Variation spatio-temporelle de l'activité d'alimentation des éléphants de mer en relation avec les paramètres physiques et biologiques de l'environnement

De nombreux travaux se sont intéressés à étudier l'activité d'alimentation des prédateurs marins en relation avec les conditions océanographiques. Cependant, l'activité alimentaire des ces prédateurs était souvent indirectement estimée à partir de l'analyse de leur trajectoire en mer, ainsi c'est plus le comportement de recherche alimentaire des prédateurs qui était étudié que leur prise alimentaire. Récemment, de nouvelles balises équipées d'accéléromètres ont été mise en œuvre afin d'évaluer les événements de prise alimentaire à fine échelle spatiale et temporelle. En combinant ces nouvelles technologies avec des enregistreurs permettant de collecter à haute fréquence des données sur l'environnement, cette thèse s'est donné pour objectif d'évaluer si le changement spatio-temporel de l'activité d'alimentation d'un prédateur marin, l'éléphant de mer du sud (SES) était relié à l'hétérogénéité des conditions physiques et biologiques rencontrées. Deux résultats principaux ont été mis en évidence. Dans un premier temps, en mettant en relation l'activité d'alimentation des SES avec trois paramètres physiques : la température, la lumière et la profondeur, cinq environnements d'alimentation distincts ont été caractérisé pour ce prédateur. Dans un deuxième temps, une relation qualitative a été montré entre la bioluminescence et l'activité d'alimentation des SES. Tout en apportant des résultats novateurs sur l'écologie des SES, cette thèse a développé des méthodes qui ont le potentiel d'être appliquées à un grand nombre de prédateurs plongeurs et qui ouvrent des perspectives de recherches importantes sur leur l'écologie et sur l'étude des relations prédateurs/proies.Numerous studies focused on the study of the foraging activity of marine predators in relation to oceanographic conditions. However, the foraging activity of marine predators was often indirectly estimated from the analysis of their trajectory at sea and consequently, it is more the searching behavior of predators which was studied than their food intake. Recently, new devices equipped with of accelerometers have been implemented to evaluate the events of food intake. By combining these technologies with devices recording high frequency data on the environment, this phD aims to assess whether the spatio-temporal variation of the foraging activity of a marine predator, the southern elephant seal (SES), is related to the heterogeneity of the physical and biological conditions encountered. Two main results were highlighted. Firstly, by linking the foraging activity of SES with three physical parameters, the temperature, the light and the depth, five distinct foraging environments were characterized for this predator. Secondly, a qualitative relationship was found between the bioluminescence and the foraging activity of SES. While providing innovative results on the ecology of SES, this phD developed methods that have the potential to be applied to a large number of marine predators and that provide research opportunities on the study of predator / prey interactions

Risk Management – Maximum Effect of Minimization Measures

Na osnovi podataka iz pretkliničkih i kliničkih ispitivanja farmaceutska kompanija koja želi staviti lijek na tržište Europske unije predlaže plan upravljanja rizicima koji agencija za lijekove odobrava neposredno prije stavljanja lijeka na tržište. Plan upravljanja rizicima definira mjere koje kompanija poduzima pri praćenju i minimizaciji rizika povezanih s lijekom. Mjere praćenja lijeka na tržištu mogu biti osnovne, tj. rutinske (prijavljivanje nuspojava, pisanje periodičkih izvješća, detekcija i analiza signala) te dodatne (dodatne studije). Sigurnu primjenu lijeka koju provode zdravstveni djelatnici i pacijenti omogućavaju rutinske mjere minimizacije rizika (prenošenje informacije o lijeku putem sažetka ili upute o lijeku) te dodatne mjere (poput edukacijskih materijala, pisma liječnicima ili programa prevencije trudnoće). Plan upravljanja rizicima ažurira se tijekom životnog ciklusa lijeka na osnovi novih informacija kako bi se osigurao pozitivan omjer koristi i rizika od lijeka te njegova sigurna primjena koju provode zdravstveni djelatnici i pacijenti. Osim toga,farmaceutska kompanija i agencija za lijekove mogu poduzeti i druge mjere edukacije zdravstvenih djelatnika i pacijenata radi smanjenja rizika povezanih s lijekovima.Based on non-clinical and clinical findings pharmaceutical companies needs to agree on a Risk Management Plan (RMP) with the authority at the time of drug approval in the European Union. RMP defines measures that a company needs to implement to collect more information and mitigate risk related to drug use. Measures are defined as either routine pharmacovigilance (reporting of adverse events, periodic reports, safety signal detection) or as additional measures (post-authorization safety studies). Safe drug use by healthcare providers and patients is assured by routine risk minimization measures (communication of information through the summary of products characteristics and patient information leaflet) and additional measures (such as educational materials, letters to healthcare providers and pregnancy prevention programs). RMP is updated during product life-cycle based on new information to assure positive benefit/risk of the drug and safe drug use by healthcare providers and patients. Pharmaceutical companies and health authorities may also take other actions to educate healthcare professionals and patients in order to decrease risks related to drug use

