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The European research vessel fleet plays a vital role in supporting scientific research and development not just in Europe but also across the globe. This document explores how the fleet has developed since the publication of the European Marine Board Position Paper 10 (EMB PP 10) "European Ocean Research Fleets – Towards a Common Strategy and Enhanced Use" (Binot et al., 2007). It looks at the current fleet and its equipment and capabilities (Chapter 2), the deep sea (Chapter 3) and Polar regions (Chapter 4) as study areas of ever- increasing importance for science and for the vessels that explore them, the role that research vessels play in the wider ocean observing landscape (Chapter 5), the importance of training personnel for research vessels (Chapter 6), and considers management of the European research vessel fleet (Chapter 7). This Position Paper considers what has changed since 2007, what the status is in 2019, and future directions for the European fleet, with a 10-year horizon to 2030. This Position Paper finds that the current European research vessel fleet is highly capable, and is able to provide excellent support to European marine science and wider scientific research and can lead on the world stage. However, with a typical life expectancy of a research vessel of 30 years, the fleet is ageing and urgently requires further investment and reinvestment to continue to be as efficient and capable as the scientific community expects and requires. The capabilities of the fleet have increased considerably since 2007, and vessels have kept up with fast-paced technological developments. The demand for complex and highly capable vessels will continue, and research vessel designs and the fleet as a whole will need to keep pace in order to remain fit-for-purpose and continue to be a key player globally. There is huge diversity in vessel types and designs in terms of capabilities and equipment, management structures and processes, and training possibilities. While it would not be possible or appropriate to highlight any one approach as the only one to use, a growing trend in collaboration through community groups, agreements, legal entities and funded projects now enables more strategic thinking in the development of these vital infrastructures. However, some issues remain in enabling equal access to research vessel time for all researchers across Europe regardless of country, and regardless of whether or not that country owns a suitable research vessel for their scientific needs.

Measuring temperature and salinity profiles in the world's oceans is crucial to understanding ocean dynamics and its influence on the heat budget, the water cycle, the marine environment and on our climate. Since 1983 the German research vessel and icebreaker Polarstern has been the platform of numerous CTD (conductivity, temperature, depth instrument) deployments in the Arctic and the Antarctic. We report on a unique data collection spanning 33 years of polar CTD data. In total 131 data sets (1 data set per cruise leg) containing data from 10 063 CTD casts are now freely available at doi:10.1594/PANGAEA.860066. During this long period five CTD types with different characteristics and accuracies have been used. Therefore the instruments and processing procedures (sensor calibration, data validation, etc.) are described in detail. This compilation is special not only with regard to the quantity but also the quality of the data – the latter indicated for each data set using defined quality codes. The complete data collection includes a number of repeated sections for which the quality code can be used to investigate and evaluate long-term changes. Beginning with 2010, the salinity measurements presented here are of the highest quality possible in this field owing to the introduction of the OPTIMARE Precision Salinometer.

Measuring temperature and salinity profiles in the world's oceans is crucial to understand ocean dynamics and its influence on the heat budget, the water cycle, the marine environment and on our climate. Since 1983 the German research vessel and icebreaker POLARSTERN has been the platform of numerous CTD deployments in the Arctic and the Antarctic. We report on a unique data collection spanning 33 years of polar CTD (conductivity, temperature, depth) data. In total 131 datasets (one dataset per cruise leg) containing data from 10063 CTD casts are now freely available at doi:10.1594/PANGAEA.860066. During this long period five CTD types with different characteristics and accuracies have been used. Therefore the instruments and processing procedures (sensor calibration, data validation etc.) are described in detail. This compilation is special not only with regard to the quantity, but also the quality of the data – the latter one being indicated for each dataset using defined quality codes. The complete data collection includes a number of repeated sections for which the quality code can be used to investigate and evaluate long-term changes. Beginning with 2010, the salinity measurements presented here are of the highest quality possible in this field owing to the introduction of the Optimare Precision Salinometer.

Pelagic zooplankton were monitored from 2000 to 2012 at a permanent location near the Svalbard archipelago, at the boundary between the central Arctic Ocean and the Greenland Sea in the eastern Fram Strait. The temporal results reveal the first evidence of successful reproduc- tion in Arctic waters by an Atlantic pelagic crustacean from temperate waters. The Atlantic hyperid amphipod Themisto compressa is shown to have expanded its range from more southerly and warmer waters from 2004 onwards. Successful reproductive activity by T. compressa in Arctic waters was confirmed in 2011, indicated by the presence of a complete temporal series of develop- mental stages including ovigerous females and recently hatched juveniles. The Arctic amphipod community is currently in transition and a continuing northward spread of southern invaders could cause a biodiversity shift from large Arctic to smaller Atlantic species.

Life-cycle characteristics of the free-swimming lysianassoid amphipod Cyclocaris guilelmi were investigated and compared to those of other regularly appearing amphipods in the Arctic deep-sea community. In this context we analysed time-series data of meso- and bathypelagic amphipods collected as swimmers in moored sediment traps from 2004-2008 at the deep-sea long-term observatory HAUSGARTEN (79°N/4°E) in the eastern Fram Strait, Arctic Ocean. Six mesopelagic and three bathypelagic deep-sea amphipod species regularly occurred in the traps. The lysianassoid C. guilelmi showed a stable interannual population size and seasonal peaks in its occurrence from August to February during the five-year sampling period. The investigation of its population structure and reproduction ecology indicated year-round breeding behavior of this species. Up to 4 cohorts consisting mainly of juvenile and female C. guilelmi were observed. We conclude that C guilelmi plays an important role within the Arctic amphipod deep water community.

