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Antoine Rocaboy. (2022). Soil microbial biomass and nutrient concentrations under the effect of vegetation cover, biological invasion and habitats of the Kerguelen Islands..
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Antoine, A. (2022).
Abstract: The sea-ice zone constitutes the breeding and foraging habitat of large populations of ice-based species, pointing at its far-reaching ecological importance. Given its sensitivity to global warming, there is an urgent need for determining how predators use their environment, to understand and predict their response to climate variability. New perspectives are offered by miniature animal-borne sensors: in 2019, 3 sonar tags were deployed on lactating female Weddell seals for 7 days in Terre Adélie to study 3D animal movement and fine-scale predator-prey interactions. Lactating females demonstrated central-place foraging strategy, with restricted foraging area (3-6 km) and mostly benthic dives (97% of dives, visualising the seafloor on echograms). Their foraging effort was constrained by the presence of their pup: females spent most of their time hauling out (77% of overall recordings). The time spent underwater was mostly dedicated to diving (>5m) (1.36 on 7days, 854 dives recorded), as opposed to shallower under ice activities (<5m) (0.3 days). A total of 331 prey capture attempts (PrCA) were recorded, using tri-axial acceleration data, of which 125 prey (4.7 ± 1.5 cm on average) were identified by the sonar on 78 dives (4.24 ± 3.99 PrCA/dive). All PCA occur on the seafloor, at shallower depth than usual Weddell seal records (88 ± 30 m). Lactation is therefore a period of physiological stress, with foraging limited by pup compared with other parts of the life cycle. Using functional principal component analysis and model-based clustering on high resolution dive data, we found that PrCAs occur mostly in 2 of the 5 dive shape clusters. Foraging dives are characterised by W or V shape and high sinuosity, at the scale of the dive (W shapes) or during the ascent phase (V shapes). During the approach phase, seals constantly scan the area by regularly moving their head left to right, suggesting opportunistic behaviour. Shallow phase behaviour was studied using video recordings (2h recorded per seal). Seals spent most of their time interacting with their pup (33%) and hauling-out (42%). Most mother-pup interactions were on sea-ice (71%), as opposed to underwater (29%). The results suggest lactating females’ energy budget changes, with lactation being a period of physiological stress. This period of feeding pressure might put them at higher risk regarding adaptation to environmental variability.
Programme: 1182
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. (2022). Stage-dependent niche segregation: insights from a multi-dimensional approach of two sympatric sibling seabirds (Vol. 199). Bachelor's thesis, , .
Abstract: Niche theory predicts that to reduce competition for the same resource, sympatric ecologically similar species should exploit divergent niches and segregate in one or more dimensions. Seasonal variations in environmental conditions and energy requirements can influence the mechanisms and the degree of niche segregation. However, studies have overlooked the multi-dimensional aspect of niche segregation over the whole annual cycle, and key facets of species co-existence still remain ambiguous. The present study provides insights into the niche use and partitioning of two morphologically and ecologically similar seabirds, the common (CDP, Pelecanoides urinatrix) and the South Georgian diving petrel (SGDP, Pelecanoides georgicus). Using phenology, at-sea distribution, diving behavior and isotopic data (during the incubation, chick-rearing and non-breeding periods), we show that the degree of partitioning was highly stage-dependent. During the breeding season, the greater niche segregation during chick-rearing than incubation supported the hypothesis that resource partitioning increases during energetically demanding periods. During the post breeding period, while species-specific latitudinal differences were expected (species specific water mass preference), CDP and SGDP also migrated in divergent directions. This segregation in migration area may not be only a response to the selective pressure arising from competition avoidance between sympatric species, but instead, could reflect past evolutionary divergence. Such stage-dependent and context-dependent niche segregation demonstrates the importance of integrative approaches combining techniques from different fields, throughout the entire annual cycle, to better understand the co-existence of ecologically similar species. This is particularly relevant in order to fully understand the short and long-term effects of ongoing environmental changes on species distributions and communities.
Keywords: Diving petrel Foraging and diving behaviour Niche partitioning Pelecanoides Trophic niche
Programme: 109,394
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. (2022). (Vol. 17).
Keywords: Animal behavior Animal sociality Birds Equipment Feathers Legs Molting Penguins
Programme: 137
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. (2022). Juvenile emperor penguin range calls for extended conservation measures in the Southern Ocean (Vol. 9).
