Community structure of macrofauna in the deep Fram Strait: A comparison between two bathymetric gradients in ice-covered and ice-free areas

This study compares the macrofaunal communities along two bathymetric transects (1000 – 2500 m water depth) in predominantly ice-covered western (offshore Greenland) and generally ice-free eastern (offshore Svalbard) regions of the Fram Strait. Material was collected using an USNEL 0.25 m2 box corer and all sediment samples were processed through a 500-μm sieve. A total of 1671 organisms from 169 species were found. Densities off Greenland were generally lower than those observed off Svalbard. On both sides of the Fram Strait, density, biomass and biodiversity generally decreased with increasing water depth. An exception was observed at the deepest station off Greenland (2500 m water depth), which was located within the Marginal Ice Zone. At this station, macrofaunal density was elevated (992 ± 281 ind. m−2) compared to the adjacent shallower sampling areas off Greenland (272 ± 208 ind. m−2 to 787 ± 172 ind. m−2) and the deeper stations (2000 and 2500 m water depth) off Svalbard (552 ± 155 ind. m−2 and 756 ± 182 ind. m−2). The most abundant species along both transects was the polychaete Galathowenia fragilis (off Greenland: 288 ind. m−2, off Svalbard: 740 ind. m−2). Sea ice coverage and water depth, as well as the associated food availability at the seafloor, seem to be crucial factors driving the macrofaunal community patterns. A strong pelago-benthic coupling is observed to be typical in Arctic deep-sea ecosystems, and is also confirmed by our study

"Wissenschaft fürs Wohnzimmer" – two years of interactive, scientific livestreams weekly on YouTube

Science communication is becoming increasingly important to connect academia and society, and to counteract fake news among climate change deniers. Online video platforms, such as YouTube, offer great potential for low-threshold communication of scientific knowledge to the general public. In April 2020 a diverse group of researchers from the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research launched the YouTube channel "Wissenschaft fürs Wohnzimmer" (translated to "Sitting Room Science") to stream scientific talks about climate change and biodiversity every Thursday evening. Here we report on the numbers and diversity of content, viewers, and presenters from 2 years and 100 episodes of weekly livestreams. Presented topics encompass all areas of polar research, social issues related to climate change, and new technologies to deal with the changing world and climate ahead. We show that constant engagement by a group of co-hosts, and presenters from all topics, career stages, and genders enable a continuous growth of views and subscriptions, i.e. impact. After 783 days the channel gained 30,251 views and 828 subscribers and hosted well-known scientists while enabling especially early career researchers to improve their outreach and media skills. We show that interactive and science-related videos, both live and on-demand, within a pleasant atmosphere, can be produced voluntarily while maintaining high quality. We further discuss challenges and possible improvements for the future. Our experiences may help other researchers to conduct meaningful scientific outreach and to push borders of existing formats with the overall aim of developing a better understanding of climate change and our planet

LTER HAUSGARTEN 2018 - Long-Term Ecological Research in the Fram Strait, Cruise No. MSM77, September 15 - October 13, 2018, Longyearbyen (Svalbard) - Edinburgh (Scotland)

The 77th cruise of the RV MARIA S. MERIAN contributed to various large national and international research and infrastructure projects (FRAM, ARCHES, INTAROS, ICOS, SIOS) as well as to the research programme PACES-II (Polar Regions and Coasts in the changing Earth System) of the Alfred-Wegener-Institute Helmholtz-Center for Polar and Marine Research (AWI). Investigations within Work Package 4 (Arctic sea ice and its interaction with ocean and ecosystems) of the PACES-II programme, aim at assessing and quantifying ecosystem changes from surface waters to the deep ocean in response to the retreating sea ice, and at exploring the most important (feedback) processes determining temporal and spatial variability. Contributions to the PACES-II Work Package 6 (Large scale variability and change in polar benthic biota and ecosystem functions) include the identification of spatial patterns and temporal trends in relevant benthic community functions, and the development of a comprehensive science community reference collection of observational data. Work carried out within WPs 4 and 6 will support the time-series studies at the LTER (Long-Term Ecological Research) observatory HAUSGARTEN (Fig. 1.1), where we document Global Change induced environmental variations on a polar deep-water ecosystem. This work is carried out in close co-operation between the HGF-MPG Joint Research Group on Deep-Sea Ecology and Technology and the PEBCAO Group (Phytoplankton Ecology and Biogeochemistry in the Changing Arctic Ocean) at AWI as well as the working group Microbial Geochemistry at the GEOMAR and the HGF Young Investigators Group SEAPUMP (Seasonal and regional food web interactions with the biological pump)