Although recent research has shown that marine litter has made it even to the remotest parts of our planet, little information is available about temporal trends on the deep ocean floor. To quantify litter on the deep seafloor over time, we analysed images from the HAUSGARTEN observatory (79N) taken in 2002, 2004, 2007, 2008 and 2011 (2500 m depth). Our results indicate that litter increased from 3635 to 7710 items km 2 between 2002 and 2011 and reached densities similar to those reported from a canyon near the Portuguese capital Lisboa. Plastic constituted the majority of litter (59%) followed by a black fabric (11%) and cardboard/paper (7%). Sixty-seven percent of the litter was entangled or colonised by invertebrates such as sponges (41%) or sea anemones (15%). The changes in litter could be an indirect consequence of the receding sea ice, which opens the Arctic Ocean to the impacts of man’s activities. 2012 Elsevier Ltd. All rights reserved.

Time-series studies of arctic marine ecosystems are rare. This is not surprising since polar regions are largely only accessible by means of expensive modern infrastructure and instrumentation. In 1999, the Alfred Wegener Institute, Helmholtz-Centre for Polar and Marine Research (AWI) established the LTER (Long-Term Ecological Research) observatory HAUSGARTEN crossing the Fram Strait at about 79° N. Multidisciplinary investigations covering all parts of the open-ocean ecosystem are carried out at a total of 21 permanent sampling sites in water depths ranging between 250 and 5500 m. From the outset, repeated sampling in the water column and at the deep seafloor during regular expeditions in summer months was complemented by continuous year-round sampling and sensing using autonomous instruments in anchored devices (i.e., moorings and free-falling systems). The central HAUSGARTEN station at 2500 m water depth in the eastern Fram Strait serves as an experimental area for unique biological in situ experiments at the seafloor, simulating various scenarios in changing environmental settings. Long-term ecological research at the HAUSGARTEN observatory revealed a number of interesting temporal trends in numerous biological variables from the pelagic system to the deep seafloor. Contrary to common intuition, the entire ecosystem responded exceptionally fast to environmental changes in the upper water column. Major variations were associated with a Warm-Water-Anomaly evident in surface waters in eastern parts of the Fram Strait between 2005 and 2008. However, even after 15 years of intense time-series work at HAUSGARTEN, we cannot yet predict with complete certainty whether these trends indicate lasting alterations due to anthropologically-induced global environmental changes of the system, or whether they reflect natural variability on multiyear time-scales, for example, in relation to decadal oscillatory atmospheric processes.

Commercial exploitation and abrupt changes of the natural conditions may have severe impacts on the Arctic deep-sea ecosystem. The present recolonisation experiment mimicked a situation after a catastrophic disturbance (e.g. by turbidites caused by destabilised continental slopes after methane hydrate decomposition) and investigated whether the recolonisation of a deep-sea habitat by meiobenthic organisms is fostered by variations in nutrition and/or sediment structure. Two “Sediment Tray Free Vehicles” were deployed for 1 year in summer 2003 at 2,500 m water depth in the Arctic deep-sea in the eastern Fram Strait. The recolonisation trays were filled with different artificial and natural sediment types (glass beads, sand, sediment mixture, pure deep-sea sediment) and were enriched with various types of food (algae, yeast, fish). After 1 year, meiobenthos abundances and various sediment-related environmental parameters were investigated. Foraminifera were generally the most successful group: they dominated all treatments and accounted for about 87 % of the total meiobenthos. Colonising meiobenthos specimens were generally smaller compared to those in the surrounding deep-sea sediment, suggesting an active recolonisation by juveniles. Although experimental treatments with fine-grained, algae-enriched sediment showed abundances closest to natural conditions, the results suggest that food availability was the main determining factor for a successful recolonisation by meiobenthos, and the structure of recolonised sediments was shown to have a subordinate influence.

Megafauna plays an important role in benthic ecosystems and contributes significantly to benthic biomass in the Arctic. The distribution is mostly studied using towed cameras. Here, we compare the megafauna from two sites located at different distances from the Kongsfjord: one station at the entrance to the fjord, another on the outer shelf. Although they are only located 25 km apart and at comparable depth, there were significant differences in their species composition. While the inshore station was characterized by shrimps (2.57±2.18 ind. m−2) and brittlestars (3.21± 3.21 ind. m−2), the offshore site harboured even higher brittlestar densities (15.23±9.32 ind. m−2) and high numbers of the sea urchin Strongylocentrotus pallidus (1.23±1.09 ind. m−2). Phytodetrital concentrations of the upper sediment centimetres were significantly higher inshore compared with offshore. At a smaller scale, there were also differences in the composition of different transect sections. Several taxa were characteriz...

The lack of extended dataset has so far prevented an inclusive understanding of the long-term relationships between primary production (PP) and vertical export in the Arctic Ocean. It is urgent to investigate these connections as Arctic ecosystems are on the verge of climate-related shifts, which could be caused by the combined effects of increase in Pacific and Atlantic inflow, climate warming, and sea ice decline. For a period of 6 years we investigated the degree of coupling between PP and export by making use of modelled PP rates and vertical particle fluxes collected with sediment traps moored at ~300 m depth in the eastern Fram Strait. Our analyses indicate that total and new simulated PP averaged for different areas centered on the mooring location (5–200 km radius) explain at best 20–44% of the observed biogenic particle fluxes at 300 m, when applying extended time-lags (55–90 days) between PP and vertical fluxes. Based on this phasing, we define a conceptual framework that presents the temporal dimension as a prime determinant of the maximum strength of the PP-export coupling at a given depth. Our results support that planktonic food webs in the Fram Strait process heavily biogenic material in the epipelagic zone, but we further suggest that Atlantic-Arctic water interactions induce a particular ecological setting responsible for the extended turn-over. In conclusion, we hypothesize that global warming could promote a transition toward a more retentive ecosystem in the Fram Strait region despite the likely increase of pelagic PP in the Arctic Ocean.