Dissolved Oxygen Sensor in Animal-Borne Instruments: An Innovation for Monitoring the Health of Oceans and Investigating the Functioning of Marine Ecosystems

International audienceThe current decline in dissolved oxygen concentration within the oceans is a sensitive indicator of the effect of climate change on marine environment. However the impact of its declining on marine life and ecosystems’ health is still quite unclear because of the difficulty in obtaining in situ data, especially in remote areas, like the Southern Ocean (SO). Southern elephant seals (Mirounga leonina) proved to be a relevant alternative to the traditional oceanographic platforms to measure physical and biogeochemical structure of oceanic regions rarely observed. In this study, we use a new stage of development in biologging technology to draw a picture of dissolved oxygen concentration in the SO. We present the first results obtained from a dissolved oxygen sensor added to Argos CTD-SRDL tags and deployed on 5 female elephant seals at Kerguelen. From October 2010 and October 2011, 742 oxygen profiles associated with temperature and salinity measurements were recorded. Whether a part of the data must be considered cautiously, especially because of offsets and temporal drifts of the sensors, the range of values recorded was consistent with a concomitant survey conducted from a research vessel (Keops-2 project). Once again, elephant seals reinforced the relationship between marine ecology and oceanography, delivering essential information about the water masses properties and the biological status of the Southern Ocean. But more than the presentation of a new stage of development in animal-borne instrumentation, this pilot study opens a new field of investigation in marine ecology and could be enlarged in a near future to other key marine predators, especially large fish species like swordfish, tuna or sharks, for which dissolved oxygen is expected to play a crucial role in distribution and behaviour

Diving behaviour of adult male white whales (Delphinapterus leucas) in Svalbard, Norway

White whales (Delphinapterus leucas) in Svalbard remain near the coast much of the year, spending most of their time in front of tidewater glaciers. In this article, the diving behaviour of adult male white whales in Svalbard (N = 16) is presented based on satellite-relay data loggers that record time and depth of diving as well as positions. The loggers transmitted data for an average of 87 ± 52 days (range 2–163 days). After filtering, 55 359 dives were available for the study. Most of the dives were extremely shallow (13 ± 26 m, maximum 350 m) and of short duration (97 ± 123 s, maximum 31.4 min). At tidewater glacier fronts, the white whales optimized their time at the bottom of dives and spent longer periods resting at the surface after dives, in accordance with what would be expected when foraging. This behaviour was also documented when animals were out in the fjords. When the whales moved between areas around the archipelago, they swam close to the coast, staying right below the surface most of the time, presumably to minimize energy expenditure during transits. When sea ice formed during the winter, the whales were forced offshore into somewhat deeper areas with drifting ice. In these areas, the whales minimized time at the surface and dove somewhat deeper, sometimes reaching the bottom, presumably to feed on neritic prey

Delineation of the southern elephant seal׳s main foraging environments defined by temperature and light conditions

