Description: PREFACE : The Laptev Sea System The Arctic Ocean, in particular the wide Eurasian shelf seas comprise some of the most sensitive elements of the global environment which are believed to respond at a very early time to Global Change. The renewed interest in the Arctic, the large scale international research efforts devoted to the Arctic, as well as the presently available new technology to carry out research in ice-infested areas, have opened many new avenues to conduct investigations On the variability of the depositional environments of the Eurasian shelf seas. The Laptev Sea is of particular importance in the string of the Eurasian shelf seas because feeding the Transpolar Drift of the Arctic sea-ice Cover it exports relatively the largest amounts of sea ice into the Open Arctic Ocean, because it is farthest away from the influence of the Atlantic and Pacific waters, and because it is under the influence of rapidly changing fresh water fluxes from the Siberian hinterland (Fig. 1, Sea ice drift paths in the Arctic Ocean). The morphology of the seafloor, the rapidly changing coast lines of the fragil Lena Delta Island frame work as well as the presence of submarine permafrost are examples for the dynamics of the entire Laptev Sea System. - Fig. 1 - In order to address the natural properties of the Laptev Sea System a joint research project is carried out between a number of Russian and German research institutions under the framework of the "Laptev Sea System Project" (Fig. 2, Research institutions under the framework of the "Laptev Sea System Project"). Every year expeditions are carried out in the area on Russian or German research vessels where multi-disciplinary and binational working groups are addressing some of the identified scientific themes. Results from these joint investigations are then discussed in a series of RussianIGerman workshops which are held alternatively in Russia or Germany. The second workshop 'Russian-German Cooperation: Laptev Sea System' was held in November 1994 in St. Petersburg in order to assess (1) the state of knowledge of the Laptev Sea and the adjacent continental margin of the deep Arctic, and (2) to develop a research strategy for the marine geosciences in the Laptev Sea and terrestrial werk in East Siberia. The workshop brought together more than 100 scientists, among them meteorologists, sea ice physicists, oceanographers, biologists, chemists, geologists and geophysicists from various Russian and German research institutions. The main goal of the workshop was to promote and coordinate scientific collaboration among scientists from Russia and Germany. Main emphasis have laid on first scientific results of the expeditions within the scope of the interdisciplinary Russian-German research project 'Laptev Sea System', that is present and past oceanography, ecology, and climatology of the Laptev Sea. The workshop was organized into serveral sessions which followed various themes of the environment of the Laptev Sea from their present situation to their geological record: (I) Ciimate and Ice (11) Modern Environment of the Laptev Sea (111) Environmental History of the Laptev Sea (IV) From Siberia to the Arctic Ocean: Land-Sea Connection (V) Strategy and Plans for Future Work (VI) Mid-long Term Perspectives The scientific content of this workshop is documented in this report containing most of the results and discussions. The publication of this volume serves various purposes. It is primarily a forum for scientists working in the Siberian shelf seas, in which the results of many years of research and preliminary shipboard results can be presented. In order to provide all the participants in the workshop with the opportunity for reporting their results, a speedy way of publication was chosen. Thus, each individual author has presented his opinions and views as he or she sees them, reflecting the diversity and complexity of the Laptev Sea system. On the other hand, this volume offers many researchers the possibility of acquainting themselves with methods and results of research into the East Siberian seas as carried out in other parts of the world. Finally, it is hoped that this collection of papers will function as another step toward joint research projects and are base for the expeditions to be carried out in 1995 and the following years. Many of the papers published identify major scientific problems, thus offering new perspectives for future scientific research in polar regions. The nature of the papers, the discussions and the disciplines of the attendees clearly demonstrate that the study of the Laptev Sea System is a multidisciplinary one in an interesting key area involving all branches of the natural sciences, such as ice physics, oceanography, biology and geology, in particular. It thus remains an important example for GLOBAL CHANGE and CLIMATE IMPACT research within international research efforts, e.g. International Arctic Science Committee (IASC), Arctic Ocean Sciences Board (AOSB) or the Nansen Arctic Drilling Programme (NAD). - Fig. 2 - The editors also made an effort, probably not wholly successful, to edit manuscripts by non-English-speaking authors to make them easier to understand. In this process, we hope we have not changed the meanings of the original papers. Above all we thank Bettina Rohr and Daniel Krüger who kindly assisted in editing the papers. The workshop has been sponsored by the German and Russian Ministries for Research and Technology and the meeting was held from the 21st to the 14th of November in 1994 in the Arctic and Antarctic Research Institute in St. Petersburg. We wish to thank these organizations for their financial and logistic support.