Five photographic transects, covering some 830 m2 of seafloor in total, were analyzed to characterize the megabenthic community along a bathymetric gradient covering water depths from 1200 to 5500 m in the eastern Fram Strait. Megafaunal densities ranged between 11 and 38 ind. m−2. The highest densities were found at 1650 m and the lowest densities occurred at 3000 m depth. The number of taxa and morphotypes ranged between 4 at 5500 m and 27 at 1650 m water depth. Ophiocten gracilis, a small white unidentified amphipod, Kolga hyalina, and Bathycrinus carpenteri were the dominant and characteristic species on the slope and continental rise. Elpidia heckeri dominated in the Molloy Hole, the deepest depression known in the Arctic Ocean. Megafaunal zonation patterns appeared to be mainly controlled by food availability, as indicated by phytodetrital matter measured at the seafloor, and by benthic biomass in the sediments, as indicated by sediment-bound particulate proteins and phospholipids. By contrast, physical factors, including water depth and seabed properties such as sediment porosity and hard substrata (e.g., dropstones), appear to play a secondary role in determining megabenthic zonation patterns along the bathymetric HAUSGARTEN gradient.

Since 2000 long-term measurements of vertical particle flux have been performed with moored sediment traps at the long-term observatory HAUSGARTEN in the eastern Fram Strait (79°N/4°E). The study area, which is seasonally covered with ice, is located in the confluence zone of the northward flowing warm saline Atlantic water with cold, low salinity water masses of Arctic origin. Current projections suggest that this area is particularly vulnerable to global warming. Total matter fluxes and components thereof (carbonate, particulate organic carbon and nitrogen, biogenic silica, biomarkers) revealed a bimodal seasonal pattern showing elevated sedimentation rates during May/June and August/September. Annual total matter flux (dry weight, DW) at ∼300 m depth varied between 13 and 32 g m−2 a−1 during 2000 and 2005. Of this total flux 6–13% was due to CaCO3, 4–21% to refractory particulate organic carbon (POC), and 3–8% to biogenic particulate silica (bPSi). The annual flux of all biogenic components together was almost constant during the period studied (8.5–8.8 g m−2 a−1), although this varied from 27% to 67% of the total annual flux. The fraction was lowest in a year characterized by the longest duration of ice coverage (91 and 70 days for the calendar year and summer season, May–September, respectively). Biomarker analyses revealed that organic matter originating from marine sources was present in excess of terrigenious material in the sedimented matter throughout most of the study period. Fluxes of recognizable phyto- and protozooplankton cells amounted up to 60×106 m−2 d−1. Diatoms and coccolithophorids were the most abundant organisms. Diatoms, mainly pennate species, dominated during the first years of the investigation. A shift in the composition occurred during the last year when numbers of diatoms declined considerably, leading to a dominance of coccolithoporids. This was also reflected in a decrease in the sedimentation of bPSi. The sedimentation of biogenic matter, however, did not differ from the amount observed during the previous years. Among the larger organisms, pteropods at times contributed significantly to both the total matter and CaCO3, fluxes.

Deep-seafloor communities, especially those from the ice-covered Arctic, are subject to severe food limitation as the amount of particulate organic matter (POM) from the surface is attenuated with increasing depth. Here, we use naturally occurring stable isotope tracers ( δ 15 N) to broaden our rudimentary knowledge of food web structure and the response of benthic organisms to decreasing food supplies along the bathymetric transect (∼1300–5600 m water depth) of the deep-sea observatory HAUSGARTEN. Encompassing five trophic levels, the HAUSGARTEN food web is among the longest indicating continuous recycling of organic material typical of food-limited deep-sea ecosystems. The δ 15 N signatures ranged from 3.0‰ for Foraminifera to 21.4‰ (±0.4) for starfish ( Poraniomorpha tumida ). The majority of organisms occupied the second and third trophic level. Demersal fish fed at the third trophic level, consistent with results from stomach contents analysis. There were significant differences in the δ 15 N signatures of different functional groups with highest δ 15 N values in predators/scavengers (13.2±0.2‰) followed by suspension feeders (11.2±0.2‰) and deposit feeders (10.2±0.3‰). Depth (=increasing food limitation) affected functional groups in different ways. While the isotopic signatures of predators/scavengers did not change, those of suspension feeders increased with depth, and the reverse was found for deposit feeders. In contrast to the results of other studies, the δ 15 N signatures in POM samples obtained below 800 m did not vary significantly with depth indicating that changes in δ 15 N values are unlikely to be responsible for the depth-related δ 15 N signature changes observed for benthic consumers. However, the δ 15 N signatures of sediments decreased with increasing depth, which also explains the decrease found for deposit feeders. Suspension feeders may rely increasingly on particles trickling down the HAUSGARTEN slope and carrying higher δ 15 N signatures than the decreasing POM supplies, which elevates the δ 15 N value of their tissues. Our results imply that a depth-stratified approach should be taken to avoid a misinterpretation of data obtained at different depths.

