Session Chair: Lauren Thompson
Session Convener: Carrie Harris
Session Coordinators: Anastasiia Ovchinnikova, Chloe Nunn, Mariel Kieval
Time: 20 May from 17:45 - 20:15 GMT
17:50 - 18:05 GMT: Spatial Dynamics Of Phytoplankton In The Gerlache Strait During The Austral Summer 2018-2019
Presenter: María José
Institution: University of Bogotá Jorge Tadeo Lozano, Colombia
Type: Oral Presentation
Abstract: During the summer of 2018-2019, in the Western Antarctic Peninsula, qualitative and quantitative samples of phytoplankton were collected at 10 stations in the southern sector and at 6 stations in the northern sector in the Gerlache Strait, in order to assess possible spatial variations in terms of composition and density. The qualitative samples were taken with a weighted frustoconical net of 20 μm, 2,2 m long and 60 cm in diameter, using trawls from 200 to 0 m deep. For quantitative purposes, Niskin bottles were used, attached to an oceanographic rosette, accessing three depths (5 m, 50 m and 100 m), except in 3 stations, where there were problems with the closure system. In addition, the measurement of physicochemical variables was performed. In qualitative terms, the assembly of both sectors was mainly made up of the Bacillariophyta phylum with Corethron pennatum, Cocconeis fasciolata, Licmophora abbreviata, Eucampia antarctica and Odontella weissfloguii, as those with the highest frequency of appearance. Regarding the quantitative analysis, the presence of five phylums were observed, with a greater contribution to the wealth of both sectors and depths of Bacillariophyta followed by Miozoa. In terms of density, Bacillariophyta continued to be the one with the highest contribution, both by sector and depth. A high contribution of Cyanobacteria in the depths of 5 m and 100 m was highlighted in the south. The species with the highest density between sectors and depths were different, obtaining for the north at 5 m and 50 m Euglenozoa 1 (87 cel / L, 160 cel / L respectively) and at 100 m Licmophora sp. 2, while in the south for the first two depths it was the centric Diatom 1 (112 cel / L, 30 cel / L) and at 100 m the cyanobacterium Chroococus sp. 1 (20 cells / L).
Presenter: Mainak Mondal
Institution: New York University Abu Dhabi, United Arab Emirates
Type: Oral Presentation
Abstract: Recent laboratory-scale experiments and turbulence resolving numerical simulations have highlighted the importance of the convective processes on the ice-loss rate at the ice-ocean interface. Large Eddy Simulations at the ice-ocean boundary (Vreugdenhil et al., 2019) indicated that, below a threshold ambient current the ice-ocean boundary layer is convectively driven and the meltrate is independent of the ambient flow, rather controlled by the thermal driving. Direct Numerical Simulations under a sloping ice-interface have showed that under such conditions, local stratification can suppress the turbulent transport at the boundary (mondal et al; 2019) and the future evolution of the ice-shelf is sensitive to the ice-shelf morphology. These results have been implemented into ROMS-MISOMIP as a modified ice-ocean scheme where a heaviside function flips between convectively driven and shear driven melt parameterization, subjected to the ambient current. Sensitivity studies have been conducted over an idealized domain with varying thermal forcing as well as adding steps like ice-bathymetry. However, when a threshold ambient current of 0.05 m/s is used, the simulations generate unrealistic overturn-circulation inside the ice cavity and melting at the ice-interface effective controlled by the stronger shear leaving the convective melt parametrization obsolete. We speculate that an uncoupled sub-grid scale buoyancy forcing might create instabilities into the momentum field followed by a faster transition into the velocity dependent melt-regime with higher ambient velocity.
18:20 - 18:25 GMT: Half A Century Of Glacier Mass Balance At Cordilleras Blanca And Huaytapallana, Peruvian Andes
Presenter: David Clark
Type: Flash presentation
Abstract: The glaciers of the tropical Andes have been observed to be losing mass for much of the last century. Changes in these glaciers are both driven by, and an indicator of global climate change. These glaciers are significant as they represent a crucial water source for downstream communities, buffering dry season discharge variations. Glacial recession also presents a hazard risk, exposing steep slopes and increasing the risk of glacial lake outburst floods (GLOF). The research presented here aims to quantify glacial mass loss for the Cordillera Blanca (CB) and Cordillera Huaytapallana (CH) and the associated changes in meteorology and hydrology. In order to do this Landsat imagery was used to identify glaciers, alongside repeat DEMs from satellite altimetry and historic maps. These were used to measure glacier surface elevation changes from 1972-2018. Analysis of the meteorological data was used to identify the key factors forcing glacial mass balance. The results of this study show that the glaciers of CB (-0.45±0.09 myr-1 w.e) and CH (-0.48±0.20 myr-1 w.e) have undergone substantial mass loss over the past half century. Variation in this mass balance was observed on different glacier aspects and elevations as well as over the different time periods studied. Meteorological analysis identified a negative relationship between CB mass balance and temperature and precipitation with a positive relationship with humidity. For CH a negative relationship with precipitation and temperature was found. No change in downstream river discharge was identified with no changes in the contributions of glacial melt to streamflow.
