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Carravieri Alice, Bustamante Paco, Tartu Sabrina, Meillère Alizée, Labadie Pierre, Budzinski Hélène, Peluhet Laurent, Barbraud Christophe, Weimerskirch Henri, Chastel Olivier, Cherel Yves, . (2014). Wandering albatrosses document latitudinal variations in the transfer of persistent organic pollutants and mercury to Southern Ocean predators.
. Environ. Sci. Technol., 48(24), 14746–55.
Abstract: Top marine predators are effective tools to monitor bioaccumulative contaminants in remote oceanic environments. Here, we used the wide-ranging wandering albatross Diomedea exulans to investigate potential geographical variations of contaminant transfer to predators in the Southern Ocean. Blood concentrations of 19 persistent organic pollutants and 14 trace elements were measured in a large number of individuals (N = 180) of known age, sex and breeding status from the subantarctic Crozet Islands. Wandering albatrosses were exposed to a wide range of contaminants, with notably high blood mercury concentrations. Contaminant burden was markedly influenced by latitudinal foraging habitats (inferred from blood δ(13)C values), with individuals feeding in warmer subtropical waters having lower concentrations of pesticides, but higher concentrations of mercury, than those feeding in colder subantarctic waters. Sexual differences in contaminant burden seemed to be driven by gender specialization in feeding habitats, rather than physiological characteristics, with females foraging further north than males. Other individual traits, such as adult age and reproductive status, had little effect on blood contaminant concentrations. Our study provides further evidence of the critical role of global distillation on organic contaminant exposure to Southern Ocean avian predators. In addition, we document an unexpected high transfer of mercury to predators in subtropical waters, which merits further investigation.
Keywords: Animals, Arsenic, Arsenic: blood, Birds, Birds: blood, Birds: physiology, Ecosystem, Environmental Monitoring, Female, Food Chain, Halogenated Diphenyl Ethers, Halogenated Diphenyl Ethers: blood, Hydrocarbons, Chlorinated, Hydrocarbons, Chlorinated: blood, Male, Metals, Heavy, Metals, Heavy: blood, Oceans and Seas, Reproduction, Water Pollutants, Chemical, Water Pollutants, Chemical: blood,
Programme: 109
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Tixier P, Gasco N, Duhamel G, Guinet C, . (2014). Habituation to an acoustic harassment device (AHD) by killer whales depredating demersal longlines
. ICES Journal of Marine Science, 72(5), 1673–1681.
Abstract: Acoustic harassment devices (AHDs) have been increasingly implemented in various fisheries that suffer significant losses caused by odontocete depredation. However, the efficacy of AHDs to deter odontocetes from fishing gear remains poorly investigated. To determine the effectiveness of AHDs in deterring depredation, we experimentally tested a high amplitude device (195 dB re 1 Pa 6.5 kHz 1 m from the source) from a Patagonian toothfish Dissostichus elegenoides longliner operating off the Crozet Islands, while it was subjected to heavy depredation by killer whales Orcinus orca. This species usually depredates longlines within a 10- to 300-m range from the vessel, as they only have access to fishing gear during hauling. We expected this distance to increase in response to the acoustic disturbance created by the AHD. The distances of 29 killer whales from the vessel (n = 1812 records) were collected during phases of AHD activation and phases during which the AHD was turned off. Two multiexposed killer whale social units fled over 700 m away from the vessel when first exposed to the AHD. However, they remained within a 10- to 300-m range and depredated longlines again past the third and seventh exposures, respectively, showing an insignificant behavioural response to further activations of the AHD. When tested through generalized linear mixed models, the effect of AHD activation was only significant when killer whales were first exposed to the device. However, the effect disappeared after successive exposures suggesting that killer whales became habituated to the AHD and may sustain potentially harmful hearing disturbance to access the resource made available by longliners. In addition to raising significant conservation concerns, this rapid return of initial depredation behaviour strongly suggests that AHDs are ineffective at deterring depredating killer whales, and that fisheries should favour the use of other mitigation techniques when facing repeated depredation by this species.
Programme: 109
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Tixier P, Vacquie Garcia J, Gasco N, Duhamel G, Guinet C, . (2014). Mitigating killer whale depredation on demersal longline fisheries by changing fishing practices
. 1054-3139, 72(5), 1610–1620.