Present theories of deep-sea community organization recognize the importance of small-scale biological disturbances, originated partly from the activities of epibenthic megafaunal organisms, in maintaining high benthic biodiversity in the deep sea. However, due to technical difficulties, in situ experimental studies to test hypotheses in the deep sea are lacking. The objective of the present study was to evaluate the potential of cages as tools for studying the importance of epibenthic megafauna for deep-sea benthic communities. Using the deep-diving Remotely Operated Vehicle (ROV) “VICTOR 6000”, six experimental cages were deployed at the sea floor at 2500 m water depth and sampled after 2 years (2y) and 4 years (4y) for a variety of sediment parameters in order to test for caging artefacts. Photo and video footage from both experiments showed that the cages were efficient at excluding the targeted fauna. The cage also proved to be appropriate to deep-sea studies considering the fact that there was no fouling on the cages and no evidence of any organism establishing residence on or adjacent to it. Environmental changes inside the cages were dependent on the experimental period analysed. In the 4y experiment, chlorophyll a concentrations were higher in the uppermost centimeter of sediment inside cages whereas in the 2y experiment, it did not differ between inside and outside. Although the cages caused some changes to the sedimentary regime, they are relatively minor compared to similar studies in shallow water. The only parameter that was significantly higher under cages at both experiments was the concentration of phaeopigments. Since the epibenthic megafauna at our study site can potentially affect phytodetritus distribution and availability at the seafloor (e.g. via consumption, disaggregation and burial), we suggest that their exclusion was, at least in part, responsible for the increases in pigment concentrations. Cages might be suitable tools to study the long-term effects of disturbances caused by megafaunal organisms on the diversity and community structure of smaller-sized organisms in the deep sea, although further work employing partial cage controls, greater replication, and evaluating faunal components will be essential to unequivocally establish their utility. © 2007 Elsevier B.V. All rights reserved.

This book describes how manmade litter, primarily plastic, has spread into the remotest parts of the oceans and covers all aspects of this pollution problem from the impacts on wildlife and human health to socio-economic and political issues. Marine litter is a prime threat to marine wildlife, habitats and food webs worldwide. The book illustrates how advanced technologies from deep-sea research, microbiology and mathematic modelling as well as classic beach litter counts by volunteers contributed to the broad awareness of marine litter as a problem of global significance. The authors summarise more than five decades of marine litter research, which receives growing attention after the recent discovery of great oceanic garbage patches and the ubiquity of microscopic plastic particles in marine organisms and habitats. In 16 chapters, authors from all over the world have created a universal view on the diverse field of marine litter pollution, the biological impacts, dedicated research activities, and the various national and international legislative efforts to combat this environmental problem. They recommend future research directions necessary for a comprehensive understanding of this environmental issue and the development of efficient management strategies. This book addresses scientists, and it provides a solid knowledge base for policy makers, NGOs, and the broader public.

According to the 2014 European Commission’s consumer scoreboard, the market for investment and pension products continues to be the worst performing market in Europe. As the new research report by Better Finance on the performance of private pensions in Europe shows, this lack of consumer trust is a direct consequence of the persistent inability of many financial intermediaries to deliver decent long term returns.The 2015 Edition of “Pension Savings: The Real Return” now covers 15 EU countries, representing 85% of the EU population and encompassing up to 15 years of returns on pension savings (2000 to 2014). It is once again the only publication to provide such comprehensive data on the real net returns on pension savings in the EU and, in doing so, has become the main source of information on the actual performance of long-term “retail” investment products for European financial supervisors and consumers alike.Despite a persistent lack of available information on aggregate fees and performance, the report clearly demonstrates that blaming poor returns on the performance of capital markets holds no water. As it stands, pension funds simply all too often significantly underperform capital markets. By combining the exceptional performance of bond markets and the lower but positive performance of equity markets over the last fifteen years, a direct investment of 50% in European equities and 50% in Euro bonds would have generated a 35% positive return in real terms (net of inflation). Regrettably though, net real returns on long term savings products have generally been far lower, and all too often negative, thereby eradicating the real value of pension savings. Unit-linked insurance products in particular delivered dismal returns. Those returns are influenced by a series of variables including asset allocation, capital markets' performance and the actual skills of asset managers. However, the reasons for the disappointingly low returns of pension saving products clearly lie elsewhere. In fact, over the years it has become increasingly clear that the actual main culprit is the excessive level of fees and commissions charged overall. That and the heavy, and increasing, tax burden on savers. Sadly the future does not look any brighter as the decades long bull market in bonds is likely to come to an end with interest rates now at historically low levels and with pension funds having increased their allocation to bonds during the last 15 years. Better Finance identified ten key policy measures that would go a long way towards improving this dire situation for European households, as well as improving growth and foster job creation in Europe. These measures were presented to the European Commission within the framework of the consultation on the “Capital Markets Union” (CMU) initiative and warrant repeating. The CMU Action Plan that was made public today is a step in the right direction but more effort needs to be put into improving long-term net returns of intermediated (packaged) investment products as a matter of urgency.In that regard - whereas Better Finance applauds the EU initiative for a much-needed, simple and cost effective Pan-European Personal Pension (PEPP) that would, at least, protect the long-term purchasing power of savings - it warns EU Member States not to discriminate and kill the project with unfavourable tax treatment.

Scavenging amphipods were studied at 6 locations in the Fram Strait (Arctic Ocean). At each location a tripod lander equipped with a time-lapse camera, acoustic doppler current profiler and baited traps was deployed at water depths between 1500 and 2600 m. All amphipods, both on photographs and captured, belonged to the superfamily Lysianassoidea or Stegocephaloidea. Differ- ences between the stations occurred in time and number of amphipod maxima, consumption rates, taxonomic composition, size structure and current direction. Scavenger aggregation dynamics and behaviour on carcasses in the Arctic Ocean differ from those in other reported deep-sea areas in arrival time at bait, abundance and length distribution of individuals sampled. The giant amphipod Eurythenes gryllus dominated in our bait experiments; it exceeded numbers counted by other work- ers by >13-fold, and the first individuals appeared up to 20 times faster than in other reported exper- iments. Specimen attraction and abundance seem to be directly linked to the organic input of food falls in the area. Relations between scavenger aggregations and trophic conditions are discussed with respect to results obtained under different trophic regimes in the Arabian Sea and in the Pacific and Atlantic Oceans.

