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Ishino S., Hattori S., Savarino J., Jourdain B., Legrand M., Preunkert S., Alexander B., Yoshida N., Huang J. |
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Title |
Regional characteristics of atmospheric sulfate formation in East Antarctica imprinted on 17O-excess signature |
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Book Chapter |
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Year |
2021 |
Publication |
EGU General Assembly, 19-30 April 2021 |
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1177 |
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Bachelor's thesis |
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yes |
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Serial |
7869 |
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Author |
Zhuang Jiang, Becky Alexander, Joel Savarino, Joseph Erbland, Lei Geng |
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Title |
Impacts of the photo-driven post-depositional processing on snow nitrate and its isotopes at Summit, Greenland: a model-based study |
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Journal |
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Year |
2021 |
Publication |
The Cryosphere |
Abbreviated Journal |
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Volume |
15 |
Issue |
9 |
Pages |
4207-4220 |
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Abstract |
Abstract. Atmospheric Information Embedded In Ice-core Nitrate Is Disturbed By Post-depositional Processing. Here We Used A Layered Snow Photochemical Column Model To Explicitly Investigate The Effects Of Post-depositional Processing On Snow Nitrate And Its Isotopes (δ15n And Δ17o) At Summit, Greenland, Where Post-depositional Processing Was Thought To Be Minimal Due To The High Snow Accumulation Rate. We Found Significant Redistribution Of Nitrate In The Upper Snowpack Through Photolysis, And Up To 21 % Of Nitrate Was Lost And/or Redistributed After Deposition. The Model Indicates Post-depositional Processing Can Reproduce Much Of The Observed δ15n Seasonality, While Seasonal Variations In δ15n Of Primary Nitrate Are Needed To Reconcile The Timing Of The Lowest Seasonal δ15n. In Contrast, Post-depositional Processing Can Only Induce Less Than 2.1 ‰ Seasonal Δ17o Change, Much Smaller Than The Observation (9 ‰) That Is Ultimately Determined By Seasonal Differences In Nitrate Formation Pathway. Despite Significant Redistribution Of Snow Nitrate In The Photic Zone And The Associated Effects On δ15n Seasonality, The Net Annual Effect Of Post-depositional Processing Is Relatively Small, Suggesting Preservation Of Atmospheric Signals At The Annual Scale Under The Present Summit Conditions. But At Longer Timescales When Large Changes In Snow Accumulation Rate Occur This Post-depositional Processing Could Become A Major Driver Of The δ15n Variability In Ice-core Nitrate. |
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1177 |
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1994-0416 |
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yes |
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Serial |
8375 |
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Author |
A. Barbero, J. Savarino, R. Grilli, C. Blouzon, G. Picard, M. M. Frey, Y. Huang, N. Caillon |
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Title |
New Estimation of the NOx Snow-Source on the Antarctic Plateau |
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Journal |
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Year |
2021 |
Publication |
Journal of Geophysical Research: Atmospheres |
Abbreviated Journal |
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Volume |
126 |
Issue |
20 |
Pages |
e2021JD035062 |
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Keywords |
Antarctic Plateau flux chamber nitrate photolysis snowpack emissions |
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Abstract |
To fully decipher the role of nitrate photolysis on the atmospheric oxidative capacity in snow-covered regions, NOx flux must be determined with more precision than existing estimates. Here, we introduce a method based on dynamic flux chamber measurements for evaluating the NOx production by photolysis of snowpack nitrate in Antarctica. Flux chamber experiments were conducted for the first time in Antarctica, at the French-Italian station Concordia, Dome C (75°06'S, 123°20’E, 3233 m a.s.l) during the 2019–2020 summer campaign. Measurements were gathered with several snow samples of different ages ranging from newly formed drifted snow to 6-year-old firn. Contrary to existing literature expectations, the daily average photolysis rate coefficient, , did not significantly vary between differently aged snow samples, suggesting that the photolabile nitrate in snow behaves as a single-family source with common photochemical properties, where a = (2.37 0.35) × 10−8 s−1 (1) has been calculated from December 10th 2019 to January 7th 2020. At Dome C summer daily average NOx flux, , based on measured NOx production rates was estimated to be (4.3 1.2) × 108 molecules cm−2 s−1, which is 1.5–7 times less than the net NOx flux observed previously above snow at Dome C using the gradient flux method. Using these results, we extrapolated an annual continental snow sourced NOx budget of 0.017 0.003 TgN y−1, 2 times the nitrogen budget, (N-budget), of the stratospheric denitrification previously estimated for Antarctica. These quantifications of nitrate photolysis using flux chamber experiments provide a road-map toward a new parameterization of the product that can improve future global and regional models of atmospheric chemistry. |
