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Maria Pia Nardelli, Corentin Guilhermic, Christine Dupuy, Hélène Howa, Eleonora Fossile, Agnès Baltzer, Aurélia Mouret, Meryem Mojtahid. (2022). Seasonal and interannual variability of benthic foraminiferal faunas under the influence of a tidal glacier.
Abstract: Kongsfjorden (Svalbard archipelago, Arctic) is subjected to intensifying environmental gradients resulting from the confrontation of fresh waters issued from tidal glacier melting and newly invasive Atlantic waters. Along a 12 km-long transect from the Kronebreen glacier front to the central fjord, Fossile et al. (2022) identified, during summer 2018, three foraminiferal biozones, responding to decreasing disturbances linked to the proximity of the tidal glacier front (i.e., high water turbidity, freshwater, and sediment inputs, reduced organic fluxes). Close to the glacier terminus (proximal biozone), few stress-tolerant or opportunistic species were present in high abundances indicating high physical and geochemical stresses on the benthic fauna. At about 6–8 km off the glacier front (medial biozone), reduced turbidity and increased organic fluxes resulted in a higher diversity and high abundances of phytodetritus-indicators. The distal biozone, at 12 km from the glacier front, was characterised by species typical of environments influenced by Atlantic waters and a relatively well diversified fauna, due to glacial reduced stressful conditions. The comparison of these assemblages with the ones observed at the same stations in spring and summer 2021, shows low interannual variability and a seasonal contrast in the proximal biozone higher than in the distal one. Stable C and N isotopes measured on the cytoplasm of target species show similar signals for a same species at different seasons and diverse trophic positions among species. This suggests that some indicator species can be used to identify changes in the trophic functioning of the ecosystems, related to seasonal or long-term changing inputs from the glacier melt waters. Overall, our results suggest that benthic foraminiferal communities can be effective bioindicators to monitor the influence of seasonal calving cycles and ongoing long-term retreat of tidewater glaciers induced by climate change in Kongsfjorden. The characteristic calving pattern of the Kronebreen, however, makes highly difficult to link the observed interannual faunal variability to glacier velocity or front retreat. Longer faunal time-series are needed to get a better signal.
Programme: 1223
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Marianna Chimienti, Akiko Kato, Olivia Hicks, Frédéric Angelier, Michaël Beaulieu, Jazel Ouled-Cheikh, Coline Marciau, Thierry Raclot, Meagan Tucker, Danuta Maria Wisniewska, André Chiaradia, Yan Ropert-Coudert. (2022). The role of individual variability on the predictive performance of machine learning applied to large bio-logging datasets (Vol. 12).
Abstract: Animal-borne tagging (bio-logging) generates large and complex datasets. In particular, accelerometer tags, which provide information on behaviour and energy expenditure of wild animals, produce high-resolution multi-dimensional data, and can be challenging to analyse. We tested the performance of commonly used artificial intelligence tools on datasets of increasing volume and dimensionality. By collecting bio-logging data across several sampling seasons, datasets are inherently characterized by inter-individual variability. Such information should be considered when predicting behaviour. We integrated both unsupervised and supervised machine learning approaches to predict behaviours in two penguin species. The classified behaviours obtained from the unsupervised approach Expectation Maximisation were used to train the supervised approach Random Forest. We assessed agreement between the approaches, the performance of Random Forest on unknown data and the implications for the calculation of energy expenditure. Consideration of behavioural variability resulted in high agreement (> 80%) in behavioural classifications and minimal differences in energy expenditure estimates. However, some outliers with < 70% of agreement, highlighted how behaviours characterized by signal similarity are confused. We advise the broad bio-logging community, approaching these large datasets, to be cautious when upscaling predictions, as this might lead to less accurate estimates of behaviour and energy expenditure.
Keywords: Behavioural ecology Ecological modelling Ecophysiology Machine learning
Programme: 1091
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Marjorie Roscian, Anthony Herrel, Paul Zaharias, Raphaël Cornette, Vincent Fernandez, Isabelle Kruta, Yves Cherel, Isabelle Rouget. (2022). Every hooked beak is maintained by a prey: Ecological signal in cephalopod beak shape (Vol. 36).