According to combined observations from vertical plankton tows, dredging with epibenthic nets 1 m above the ocean floor, video recordings and acoustic data from a scanning sonar obtained during descent and during deployment on the ocean floor, the calanoid copepod Calanus hyperboreu s was aggregated in high concentrations near the ocean floor of the Greenland Sea between 2300 and 2500 m during late July and August. Concentrations were highest very close to the ocean floor and decreased rapidly further upward. These nearly mono-specific aggregations were apparently drifting in cloud-like formations with a horizontal extension of ca. 270 m with the near-bottom currents. Maximum abundances observed were up to 2 orders of magnitude higher than in the water column. The biomass in the bottom 20 m layer was around 18% of the biomass in the rest of the water column. Stage composition, reduced metabolic rates and insensibility to mechanical stimuli indicate that these C. hyperboreus were representing the resting population. The fact that high concentrations were observed during deployments lasting >1 d and in 3 years suggests that aggregation near the ocean floor is a regular, rather than an extraordinary, pattern in the life history of C. hyperboreus in the Greenland Sea, but there is need for comparison with other seas and eventually other Calanus species.

The marine Arctic has played an essential role in the history of our planet over the past 130 million years and contributes considerably to the present functioning of Earth and its life. The global cycles of a variety of materials fundamental to atmospheric conditions and thus to life depend to a signifi cant extent on Arctic marine processes (Aargaard et al., 1999). The past decades have seen remarkable changes in key Arctic variables. The decrease of sea-ice extent and sea-ice thickness in the past decade is statistically signifi - cant (Cavalieri et al., 1997; Parkinson et al., 1999; Walsh and Chapman, 2001; Partington et al., 2003; Johannessen et al., 2004). There have also been large changes in the upper and intermediate layers of the ocean, which have environmental implications. For instance, the deep Greenland Sea has continued its decadal trend towards warmer and saltier conditions, with a corresponding decrease in oxygen content, refl ecting the lack of effective local convection and ventilation (Dickson et al., 1996; Boenisch et al., 1997). Changes in temperature and salinity and associated shifts in nutrient distributions will directly affect the marine biota on multiple scales from communities and populations to individuals, consequently altering food-web structures and ecosystem functioning (Benson and Trites, 2002; Moore, 2003; Schumacher et al., 2003; Wiltshire and Manly, 2004; Perry et al., 2005). Today, we do not know whether the severe alterations in abiotic parameters represent perturbations due to human impacts, natural long-term trends, or new equilibriums (Bengtson et al., 2004). Because Arctic organisms are highly adapted to extreme environmental conditions with strong seasonal forcing, the accelerating rate of recent climate change challenges the resilience of Arctic life (Hassol, 2004). The entire system is likely to be severely affected by changing ice and water conditions, varying primary production and food availability to faunal communities, an increase in contaminants, and possibly increased UV irradiance. The stability of a number of Arctic populations and ecosystems is probably not strong enough to withstand the sum of these factors, which might lead to a collapse of subsystems. To detect and track the impact of large-scale environmental changes in the transition zone between the northern North Atlantic and the central Arctic Ocean, and to determine experimentally the factors controlling deep-sea biodiversity, the German Alfred Wegener Institute for Polar and Marine Research (AWI) established the deepsea, long-term observatory HAUSGARTEN, representing the fi rst, and by now only, open-ocean, long-term station in a polar region.

High-latitude seas are mostly covered by multi-year ice, which impacts processes of primary production and sedimentation of organic matter. Because of the warming effect of West Spitsbergen Current (WSC), the waters off West Spitsbergen have only winter ice cover. That is uncommon for such a high latitude and enables to separate effects of multiyear-ice cover from the latitudinal patterns. Macrofauna was sampled off Kongsfjord (791N) along the depth gradient from 300 to 3000 m. The density, biomass and diversity at shallow sites situated in a canyon were very variable. Biomass was negatively correlated with depth (R ¼� 0:86; po0.001), and ranged from 61 g ww m � 2 (212 m) to 1 g ww m � 2 (2025 m). The biomasses were much higher than in the multiyear-ice covered High Arctic at similar depths, while resembling those from temperate and tropical localities. Species richness (expressed by number of species per sample and species–area accumulation curves) decreased with depth. There was no clear depth-related pattern in diversity measures: Hurbert rarefaction, Shannon–Wiener or Pielou. The classic increase of species richness and diversity with depth was not observed. Species richness and diversity of deep-sea macrofauna were much lower in our study than in comparable studies of temperate North Atlantic localities. That is related to geographic isolation of Greenland–Icelandic–Norwegian (GIN) seas from the Atlantic pool of species. r 2004 Elsevier Ltd. All rights reserved.

Although the use of deep-sea imagery considerably increased during the last decades, reports on nekton falls to the deep seafloor are very scarce. Whereas there are a few reports describing the finding of whale carcasses in the deep north-eastern and south-eastern Pacific, descriptions of invertebrate or vertebrate food-falls at centimetre to metre scale are extremely rare. After 4 years of extensive work at a deep-sea long-term station in northern polar regions (AWI-“Hausgarten”), including large-scale visual observations with various camera systems covering some 10 000 m 2 of seafloor at water depths between 1250 and 5600 m, this paper describes the first observation of a fish carcass at about 1280 m water depth, west off Svalbard. The fish skeleton had a total length of 36 cm and an approximated biomass of 0.5 kg wet weight. On the basis of in situ experiments, we estimated a very short residence time of this particular carcass of about 7 h at the bottom. The fast response of the motile deep-sea scavenger community to such events and the rapid utilisation of this kind of organic carbon supply might partly explain the extreme rarity of such an observation.