Abstract: Odontocete depredation on longlines involves socioeconomic and conservation issues with significant losses for fisheries and potential impacts on wild populations of depredating species. As technical solutions to this conflict are limited and difficult to implement, this study aimed to identify fishing practices that could reduce odontocete depredation, with a focus on killer whales (Orcinus orca) interacting with Patagonian toothfish (Dissostichus eleginoides) longliners off the Crozet islands. Data collected by fishery observers from 6013 longline sets between 2003 and 2013 allowed us to statistically detect the significant influence of five operational variables using GLMMs. The probability of interactions between vessels and killer whales was decreased by (i) the number of vessels operating simultaneously in the area: the limited number of depredating killer whales may induce a dilution effect with increased fleet size, and (ii) depth of longline sets: vessels operating in shallow waters may be more accessible to whales that are initially distributed on peri-insular shelves. The cpue was negatively influenced by (iii) length of longlines: longer sets may provide killer whales access to a greater proportion of hooked fish per set, and positively influenced by (iv) hauling speed: increased speed may shorten the time during which toothfish are accessible to whales during hauling. The time it takes for killer whales to reach vessels was positively correlated to (v) the distance travelled between longline sets with an estimated threshold of 100 km beyond which whales seem to temporarily lose track of vessels. These findings provide insightful guidelines about what fishing strategy to adopt given these variables to reduce killer whale depredation here and in similar situations elsewhere. To a greater extent, this study is illustrative of how collaborative work with fishermen in a fully controlled fishery framework may lead to the definition of cost-limited and easy-to-implement mitigation solutions when facing such human-wildlife conflict.
Programme: 109
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Tixier P, Authier M, Gasco N, Guinet C, . (2015). Influence of artificial food provisioning from fisheries on killer whale reproductive output
. 1367-9430, 18(2), 207–218.
Abstract: Prey availability is a critical factor influencing demographic trajectories of long-lived, top predators, which may therefore be strongly affected by artificial food provisioning. In the Crozet archipelago, killer whales feed on a wide range of species including birds, marine mammals and fish. Following the development of the Patagonian toothfish fisheries in 1996, killer whales began to also depredate longlines. Social groups, hereafter referred to as matrilines, exhibited different levels of interaction; some were involved in most of the depredation events, while others were never observed interacting with fisheries. These differences in interaction levels influenced reproduction. An extensive photo-identification effort from 2003 to 2012 allowed us to estimate the probability of calving for 21 reproductive females. Using multi-model inference, we found a positive effect of depredation on female calving rate. These results suggest an effect of artificial food provisioning on female reproductive output with potentially far-reaching consequences on the demography of the Crozet killer whale population. Our findings evidence the need to account for both intra-population heterogeneity and level of interaction with fisheries when assessing conservation strategies of long-lived marine predators involved in similar depredation worldwide.
Programme: 109
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O'Toole Malcolm D., Hindell Mark A., Charrassin Jean-Benoit, Guinet Christophe . (2014). Foraging behaviour of southern elephant seals over the Kerguelen Plateau. 0171-8630, .
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Guinet C, Tixier P, Gasco N, Duhamel G, . (2014). Long-term studies of Crozet Island killer whales are fundamental to understanding the economic and demographic consequences of their depredation behaviour on the Patagonian toothfish fishery
. ICES Journal of Marine Science, 72(5), 1587–1597.
Abstract: This paper provides a synthesis of results obtained as part of a long-term collaborative study involving biologists, fishers, and resource managers--centring on the occurrence of killer whales in the Crozet Archipelago before and after the implementation of a demersal longline fishery for Patagonian toothfish. Depredation behaviour was reported as soon as the fishery was initiated, with dramatic effects on both the demographic trajectories of the killer whales and on the amount of fish lost by the fishers. Killer whales interacting with the fishery exhibited very high mortality rates when illegal fishing took place, while killer whales not interacting were unaffected. However, after illegal fishing ended, killer whales interacting with the fishery exhibited both higher fecundity and survival rates compared with killer whales not interacting. Since whales typically removed fish entirely from the hooks, an adapted methodology that did not rely on determining the number of damaged fish was developed to estimate depredation rates. In the Crozet EEZ over a 10-year period, 33.9% of the total amount of Patagonian toothfish caught, representing a total of 28 million {euro}, was estimated to be lost due to the combined effects of killer whale and sperm whale depredation. In an effort to reduce depredation losses, modifications to fishing methods, such as changing the fishing season, changing fishing areas when exposed to depredation and changing longline length and hauling speed were successfully tested. Acoustic deterrent devices were ineffective in deterring killer whales from depredating longlines. Alternative fishing gears, such as fish pots, were also tested. However, while providing encouraging results regarding the suppression of depredation and seabird bycatch, fish pots were not efficient enough to sustain an economically viable fishery. In conclusion, we discuss how the findings of this comprehensive study can be used elsewhere in fisheries confronted with depredation.