Abstract: Beaks are among the few hard parts of coleoid cephalopods and are informative for species identification. Although mandible shape has been shown to be adaptive in many vertebrate taxa, it has been suggested that the shape of coleoid beaks does not bear any ecological signal. Yet, previous studies only explored beak shape in 2D and none have provided an in-depth investigation of the potential relationship with ecological variables such as habitat use or diet. The goal of the present study was to understand whether variation in cephalopod beak shape reflects ecology and/or is more driven by phylogenetic relatedness as suggested previously. We imaged 101 lower and 108 upper beaks in 3D using underwater photogrammetry and micro-CT scanning. Our 3D morphometric analysis conducted on 75 species of cephalopod shows that there is a significant but moderate phylogenetic signal. However, comparative phylogenetically informed analyses demonstrate that beak shape is also driven by ecology. We detected significant differences in beak shape between species inhabiting different habitats (pelagic, benthic or demersal) and of different trophic levels. Our results further suggest that beak shape variation can be summarized along a continuum between two main functions: fast closing versus hard biting. These results provide novel insights into the drivers of beak shape diversity in coleoid cephalopods and suggest that beak shape has evolved adaptively in relation to diet and habitat use. Read the free Plain Language Summary for this article on the Journal blog.
Keywords: 3D geometric morphometrics beak cephalopod ecology phylogenetic signal
Programme: 109
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Mark Andrew Hindell, Clive Reginald McMahon, Christophe Guinet, Rob Harcourt, Ian David Jonsen, Ben Raymond, Dale Maschette. (2022). Assessing the potential for resource competition between the Kerguelen Plateau fisheries and southern elephant seals (Vol. 9). Bachelor's thesis, , .
Abstract: Indirect ecological interactions such as competition for resources between fisheries and marine predators have often been proposed but can be difficult to demonstrate empirically. The Kerguelen Plateau in the Southern Indian Ocean supports fisheries for both Patagonian toothfish and mackerel icefish and is also an important foraging ground for several avian and mammalian predators, including the southern elephant seal. We quantified the spatio-temporal use of the plateau by southern elephant seals and found that males and females spent 30% of their time on the plateau within the commonly used fishing grounds, indicating the possibility of competition for resources there. We then contrasted the seals’ use of two habitat types, the benthos (where interactions with the long-line fisheries are most likely) and the epi-pelagic zone. The likelihood of feeding on the benthos declined as ocean depth increased and was also less likely at night. Males were also more likely to feed on the benthos than females. The sub-adult male seals consumed an estimated 6,814 – 14,848 tons of high energy content prey (including toothfish) and females 7,085 – 18,037 tons from the plateau during the post-molt winter months. For males this represented 79.6 – 173.4% of the mean annual catch by the Kerguelen fishery compared to 82.8 – 210.7% for adult females. When considering the seals consumption of fish from the benthos within the fishing grounds these estimates decreased to 3.6 – 15.1% of the fishery’s total annual catch for females and 7.8 – 19.1% for males. While this further indicates the possibility of indirect ecological interactions (with the fishery taking more fish than the seals), the lack of detailed diet information for the seals precludes us from establishing the degree or nature of the possible interactions because the importance of toothfish and icefish in the diet of the seals is unknown. However, the unique life history and highly polygynous nature of this species, and the lack of evidence of a measurable effect on either the seal’s population growth rates or the catch per unit of the fishery, suggest that any indirect ecological interactions are not of sufficient magnitude to affect either the seal population or the fishery.
Programme: 109,1201
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Mathilde Chevallay, Christophe Guinet, Tiphaine Jeanniard-Du-Dot. (2022). Should I stay or should I go? Behavioral adjustments of fur seals related to foraging success (Vol. 33).
Abstract: Understanding foraging strategies and decision-making processes of predators provide crucial insights into how they might respond to changes in prey availability and in their environment to maximize their net energy input. In this work, foraging strategies of Antarctic fur seals (Arctocephalus gazella, AFS) and Northern fur seals (Callorhinus ursinus, NFS) were studied to determine how they adjust their foraging behavior according to their past prey capture experiences. AFS on Kerguelen Islands are exclusively oceanic divers, while NFS population of St Paul Island shows both oceanic and neritic divers. We thus hypothesized that the two species would respond differently to a change in prey capture success depending on their foraging strategy. To test this, 40 females were equipped with tags that measured tri-axial acceleration, dive depth, and GPS coordinates, from which we derived prey capture attempts and behavioral metrics. Influence of prey capture success on horizontal and vertical movements of seals was investigated at different time scales: multi-dive, night, and trip. Both AFS and NFS traveled further during the day if they encountered low prey capture periods during the previous night. However, at the multi-dive scale, neritic NFS differed from oceanic NFS and AFS in terms of decision-making processes, e.g., both AFS and oceanic NFS dived deeper in response to low prey capture rate periods, while neritic NFS did not. Similarities in decision-making processes between NFS and AFS foraging on pelagic prey suggest that pelagic vs. neritic prey type is a key factor in defining foraging decisions of diving marine predators.
Programme: 109
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Maxime Allioux, Stéven Yvenou, Alexander Merkel, Marc Cozannet, Johanne Aubé, Jolann Pommellec, Marc Le Romancer, Véronique Lavastre, Damien Guillaume, Karine Alain. (2022). A metagenomic insight into the microbiomes of geothermal springs in the Subantarctic Kerguelen Islands (Vol. 12).