In August 2000 high concentrations of the dominant herbivorous copepod Calanus hyperboreus were detected in the Arctic Fram Strait, west of Spitsbergen, 1 m above the seafloor at 2,290 m water depth. Individuals from that layer were sampled by a hyper-benthic net attached to the frame of an epi-benthic sledge. For comparison, the vertical distribution of C. hyperboreus in the water column was studied simultaneously by a multiple opening/closing net haul from 2,250 m depth to the surface. Maximum abundance was found close to the surface with 6.6 and 10.0 ind. m−3 at 0–50 m and 50–100 m depth, respectively. However, the major fraction of the population (>40%) occurred between 1,000 and 1,500 m depth. In the deepest layer (2,000–2,250 m) abundance measured 2.2 ind. m−3 and was twice as high as between 100 and 1,000 m depth. In comparison to individuals from surface waters, copepods from the hyper-benthic layer were torpid and did not react to mechanical stimuli. Stage CV copepodids and females from the deep sample contained 4–10% less lipid and showed significantly reduced respiration rates of 0.24 and 0.26 ml O2 h−1 g−1 dry mass (DM) as compared to surface samples (0.49 and 0.43 ml O2 h−1 g−1 DM). All these observations indicate that the hyper-benthic part of the population had already started a dormant overwintering phase at great depth. Based on the lipid deposits and energy demands, the potential maximum duration of the non-feeding dormant phase was estimated at 76–110 days for females and at 98–137 days for CV copepodids, depending on what indispensable minimum lipid content was assumed. In any case, the estimated times could not meet the necessary requirements for a starvation period of >6 months until the next phytoplankton bloom in the following spring. The ecological implications of these results are discussed with respect to the life cycle and eco-physiological adaptations of C. hyperboreus to its high-Arctic habitat.

There is much speculation about chemoreception being involved in food-finding strategies of deep-sea scavengers in the literature (Dahl, 1979; Meador, 1981; Busdosh et al., 1982; Sainte-Marie, 1992). Most of these ideas have emerged from analysing time-lapse photographs and video recordings of bait deployments in the deep sea (Thurston, 1979; Lampitt et al., 1983; Hargrave, 1985; Priede et al., 1990). However, optical instruments have considerable restrictions in spatial coverage, thus all past efforts in determining any directionality in the appearance of scavengers have been limited from 0.9 to 4 m 2 only (Smith, 1985; Wilson and Smith, 1984). In this work, we present data obtained by using a scanning sonar system (SSS) which allows detection of single objects larger than 2 cm at a maximum distance of 50 m in a horizontal plane. Together with the SSS, a baited time-lapse camera attached to a free falling lander was used in the Arctic deep sea at two locations in the Fram Strait at about 2500 m water depths. We would like to point out that this combination of optical and acoustical measurements allowed, for the first time, the long-range detection of approaching scavenging amphipods in the deep sea. Eurythenes gryllus (Lichtenstein, 1822), a cosmopolitan deep-sea scavenging amphipod, was recorded to attend our bait experiments with a maximum of 618 individuals with first arrival 12 min after deployment, which is one of the fastest arrivals ever observed. We found a significant temporal correlation between integrated backscatter energy (IBE), based on measurements of the SSS and amphipod individuals counted on photographs.

There is strong evidence in the literature that energy supply for deep-sea scavengers is largely restricted to food falls of dead vertebrates such as fish and mammals. The problem for any scavenger inhabiting the seafloor is the unpredictability both in space and time of food fall events. It is generally accepted that chemoreception is one of the major means by which marine organisms detect food sources. Another major source of potential information, however, may come from hydroacoustic stimuli, which have long-range penetration. Such hydroacoustic stimuli will either arise when a large carcass hits and impacts the seafloor or during food consumption of scavengers producing feeding noises. The intensity and transmission characteristics depend upon sediment properties, size, weight and composition of the carcass as well as on size and mouthpart morphology of feeding individuals. In this study the relevance of hydroacoustic stimuli for food fall detection has been investigated in the pandalid shrimp Pandalus borealis Kroyer, 1838. The sensitivity of P. borealis to particle displacement amplitude was found to be close to values measured in other crustaceans. Based on 228 single experiments carried out with five specimens, our results indicate that low-frequency noises may be helpful in detecting food fall events but only in the near-field. In this paper we suggest that the impact of a sinking carcass at the seafloor is a likely source producing elastic waves at the water–seafloor interface. Based on both empirical findings and general theoretical calculations of elastic waves originating from a sinking object hitting the seafloor we conclude that such “micro seismic events” may allow resting scavengers even several hundred metres away to detect a food source.