Abstract: To protect the unique and rich biodiversity of the Southern Ocean, conservation measures such as marine protected areas (MPAs) have been implemented. Currently, the establishment of several additional protection zones is being considered based on the known habitat distributions of key species of the ecosystems including emperor penguins and other marine top predators. However, the distribution of such species at sea is often insufficiently sampled. Specifically, current distribution models focus on the habitat range of adult animals and neglect that immatures and juveniles can inhabit different areas. By tracking eight juvenile emperor penguins in the Weddell Sea over 1 year and performing a meta-analysis including previously known data from other colonies, we show that conservation efforts in the Southern Ocean are insufficient for protecting this highly mobile species, and particularly its juveniles. We find that juveniles spend approximately 90% of their time outside the boundaries of proposed and existing MPAs, and that their distribution extends beyond (greater than 1500 km) the species' extent of occurrence as defined by the International Union for Conservation of Nature. Our data exemplify that strategic conservation plans for the emperor penguin and other long-lived ecologically important species should consider the dynamic habitat range of all age classes.
Keywords: conservation biology early life MPA network polar regions seabirds
Programme: 137
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B. L. Woods, A. Walters, M. Hindell, A. T. Revill, I. Field, S. A. McCormack, Y. Cherel, R. Trebilco. (2022). Trophic structure of Southern Ocean squid: a cross-basin analysis of stable isotopes in archived beaks from predator stomachs (Vol. 685).
Abstract: Cephalopods are an important component of Southern Ocean food webs, but aspects of their trophic ecology remain unresolved. Here, we used archived squid (order Teuthida) beaks, collected from stomach contents of predators at Macquarie and Kerguelen Islands, to investigate the trophic structure within an assemblage of pelagic squids (Alluroteuthis antarcticus, Filippovia knipovitchi, Gonatus antarcticus, Histioteuthis eltaninae, Martialia hyadesi and Brachioteuthis linkovskyi). We combined bulk nitrogen stable isotopes (?15Nbulk) with compound-specific isotope analysis of amino acids (CSIA-AA) to estimate the trophic position (TP) of species and to assess isotopic relationships with body size at the species, community, and ocean basin levels. We observed significantly higher mean ?15Nbulk values for species at the Kerguelen Islands compared to conspecifics at Macquarie Island. This result was explained by regional variability in ?15N values of phenylalanine (?15NPhe), suggesting that predator species were accessing different isotopic baselines at each region. This may highlight the different foraging strategies of both species. The overlap in species TP estimates from CSIA-AA (TPCSIA) between the 2 communities (Macquarie Island TPCSIA min: 2.3, max: 5.3; Kerguelen Islands TPCSIA min: 2.7, max: 5.3) indicated a similar trophic structure at both locations. We note unrealistically low TPCSIA for some species, which we attribute to uncertainty of trophic discrimination factors. TP estimates suggested that squid encompass 3 trophic levels from mid-trophic levels to higher predators. We did not find strong or consistent relationships between TP and body size at either the species- or community-level. One of the largest squid species, M. hyadesi, occupied the lowest TP in both communities. These new insights into the trophic structure of the Southern Ocean squid community have important implications for the future representation of pelagic squids in ecosystem models.
Programme: 109
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. (2022). What is the menu today in a subantarctic kelp food web from the Kerguelen Islands? Phytodetritus, phytoplankton and phytobenthos; not living kelp (Vol. 169).
Abstract: Kelp forests dominated by Macrocystis pyrifera are widely distributed in coastal waters from boreal, temperate and subantarctic regions. This widespread distribution may result in regional differences in food web structure and functioning. In temperate northern regions, where most studies on kelp forest benthic food webs have been conducted, kelp grazing is a well-documented phenomenon and can lead to the overgrazing of M. pyrifera by sea urchins when their predators (e.g., sea otters) are absent. In contrast, little is known about their counterparts in subantarctic areas. The present study aimed to reconstruct the benthic food web of a kelp forest dominated by M. pyrifera in a subantarctic environment using stable isotope analysis. Stable carbon (?13C), nitrogen (?15N) and sulfur (?34S) isotope ratios were measured from food sources (macrophytobenthos, suspended particulate organic matter SPOM, and sediment) and consumers (sponges, bivalves, gastropods, sedentary and mobile polychaetes, arthropods and echinoderms) which were sampled in a kelp forest of the Kerguelen archipelago. Mixing models highlighted two interconnected trophic pathways which were either supported by SPOM and resuspended macrophytobenthos detritus (bentho-pelagic), or by live micro/macrophytobenthos (phytobenthos-based). No major prey were highlighted for several consumers, indicating the existence of potential supplementary trophic pathways. No consumer relying primarily on living M. pyrifera was highlighted by the mixing models. The investigated kelp forest is hence a complex ecosystem supporting multiple trophic pathways, and direct consumption of M. pyrifera is limited. Nonetheless, M. pyrifera and other macrophytobenthos species may constitute a pool of detritus supporting several trophic pathways.