Description: In times of accelerating climate change, species are challenged to respond to rapidly shifting environmental settings. Yet, faunal distribution and composition are still scarcely known for remote and little explored seas, where observations are limited in number and mostly refer to local scales. Here, we present the first comprehensive study on Eurasian-Arctic macrobenthos that aims to unravel the relative influence of distinct spatial scales and environmental factors in determining their large-scale distribution and composition patterns. To consider the spatial structure of benthic distribution patterns in response to environmental forcing, we applied Moran’s eigenvector mapping (MEM) on a large dataset of 341 samples from the Barents, Kara and Laptev Seas taken between 1991 and 2014, with a total of 403 macrobenthic taxa (species or genera) that were present in ≥ 10 samples. MEM analysis revealed three spatial scales describing patterns within or beyond single seas (broad: ≥ 400 km, meso: 100–400 km, and small: ≤ 100 km). Each scale is associated with a characteristic benthic fauna and environmental drivers (broad: apparent oxygen utilization and phosphate, meso: distance-to-shoreline and temperature, small: organic carbon flux and distance-to-shoreline). Our results suggest that different environmental factors determine the variation of Eurasian-Arctic benthic community composition within the spatial scales considered and highlight the importance of considering the diverse spatial structure of species communities in marine ecosystems. This multiple-scale approach facilitates an enhanced understanding of the impact of climate-driven environmental changes that is necessary for developing appropriate management strategies for the conservation and sustainable utilization of Arctic marine systems.

Description: Ecological forecasts predict the immigration of boreal species into Arctic waters as one consequence of rising sea temperatures. Here, we report the finding of Atlantic snake pipefish (Entelurus aequoreus) off the western coast of Spitsbergen at 79°N in August 2006. This syngnathid fish species, which was presumed to be confined to waters south of Iceland, has dramatically increased in population size in its core distribution area in the northeastern Atlantic since 2002, probably in response to greater reproduction success due to higher water temperatures. We conclude that our finding is an indication of the predicted northward extension of the distribution range of boreal species.

Description: Our knowledge on distribution, habitats and behavior of Southern Ocean fishes living at water depths beyond scuba-diving limits is still sparse, as it is difficult to obtain quantitative data on these aspects of their biology. Here, we report the results of an analysis of seabed images to investigate species composition, behavior, spatial distribution and preferred habitats of demersal fish assemblages in the southern Weddell Sea. Our study was based on a total of 2736 high-resolution images, covering a total seabed area of 11,317 m2, which were taken at 13 stations at water depths between 200 and 750 m. Fish were found in 380 images. A total of 379 notothenioid specimens were recorded, representing four families (Nototheniidae, Artedidraconidae, Bathydraconidae, Channichthyidae), 17 genera and 25 species. Nototheniidae was the most speciose fam- ily, including benthic species (Trematomus spp.) and the pelagic species Pleuragramma antarctica, which was occasionally recorded in dense shoals. Bathydraconids ranked second with six species, followed by artedidraconids and channichthyids, both with five species. Most abundant species were Trematomus scotti and T. lepidorhinus among nototheniids, and Dol- loidraco longedorsalis and Pagetopsis maculatus among artedidraconids and channichthyids, respectively. Both T. lepi- dorhinus and P. maculatus preferred seabed habitats characterized by biogenous debris and rich epibenthic fauna, whereas T. scotti and D. longedorsalis were frequently seen resting on fine sediments and scattered gravel. Several fish species were recorded to make use of the three-dimensional structure formed by epibenthic foundation species, like sponges, for perching or hiding inside. Nesting behavior was observed, frequently in association with dropstones, in species from various families, including Channichthyidae (Chaenodraco wilsoni and Pagetopsis macropterus) and Bathydraconidae (Cygnodraco mawsoni).