In modern polar marine research, Autonomous Underwater Vehicles (AUV) gain increasing importance due to their ability to take on high risk or time-consuming tasks in the harsh physical environment of the polar seas. They represent a relatively new group of robots that can investigate large areas in all three dimensions without the direct need of human surveillance. The most common objective for these vehicles that are currently operated worldwide is to gather sonar data and create high-resolution maps of the sea floor. A relatively new task is their deployment within the framework of water column studies dealing with the investigation of biogeochemical processes in the open sea or in ice-covered areas. The Alfred Wegener Institute for Polar and Marine Research (AWI) in Bremerhaven, Germany operates a 21-inch class AUV by the American manufacturer Bluefin Robotics (Quincy, Massachusetts) named PAUL. The main objectives of the herein described AUV project at AWI are the investigation of biogeochemical processes in the surface water and to analyze the stratification of the upper water column in the marginal ice zone as well as the dynamic interaction between ice and ocean. For this reason, since 2008, PAUL has been equipped with a number of biogeochemical sensors (e.g. Nitrate, Oxygen, Fluorescence, etc.) and a newly designed water sample collector all specified for operations in icy waters. In the course of several Arctic expeditions onboard the RV Polarstern, the vehicle was deployed in the Fram Strait close to the AWI deep sea observatory “HAUSGARTEN”. In a first series of diving trials in ice covered areas, the first mission under ice accomplished by PAUL occurred at the HAUSGARTEN site in summer 2010. Here, the description of the vehicle, the mode of operations and especially the structure of the payload is detailed. The payload development process took advantage of complementary instruments: combining data of different sensors with water samples. The samples allow data to be obtained for parameters that cannot be measured in situ, for example the amount of microscopic plankton, and in addition, they can also be used for validation purposes. For example, by measuring the amount of chlorophyll a in distinct samples, the flow-through chlorophyll a fluorometer of the AUV can be calibrated. This provides more accurate values than a calibration with laboratory standards. Results of such measurements gathered from 2010 to 2012 (ARK 25/2 - ARK 27/2, RV Polarstern) are presented exemplarily for the scientific use of the vehicle. Additionally, a description will be given for the new technologies that were developed (remotely operated flying drones, GPS tracking of the ice edge) the new procedures (vehicle tracking, special dive maneuvers) introduced into the AUV project in order to acquire a comprehensive picture of the physical and biogeochemical conditions of the pelagic environment assessed. These steps were mandatory, not only to ensure the safety of the vehicle, but also to be able to place the measured data into the greater context of challenges in understanding the dynamics of ice-covered seas.

Our ability to understand the complex interactions of biological, chemical, physical, and geological processes in the ocean and on land is still limited by the lack of integrative and interdisciplinary observation infrastructures. The main purpose of the planned open-ocean infrastructure FRAM (FRontiers in Arctic marine Monitoring) is permanent presence at sea, from surface to depth, for the provision of near real-time data on climate variability and ecosystem change in a marine Arctic system. The Alfred-Wegener-Institut - Helmholtz-Zentrum fur Polar- und Meeresforschung (AWI), together with partner institutes in Germany and Europe, aims at providing such infrastructure for the polar ocean as a major contribution to the grand challenges of Earth observation and environmental status. The FRAM Ocean Observing System targets the gateway between the North Atlantic and the Central Arctic, representing a highly climate-sensitive and rapidly changing region of the Earth system. It will serve national and international tasks towards a better understanding of the effects of change in ocean circulation, water mass properties and sea-ice retreat on Arctic marine ecosystems and their main functions and services. FRAM will implement existing and nextgeneration sensors and observatory platforms, allowing synchronous observation of relevant ocean variables, as well as the study of physical, chemical and biological processes in the water column and at the seafloor. Experimental and event-triggered platforms will complement observational platforms. Products of the infrastructure are continuous long-term data with appropriate resolution in space and time, as well as ground-truthing information for ocean models and remote sensing. FRAM will integrate and develop already existing observatories, i.e. the oceanographic mooring array HAFOS (Hybrid Arctic/Antarctic Float Observing System) and the Long-Term Ecological Research (LTER) site HAUSGARTEN.

To understand the complexity of the global methane cycle with its relation to climate change, it is necessary to identify relevant methane sources and to assess their environmental functions. The contribution of the various marine methane sources to the global cycle is only poorly understood so far. Methods are needed to survey efficiently methane release from the sea floor. Remote techniques are favoured since they allow a survey of larger areas than, for example, sediment sampling. Low frequency echosounders, as used in fishery, were recognized to be appropriate tools for plume detection and are hoped to be the key for efficient plume mapping and gas quantification. Here, we present methane plumes from three different marine environments.

The HAUSGARTEN observatory is located in the eastern Fram Strait (Arctic Ocean) and used as long-term monitoring site to follow changes in the Arctic benthic ecosystem. Linear inverse modelling was applied to decipher carbon flows among the compartments of the benthic food web at the central HAUSGARTEN station (2500 m) based on an empirical data set consisting of data on biomass, prokaryote production, total carbon deposition and community respiration. The model resolved 99 carbon flows among 4 abiotic and 10 biotic compartments, ranging from prokaryotes up to megafauna. Total carbon input was 3.78±0.31 mmol C m −2 d −1 , which is a comparatively small fraction of total primary production in the area. The community respiration of 3.26±0.20 mmol C m −2 d −1 is dominated by prokaryotes (93%) and has lower contributions from surface-deposit feeding macro- (1.7%) and suspension feeding megafauna (1.9%), whereas contributions from nematode and other macro- and megabenthic compartments were limited to

The geographical distribution and depth zonation of Eusirus perdentatus Chevreux, 1912 in the eastern Weddell Sea and adjacent Lazarev Sea (Antarctica) is described. A total of 963 individuals of this carnivorous predator caught during six successive cruises at 71 stations between 176 and 799 metres water depths were used. Individuals of E. perdentatus have been kept alive for nearly five months in the laboratory. During this period females released 53 juveniles in April. Oocytes and embryos of females have been counted and measured. The duration of embryonic development in E. perdentatus was estimated at c. 12 months, using an empirical relationship based on the mean diameter of 4390 fertilized eggs. There is strong evidence that this species is semelparous with hatching of juveniles at the end of austral summer. Two methods, herein termed as Year Class Model and Moult Class Model, have been applied in order to describe the growth of females by means of cumulative length-frequency data.