18:35 - 18:50 GMT: Study Of The Lange Glacier King George Island, Antarctic Peninsula: The Oceanic Impact Of The Marine-terminating Glacier At The Admiralty Bay
Presenter: Jhon Mojica
Institution: Center for global Sea Level Chance, New York University Abu Dhabi (CSLC-NYUAD), United Arab Emirates
Type: Oral Presentation
Abstract: Coastal regions of West Antarctica and the Glaciers of the Antarctic peninsula are thinning by atmospheric and oceanic interaction, contributing to increasing its temperature with main effects on the sea level. To characterize the implications of the sea-ice interaction, we selected the bay in front of the Lange Glacier (LG) on King George Island. At this location during the Antarctic summer 2018-2019, a bathymetric survey, a digital elevation model (DEM), and 29 CTD casts were recorded to determine the frontal ice location and the water conditions. The bathymetric survey recorded a range of depths of 10 – 220 m, corresponding to the ice thickness below sea level. External intrusions of warm water were identified, destabilizing the water column through convection processes; as a result, the ocean influences the glacier front, driving the subsurface glacier retreatment and basal melt. Our findings together indicated a continuous glacier fusion that increases its dynamics due to the increase of temperature, with a contribution of freshwater to the Admiralty Bay. Systematic monitoring is required to establish the direct implications of the LG climate change and water contributions to sea-level rise.
18:50 - 18:55 GMT: What Is The Sea Slug Doris Kerguelenensis Feeding Upon In Deception Island (south Shetland Is., Antarctica)?
Presenter: Paula de Castro-Fernández
Institution: University of Barcelona & Institute of Research in Biodiversity (IRBio), Spain
Type: Flash presentation
Abstract: Doris kerguelenensis is an Antarctic heterobranch mollusc feeding on several demosponges and hexactinellid sponges. To assess the contribution of several sponge species to its diet at Deception Island we used stable isotopes of C and N, as well as fatty acids. We examined the demosponges Axinella crinita, Dendrilla antarctica, Hemigellius pilosus, Kirkpatrickia variolosa, Mycale acerata, Sphaerotylus antarcticus, and Haliclona sp. We also analyzed the macroalgae Desmarestia anceps and Himantothallus grandifolius, and phytoplankton. D. anceps was the most 13C depleted one and phytoplankton the most enriched. The δ13C values of sponges and D. kerguelenensis laid in between. The δ15N values of A. crinita, D. antarctica, M. acerata and Haliclona sp. suggested a trophic position between 2-3, and for H. pilosus and S. antarcticus between 3-4. Kirkpatrickia variolosa was in between the two groups. The δ15N values of D. kerguelenensis revealed a trophic position from 3-4. All sponges and D. kerguelenensis had high levels of 15:0 and EPA and low levels of arachidonic acid, largely differing from macroalgae. Fatty acid profiles of A. crinita, D. antarctica, K. variolosa, M. acerata, S. antarcticus, and Haliclona sp. were similar to phytoplankton, but D. kerguelenensis and H. pilosus were enriched in 17:0, 20:1n9 and 20:2. D. kerguelenensis, A. crinita, D. antarctica, K. variolosa, Haliclona sp. and S. antarcticus shared a long chain fatty acid absent in phytoplankton and macroalgae. The overall evidence suggests that A. crinita, D. antarctica, K. variolosa and Haliclona sp. are the most likely prey of D. kerguelenensis at Deception Island.