Programme: 109
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Widmann M, Kato A, Raymond B, Pellé M, Chastel O, Angelier F, Arthur B, Raclot T, Ropert-Coudert Y
. (2014). Foraging strategies of Adélie penguin (Pygoscelis adeliae) throughout the breeding season and with changing sea-ice conditions.
Abstract: 5th International Bio-Logging Science Symposium, Strasbourg, 21-27 September 2014
Programme: 1091
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Kennicutt Mahlon C, Chown Steven L, Cassano John J, Liggett Daniela, Massom Rob, Peck Lloyd S, Rintoul Steve R, Storey John W V, Vaughan David G, Wilson Terry J, Sutherland William J, . (2014). Polar research: Six priorities for Antarctic science.
. Nature, 512(7512), 23–5.
Abstract: On behalf of attendees at the 1st SCAR Antarctic and Southern Ocean Science Horizon Scan Retreat, 20–23 April 2014, Queenstown, New Zealand. See Supplementary Information for a full list of co-signatories that include the PI of the program
Keywords: Antarctic Regions, Astronomy, Atmosphere, Atmosphere: chemistry, Biological Evolution, Budgets, Climate Change, Conservation of Natural Resources, Conservation of Natural Resources: methods, Ecology, Exobiology, Ice Cover, International Cooperation, Oceans and Seas, Policy Making, Research, Research: economics, Research: trends,
Programme: 1091
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Deuss Arwen, . (2014). Heterogeneity and Anisotropy of Earth's Inner Core
. 0084-6597, 42(1), 103–126.
Abstract: Seismic observations provide strong evidence that Earth's inner core is anisotropic, with larger velocity in the polar than in the equatorial direction. The top 60–80 km of the inner core is isotropic; evidence for an innermost inner core is less compelling. The anisotropy is most likely due to alignment of hcp (hexagonal close-packed) iron crystals, aligned either during solidification or by deformation afterward. The existence of hemispherical variations used to be controversial, but there is now strong evidence from both seismic body wave and normal mode observations, showing stronger anisotropy, less attenuation, and a lower isotropic velocity in the western hemisphere. Two mechanisms have been proposed to explain the hemispherical pattern: either (a) inner core translation, wherein one hemisphere is melting and the other is solidifying, or (b) thermochemical convection in the outer core, leading to different solidification conditions at the inner core boundary. Neither is (yet) able to explain all se...
Keywords: body waves, dynamics, free oscillations, iron, mineralogy, seismology, solidification,
Programme: 133
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Gualtieri L, Stutzmann E, Farra V, Capdeville Y, Schimmel M, Ardhuin F, Morelli A, . (2014). Modelling the ocean site effect on seismic noise body waves
. Geophysical Journal International, 197(2), 1096–1106.
Abstract: Secondary microseismic noise is generated by non-linear interactions between ocean waves at the ocean surface. We present here the theory for computing the site effect of the ocean layer upon body waves generated by noise sources distributed along the ocean surface. By defining the wavefield as the superposition of plane waves, we show that the ocean site effect can be described as the constructive interference of multiply reflected P waves in the ocean that are then converted to either P or SV waves at the ocean-crust interface. We observe that the site effect varies strongly with period and ocean depth, although in a different way for body waves than for Rayleigh waves. We also show that the ocean site effect is stronger for P waves than for S waves. We validate our computation by comparing the theoretical noise body wave sources with the sources inferred from beamforming analysis of the three seismogram components recorded by the Southern California Seismic Network. We use rotated traces for the beamforming analysis, and we show that we clearly detect P waves generated by ocean gravity wave interactions along the track of typhoon Ioke (2006 September). We do not detect the corresponding SV waves, and we demonstrate that this is because their amplitude is too weak.
Programme: 133
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