International audienceChanges in marine environments, induced by the global warming, are likely to influence the prey field distribution and consequently the foraging behaviour and the distribution of top marine predators. Thanks to bio-logging, the simultaneous measurements of fine-scale foraging behaviors and oceanographic parameters by predators allow characterizing their foraging environments and provide insights into their prey distribution. In this context, we propose to delimit and to characterize the foraging environments of a marine predator, the Southern Elephant Seal (SES). To do so, the relationship between oceanographic factors and prey encounter events (PEE) was investigated in 12 females SES from Kerguelen Island simultaneously equipped with accelerometers and with a range of physical sensors (temperature, light and depth). PEEs were assessed from the accelerometer data at high spatio-temporal precision while the physical sensors allowed the continuous monitoring of environmental conditions encountered by the SES when diving. First, visited and foraging environments were distinguished according to the oceanographic conditions encountered in the absence and in presence of PEE. Then, a hierarchical classification of the physical parameters recorded during PEEs led to the distinction of five different foraging environments. These foraging environments were structured according to the main frontal systems of the SO. One was located north to the subantarctic front (SAF) and characterized by high temperature and depth, and low light levels. Another, characterized by intermediate levels of temperature, light and depth, was located between the SAF and the polar front (PF). And finally, the last three environments were all found south to the PF and, characterized by low temperature but highly variable depth and light levels. The large physical and/or spatial differences found between these environments suggest that, depending on the location, different prey communities are targeted by SES over a broad range of water temperature, light level and depth conditions. This result highlights the versatility of this marine predator. In addition, in most cases, PEEs were found deeper during the day than during the night, which is indicative of mesopelagic prey performing nycthemeral migration, a behaviour consistent with myctophids species thought to represent the bulk of Kerguelen SES female diets

Habitats and movement patterns of white whales Delphinapterus leucas in Svalbard, Norway in a changing climate

Abstract Background The Arctic is experiencing rapid reductions in sea ice and in some areas tidal glaciers are melting and retracting onto land. These changes are occurring at extremely rapid rates in the Northeast Atlantic Arctic. The aim of this study was to investigate the impacts of these environmental changes on space use by white whales (Delphinapterus leucas) in Svalbard, Norway. Using a unique biotelemetry data set involving 34 animals, spanning two decades, habitat use and movement patterns were compared before (1995–2001) and after (2013–2016) a dramatic change in the regional sea ice regime that began in 2006. Results White whales were extremely coastal in both study periods, remaining near the islands within the Svalbard Archipelago, even when winter sea ice formation pushed them offshore somewhat (later in the year in the recent period), into areas with drifting sea ice (concentrations up to 90%). In both periods, the whales followed the same basic patterns seasonally; they occupied the west coast in summer and shifted to the east coast as winter approached. However, space use did change between the two periods, with the whales spending less time close to tidal glacier fronts in the second period compared to the first (2nd-36% vs 1st-51%), a habitat characterized by low swimming speeds and high turning angles, and more time out in the fjords (2nd-26% vs1st-10%). Use of coastal transit corridors remained the same in both periods; the whales appear to minimize time spent moving between fjords. Conclusions Glacier fronts have previously been shown to be important foraging areas for white whales in Svalbard and the movement metrics documented in this study confirms that this is still the case. However, use of the Fjords habitat in summer and fall (frequency of occupancy and movement metrics) seen in the recent period suggests that the white whales might now also be feeding on Atlantic prey that is increasingly common in the fjords, concomitant with influxes of Atlantic Water along the west coast of Svalbard. Such behavioural flexibility, if confirmed by further diet studies, would likely be important for white whales in adapting to new conditions in Svalbard

Habitats and movement patterns of white whales Delphinapterus leucas in Svalbard, Norway in a changing climate

Background: The Arctic is experiencing rapid reductions in sea ice and in some areas tidal glaciers are melting and retracting onto land. These changes are occurring at extremely rapid rates in the Northeast Atlantic Arctic. The aim of this study was to investigate the impacts of these environmental changes on space use by white whales (Delphinapterus leucas) in Svalbard, Norway. Using a unique biotelemetry data set involving 34 animals, spanning two decades, habitat use and movement patterns were compared before (1995–2001) and after (2013–2016) a dramatic change in the regional sea ice regime that began in 2006. Results: White whales were extremely coastal in both study periods, remaining near the islands within the Svalbard Archipelago, even when winter sea ice formation pushed them offshore somewhat (later in the year in the recent period), into areas with drifting sea ice (concentrations up to 90%). In both periods, the whales followed the same basic patterns seasonally; they occupied the west coast in summer and shifted to the east coast as winter approached. However, space use did change between the two periods, with the whales spending less time close to tidal glacier fronts in the second period compared to the first (2nd-36% vs 1st-51%), a habitat characterized by low swimming speeds and high turning angles, and more time out in the fjords (2nd-26% vs1st-10%). Use of coastal transit corridors remained the same in both periods; the whales appear to minimize time spent moving between fjords. Conclusions: Glacier fronts have previously been shown to be important foraging areas for white whales in Svalbard and the movement metrics documented in this study confirms that this is still the case. However, use of the Fjords habitat in summer and fall (frequency of occupancy and movement metrics) seen in the recent period suggests that the white whales might now also be feeding on Atlantic prey that is increasingly common in the fjords, concomitant with influxes of Atlantic Water along the west coast of Svalbard. Such behavioural flexibility, if confirmed by further diet studies, would likely be important for white whales in adapting to new conditions in Svalbard

