;#8242;S, 7030&amp;#8242;E) was investigated in relation to the oceanographic regions of the Southern Ocean. The oceanographic and the seal behaviour data, including location and diving activity, were collected using a new generation of satellite-relayed devices measuring and transmitting pressure, temperature, and salinity along with locations. Dive duration, maximum diving depth, time spent at the bottom of the dives, and shape of dive profiles were compared between male and female seals, and were related to the oceanographic characteristics of areas prospected by the seals. Most animals travelled to the Antarctic shelf. However, during winter, adult females travelled away from the...
Tipo: Text
Palavras-chave: Mirounga leonina; Diving Behaviour; Pelagic environment; Benthic environment; Temperature profiles; Marine ecology.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-2500.pdf

Commercial fishing patterns influence odontocete whale-longline interactions in the Southern Ocean
Provedor de dados: 5
Autores: Tixier, Paul; Burch, Paul; Richard, Gaetan; Olsson, Karin; Welsford, Dirk; Lea, Mary-anne; Hindell, Mark A.; Guinet, Christophe; Janc, Anais; Gasco, Nicolas; Duhamel, Guy; Villanueva, Ching-maria; Suberg, Lavinia; Arangio, Rhys; Söffker, Marta; Arnould, John P.y.
The emergence of longline fishing around the world has been concomitant with an increase in depredation-interactions by odontocete whales (removal of fish caught on hooks), resulting in substantial socio-economic and ecological impacts. The extent, trends and underlying mechanisms driving these interactions remain poorly known. Using long-term (2003–2017) datasets from seven major Patagonian toothfish (Dissostichus eleginoides) longline fisheries, this study assessed the levels and inter-annual trends of sperm whale (Physeter macrocephalus) and/or killer whale (Orcinus orca) interactions as proportions of fishing time (days) and fishing area (spatial cells). The role of fishing patterns in explaining between-fisheries variations of probabilities of...
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00481/59242/61961.pdf

Relationship between Chlorophyll a Concentration, Light Attenuation and Diving Depth of the Southern Elephant Seal Mirounga leonina
Provedor de dados: 5
Autores: Jaud, Thomas; Dragon, Anne-cecile; Vacquie Garcia, Jade; Guinet, Christophe.
Recently, a number of Antarctic marine environmental studies have used oceanographic parameters collected from instrumented top predators for ecological and physical information. Phytoplankton concentration is generally quantified through active measurement of chlorophyll fluorescence. In this study, light absorption coefficient (K-0.75) was used as an indicator of phytoplankton concentration. This measurement, easy to obtain and requiring low electric power, allows for assessing of the fine scale horizontal structuring of phytoplankton. As part of this study, Southern elephant seals (SES) were simultaneously equipped with a fluorometer and a light logger. Along the SES tracks, variations in K-0.75 were strongly correlated with chlorophyll, a concentration...
Tipo: Text
Ano: 2012
URL: https://archimer.ifremer.fr/doc/00589/70150/68129.pdf

Correction and Accuracy of High- and Low-Resolution CTD Data from Animal-Borne Instruments
Provedor de dados: 5
Autores: Siegelman, Lia; Roquet, Fabien; Mensah, Vigan; Riviere, Pascal; Pauthenet, Etienne; Picard, Baptiste; Guinet, Christophe.
Most available CTD Satellite Relay Data Logger (CTD-SRDL) profiles are heavily compressed before satellite transmission. High-resolution profiles recorded at the sampling frequency of 0.5 Hz are, however, available upon physical retrieval of the logger. Between 2014 and 2018, several loggers deployed on elephant seals in the Southern Ocean have been set in continuous recording mode, capturing both the ascent and descent for over 60 profiles per day during several months, opening new horizons for the physical oceanography community. Taking advantage of a new dataset made of seven such loggers, a postprocessing procedure is proposed and validated to improve the quality of all CTD-SRDL data: that is, both high-resolution profiles and compressed low-resolution...
Tipo: Text
Palavras-chave: Algorithms; Data processing; In situ oceanic observations.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00494/60567/64043.pdf

Validation of Dive Foraging Indices Using Archived and Transmitted Acceleration Data: The Case of the Weddell Seal
Provedor de dados: 5
Autores: Heerah, Karine; Cox, Samantha; Blevin, Pierre; Guinet, Christophe; Charrassin, Jean-benoît.
Dive data collected from archival and satellite tags can provide valuable information on foraging activity via the characterization of movement patterns (e.g., wiggles, hunting time). However, a lack of validation limits interpretation of what these metrics truly represent in terms of behavior and how predators interact with prey. Head-mounted accelerometers have proven to be effective for detecting prey catch attempt (PrCA) behaviors, and thus can provide a more direct measure of foraging activity. However, device retrieval is typically required to access the high-resolution data they record, restricting use to animals returning to predictable locations. In this study, we present and validate data obtained from newly developed satellite-relay data tags,...
Tipo: Text
Palavras-chave: Satellite relayed data logger; Accelerometers; Diving behavior; Movement ecology; Foraging; Sea-ice; Biologging.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00595/70687/68895.pdf

