Session Chair: Kara Layton; Technical Support: Deniz Vural. The recording of the session is available below.
21:05 - 21:20 GMT: Vegetation and disturbance drive variability in pond DOM at Cape Bounty Arctic Watershed Observatory
Presenter: Joanne Heslop
Institution: Queen's University, Canada
Type: Oral presentation
Abstract: Inland waters receive and process significant but poorly-constrained amounts of terrestrial carbon (C). A portion of terrestrially-derived C in inland waters is microbially processed into the greenhouse gas carbon dioxide (CO2) and outgassed into the atmospheric C pool, making inland waters an important component of the global C cycle. In the Arctic, ponds represent a substantial portion of inland water surface area. Thus, C processing and subsequent CO2 outgassing from ponds could play a significant role in the Arctic C cycle and potential greenhouse gas emissions. We quantified and characterized terrestrially-derived C export and composition from 19 ponds at the Cape Bounty Arctic Watershed Observatory, Nunavut, Canada. The ponds were selected to represent a range of hydrological inputs (precipitation-fed versus soil water-influenced), surrounding vegetation types (mesic tundra, polar desert), and permafrost disturbance regimes (active layer detachment, undisturbed). Ponds were sampled weekly from 16 July to 12 August 2018 and analyzed for: dissolved organic carbon (DOC), total dissolved nitrogen (TDN), major ions, and dissolved organic matter (DOM) optical properties. Ponds located in undisturbed, vegetated regions generally had the highest DOC concentrations. Ponds in disturbed regions had lower DOC concentrations than undisturbed ponds, but higher TDN and major ion concentrations. DOM optical properties suggest DOC in disturbed ponds is more bioavailable than DOC in undisturbed ponds. Results from this study will be compared to measured dissolved gas concentrations in the same ponds, with the objective of identifying major controls on CO2 production and upscaling pond CO2 emission estimates to the whole watershed.
21:20 - 21:30 GMT: Evolutionary processes that shaped the diversity of the amphipod genus Eusirus in the Southern Ocean
Presenter: Lourine Salabao
Institution: University of Liege/University of Hasselt, Belgium
Type: Flash presentation
Abstract: Diversity of the current Antarctic marine fauna. In the past, these Antarctic species have survived different glacial cycles through dispersal to refugia, and/or adaptations to novel abiotic and biotic conditions. With the increasing temperatures in the polar regions, marine fauna is currently faced with three possible outcomes: adaptation, migration or extinction. Based on how these organisms were able to survive environmental changes in the past will allow us to predict their future response. In this study, amphipods of the genus Eusirus are as model organisms as knowledge on their ecology and biogeography is still very limited. The evolutionary history of Eusirus amphipods is phylogenetically reconstructed through time with molecular data. DNA sequence data are obtained by sequencing the complete mitochondrial genomes, using a combination of skimming sequencing and long-range PCRs amplicons of different Eusirus species. Mitochondrial data will be complemented with additional sequence data from nuclear genes. Time-calibrated phylogenies will be used as basis for plotting ecological and trophic data generated by stable isotope analyses as well as morphological information. By combining data from time-calibrated phylogenies as well as from ecology and morphology, we aim to understand the evolutionary processes that led to the current diversity of Eusirus amphipods.