Southern Elephant Seals Replenish Their Lipid Reserves at Different Rates According to Foraging Habitat

International audienceAssessing energy gain and expenditure in free ranging marine predators is difficult. However,such measurements are critical if we are to understand how variation in foraging efficiency,and in turn individual body condition, is impacted by environmentally driven changesin prey abundance and/or accessibility. To investigate the influence of oceanographic habitattype on foraging efficiency, ten post-breeding female southern elephant seals Miroungaleonina (SES) were equipped and tracked with bio-loggers to give continuous information ofprey catch attempts, body density and body activity. Variations in these indices of foragingefficiency were then compared between three different oceanographic habitats, delineatedby the main frontal structures of the Southern Ocean. Results show that changes in bodydensity are related not only to the number of previous prey catch attempts and to the bodyactivity (at a 6 day lag), but also foraging habitat type. For example, despite a lower dailyprey catch attempt rate, SESs foraging north of the sub-Antarctic front improve their bodydensity at a higher rate than individuals foraging south of the sub-Antarctic and polar fronts,suggesting that they may forage on easier to catch and/or more energetically rich prey inthis area. Our study highlights a need to understand the influence of habitat type on toppredator foraging behaviour and efficiency when attempting a better comprehension ofmarine ecosystems.Introductio

Foraging in the darkness of the Southern Ocean: influence of bioluminescence on a deep diving predator.

How non-echolocating deep diving marine predators locate their prey while foraging remains mostly unknown. Female southern elephant seals (SES) (Mirounga leonina) have vision adapted to low intensity light with a peak sensitivity at 485 nm. This matches the wavelength of bioluminescence produced by a large range of marine organisms including myctophid fish, SES's main prey. In this study, we investigated whether bioluminescence provides an accurate estimate of prey occurrence for SES. To do so, four SES were satellite-tracked during their post-breeding foraging trip and were equipped with Time-Depth-Recorders that also recorded light levels every two seconds. A total of 3386 dives were processed through a light-treatment model that detected light events higher than ambient level, i.e. bioluminescence events. The number of bioluminescence events was related to an index of foraging intensity for SES dives deep enough to avoid the influence of natural ambient light. The occurrence of bioluminescence was found to be negatively related to depth both at night and day. Foraging intensity was also positively related to bioluminescence both during day and night. This result suggests that bioluminescence likely provides SES with valuable indications of prey occurrence and might be a key element in predator-prey interactions in deep-dark marine environments

Predicting prey capture rates of southern elephant seals from track and dive parameters

International audienceIn the marine environment, track and dive parameter data (obtained using Argos or GPS tags and time–depth recorders) are commonly used to provide proxies for foraging behaviour of marine predators. However, their accuracy is rarely assessed. Recently, the addition of head-mounted accelerometers has allowed for detection of prey capture attempts (PCAs) at sea, allowing for more accurate estimations of foraging behaviour. Despite increased numbers of such devices being deployed, their use is still marginal compared with other tools which measure track and dive parameters. The objectives of our study were (1) to identify the most relevant combination of tracking and diving metrics in predicting the frequency of PCAs in female southern elephant seals Mirounga leonina from the Kerguelen Islands, and (2) to apply it to a broader range of individuals for which only tracking and diving data were available. The results of our models were consistent with the optimal foraging theory as well as the optimal diving theory. The model with the best predictive performance was the one that combined both tracking and diving information. However, most of the variability in the number of PCAs could be solely explained by changes in the diving behaviour of seals. Finally, we used the best predictive model on 20 individuals, which had not been fitted with accelerometers, to determine their main foraging zones. The behavioural indicators established in this study constitute a useful ecological tool for population monitoring and conservation purposes