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Hezel P J, Alexander B, Bitz C M, Steig E J, Holmes C D, Yang X, Sciare J, . (2011). Modeled methanesulfonic acid (MSA) deposition in Antarctica and its relationship to sea ice
. Journal of Geophysical Research: Atmospheres, 116(D23), D23214–.
Abstract: Methanesulfonic acid (MSA) has previously been measured in ice cores in Antarctica as a proxy for sea ice extent and Southern Hemisphere circulation. In a series of chemical transport model (GEOS-Chem) sensitivity experiments, we identify mechanisms that control the MSA concentrations recorded in ice cores. Sea ice is linked to MSA via dimethylsulfide (DMS), which is produced biologically in the surface ocean and known to be particularly concentrated in the sea ice zone. Given existing ocean surface DMS concentration data sets, the model does not demonstrate a strong relationship between sea ice and MSA deposition in Antarctica. The variability of DMS emissions associated with sea ice extent is small (1130%) due to the small interannual variability of sea ice extent. Wind plays a role in the variability in DMS emissions, but its contribution relative to that of sea ice is strongly dependent on the assumed DMS concentrations in the sea ice zone. Atmospheric sulfur emitted as DMS from the sea ice undergoes net transport northward. Our model runs suggest that DMS emissions from the sea ice zone may account for 2662% of MSA deposition at the Antarctic coast and 3695% in inland Antarctica. Though our results are sensitive to model assumptions, it is clear that an improved understanding of both DMS concentrations and emissions from the sea ice zone are required to better assess the impact of sea ice variability on MSA deposition to Antarctica.
Keywords: DMS, MSA, dimethylsulfide, ice core, methanesulfonic acid, sea ice, 0368 Troposphere: constituent transport and chemistry, 0750 Sea ice, 0793 Biogeochemistry, 3344 Paleoclimatology,
Programme: 414
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. (2013). Three-dimensional use of marine habitats by juvenile emperor penguins Aptenodytes forsteri during post-natal dispersal
. Antarct. Sci., 25(04), 536–544.
Keywords: Diving, foraging ecology, immaturity period, migration, seabirds, Southern Ocean, tracking,
Programme: 109,394
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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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. (2020). Cryptic speciation in gentoo penguins is driven by geographic isolation and regional marine conditions: Unforeseen vulnerabilities to global change (Vol. 26). Bachelor's thesis, , .
Abstract: Aim The conservation of biodiversity is hampered by data deficiencies, with many new species and subspecies awaiting description or reclassification. Population genomics and ecological niche modelling offer complementary new tools for uncovering functional units of phylogenetic diversity. We hypothesize that phylogenetically delineated lineages of gentoo penguins (Pygoscelis papua) distributed across Antarctica and sub-Antarctic Islands are subject to spatially explicit ecological conditions that have limited gene flow, facilitating genetic differentiation, and thereby speciation processes. Location Antarctica and sub-Antarctic area. Methods We identify divergent lineages for gentoo penguins using ddRAD-seq and mtDNA, and generated species distribution models (SDMs) based on terrestrial and marine parameters. Results Analyses of our genomic data supports the existence of four major lineages of gentoo penguin: (i) spanning the sub-Antarctic archipelagos north of the Antarctic Polar Front (APF); (ii) Kerguelen Island; (iii) South America; and (iv) across maritime Antarctic and the Scotia Arc archipelagos. The APF, a major current system around Antarctica, acts as the most important barrier separating regional sister lineages. Our ecological analyses spanning both the terrestrial (breeding sites) and marine (feeding sites) realms recover limited niche overlap among the major lineages of gentoo penguin. We observe this pattern to correspond more closely with regional differentiation of marine conditions than to terrestrial macroenvironmental features. Main conclusions Recognition of regional genetic lineages as discrete evolutionary entities that occupy distinct ecological niches and also differ morphologically should be considered a priority for conservation. Gentoo penguins provide a good example of how conservation policy can be directly impacted by new insights obtained through the integration of larger genomic datasets with novel approaches to ecological modelling. This is particularly pertinent to polar environments that are among the most rapidly changing environments on earth.