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1177 |
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2169-8996 |
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yes |
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Serial |
8393 |
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Author |
S. Ishino, S. Hattori, M. Legrand, Q. Chen, B. Alexander, J. Shao, J. Huang, L. Jaeglé, B. Jourdain, S. Preunkert, A. Yamada, N. Yoshida, J. Savarino |
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Title |
Regional Characteristics of Atmospheric Sulfate Formation in East Antarctica Imprinted on 17O-Excess Signature |
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Journal |
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Year |
2021 |
Publication |
Journal of Geophysical Research: Atmospheres |
Abbreviated Journal |
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Volume |
126 |
Issue |
6 |
Pages |
e2020JD033583 |
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Keywords |
aerosols Antarctica isotope methanesulfonate sulfate |
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Abstract |
17O-excess (Δ17O = δ17O − 0.52 × δ18O) of sulfate trapped in Antarctic ice cores has been proposed as a potential tool for assessing past oxidant chemistry, while insufficient understanding of atmospheric sulfate formation around Antarctica hampers its interpretation. To probe influences of regional specific chemistry, we compared year-round observations of Δ17O of non-sea-salt sulfate in aerosols (Δ17O(SO42−)nss) at Dome C and Dumont d'Urville, inland and coastal sites in East Antarctica, throughout the year 2011. Although Δ17O(SO42−)nss at both sites showed consistent seasonality with summer minima (∼1.0‰) and winter maxima (∼2.5‰) owing to sunlight-driven changes in the relative importance of O3 oxidation to OH and H2O2 oxidation, significant intersite differences were observed in austral spring–summer and autumn. The cooccurrence of higher Δ17O(SO42−)nss at inland (2.0‰ ± 0.1‰) than the coastal site (1.2‰ ± 0.1‰) and chemical destruction of methanesulfonate (MS–) in aerosols at inland during spring–summer (October–December), combined with the first estimated Δ17O(MS–) of ∼16‰, implies that MS– destruction produces sulfate with high Δ17O(SO42−)nss of ∼12‰. If contributing to the known postdepositional decrease of MS– in snow, this process should also cause a significant postdepositional increase in Δ17O(SO42−)nss over 1‰, that can reconcile the discrepancy between Δ17O(SO42−)nss in the atmosphere and ice. The higher Δ17O(SO42−)nss at the coastal site than inland during autumn (March–May) may be associated with oxidation process involving reactive bromine and/or sea-salt particles around the coastal region. |
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1177 |
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2169-8996 |
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yes |
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Serial |
8412 |
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Author |
Damien Ertz, Neil Sanderson, Marc Lebouvier |
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Title |
Thelopsis challenges the generic circumscription in the Gyalectaceae and brings new insights to the taxonomy of Ramonia |
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Journal |
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Year |
2021 |
Publication |
The Lichenologist |
Abbreviated Journal |
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Volume |
53 |
Issue |
1 |
Pages |
45-61 |
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Keywords |
Arthoniales Gyalectales lichen multispory phylogeny |
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Abstract |
The genus Thelopsis was classified in the family Stictidaceae but its systematic position has never been investigated by molecular methods. In order to determine its family placement and to test its monophyly, fungal DNA of recent collections of Thelopsis specimens was sequenced. Phylogenetic analyses using nuLSU, RPB2 and mtSSU sequences reveal that members of Thelopsis form a monophyletic group within the genus Gyalecta as currently accepted. The placement of Thelopsis, including the generic type T. rubella, within the genus Gyalecta challenges the generic circumscription of this group because Thelopsis is well recognized by the combination of morphological characters: perithecioid ascomata, well-developed periphysoids, polysporous asci and small, few-septate ellipsoid-oblong ascospores. The sterile sorediate Opegrapha corticola is also placed