Presenter: Indrani Roy
Institution: University College London, United Kingdom
Type: Oral presentation
Abstract: The role of the eleven-year solar cycle was investigated on the Arctic during the period of 1979–2016. It shows in years, when the winter solar sunspot number (SSN) falls below the mean value, the warming in the Arctic extends from all the way from the upper stratosphere down to the lower troposphere. It is opposite when the SSN is above the mean. The cooling for SSN maximum years in the atmospheric column reflects an anomaly of westerly zonal wind consistent with negative anomalies of geopotential height and cold air and vice versa for the minimum years. Using three different techniques – Multiple Linear Regression, Compositing, and Correlation – we observe the same influence of the sun on the Arctic and it comes via the Arctic Oscillation. Involving the stratospheric route, it presented a schematic and discussed the mechanisms of how the Arctic climate is influenced by solar cycle variability. For Eurasian snow-cover, Compositing, however, notes a reverse solar signature, which is warming during Maximum years, while cooling in minimum. This study hypothesizes that growth of ice in Eurasia, in recent winters, while a reduction in the Arctic, may in part, be due to weaker solar cycles of current decades.
19:10 - 19:25 GMT: Sinking Particle Flux And Composition At Three Sites Of Different Annual Sea Ice Cover In The Amundsen Sea, Antarctica
Presenter: Minkyoung Kim
Institution: ETH Zurich, Switzerland
Type: Oral presentation
Abstract: The Amundsen Sea in the western Antarctic is experiencing rapid declining of sea ice cover and melting of ice shelves. This physical change is expected to influence the carbon cycling in the Amundsen Sea and therefore, it is important to understand the organic carbon cycling in the Amundsen Sea to project the role of the Amundsen Sea in the future. To further our understanding of organic carbon cycling on the Amundsen Shelf, a research was carried out in collaboration with KOPRI (Korea Polar Research Institute), adopting multidimensional and multidisciplinary approaches. Sediment trap is the only way to investigate year-round biological pump system in this region due to observational constraints. Sinking particle samples were collected during 4 cruises and sediment trap moorings from 2011 to 2018. Sinking particles, collected by a sediment trap deployed at three different sites (perennial sea ice zone, Amundsen Sea Polynya (ASP), and in front of the Dotson Ice Shelf). POC flux in the perennial ice-covered area where diatoms are dominant phytoplankton species can be high and comparable to that of the central polynya. Two years of sediment trap data covering three summers were obtained and examined sea ice evolution and POC export and their relationship. The summertime POC flux showed high interannual variability with the reduction in sea ice cover in early summer for sufficient insolation being critical to enhanced sinking POC flux. Large benthic invertebrates including juvenile scallops, a sea urchin, and long and slender worms were collected in sediment traps for 2 years at three locations. Organic carbon supplied by worms and plausible source region and transport mechanisms of these benthic organisms and the impacts on Antarctic biology, as a disturbance to benthic ecosystems, a dispersal mechanism for benthic invertebrates, and an energy supply to the deeper benthic ecosystems will be presented.
19:25 - 19:40 GMT: Understanding an ice stream in Greenland at the EastGRIP camp: An international-multidisciplinary effort and knowledge transfer among scientists.
Presenter: Steven Franke
Institution: Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Germany
Type: Oral Presentation
Co-authors: 1Steven Franke, 1Nicolas Stoll, 1Daniela Jansen, 2Iben Koldtoft
1 Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
2 Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
Abstract: The East Greenland Ice-core Project (EastGRIP) aims to retrieve a 2650m long ice core by drilling through the Northeast Greenland Ice Stream (NEGIS).
Scientists from a variety of physical sciences and engineers hope to gain new knowledge on ice stream dynamics and about the past climate. The project has many partners from all around the world, who contribute to the science, logistics and economics of the project. Most of the data is processed and analysed in the field. As there is limited capacity in the field camp, scientists and technical staff are encouraged to learn different working techniques to support their project partners. The community also invites scientists, who work on theoretical aspects on the ice stream to communicate the perspective on the procedures and challenges of data collection in the field. And so it happens that earth system modellers learn how to drill an ice core or non-scientific staff helps with the preparation of the ice core samples. Also, the project partners are motivated to bring together scientists at early stages in their careers to gain fieldwork experience. Once each season the field camp also welcomes high school students and teachers as a part of a joint science and education programme.