Keywords: diversification ecological niche overlap gentoo penguin subspecies
Programme: 137,354
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. (2013). From surface fault traces to a fault growth model: The Vogar Fissure Swarm of the Reykjanes Peninsula, Southwest Iceland
. JOURNAL OF STRUCTURAL GEOLOGY, 51, 38–51.
Abstract: The Vogar Fissure Swarm is one of four en-echelon fracture swarms that connect the Reykjanes Ridge to the South Iceland Seismic Zone and the Western Volcanic Zone. Occurring in an area of flat topography, this fissure swarm is clearly visible at the surface, where it can be seen to affect recent postglacial lavas. Using remote sensing methods to identify and measure all the faults and fractures in the swarm, combined with additional field observations and measurements, we measured 478 individual fractures, 33% of them being faults and 67% being fissures. The fracture lengths show roughly log-normal distributions. Most of the individual fractures belong to 68 main composite fractures, seven of which are longer than 2500 m and correspond to the main fault scarps of the fissure swarm. We showed that these main faults are distributed along five, equally spaced zones, ∼500 m apart and a few kilometers long. We drawn 71 across-strike profiles to characterize the shape of the fault scarps, and 5 along-strike profiles to characterize the evolution of vertical throw along the main faults. Each fault consists of a coalescence of individual segments of approximately equal length. Fault throws are never larger than 10 m and are smallest at the junctions between individual segments. Analyses of along-strike throw profiles allowed us to determine the early stages of growth after coalescence. The earliest stage is characterized by an increase in the throw of the central parts of segments. This is followed by a second stage during which the throw increases at the junctions between segments, progressively erasing these small-throw zones.
Keywords: Divergent plate boundary, Fissure swarm, Icelandic rift, Normal fault growth, Photogrammetric techniques, remote sensing,
Programme: 316
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Maxime Pineaux, Thomas Merkling, Etienne Danchin, Scott Hatch, David Duneau, Pierrick Blanchard, Sarah Leclaire. (2020). Sex and hatching order modulate the association between MHC-II diversity and fitness in early-life stages of a wild seabird (Vol. 29).
Keywords: divergent allele advantage fitness heterozygote advantage immunity Ixodes uriae parasite-mediated selection
Programme: 1162
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Malcolm O'Toole, Christophe Guinet, Mary-Anne Lea, Mark A. Hindell. (2017). Marine predators and phytoplankton: how elephant seals use the recurrent Kerguelen plume (Vol. 581). Bachelor's thesis, , .
Keywords: Dive behaviour Foraging strategy Kerguelen phytoplankton plume Mirounga leonina Prey access Prey encounter events
Programme: 109,1201
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Flatberg I, Whinam Jennie, Lebouvier Marc, . (2011). 0373-6687, 33(2), 105–121.
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. (2012). Projected poleward shift of king penguins' (Aptenodytes patagonicus) foraging range at the Crozet Islands, southern Indian Ocean
. PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON, 279(1738), 2515–2523.
Abstract: Seabird populations of the Southern Ocean have been responding to climate change for the last three decades and demographic models suggest that projected warming will cause dramatic population changes over the next century. Shift in species distribution is likely to be one of the major possible adaptations to changing environmental conditions. Habitat models based on a unique long-term tracking dataset of king penguin (Aptenodytes patagonicus) breeding on the Crozet Islands (southern Indian Ocean) revealed that despite a significant influence of primary productivity and mesoscale activity, sea surface temperature consistently drove penguins' foraging distribution. According to climate models of the Intergovernmental Panel on Climate Change (IPCC), the projected warming of surface waters would lead to a gradual southward shift of the more profitable foraging zones, ranging from 25 km per decade for the B1 IPCC scenario to 40 km per decade for the A1B and A2 scenarios. As a consequence, distances travelled by incubating and brooding birds to reach optimal foraging zones associated with the polar front would double by 2100. Such a shift is far beyond the usual foraging range of king penguins breeding and would negatively affect the Crozet population on the long term, unless penguins develop alternative foraging strategies.
Keywords: distribution shift, habitat model, IPCC climate models, penguins, polar front,
Programme: 394
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. (2017). Important marine sectors for the top predator community around Kerguelen Archipelago (Vol. 40).
Keywords: Distribution Habitat modelling Marine mammals Seabirds Tracking
Programme: 109
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