in the Gyalectaceae as sister species to Thelopsis byssoidea + T. rubella. Ascomata of O. corticola are illustrated for the first time and support its placement in the genus Thelopsis. The hypothesis that O. corticola might represent the sorediate fertile morph of T. rubella is not confirmed because the species is phylogenetically and morphologically distinct. Thelopsis is recovered as polyphyletic, with T. melathelia being placed as sister species to Ramonia. The new combinations Thelopsis corticola (Coppins & P. James) Sanderson & Ertz comb. nov. and Ramonia melathelia (Nyl.) Ertz comb. nov. are introduced and a new species of Gyalecta, G. amsterdamensis Ertz, is described from Amsterdam and Saint-Paul Islands, characterized by a sterile thallus with discrete soralia. Petractis luetkemuelleri and P. nodispora are accommodated in the new genus Neopetractis, differing from the generic type (P. clausa) by having a different phylogenetic position and a different photobiont. Francisrosea bicolor Ertz & Sanderson gen. & sp. nov. is described for a sterile sorediate lichen somewhat similar to Opegrapha corticola but having an isolated phylogenetic position as sister to a clade including Gyalidea praetermissa and the genera Neopetractis and Ramonia. Gyalecta farlowii, G. nidarosiensis and G. carneola are placed in a molecular phylogeny for the first time. The taxonomic significance of morphological characters in Gyalectaceae is discussed. |
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1167 |
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ISSN |
0024-2829, 1096-1135 |
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yes |
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Serial |
7078 |
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Author |
Emilia Trudnowska, Léo Lacour, Mathieu Ardyna, Andreas Rogge, Jean Olivier Irisson, Anya M. Waite, Marcel Babin, Lars Stemmann |
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Title |
Marine snow morphology illuminates the evolution of phytoplankton blooms and determines their subsequent vertical export |
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Journal |
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Year |
2021 |
Publication |
Nature Communications |
Abbreviated Journal |
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Volume |
12 |
Issue |
1 |
Pages |
2816 |
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Keywords |
Carbon cycle Marine biology |
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Abstract |
The organic carbon produced in the ocean’s surface by phytoplankton is either passed through the food web or exported to the ocean interior as marine snow. The rate and efficiency of such vertical export strongly depend on the size, structure and shape of individual particles, but apart from size, other morphological properties are still not quantitatively monitored. With the growing number of in situ imaging technologies, there is now a great possibility to analyze the morphology of individual marine snow. Thus, automated methods for their classification are urgently needed. Consequently, here we present a simple, objective categorization method of marine snow into a few ecologically meaningful functional morphotypes using field data from successive phases of the Arctic phytoplankton bloom. The proposed approach is a promising tool for future studies aiming to integrate the diversity, composition and morphology of marine snow into our understanding of the biological carbon pump. |
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1164 |
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ISSN |
2041-1723 |
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yes |
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Serial |
8250 |
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Author |
Christopher Burot, Rémi Amiraux, Patricia Bonin, Sophie Guasco, Marcel Babin, Fabien Joux, Dominique Marie, Laure Vilgrain, Hermann J. Heipieper, Jean-François Rontani |
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Title |
Viability and stress state of bacteria associated with primary production or zooplankton-derived suspended particulate matter in summer along a transect in Baffin Bay (Arctic Ocean) |
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Journal |
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Year |
2021 |
Publication |
Science of The Total Environment |
Abbreviated Journal |
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Volume |
770 |
Issue |
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Pages |
145252 |
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Keywords |
Bacterial viability EPS isomerase Micro- and macro-zooplankton Salinity stress Sea ice algae |
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Abstract |