Sub‐mesoscale fronts modify elephant seals foraging behavior
Provedor de dados: 5
Autores: Rivière, Pascal; Jaud, Thomas; Siegelman, Lia; Klein, Patrice; Cotté, Cedric; Le Sommer, Julien; Dencausse, Guillaume; Guinet, Christophe.
Sub‐mesoscale fronts—with scales from 1 to 50 km are ubiquitous in satellite images of the world oceans. They are known to generate strong vertical velocities with significant impacts on biogeochemical fluxes and pelagic ecosystems. Here, we use a unique data set, combining high‐resolution behavioral and physical measurements, to determine the effects of sub‐mesoscale structures on the foraging behavior of 12 instrumented female southern elephant seals. These marine mammals make long voyages (several months over more than 2000 km), diving and feeding continuously in the Antarctic Circumpolar Current. Our results show that elephant seals change their foraging behavior when crossing sub‐mesoscale fronts: They forage more and at shallower depths inside...
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00584/69636/67497.pdf

Détection de la coelentérazine chez cinq espèces de Myctophidae du plateau des Iles Kerguelen
Provedor de dados: 5
Autores: Duchatelet, Laurent; Hermans, Claire; Duhamel, Guy; Cherel, Yves; Guinet, Christophe; Mallefet, Jérôme.
Myctophidae comprise the largest biomass of mesopelagic fishes in the Southern Ocean. This family has the ability to emit light – bioluminescence – via specific organs called photophores, and from the head and caudal organs. Through biochemical analyses, this study reveals that coelenterazine is the substrate for light reaction in the five most common myctophid species from the Southern Ocean. The results also support the hypothesis of the acquisition of this molecule via the food chain and reveal the presence of two stabilised storage forms of coelenterazine (enol-sulfate and dehydrocoelenterazine) within various tissues of the studied species. Finally, detection of coelenterazine in the gonads also suggests the potential maternal transfer of the...
Tipo: Text
Palavras-chave: Myctophidae; Bioluminescence; Coelenterazine; Dehydrocoelenterazine; Enol-sulfate; Biochemical assays.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00502/61405/65084.pdf

Body condition influences ontogeny of foraging behavior in juvenile southern elephant seals
Provedor de dados: 5
Autores: Orgeret, Florian; Cox, Samantha; Weimerskirch, Henri; Guinet, Christophe.
Ontogeny of diving and foraging behavior in marine top predators is poorly understood despite its importance in population recruitment. This lack of knowledge is partly due to the difficulties of monitoring juveniles in the wild, which is linked to high mortality early in life. Pinnipeds are good models for studying the development of foraging behaviors because juveniles are large enough to robustly carry tracking devices for many months. Moreover, parental assistance is absent after a juvenile departs for its first foraging trip, minimizing confounding effects of parental input on the development of foraging skills. In this study, we tracked 20 newly weaned juvenile southern elephant seals from Kerguelen Islands for up to 338 days during their first trip...
Tipo: Text
Palavras-chave: Accelerometers; Diving behavior; Early-life; First-year juveniles; Foraging behavior; Ontogeny; Satellite relay tags; Southern elephant seals.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00482/59380/62484.pdf

Impacts of climatic anomalies on provisioning strategies of a Southern Ocean predator
Provedor de dados: 5
Autores: Lea, Mary-anne; Guinet, Christophe; Cherel, Yves; Duhamel, Guy; Dubroca, Laurent; Pruvost, Patrice; Hindell, Mark.
The large temporal and spatial variability in marine productivity encountered by marine predators may negatively influence breeding success. The Antarctic fur seal Arctocephalus gazella (AFS), a marine predator in the Southern Ocean (SO) ecosystem with a circumpolar distribution, exhibits a short, 4 mo lactation coinciding with increased summer marine productivity. The diet of AFS, and the distance to significant and productive oceanographic features, such as the Antarctic Polar Frontal Zone (PFZ), varies considerably between populations. We studied the foraging activity, foraging efficiency and the pup provisioning strategies of lactating AFS at a key breeding site in the southern Indian Ocean, the Kerguelen Archipelago. Foraging parameters were examined...
Tipo: Text
Palavras-chave: Antarctic fur seal; Polar front; Pinniped; ENSO; Foraging; Growth; Diving; Seabird; Myctophid; Maternal care.
Ano: 2006
URL: https://archimer.ifremer.fr/doc/00247/35847/34356.pdf