Welcome to the dark side – Die Tiefsee im Wandel

Unterhalb des lichtdurchfluteten Teil des Meers beginnt sie – die Tiefsee. Nicht nur die Dunkelheit, sondern auch der hohe Druck und ein geringes Nahrungsangebot lassen diesen Ort als lebensfeindlich erscheinen. Doch die Tiefsee ist nicht nur Lebensraum für faszinierende Geschöpfe wie Vampirtintenfische, Asselspinnen oder Schlangensterne. Sie ist auch an zentralen Prozessen wie Nährstoffkreisläufen und Kohlenstoffspeicherung beteiligt. Umweltveränderungen aufgrund des Klimawandels können in der Tiefsee z.B. zu Veränderungen in der Artenvielfalt und den Nährstoffkreisläufen führen. Mit Blick auf die arktischen Tiefseeregionen ist hier die Framstraße zwischen Grönland und Spitzbergen von besonderer Bedeutung. Sie ist die einzige tiefe Wasserstraße zwischen dem nördlichen Atlantik und dem zentralen Arktischen Ozean, wodurch ein Austausch von großen Wassermassen gewährleistet wird. Um die Auswirkungen des Klimawandels in der Framstraße besser zu erforschen, hat das Alfred-Wegner-Institut für Polar- und Meeresforschung (AWI) vor 20 Jahren das HAUSGARTEN Observatorium errichtet. Dauerhaft installierte Messstationen sowie jährliche Untersuchungen vor Ort liefern unerlässliche Daten über Veränderungen durch den Klimawandel – von der Meeresoberfläche bis hin zum Tiefseeboden. Am Beispiel der Framstraße beleuchte ich in diesem Vortrag, welche Folgen der Klimawandel für die arktische Tiefsee hat und warum diese auch direkt den Menschen betreffen

Was wühlt denn da? Der arktische Tiefseeboden unter der Lupe

Unterhalb des lichtdurchfluteten Teils des Meeres beginnt sie – die Tiefsee. Nicht nur Dunkelheit, sondern auch hoher Druck und ein geringes Nahrungsangebot lassen die Tiefsee wie einen lebensfeindlichen Ort erscheinen. Doch manch einer fühlt sich hier besonders wohl. Welche Tiere findet man auf dem arktischen Tiefseeboden und was machen die da eigentlich? Melissa Käß vom Alfred-Wegener-Institut für Polar- und Meeresforschung (AWI) bringt heute Licht ins Dunkel

Community structure of macrobenthos along two bathymetrical transects off Svalbard and on the Eastern Greenland continental margin – A comparative study at the LTER (Long-Term Ecological Research) observatory HAUSGARTEN

The eastern side of the Fram Strait is significantly influenced by the northern-bound warm West Spitsbergen Current (WSC) whereas the western side is affected by the cold and less saline East Greenland Current (EGC) flowing in a southerly direction. These current regimes are major factors in regulating the ice coverage in the Fram strait. In turn, this coverage plays an important role in determining the flux of food to the seafloor. The objective of this study is to compare the macrofaunal community structure along two bathymetrical transects (1000 to 2500 m) at the LTER (Long-Term Ecology Research) observatory HAUSGARTEN; one transect in the eastern Fram Strait and a second in the western region of the strait. Material was collected during RV Polarstern expedition PS99.2 in June/July 2016 using an USNEL box corer with a sampling area of 0.25 m². Samples were processed through a 500 μm mesh size sieve. Results showed a higher macrofaunal density at the stations located in the eastern Fram Strait. Species richness, biomass and biodiversity showed a trend to decrease with increase in depth on both sides of the strait. An exception was observed at one station at 2500 m depth off Greenland, which was located in the marginal ice zone. Densities and species diversity were higher at this station than at the adjacent shallower sampling locations. Polychaetes were the generally most abundant taxon, followed by crustaceans and molluscs. Species composition along the two bathymetrical transects on both sides of the strait clearly changed with increasing depth. Sea ice coverage and depth, with the associated variabilities in food quality and quantity reaching the seafloor seemed to be crucial factors driving community patterns