In the framework of the GreenEdge Project (whose the general objective is to understand the dynamic of the phytoplankton spring bloom in Arctic Ocean), lipid composition and viability and stress state of bacteria were monitored in sea ice and suspended particulate matter (SPM) samples collected in 2016 along a transect from sea ice to open water in Baffin Bay (Arctic Ocean). Lipid analyses confirmed the dominance of diatoms in the bottommost layer of ice and suggested (i) the presence of a strong proportion of micro-zooplankton in SPM samples collected at the western ice covered St 403 and St 409 and (ii) a high proportion of macro-zooplankton (copepods) in SPM samples collected at the eastern ice covered St 413 and open water St 418. The use of the propidium monoazide (PMA) method allowed to show a high bacterial mortality in sea ice and in SPM material collected in shallower waters at St 409 and St 418. This mortality was attributed to the release of bactericidal free fatty acids by sympagic diatoms under the effect of light stress. A strong cis-trans isomerization of bacterial MUFAs was observed in the deeper SPM samples collected at the St 403 and St 409. It was attributed to the ingestion of bacteria stressed by salinity in brine channels of ice by sympagic bacterivorous microzooplankton (ciliates) incorporating trans fatty acids of their preys before to be released in the water column during melting. The high trans/cis ratios also observed in SPM samples collected in the shallower waters at St 413 and St 418 suggest the presence of positively or neutrally buoyant extracellular polymeric substances (EPS)-rich particles retained in sea ice and discharged (with bacteria stressed by salinity) in seawater after the initial release of algal biomass. Such EPS particles, which are generally considered as ideal vectors for bacterial horizontal distribution in the Arctic, appeared to contain a high proportion of dead and non-growing bacteria. |
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1164 |
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ISSN |
0048-9697 |
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yes |
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Serial |
8253 |
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Author |
Makoto Sampei, Louis Fortier, Patrick Raimbault, Kohei Matsuno, Yoshiyuki Abe, Bernard Quéguiner, Augustin Lafond, Marcel Babin, Toru Hirawake |
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Title |
An estimation of the quantitative impacts of copepod grazing on an under sea-ice spring phytoplankton bloom in western Baffin Bay, Canadian Arctic |
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Journal |
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Year |
2021 |
Publication |
Elementa: Science of the Anthropocene |
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Volume |
9 |
Issue |
1 |
Pages |
00092 |
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Abstract |
This study aimed to quantify the impact of copepod grazing on the productivity of phytoplankton during an under sea-ice spring phytoplankton bloom (USPB) in western Baffin Bay. To quantify positive and/or negative impacts of copepod grazing on primary production and the interaction between copepod grazing and phytoplankton species, we sampled seawater and zooplankton under the landfast sea ice every 2–3 days between May 24 and July 10, 2016. Samples were analyzed for estimation of primary production, chlorophyll-a (chl-a) concentration, diatom abundance, and copepod fecal pellet (FP) production/grazing rate. Analyses of chl-a concentration, primary production, and FP production/grazing rate revealed clear temporal changes and a mismatch between primary production and copepod consumption. The FP production/grazing rate reached a maximum (9.4/31.2 mg C m–2 d–1) on June 16 before the USPB phase and suddenly decreased to 0.7/2.4 mg C m–2 d–1 on June 21, despite an increase in primary production to 74.0 mg C m–2 d–1. The copepod grazing rate (3.7 mg C m–2 d–1) was low relative to primary production (344.6 mg C m–2 d–1) during the USPB phase (after June 20). While our estimates illustrate that copepod grazing did not limit the maximum daily primary production during the USPB, the low grazing pressure (2% of primary production) may have been an additional contributor to the reduction in total primary productivity at the end of the USPB period due primarily to the low supply of regenerated nitrogen-containing nutrients to drive regenerated production. |
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1164 |
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ISSN |
2325-1026 |
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yes |
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Serial |
8255 |
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Author |
Anika Immer, Thomas Merkling, Olivier Chastel, Scott A. Hatch, Etienne Danchin, Pierrick Blanchard, Sarah Leclaire |
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Title |
Spying on your neighbours? Social information affects timing of breeding and stress hormone levels in a colonial seabird |
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Journal |
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Year |
2021 |
Publication |
Evolutionary Ecology |
Abbreviated Journal |
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Volume |
35 |
Issue |
3 |
Pages |
463-481 |
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Abstract |
