Description: Survival of larval Antarctic krill (Euphausia superba) during winter is largely dependent upon the presence of sea ice as it provides an important source of food and shelter. We hypothesized that sea ice provides additional benefits because it hosts fewer competitors and provides reduced predation risk for krill larvae than the water column. To test our hypothesis, zooplankton were sampled in the Weddell-Scotia Confluence Zone at the ice-water interface (0–2 m) and in the water column (0–500 m) during August–October 2013. Grazing by mesozooplankton, expressed as a percentage of the phytoplankton standing stock, was higher in the water column (1.97 ± 1.84%) than at the ice-water interface (0.08 ± 0.09%), due to a high abundance of pelagic copepods. Predation risk by carnivorous macrozooplankton, expressed as a percentage of the mesozooplankton standing stock, was significantly lower at the ice-water interface (0.83 ± 0.57%; main predators amphipods, siphonophores and ctenophores) than in the water column (4.72 ± 5.85%; main predators chaetognaths and medusae). These results emphasize the important role of sea ice as a suitable winter habitat for larval krill with fewer competitors and lower predation risk. These benefits should be taken into account when considering the response of Antarctic krill to projected declines in sea ice. Whether reduced sea-ice algal production may be compensated for by increased water column production remains unclear, but the shelter provided by sea ice would be significantly reduced or disappear, thus increasing the predation risk on krill larvae.

Description: Climate change is influencing some environmental variables in the Southern Ocean (SO) and this will have an effect on the marine biodiversity. Peracarid crustaceans are one of the dominant and most species-rich groups of the SO benthos. To date, our knowledge on the influence of environmental variables in shaping abundance and species composition in the SO’s peracarid assemblages is limited, and with regard to ice coverage it is unknown. The aim of our study was to assess the influence of sea ice coverage, chlorophyll-a, and phytoplankton concentrations on abundance, distribution and assemblage structure of peracarids. In addition, the influence of other physical parameters on peracarid abundance was assessed, including depth, temperature, salinity, sediment type, current velocity, oxygen, iron, nitrate, silicate and phosphate. Peracarids were sampled with an epibenthic sledge (EBS) in different areas of the Atlantic sector of the SO and in the Weddell Sea. Sampling areas were characterized by different regimes of ice coverage (the ice free South Orkney Islands, the seasonally ice-covered Filchner Trough and the Eastern Antarctic Peninsula including the Prince Gustav Channel which was formerly covered by a perennial ice shelf). In total 64766 individuals of peracarids were collected and identified to order level including five orders: Amphipoda, Cumacea, Isopoda, Mysidacea, and Tanaidacea. Amphipoda was the most abundant taxon, representing 32% of the overall abundances, followed by Cumacea (31%), Isopoda (29%), Mysidacea (4%), and Tanaidacea (4%). The Filchner Trough had the highest abundance of peracarids, while the South Orkney Islands showed the lowest abundance compared to other areas. Ice coverage was the main environmental driver shaping the abundance pattern and assemblage structure of peracarids and the latter were positively correlated with ice coverage and chlorophyll-a concentration. We propose that the positive correlation between sea ice and peracarid abundances is likely due to phytoplankton blooms triggered by seasonal sea ice melting, which might increase the food availability for benthos. Variations in ice coverage extent and seasonality due to climate change would strongly influence the abundance and assemblage structure of benthic peracarids.

Description: The occurrence of microplastics throughout marine environments worldwide, from pelagic to benthic habitats, has become serious cause for concern. Hadal zones were recently described as the “trash bins of the oceans” and ultimate sink for marine plastic debris. The Kuril region covers a substantial area of the North Pacific Ocean and is characterised by high biological productivity, intense marine traffic through the Kuril straits, and anthropogenic activity. Moreover, strong tidal currents and eddy activity, as well as the influence of Pacific currents, have the potential for long distance transport and retention of microplastics in this area. To verify the hypothesis that the underlying Kuril Kamchatka Trench might accumulate microplastics from the surrounding environments and act as the final sink for high quantities of microplastics, we analysed eight sediment samples collected in the Kuril Kamchatka Trench at a depth range of 5143–8250 m during the Kuril Kamchatka Biodiversity Studies II (KuramBio II) expedition in summer 2016. Microplastics were characterised via Micro Fourier Transform Infrared spectroscopy. All samples were analysed in their entirety to avoid inaccuracies due to extrapolations of microplastic concentrations and polymer diversities, which would otherwise be based on commonly applied representative aliquots. The number of microplastic particles detected ranged from 14 to 209 kg−1 sediment (dry weight) with a total of 15 different plastic polymers detected. Polypropylene accounted for the largest proportion (33.2%), followed by acrylates/polyurethane/varnish (19%) and oxidized polypropylene (17.4%). By comparing extrapolated sample aliquots with in toto results, it was shown that aliquot-based extrapolations lead to severe under- or overestimations of microplastic concentrations, and an underestimation of polymer diversity.