Keywords: Benthic communities Food web Kelp forests Mixing models Stable isotopes
Programme: 1044
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Blévin P., Chastel O., Angelier F., Bech C., Bustamante P., Bustnes J.o., Herzke D., Goutte A., Jouanneau W., Krogseth I.s., Léandri-breton D.j., Moe B., Sagerup K., Sebastiano M., Stople T., Tartu S., Eulaers I., Gabrielsen G.w. (2022). Temporal trends of persistent organic pollutants in a high Arctic seabird over 15 years: influenced by climate variability and dietary plasticity?.
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Brice Temime Roussel, Meeta Cesler-Maloney, Benjamin Chazeau, Amna Ijaz, Natalie Brett, Katharine Law, Slimane Bekki, Jingqiu Mao, Damien Ketcherside, Vanessa Selimovic, Lu Hu, William R. Simpson, Barbara D'Anna. (2022). Concentrations and Sources of VOCs during wintertime urban pollution at Fairbanks, Alaska (Vol. 2022).
Abstract: Fairbanks, Alaska is an urban area that has multiple local emission sources including power plants, domestic heating, and mobile sources, leading to severe wintertime pollution events during cold stable episodes where strong temperature inversions limit pollutant dispersion. In order to evaluate the individual contribution of these sources on Volatile Organic Compounds (VOCs) concentrations, ground-based measurements were carried out at high temporal resolution (2 minutes) using on-line instrumentation (Proton Transfer Reaction Time of Flight Mass Spectrometer: PTR-ToF-MS) during the winter 2022 in downtown Fairbanks as part of the Alaskan Layered Pollution and Chemical Analysis (ALPACA) 2022 field experiment. These measurements are recorded in the urban business district, which probably enhances the traffic component compared to domestic heating. From the detailed analysis of the mass spectra acquired in the 0-500 amu range, more than 330 ions were found of interest for further investigation. Source apportionment analysis was performed using Positive Matrix Factorization (PMF) resolved with the multilinear engine (ME-2) approach. Based on their mass spectral profiles, diurnal cycles and correlation with external collocated measurements (gaseous pollutants: CO, CO2, NOx, SO2, ozone, and specific particulate matter markers), the factors identified could be related to mobile sources (gasoline-like and diesel-like traffic), to heating (residential, diesel-like heating in addition to a couple of specific biomass burning, and to non-combustion sources attributed to secondary processes. This study contributes to the Air Pollution in the Arctic: Climate, Environment and Societies – Alaskan Layered Pollution And Chemical Analysis (PACES-ALPACA) initiative. The French contribution is part of the CASPA (Climate-relevant Aerosol Sources and Processes in the Arctic)/IPEV project.
Programme: 1215
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Bruyant, F., Amiraux, R., Amyot, M. P., Archambault, P., Artigue, L., Bardedo de Freitas, L., ...Fort, J.,... & Babin, M. (2022). The Green Edge cruise: Understanding the onset, life and fate of the Arctic phytoplankton spring bloom.
Abstract: The Green Edge project was designed to investigate the onset, life and fate of a phytoplankton spring bloom (PSB) in the Arctic Ocean. The lengthening of the ice-free period and the warming of seawater, amongst other factors, have induced major changes in arctic ocean biology over the last decades. Because the PSB is at the base of the Arctic Ocean food chain, it is crucial to understand how changes in the arctic environment will affect it. Green Edge was a large multidisciplinary collaborative project bringing researchers and technicians from 28 different institutions in seven countries, together aiming at understanding these changes and their impacts into the future. The fieldwork for the Green Edge project took place over two years (2015 and 2016) and was carried out from both an ice-camp and a research vessel in the Baffin Bay, canadian arctic. This paper describes the sampling strategy and the data set obtained from the research cruise, which took place aboard the Canadian Coast Guard Ship (CCGS) Amundsen in spring 2016. The dataset is available at https://doi.org/10.17882/59892 (Massicotte et al., 2019a).
Programme: 388
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