A good overlap between offspring energetic requirements and availability of resources is required for successful reproduction. Accordingly, individuals from numerous species fine-tune their timing of breeding by integrating cues that predict environmental conditions during the offspring period. Besides acquiring information from their direct interaction with the environment (personal information), individuals can integrate information by observing the behaviours or performance of others (social information). The use of social information is often beneficial because the accumulated knowledge of conspecifics may represent a source of information more reliable than the intrinsically more limited personal information. However, although social information constitutes the major source of information in a wide range of contexts, studies investigating its use in the context of timing of breeding are scarce. We investigated whether black-legged kittiwakes (Rissa tridactyla) used social information to adjust the timing of egg-laying. We manipulated social information using a food-supplementation experiment, known to advance kittiwakes' reproductive phenology. We expected food-supplemented and unsupplemented pairs to delay and advance, respectively, their timing of laying when surrounded by a majority of neighbours from the opposite food-treatment. However, both unsupplemented and food-supplemented kittiwakes delayed egg-laying when surrounded by a higher proportion of neighbours from the opposite food-treatment. This result shows that kittiwakes use social information to time egg-laying, but that it is not used to match the seasonal peak of food availability. We suggest that when social and personal cues give contradictory environmental information, individuals may benefit from delaying laying to gather more information to make better decisions about investment into eggs. Further, we explored a potential proximate mechanism for the pattern we report. We show that baseline corticosterone, known to mediate reproductive decisions, was lower in unsupplemented females facing a higher proportion of food-supplemented neighbours. Altogether, our results suggest that to fine-tune their timing of laying, kittiwakes use complex decision-making processes in which social and personal information interplay. |
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1162 |
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ISSN |
1573-8477 |
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1573-8477 |
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yes |
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8245 |
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Author |
Guillaume Bridier, Frédéric Olivier, Laurent Chauvaud, Mikael K. Sejr, Jacques Grall |
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Title |
Food source diversity, trophic plasticity, and omnivory enhance the stability of a shallow benthic food web from a high-Arctic fjord exposed to freshwater inputs |
Type |
Journal |
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Year |
2021 |
Publication |
Limnology and Oceanography |
Abbreviated Journal |
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Volume |
66 |
Issue |
S1 |
Pages |
S259-S272 |
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Abstract |
Under climate change, many Arctic coastal ecosystems receive increasing amounts of freshwater, with ecological consequences that remain poorly understood. In this study, we investigated how freshwater inputs may affect the small-scale structure of benthic food webs in a low-production high-Arctic fjord (Young Sound, NE Greenland). We seasonally sampled benthic invertebrates from two stations receiving contrasting freshwater inputs: an inner station exposed to turbid and nutrient-depleted freshwater flows and an outer station exposed to lower terrestrial influences. Benthic food web structure was described using a stable isotope approach (δ13C and δ15N), Bayesian models, and community-wide metrics. The results revealed the spatially and temporally homogeneous structure of the benthic food web, characterized by high trophic diversity (i.e., a wide community isotopic niche). Such temporal stability and spatial homogeneity mirrors the high degree of trophic plasticity and omnivory of benthic consumers that allows the maintenance of several carbon pathways through the food web despite different food availability. Furthermore, potential large inputs of shelf organic matter together with local benthic primary production (i.e., macroalgae and presumably microphytobenthos) may considerably increase the stability of the benthic food web by providing alternative food sources to locally runoff-impacted pelagic primary production. Future studies should assess beyond which threshold limit a larger increase in freshwater inputs might cancel out these stability factors and lead to marked changes in Arctic benthic ecosystems. |
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1939-5590 |
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yes |
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6791 |
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