Description: A strong decline and thinning of the Arctic sea-ice cover over the past five decades has been documented. The former multiyear sea-ice system has largely changed to an annual system and with it the dynamics of sea-ice transport across the Arctic Ocean. Less sea ice is reaching the Fram Strait and more ice and ice-transported material is released in the northern Laptev Sea and the central Arctic Ocean. This trend is expected to have a decisive impact on ice associated (“sympagic”) communities. As sympagic fauna plays an important role in transmitting carbon from the ice-water interface to the pelagic and benthic food webs, it is important to monitor its community composition under the changing environmental conditions. We investigated the taxonomic composition, abundance and distribution of sea-ice meiofauna (here heterotrophs 〉10 μm; eight stations) and under-ice fauna (here metazoans 〉300 μm; fourteen stations) in Arctic 1.5 year-old pack ice north of Svalbard. Sampling was conducted during spring 2015 by sea-ice coring and trawling with a Surface and Under-Ice Trawl. We identified 42 taxa associated with the sea ice. The total abundance of sea-ice meiofauna ranged between 580 and 17,156 ind.m–2 and was dominated by Ciliophora (46%), Copepoda nauplii (29%), and Harpacticoida (20%). In contrast to earlier studies in this region, we found no Nematoda and few flatworms in our sea-ice samples. Under-ice fauna abundance ranged between 15 and 6,785 ind.m–2 and was dominated by Appendicularia (58%), caused by exceptionally high abundance at one station. Copepoda nauplii (23%), Calanus finmarchicus (9%), and Calanus glacialis (6%) were also very abundant while sympagic Amphipoda were comparatively rare (0.35%). Both sympagic communities showed regional differences in community composition and abundance between shelf and offshore stations, but only for the under-ice fauna those differences were statistically significant. Selected environmental variables moderately explained variations in abundances of both faunas. The results of this study are consistent with predictions of diversity shifts in the new Arctic.

Description: Germany’s national ocean observing activities are carried out by multiple actors including governmental bodies, research institutions, and universities, and miss central coordination and governance. A particular strategic approach to coordinate and facilitate ocean research has formed in Germany under the umbrella of the German Marine Research Consortium (KDM). KDM aims at bringing together the marine science expertise of its member institutions and collectively presents them to policy makers, research funding organizations, and to the general public. Within KDM, several strategic groups (SGs), composed of national experts, have been established in order to strengthen different scientific and technological aspects of German Marine Research. Here we present the SG for sustained open ocean observing and the SG for sustained coastal observing. The coordination effort of the SG’s include (1) Representing German efforts in ocean observations, providing information about past, ongoing and planned activities and forwarding meta-information to data centers (e.g., JCOMMOPS), (2) Facilitating the integration of national observations into European and international observing programs (e.g. GCOS, GOOS, BluePlanet, GEOSS), (3) Supporting innovation in observing techniques and the development of scientific topics on observing strategies, (4) Developing strategies to expand and optimize national observing systems in consideration of the needs of stakeholders and conventions, (5) Contributing to agenda processes and roadmaps in science strategy and funding, and (6) Compiling recommendations for improved data collection and data handling, to better connect to the global data centers adhering to quality standards.

Description: Crustaceans are an important component in the diet of numerous predators of the Southern Ocean (water masses located south of the Subtropical Front). As identifying crustaceans from food samples using conventional methods is not easy, a crustacean guide was written to aid scientists working on trophic relationships within the Southern Ocean. Having the needs of the scientists in mind, we gathered information from 〉 100 species from 53 families of the most relevant crustaceans in the diet of subantarctic and Antarctic meso- and top predators, including information on distribution, their relevance in predator diets, sizes, availability of allometric equations and practical procedures to differentiate crustacean species within each family. Additional information of bibliography is added if families possess more that the species mentioned in this book. It is noted that a large number of species still has no allometric equations and some species have to clarify their status (one or various species). The book was produced within the international effort under the Scientific Committee on Antarctic Research (SCAR) programs, expert and action groups, namely SCAR AnT-ERA, SCAR AnT-ECO, SCAR EGBAMM and ICED.