Abstract: The Kerguelen Islands, located in the southern part of the Indian Ocean, are very isolated geographically. The microbial diversity and communities present on the island, especially associated to geothermal springs, have never been analyzed with high-throughput sequencing methods. In this article, we performed the first metagenomics analysis of microorganisms present in Kerguelen hot springs. From four hot springs, we assembled metagenomes and recovered 42 metagenome-assembled genomes, mostly associated with new putative taxa based on phylogenomic analyses and overall genome relatedness indices. The 42 MAGs were studied in detail and showed putative affiliations to 13 new genomic species and 6 new genera of Bacteria or Archaea according to GTDB. Functional potential of MAGs suggests the presence of thermophiles and hyperthermophiles, as well as heterotrophs and primary producers possibly involved in the sulfur cycle, notably in the oxidation of sulfur compounds. This paper focused on only four of the dozens of hot springs in the Kerguelen Islands and should be considered as a preliminary study of the microorganisms inhabiting the hot springs of these isolated islands. These results show that more efforts should be made towards characterization of Kerguelen Islands ecosystems, as they represent a reservoir of unknown microbial lineages.
Keywords: Computational biology and bioinformatics Ecology Genetics Microbiology
Programme: 1077
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Maxime Pineaux, Thomas Merkling, Etienne Danchin, Scott A Hatch, Sarah Leclaire, Pierrick Blanchard. (2022). MHC-II distance between parents predicts sex allocation decisions in a genetically monogamous bird (Vol. 33).
Abstract: Theory predicts that parental heritable characteristics should shape sex allocation decisions when their effects on reproduction or survival are offspring sex-dependent. Numerous studies have questioned to what extent characteristics displayed by one of the parents matched theoretical expectations. This contrasts with the handful of studies that investigated whether compatibility between parents could also trigger selective pressures for sex allocation adjustments. We studied the genetically monogamous black-legged kittiwake (Rissa tridactyla), where previous data revealed that female chicks suffered higher fitness costs from low diversity at genes of the major histocompatibility complex (MHC) than male chicks. We predicted, and found in our dataset, that MHC-similar parents, producing low MHC-diverse offspring, should avoid the production of females. The relation between MHC-distance between parents (i.e. the functional distinctness of their MHC alleles) and offspring sex was not linear, such that MHC-dissimilar parents also overproduced sons. Overall, our results suggest that the genetically monogamous black-legged kittiwake parents flexibly adapt their reproduction and circumvent the costs of suboptimal pairing by manipulating offspring sex.
Programme: 1162
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Meagan Dewar, Michelle Wille, Amandine Gamble, Ralph Vanstreels, Thierry Boulinier, Adrian Smith, Arvind Varsani, Norman Ratcliffe, Jennifer Black, Amanda Lynnes. (2022). The Risk of Avian Influenza in the Southern Ocean: A practical guide.
Abstract: Advice from Avian Influenza experts suggests that there is a high risk that Highly Pathogenic Avian Influenza will arrive in the Southern Ocean 2022/23-2024/25 austral summers. Since the beginning of 2022, the increasing intensity of highly pathogenic avian influenza (HPAI) H5N1 outbreaks has resulted in the death of hundreds of thousands of seabirds in the Northern Hemisphere, around the Atlantic and Pacific Oceans and southern Africa. The SCAR Antarctic Wildlife Health Working Group (AWHWG) is highly concerned about the likely arrival and subsequent impact HPAI H5N1 might have on Southern Ocean wildlife. Due to the heightened risk of HPAI being introduced to Antarctica during the the 2022/23 Austral summer by migrating seabirds, the AWHWG recommends that: People working with or close to wildlife should assume that HPAI will arrive in the sub-Antarctic and Antarctica and take precautions to protect themselves when working around wildlife (including appropriate PPE) and maintain the highest biosecurity to prevent transmission between wildlife aggregations. All National Programmes (NPs) and tourism operators should monitor colonies for signs of H5N1 before approaching, especially in migratory species such as skuas, gulls and giant petrels. Tourists should not enter colonies and high wildlife density areas with suspected HPAI and NPs should conduct risk analysis as to which activities need to continue. A more detailed protocol on how to assess wildlife aggregations for HPAI prior to a visit and what to do if HPAI is detected should be provided to all stakeholders physically present in Antarctica this season. If you detect signs of HPAI, you should report this to your permit issuer. Videos of affected animals are very helpful for experts to help determine whether or not this is HPAI. Operators should refresh themselves with and review all biosecurity and any response guidelines to unusual/mass mortality events. This document aims to: Outline the likely risk to Southern Ocean taxa (a more technical assessment will follow in a separate document). Suggest which risks can be mitigated in light of human activity, transmission into and out of Antarctica and the sub-Antarctic regions through all operators as well as movements between sites within the Southern Ocean (primarily for science and tourism), Start discussion with National Programmes about ongoing monitoring for disease and consequences.