Description: Ascidians (Ascidiacea: Tunicata) are sessile suspension feeders that represent dominant epifaunal components of the Southern Ocean shelf benthos and play a significant role in the pelagic–benthic coupling. Here, we report the results of a first study on the relationship between the distribution patterns of eight common and/or abundant (putative) ascidian species, and environmental drivers in the waters off the northern Antarctic Peninsula. During RV Polarstern cruise XXIX/3 (PS81) in January–March 2013, we used seabed imaging surveys along 28 photographic transects of 2 km length each at water depths from 70 to 770 m in three regions (northwestern Weddell Sea, southern Bransfield Strait and southern Drake Passage), differing in their general environmental setting, primarily oceanographic characteristics and sea-ice dynamics, to comparatively analyze the spatial patterns in the abundance of the selected ascidians, reliably to be identified in the photographs, at three nested spatial scales. At a regional (100-km) scale, the ascidian assemblages of the Weddell Sea differed significantly from those of the other two regions, whereas at an intermediate 10-km scale no such differences were detected among habitat types (bank, upper slope, slope, deep/canyon) on the shelf and at the shelf break within each region. These spatial patterns were superimposed by a marked small-scale (10-m) patchiness of ascidian distribution within the 2-km-long transects. Among the environmental variables considered in our study, a combination of water-mass characteristics, sea-ice dynamics (approximated by 5-year averages in sea-ice cover in the region of or surrounding the photographic stations), as well as the seabed ruggedness, was identified as explaining best the distribution patterns of the ascidians.

Description: Seasonal dynamics in the activity of Arctic shelf benthos have been the subject of few local studies, and the pronounced among-site variability characterizing their results makes it difficult to upscale and generalize their conclusions. In a regional study encompassing five sites at 100–595 m water depth in the southeastern Beau- fort Sea, we found that total pigment concentrations in surficial sediments, used as proxies of general food supply to the benthos, rose significantly after the transition from ice-covered conditions in spring (March–June 2008) to open-water conditions in summer (June–August 2008), whereas sediment Chl a concentrations, typical markers of fresh food input, did not. Macrobenthic biomass (including agglutinated foraminifera [500 lm) varied significantly among sites (1.2–6.4 g C m-2 in spring, 1.1–12.6 g C m-2 in summer), whereas a general spring-to-summer increase was not detected. Benthic carbon remineralisation also ranged significantly among sites (11.9–33.2 mg C m-2 day-1 in spring, 11.6–44.4 mg C m-2 day-1 in summer) and did in addition exhibit a general significant increase from spring-to-summer. Multiple regression analysis suggests that in both spring and summer, sediment Chl a concentration is the prime determinant of benthic carbon remineralisation, but other factors have a significant secondary influence, such as foraminiferan biomass (negative in both seasons), water depth (in spring) and infaunal biomass (in summer). Our findings indicate the importance of the combined and dynamic effects of food supply and benthic community patterns on the carbon remineralisation of the polar shelf benthos in seasonally ice-covered seas.

Description: Benthic communities north of Svalbard are less investigated than in other Arctic shelf regions, as this area was covered by sea-ice during most of the year. Improving our knowledge on this region is timely, however, since climate change is strongly evident there, particularly with regard to the extent of sea-ice decline and its huge eco- logical impact on all marine biota, including the benthos. Moreover, longer ice-free periods will certainly lead to an increase in human activity levels in the area, including bottom trawling. In two adjacent shelf and slope regions off northern Svalbard, we studied the composition of epibenthic megafauna and seafloor habitat structures by analyzing seabed images taken with both still and video cameras. In addition, we also used an Agassiz trawl to catch epibenthic organisms for ground-truthing seabed- image information. A wide variety of mostly sessile organisms 141 epibenthic taxa were identified in the ima- ges. The brittle star Ophiura sarsii and the soft coral Gersemia rubiformis were the most common species. At all stations [300 m in depth, evidence of trawling activities was detected at the seabed. The distribution of the benthic fauna in the study area exhibited a clear depth zonation, mainly reflecting depth-related differences in seabed composition. We conclude that natural factors determining the composition of the seafloor mostly affect the distribu- tion and composition of epibenthic assemblages. Anthro- pogenic impact indicated by the trawl scours found is likely also important at smaller spatial scales.