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- Linnebjerg, Jannie Fries, et al.
(författare)
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Deciphering the structure of the West Greenland marine food web using stable isotopes (δ13C, δ15N)
- 2016
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 163:11
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Tidskriftsartikel (refereegranskat)abstract
- The Arctic is facing major environmental changes impacting marine biodiversity and ecosystem functioning. One way of assessing the responses of an ecosystem to these changes is to quantitatively study food web dynamics. Here, we used stable isotope (δ15N and δ13C) analyses of 39 Arctic marine species to investigate trophic relationships and isotopic niches of the West Greenland food web in 2000–2004. The lowest δ15N values were found for suspension feeding blue mussel (Mytilus edulis; 6.1 ‰) and the highest for polar bear (Ursus maritimus; 20.2 ‰). For δ13C, copepods (Calanus spp.) had the lowest values (−20.4 ‰) and snow crab (Chionoecetes opilio) the highest values (−15.8 ‰). Our results show that the three trophic enrichment factor (TEF) approaches used to quantify species trophic positions (fixed TEF of 3.8 and 3.4 ‰ or scaled TEF) did not generally affect trophic modelling and provided similar conclusions. Overall, the findings in this study are in good agreement with previous investigations of other Arctic marine ecosystems. Interestingly, we found little overlap of core isotopic niches used by the four investigated functional groups (mammals, seabirds, fish and invertebrates), except for seabirds and fish where an overlap of 24 % was found. These results provide new insights into species and functional group interactions, as well as into the food web structure and ecosystem functioning of an important Arctic region that can be used as a template to guide future modelling of carbon, energy and contaminant flow in the region.
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| 2. |
- Linnebjerg, Jannie Fries, et al.
(författare)
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Non-breeding areas of three sympatric auk species breeding in three Icelandic colonies
- 2018
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Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 41:10, s. 1951-1961
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Tidskriftsartikel (refereegranskat)abstract
- Like many seabirds, auks spend most of the year in offshore areas. Information on which oceanic areas they rely on throughout the winter is therefore important in understanding their population dynamics and establishing appropriate conservation measures. The breeding populations of Thick-billed Murres (Uria lomvia), Common Murres (Uria aalge) and Razorbills (Alca torda) in Iceland have been reported declining for the last 30 years. Thick-billed Murres have shown the most alarming rate of decrease, while Razorbills have declined the least. To help understand these changes, we collected information about the non-breeding distribution of these three species by using light-based geolocation. Geolocators were deployed on breeding adults in three different colonies in Iceland in 2013 and 2014. Data showed that the three species’ wintering areas differed substantially. Thick-billed Murres wintered off the west coast of Greenland and East Greenland/Northern Iceland, Common Murres favoured areas around Iceland/East Greenland and to the southwest along the Mid-Atlantic Ridge, and Razorbills were mostly distributed around Iceland. Although some intraspecific variation was evident, we conclude that the population development of Thick-billed Murres in Iceland is likely to be largely influenced by environmental conditions in west Greenland, while Common Murres and Razorbills are more dependent on the oceanic area around Iceland. The results may therefore prove to be an important platform for understanding the population dynamics of these three species in Iceland and informing conservation actions.
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| 3. |
- Patterson, Allison, et al.
(författare)
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Foraging range scales with colony size in high-latitude seabirds
- 2022
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 32:17, s. 3800-3807
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Tidskriftsartikel (refereegranskat)abstract
- Density-dependent prey depletion around breeding colonies has long been considered an important factor controlling the population dynamics of colonial animals.1, 2, 3, 4 Ashmole proposed that as seabird colony size increases, intraspecific competition leads to declines in reproductive success, as breeding adults must spend more time and energy to find prey farther from the colony.1 Seabird colony size often varies over several orders of magnitude within the same species and can include millions of individuals per colony.5,6 As such, colony size likely plays an important role in determining the individual behavior of its members and how the colony interacts with the surrounding environment.6 Using tracking data from murres (Uria spp.), the world’s most densely breeding seabirds, we show that the distribution of foraging-trip distances scales to colony size0.33 during the chick-rearing stage, consistent with Ashmole’s halo theory.1,2 This pattern occurred across colonies varying in size over three orders of magnitude and distributed throughout the North Atlantic region. The strong relationship between colony size and foraging range means that the foraging areas of some colonial species can be estimated from colony sizes, which is more practical to measure over a large geographic scale. Two-thirds of the North Atlantic murre population breed at the 16 largest colonies; by extrapolating the predicted foraging ranges to sites without tracking data, we show that only two of these large colonies have significant coverage as marine protected areas. Our results are an important example of how theoretical models, in this case, Ashmole’s version of central-place-foraging theory, can be applied to inform conservation and management in colonial breeding species.
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