21:30 - 21:40 GMT: An interdisciplinary approach to test population structure and life history connectivity of Antarctic silverfish (Pleuragramma antarctica) in the southern Weddell Sea
Presenter: Jilda Alicia Caccavo
Institution: Alfred Wegener Institute (AWI) / Berlin Center for Genomics in Biodiversity (BeGenDiv), Germany
Type: Flash presentation
Abstract: The Antarctic silverfish (Pleuragramma antarctica) is a critically important forage species with a circumpolar distribution and is unique among notothenioid species for its wholly pelagic life cycle. Studies have provided mixed evidence of population structure in silverfish over regional and circumpolar scales. Microsatellite markers previously showed homogeneity in allele frequencies along the Antarctic Slope Current westward from the Ross Sea to the northern tip of the Antarctic Peninsula. However, spatially recurring length modes observed in the Weddell Sea provide evidence for episodic connectivity. In this study, as part of a hydrographic survey of the Filchner Trough system in the southern Weddell Sea, otolith nucleus chemistry, which provides a record of environmental exposure during early life, was used to test between physical-biological hypotheses of silverfish population connectivity. Despite strong gene flow observed throughout areas of the southern Weddell Sea, significant population structuring was found using otolith chemistry, in the same samples as used for a previous genetic study. Self-recruitment shaped by circulation associated with the Filchner Trough, fluctuations in mixing between immigrant and locally-recruited fish, and feeding opportunities between inflowing Modified Warm Deep Water and outflowing Ice Shelf Water, help explain structuring revealed by otolith chemistry, length, abundance and biomass data, as well as gene flow along the continental slope. These results illustrate how comparisons between interdisciplinary techniques based on integrated sampling designs that incorporate hydrography can enhance understanding of population structure and connectivity of species around the Southern Ocean.
Presenter: Jean Holloway
Institution: University of Ottawa, Canada
Type: Oral presentation
Abstract: Effects of climate change are being felt in all aspects of the cryosphere, and how permafrost will respond to these variations is of concern. Forest fire is rarely taken into account in predictive modelling of permafrost change even though severe fires have been shown to accelerate degradation. Moreover, the frequency and magnitude of fires is increasing as the climate warms. We are examining permafrost change following the 2014 fires in the Northwest Territories, Canada in order to improve our understanding of the fate of permafrost in the region. A total of 18 burned and unburned sites representing a range of conditions were established in 2015 and 2016. At each site, air and ground temperature are being monitored continuously, and direct current electrical resistivity tomography (ERT) surveys and frost table measurements are being conducted annually. Burned sites were warmer than unburned ones: surface offsets averaged 0.5°C greater and the thermal offsets 0.1°C smaller. Average frost table depths at burned sites were 17 cm greater than at unburned sites, and were generally greater in 2017 compared to 2015. This reflects impacts of the burn as mean summer air temperatures differed by only 0.3°C. Results from ERT surveys show the possible loss of permafrost within some sites. The most-affected sites are underlain by coarser-grained substrates with thin organic layers, whereas peatland sites are less impacted. These results indicate the heterogeneity of permafrost reaction to fire at the landscape scale and suggest that permafrost may persist in peatlands while degrading elsewhere in the region.
Presenter: Zdenka Sokolickova
Institution: University of Oslo // University of Hradec Kralove, Norway
Type: Oral presentation
Abstract: Svalbard in the high Arctic is often promoted as a peripheral „disappearing destination“. In reality, it is very much central when it comes to global trends such as climate change or overheating in terms of economy and culture & identity. Changing climate in Longyearbyen means temperature rise, heavy rain periods, melting glaciers, thawing permafrost, disappearing sea ice, avalanches, erosion and landslides. By changing economy, we mean that the former economic backbone of the community - the mining industry - is diminishing, while tourism and research activities are on rise and there is no substitute for the mining in sight. These developments influence the structure of the town's population, causing less stability, less integration and more transience. The so-called local community cannot be easily defined because it is being contested and deconstructed as the changes speed up. Several, sometimes only vaguely interlinked communities identify with the place, which leads to a feeling of segregation and, to some extent, alienation. This is strengthened by the mismatch between the official Norwegian policy promoting Longyearbyen as a Norwegian community, and the reality of numerous foreign citizens (including Thai or Philippino people) settling down, looking for jobs, housing and education for their children. In this small town with 2,500 inhabitants, global forces are translated into local side-effects, challenging the future of the overheated place. The talk summarizes preliminary results of the first 4 months of an ethnographic fieldwork planned to last for 2 years, based on in-depth interviews with residents and intense participant observation.
