Abstract: BACKGROUND: In the open ocean, eddies and associated structures (fronts, filaments) have strong influences on the foraging activities of top-predators through the enhancement and the distribution of marine productivity, zooplankton and fish communities. Investigating how central place foragers, such as penguins, find and use these physical structures is crucial to better understanding their at-sea distribution. In the present study, we compared the travel heading and speed of the world's most abundant penguin, the Macaroni penguin (Eudyptes chrysolophus), with the distribution of surface physical structures (large-scale fronts, eddies and filaments).

Abstract: Invited talk in the Symposium 'SEABIRD HEALTH' of the 2nd World Seabird Conference, Cape Town, South Africa, October 2015.
Infectious diseases have the potential to cause rapid declines and extinction in endangered vertebrate species. Animals in Antarctica and in the surrounding islands of the Southern Ocean have evolved in relative isolation and are likely to be particularly sensitive to the introduction of pathogens. In spite of this spatial isolation, increased exposition to humans and exotic species has generated opportunities for the introduction of pathogens to native and endemic species. A dramatic example is the recurrent chick mortality occurring in seabird populations of Amsterdam Island, where breeds the endangered and endemic Amsterdam albatross. On this island, the impact and extent of epizootics have increased during the last ten years and stress the urgent need for (1) the identification of the etiologic agents involved in these epizootics, and (2) the investigation of the epizootiology of these pathogens to better understand the ecology of the disease and accordingly define mitigation and prevention methods. Based on molecular analyses, we provide evidence for the presence of two potentially pathogenic bacteria species, Pasteurella multocida and Erysipelothrix rhusiopathiae, in the five seabird species breeding on Amsterdam. Demographic parameters and count surveys conducted on these species suggested that epizootics might affect only three of them, the sooty and yellow-nosed albatrosses and northern rockhopper penguins. P. multocida was isolated in pure culture on corpses of the two former species, which strongly suggests the role of this agent in the deaths reported. Genetic characterization of the isolates suggests that the bacteria could have been introduced to the island, where poultry have been locally reared until the last decade. Although there has not been evidence of epizootics in the Amsterdam albatross, recurrent chick mortalities on this species would have dramatic consequences. Strict biosecurity procedures have been designed and applied to limit the risk of dispersion of pathogens among the different populations, in particular during the course of bird monitoring by scientists.

Abstract: During July 7-12, 2012, extreme moist and warm conditions occurred over Greenland, leading to widespread surface melt. To investigate the physical processes during the atmospheric moisture transport of this event, we study the water vapour isotopic composition using surface in situ observations in Bermuda Island, South Greenland coast (Ivittuut) and Northwest Greenland ice sheet (NEEM), as well as remote sensing observations (IASI instrument on-board MetOp-A), depicting propagation of similar surface and mid-tropospheric humidity and δD signals. Simulations using Lagrangian moisture source diagnostic and water tagging in a regional model showed that Greenland was affected by an atmospheric river transporting moisture from the western subtropical North Atlantic Ocean, which is coherent with observations of snow pit impurities deposited at NEEM. At Ivittuut, surface air temperature, humidity and δD increases are observed. At NEEM, similar temperature increase is associated with a large and long-lasting ~100 δD enrichment and ~15 deuterium excess decrease, thereby reaching Ivittuut level. We assess the simulation of this event in two isotope-enabled atmospheric general circulation models (LMDz-iso and ECHAM5-wiso). LMDz-iso correctly captures the timing of propagation for this event identified in IASI data but depict too gradual variations when compared to surface data. Both models reproduce the surface meteorological and isotopic values during the event but underestimate the background deuterium excess at NEEM. Cloud liquid water content parametrization in LMDz-iso poorly impacts the vapour isotopic composition. Our data demonstrate that during this atmospheric river event the deuterium excess signal is conserved from the moisture source to Northwest Greenland.