Presenter: Ada Pastor
Institution: Aarhus University, Denmark
Type: Oral presentation
Abstract: The Arctic is warming at over six times the rate of the global average, causing permafrost thaw through the gradual deepening of the active layer and increasing soil mass wasting processes. These climate-driven changes will affect the hydrological and hydrochemical fluxes reaching aquatic ecosystems. However, it is unclear how nitrogen sources and the ecological consequences will change in high-latitude running waters. In this talk, we will (i) assess the biogeochemical role of high-Arctic riparian soils as sources of nitrogen, and (ii) evaluate how nitrogen is used by aquatic biofilm. We studies two riparian areas and six stream reaches subjected to a gradient of vegetation coverage, soil physical perturbation and geomorphological units in NE Greenland (74ºN).
Our results showed that riparian soils had low nitrate concentrations in the valley, associated to negligible net nitrification rates and negative net nitrogen mineralization rates, thus indicating efficient soil microbial nitrogen uptake. Low soil NO3− content is consistent with low NO3− concentrations found in most streams. However, upstream reaches with high channel instability and erosion in the watershed had NO3- concentrations 10 times higher than downstream sites, and had the highest autotrophic biofilm growth. Overall, we showed that low soil NO3− availability could limit hydrological transport, thus influencing stream autotrophic production in high-Arctic region. Our study further suggest that terrestrial-aquatic nitrogen export and ecological effects depend on the geomorphological features, vegetation and erosion in the watershed, which are extremely vulnerable to climate changes.
Presenter: Marco Volpe
Institution: Italian Society for International Organization, Italy
Type: Flash presentation
Abstract: As a permanent observer within the Arctic Council, China has a relevant but limited role in the Arctic governance. The white paper China’s Arctic Policy (2018) affirms that China will develop its strategy in accordance with the current legal framework and by adopting a strong cooperative attitude. Besides the international institutionalized field, through a consistent improvement of bilateral cooperation with Arctic States, China is also engaging a new space of maneuver in order to improve its role in the Arctic governance: the win-win strategy, which consists in the improvement of bilateral relationships with Arctic States bolstering China’s involvement in Arctic matters. Within this framework, Greenland may play a relevant role for China’s strategy: extremely rich of mineral and hydrocarbon resources, it represents not only an excellent spot to improve research activities, but also an ideal arrival point for the Polar Silk Road through the Transpolar Route, the only passage in the Arctic that does not include the navigation in territorial waters. With the Self-Rule Act (2009), the Greenlandic government assumed the responsibility to administrate justice, business, labor, aviation, border control as well as the control over natural resources. However, exploitation of uranium and rare earth elements remains a very sensitive topic because it would mark a radical change about the zero-tolerance policy previously imposed by the Danish government and because extremely linked to the independence discourse. This presentation aims to shed light on how China-Greenland cooperation finds its place within China’s Arctic Strategy by exploring the main points of this relationship and the relevant social and political issues related to it.
20:00 - 20:15 GMT: Entering A Pristine Ecosystem - The Effects Of Human Hunting Activities In Svalbard
Presenter: Franziska Paul & Henriette Müller-Hillebrand
Institution: Christian-Albrechts-Universität zu Kiel, Germany
Type: Oral presentation
Abstract: Supervised by Frigga Kruse we are working within the project “Timeless Arctic - Commercial Hunting in the Reconstruction of Human Impact in Svalbard”, a Freigeist Fellowship by the Volkswagen Stiftung. The Norwegian archipelago Svalbard lies in the polar arctic and constitutes a unique landscape, as it was remote from human influence until the 16th century. Since it was untouched before, it offers the opportunity to reconstruct populations of game animals and the ecosystem, as well as the impact humans had on its development.
Due to the lack of indigenous knowledge, population reconstruction is based solely on historical logbooks. Attempts of reconstruction for the pre-commercial hunting era and stock development over time have been attempted by predecessors but the implementation proved to be of high difficulty. We continue this research and focus on five mammals, which were most affected by commercial hunting and are representatives of their respective habitat: The Bowhead whale, the Atlantic walrus, the Polar bear, the Polar fox and the Svalbard reindeer.
Using modern statistical techniques supplemented by present knowledge on the species’ ecology, we validate the historical observation data in commercial hunting logbooks. In case of realisticity, the logbooks data becomes a valuable resource for filling knowledge gaps in species’ behaviour and ecology.
Since archaeozoology offers an interdisciplinary approach, we are using different methods and techniques such as archaeological fieldwork. The remaining bone assemblages at former slaughtering sites provide the quantification needed to judge the extent of human exploitation and is also giving an indication of the population size.
To complete our research approach and also give a direction for future research projects, we want to create a user-friendly database, to which access is open for other stakeholders and acts as an information system.