Keywords: Antarctica, Avian Influenza, Infectious disease, Seabirds, sub-Antarctic
Programme: 1151
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Meeta Cesler-Maloney, William R. Simpson, Tate Miles, Jingqiu Mao, Kathy S. Law, Tjarda J. Roberts. (2022). Differences in Ozone and Particulate Matter Between Ground Level and 20 m Aloft are Frequent During Wintertime Surface-Based Temperature Inversions in Fairbanks, Alaska (Vol. 127).
Abstract: During winter in Fairbanks, Alaska, fine particulate matter (PM2.5) accumulates to large concentrations at breathing level; yet little is known about atmospheric composition aloft. To investigate vertical differences of pollutants, we measured PM2.5 and ozone (O3) at 3 and 20 m above ground level (AGL) in Fairbanks during winter (November 2019–March 2020). We measured temperature and PM2.5 at 3, 6, 9, and 11 m AGL on a tower to quantify surface-based temperature inversions (SBIs) and near-surface PM2.5 gradients. We defined SBIs as data with an 11 m minus 3 m temperature difference greater than 0.5°C. We observed the largest differences in PM2.5 and O3 when SBIs were present. During SBIs, PM2.5 accumulated to large concentrations at 3 m but to a lesser extent at 20 m, demonstrating reduced vertical mixing. During SBIs, the median PM2.5 concentration was 4.8 μg m−3 lower at 20 m than at 3 m. When PM2.5 concentrations were large at 3 m, O3 was often completely chemically removed (titrated) but was still present at 20 m. During SBIs, the O3 mixing ratio was more than 2 nmol mol−1 larger at 20 m than at 3 m in 48% of the data. Results show that during SBIs, pollution in Fairbanks is mixed to altitudes below 20 m AGL and that the oxidation regime of the atmosphere changes from 3 to 20 m AGL as large differences in O3 mixing ratios were measured during SBIs.
Keywords: Alaska inversion ozone PM2.5 pollution vertical
Programme: 1215
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Mojtahid M., Fossile E., Santoni S., Husum K., Streuff K., Forwick M., Howa H., Nardelli MP. (2022). Benthic foraminifera as tools to reconstruct past tidewater glacier dynamics: A case study from Kongsfjorden (Svalbard).
Abstract:
Located at the interface between terrestrial and marine systems, high latitude glaciated fjords are sensitive spots to current and past climate change. Kongsfjorden is located on the western part of the Svalbard archipelago and is characterized by steep environmental gradients, due to the dynamics of the tidewater glaciers, and the inflow of warm Atlantic Water (AW). Here we analyze fossil benthic foraminiferal assemblages in two main sediment cores in order to reconstruct past environmental changes in link with these environmental gradients. Sediment core 10JM-GLACIBAR-GC01, located in front of a surge-type tidewater glacier (Kronebreen complex) in the inner Kongsfjorden, represents a historical record spanning the period from 1950 to 2010 AD. In this record, we tested relationships between taxonomic and functional diversity metrics and the reconstructed distance from the glacier front. We observed a general increase in foraminiferal fluxes and diversity with the progressive glacier retreat, confirming a positive benthic response to reduced glacier-induced disturbance through time. This historical record confirms therefore the successful use of diversity metrics as proxies for tidewater glacier retreat. A study of a second sediment core, NP07-13/58-GC, spanning the last 3000 years and located in the central Kongsfjorden, was initiated to reconstruct the two end-members relationship between AW inflow and glacier retreat using benthic foraminiferal assemblages and diversity metrics applied in the historical record. The preliminary results show that until 1.6 cal ka BP and between 800 and 500 yrs cal BP, a low diversity and high relative abundances of glacier proximal species characterized the assemblages. According to the developed diversity metrics models, this suggests that the glacier grounding line/ice sheet was advanced by about 10 km compared to its position during the mid XXth century. From 1.6 to 0.8 cal ka BP and between 500 and 200 yr cal BP, taxonomic diversity increased, suggesting decreased glacial influence at the core site (in the central Kongsfjorden). Additionally, the most recent part of the record (500 – 200 yr cal BP) recorded increased relative abundance of the AW indicator Adercotryma glomeratum, suggesting increased influence of the AW carried by the West Spitsbergen Current in the central Kongsfjorden. These ecological observations need further investigations and comparison with published studies from Kongsfjorden and other Svalbard fjords. Investigations with multivariate analyses and Generalised Additive Models could help better interpret the patterns observed in term of species composition and general diversity. Programme: 1223
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