Presenter: Tobias Staal
Institution: University of Tasmania, Australia
Type: Oral presentation
Abstract: Numerous data compilations, models and interpretations constrain aspects of Arctic and Antarctic solid Earth and cryosphere. Combinig datasets can be difficult as spatial data comes in different resolution, projection and extent. The interdisciplinary polar research community therefore needs a way of handling multiple models and constraints such that discrepancies may be understood. The platform should also contain uncertainty, provenance and likelihood information. I present a computational environment 'agrid', that aims to provide gridded multidimensional models. The environment is built using Python high level programming language, with the aim of providing an accessible user interface. Rasters, unstructured grids, vector data can be imported to the regular grid. It can be populated by datasets in a way that facilitates dynamic updating as the underlying geological and geophysical compilations improve. The grid can be linked the original data to allow for full reproducibility. The implementation is flexible and allows for stochastic modelling and increased dimensionality. Export formats are interoperable for a wide range of applications, and the code also contains methods for generation of maps and basic 3D visualisation. I illustrate the use through a comparison of segmentations of East Antarctica and implementations for subglacial heat flow.
22:25 - 22:40 GMT: Constraint of North American Glacial Cycle Histories in a Coupled Ice/Sediment/Hydrology Model
Presenter: Matthew Drew
Institution: Memorial University, Canada
Type: Oral presentation
Abstract: What new constraints does the addition of fully coupled subglacial hydrology and sediment production/transport add to data-constrained glacial cycle ice sheet modelling? As a corollary, what are the inferred local erosion/denudation rates and relative contribution from relevant processes? We probe these questions for the context of the last glacial cycle of the North American ice sheet complex.
Currently there are few ice sheet models which implement sediment production/transport and even fewer with a realistic hydrology which modulates these sedimentary processes. To date, models of subglacial hydrology have been designed for either glacier scale (complex description of processes) or continental scale (heavily simplified for basal drag calculation). The model presented here represents a trade off: a parameterized choice of poroelastic and linked-cavity systems for inefficient drainage with a flux switch to efficient (tunnel) drainage. The subglacial sediment model incorporates both abrasion and quarrying with transport via both glacial entrainment and soft sediment deformation.
These sediment and hydrology models have been fully coupled to the Glacial Systems Model (GSM), a 3D ice sheet model with full suite of ice dynamics, solid earth processes, and range of climate representations. GSM ensemble parameters are constrained by comparison of resultant ice histories against a range of geophysical and geological data. An esker-margin density time series is used to constrain the drainage regime, debris trains provide a control on sediment transport, and the present day distribution of sediment over North America is an outcome requirement. Our probe will invoke comparison of a large ensemble of last glacial model runs against the above constraints.
22:40 - 23:15 GMT: Keynote: Inspiring Girls Expeditions: Fostering scientific inquiry in young womxn through interdisciplinary field science immersion programs
Presenter: Aurora Roth
Institution: University of Alaska Fairbanks, USA
Type: Keynote presentation
Abstract: For 20 years, Inspiring Girls Expeditions (formally known as Girls on Ice) has been empowering young womxn (ages 16-17) through tuition-free wilderness-based science programs. Our programs interweave science, art, and wilderness travel skills to inspire future confidence, leadership, and success in our participants, particularly those who couldn't have an experience like this otherwise. 8-9 participants spend 12 days on glaciers, in kayaks, or rock climbing with an instructor team made up of professional earth scientists (glaciologists, ecologists, biologists, oceanographers, and more!), wilderness guides, and artists. Our participants create and conduct their own field science research projects and explore the landscape they are immersed in from many perspectives. This talk will focus on why an interdisciplinary approach and curriculum is essential to the mission of Inspiring Girls Expeditions, why it is necessary that our programs promote diversity in the sciences, and how YOU can become involved with our programs.