Welcome to the dark side - Die Tiefsee im Wandel

Unterhalb des lichtdurchfluteten Teils des Meeres beginnt sie – die Tiefsee. Nicht nur Dunkelheit, sondern auch hoher Druck und ein geringes Nahrungsangebot lassen die Tiefsee wie einen lebensfeindlichen Ort erscheinen. Vielmehr bildet sie aber ein einzigartiges und artenreiches globales Ökosystem. Doch die Tiefsee ist nicht nur Lebensraum für faszinierende Geschöpfe wie Vampirtintenfische, Asselspinnen oder Schlangensterne. Sie ist auch an zentralen Funktionen wie Nährstoffkreisläufen und Kohlenstoffspeicherung beteiligt. Umweltveränderungen aufgrund des Klimawandels können in der Tiefsee beispielsweise zu Veränderungen in der Artenvielfalt und den Nährstoffkreisläufen führen. Trotz ihrer großen Bedeutung und drohender Umweltveränderungen, insbesondere in den Polarregionen, ist die Tiefsee noch wenig erforscht. Mit Blick auf die arktischen Tiefseeregionen kann die Framstraße zwischen Grönland und Spitzbergen als Schlüsselregion betrachtet werden. Sie ist die einzige tiefe Wasserstraße zwischen dem nördlichen Atlantik und dem zentralen Arktischen Ozean, wodurch ein Austausch von großen Wassermassen gewährleistet wird. Um die Auswirkungen des Klimawandels in der Framstraße besser zu erforschen, hat das Alfred-Wegner-Institut für Polar- und Meeresforschung (AWI) vor 20 Jahren das HAUSGARTEN Observatorium errichtet. Dauerhaft installierte Messstationen sowie jährliche Untersuchungen vor Ort liefern unerlässliche Daten über Veränderungen durch den Klimawandel - von der Meeresoberfläche bis hin zum Tiefseeboden. Welche Folgen der Klimawandel für die arktische Tiefsee hat und warum diese auch direkt den Menschen betreffen, wird in diesem Vortrag am Beispiel der Framstraße mit Fokus auf biologische Prozesse beleuchtet

Community structure of macrobenthos along bathymetrical transects off Svalbard and Eastern Greenland - A comparative study at the deep-sea observatory HAUSGARTEN

The Fram Strait is one of the most important gateways between the Arctic Ocean and its connected water bodies as it is the deepest passage and therefore provides exchanges of deep waters. The part of the eastern Fram Strait is significantly influenced by the northern-bound warm West Spitsbergen Current (WSC) whereas the western part is influenced by the cold and less saline East Greenland Current (EGC) flowing southerly direction. Sea ice from the Arctic Ocean is passing the Fram Strait on its southward flow. Sea ice loss is affecting the entire marine ecosystem as vertical energy fluxes are coupled even to the deep sea. The objective of this study is to investigate whether there are dissimilarities in deep-sea benthic macrofaunal communities such as species composition and diversity in eastern and western parts of the Fram Strait due to different energy input to the benthic communities. Sampling sites along the bathymetric transect of the LTER (Long-Term Ecology Research) observatory HAUSGARTEN off western Svalbard and the macrofauna sampling methodology were chosen following previous studies, while the East Greenland slope has been sampled for the first time at this location. Samples were taken during RV Polarstern expedition PS99.2 in June/July 2016 using an UNSEL box corer with a sampling area of 0.25 m² at water depths of 1000 - 5500 m (Vestnesa Ridge) and 1000 - 2500 m (East Greenland slope). Samples were washed through a 500 μm mesh size sieve and fixed in ethanol 96 %. Macrobenthic organisms were identified to the lowest possible taxonomical level in the laboratory after the expedition. Recent results suggest a trend that stations located on the East Greenland slope are lower in species richness (total number of species) but higher in diversity of taxa than stations on the Vestnesa Ridge. Polychaeta are the dominant taxa at both bathymetrical transects but in noticeably varying proportions. Oweniidae and Cirratulidae show among other families highest abundance at both transects. The differences in macrofauna community structure in the western and eastern Fram Strait might be a result of differences in food availability. Sea ice coverage as well as regions of contrasting primary production could be crucial factors driving community patterns

Ecological function of macrobenthic communities, Arctic

Macrobenthos plays an important role in ecosystem processes such as bioturbation, particle reworking and ventilation of the soil. Nevertheless, explaining the relationship between biodiversity and ecosystem function (BEF) remains a difficult task. This holds also true in remote polar regions such as the LTER observatory HAUSGARTEN in the Fram Strait. The local hydrographic regime is mainly influenced by the warm northern-bound West Spitsbergen Current, and the southwards flowing cold and less saline East Greenland Current. The currents are causing regional differences in sea-ice coverage. Distribution patterns of the sea-ice play a major role in determining the flux of potential food to the seafloor, thus shaping benthic communities. Recently, functional and biological trait analysis (BTA) became an important tool to investigate BEF-relationships in marine environments. However, this approach is relatively new for Arctic regions, especially deep-sea ecosystems. Therefore, our study aims to determine functional characteristics on a depth gradient in the deep Fram Strait. Deep-sea samples (1000 – 5500m) were collected in the Arctic autumn of 2018 on board of RV Maria S. Merian. An USNEL box corer (0.25m²) was deployed at nine sites along the bathymetric transect of the LTER observatory HAUSGARTEN offshore Svalbard. All material was treated trough a 0.5-mm sieve and fixed in 4% formalin. The specimens were identified to species level wherever possible and after assigning to modalities of selected traits used for BTA to observe functional changes along the depth gradient. Preliminary results on community structure and resulting functional differences between the benthic communities will be presente