The responsiveness of benthic biological communities to climatic drivers and shifts makes them powerful indicators of biogeochemical and other environmental change in the oceans. In addition, benthic ecosystems have an economic value and are considered a vital marine resource. However deep-sea faunal dynamics and ecosystem functioning is not well defined. This has placed a higher priority in recent years on developing and sustaining long-term, time-series studies of benthic biodiversity, rate processes, and ecosystem change in deep-sea and extreme habitats. A few key long-term time-series sites exist across the global Ocean. Many of these sites are reviewed in this paper. However, much of the existing research is uncoordinated and the data collected are not integrated or standardized. This currently limits the use of these valuable datasets, which could be used for benthic modeling, global model validation and other societal benefits related to more effective and environmentally sustainable governance of human activities in the deep ocean. Furthermore, the time scales that can be studied within existing research frameworks are not currently sufficient to adequately address internationally-identified science priorities. These include assessing regional and global biodiversity, ecosystem functioning and the links between climate, terrestrial and marine ecosystems. In addition, the contribution of deep-sea ecosystems to global biogeochemical cycles and the potential alteration to ecosystem value and services due to anthropogenic activities is largely unknown. In order to maximize the societal benefit, biological time-series, in particular deep-sea sites, urgently require more coordination, integration, sustained funding and infrastructure. This is necessary to unify research methodologies, create synergies in the use of deep-sea technology, develop benthic models, and to stimulate more collaboration between programmes. National and international research organizations may provide a suitable framework within which further advances can be achieved. Only then will we better understand the goods and services provided by deep-sea ecosystems and the potential for environmentally sustainable exploitation of the deep ocean.

Societal concerns over the potential impacts of recent global change have prompted renewed interest in the long-term ecological monitoring of large ecosystems. The deep sea is the largest ecosystem on the planet, the least accessible, and perhaps the least understood. Nevertheless, deep-sea data collected over the last few decades are now being synthesised with a view to both measuring global change and predicting the future impacts of further rises in atmospheric carbon dioxide concentrations. For many years, it was assumed by many that the deep sea is a stable habitat, buffered from short-term changes in the atmosphere or upper ocean. However, recent studies suggest that deep-seafloor ecosystems may respond relatively quickly to seasonal, inter-annual and decadal-scale shifts in upper-ocean variables. In this review, we assess the evidence for these long-term (i.e. inter-annual to decadal-scale) changes both in biologically driven, sedimented, deep-sea ecosystems (e.g. abyssal plains) and in chemosynthetic ecosystems that are partially geologically driven, such as hydrothermal vents and cold seeps. We have identified 11 deep-sea sedimented ecosystems for which published analyses of long-term biological data exist. At three of these, we have found evidence for a progressive trend that could be potentially linked to recent climate change, although the evidence is not conclusive. At the other sites, we have concluded that the changes were either not significant, or were stochastically variable without being clearly linked to climate change or climate variability indices. For chemosynthetic ecosystems, we have identified 14 sites for which there are some published long-term data. Data for temporal changes at chemosynthetic ecosystems are scarce, with few sites being subjected to repeated visits. However, the limited evidence from hydrothermal vents suggests that at fast-spreading centres such as the East Pacific Rise, vent communities are impacted on decadal scales by stochastic events such as volcanic eruptions, with associated fauna showing complex patterns of community succession. For the slow-spreading centres such as the Mid-Atlantic Ridge, vent sites appear to be stable over the time periods measured, with no discernable long-term trend. At cold seeps, inferences based on spatial studies in the Gulf of Mexico, and data on organism longevity, suggest that these sites are stable over many hundreds of years. However, at the Haakon Mosby mud volcano, a large, well-studied seep in the Barents Sea, periodic mud slides associated with gas and fluid venting may disrupt benthic communities, leading to successional sequences over time. For chemosynthetic ecosystems of biogenic origin (e.g. whale-falls), it is likely that the longevity of the habitat depends mainly on the size of the carcass and the ecological setting, with large remains persisting as a distinct seafloor habitat for up to 100 years. Studies of shallow-water analogs of deep-sea ecosystems such as marine caves may also yield insights into temporal processes. Although it is obvious from the geological record that past climate change has impacted deep-sea faunas, the evidence that recent climate change or climate variability has altered deep-sea benthic communities is extremely limited. This mainly reflects the lack of remote sensing of this vast seafloor habitat. Current and future advances in deep-ocean benthic science involve new remote observing technologies that combine a high temporal resolution (e.g. cabled observatories) with spatial capabilities (e.g. autonomous vehicles undertaking image surveys of the seabed).

In situ enrichment experiments were carried out in the Arctic deep sea (Fram Strait region) to observe the response of benthic microbial communities to chitin supply. Chambers of a benthic lander were filled in July 2004 with deep-sea sediments enriched with 1.3–7.0 g m−2 of chitin and the effects of chitin enrichment were assessed on the microbial hydrolytic activity potential, cell number and community structure after periods of 1 week and 1 year of in situ deployment. The input of chitin had no effect on microbial abundance and chitobiase activity after 7 days of incubation, whereas community structure in enriched sediments, determined by terminal restriction fragment length polymorphism analysis of 16S rRNA genes, was different from the controls. After 1 year, microbial numbers and activity significantly increased in sediments enriched with high chitin concentrations and bacterial community structure was different from that of the other treatments. The present study suggests that microbial community structure in Arctic deep-sea sediments can react quickly to sudden large chitin inputs into the sediments and that this appears to precondition subsequent enhanced growth and enzymatic activity changes.

Nineteen holothurian specimens were photographed or videotaped in situ on the deeper shelf of the Weddell Sea (Antarctica). These specimens show a different gradient and combinations of characteristics which are found in Bathyplotes rubipunctatus Gutt, 1990. A close relationship to this species is therefore suggested. However, based on external features which are conspicuous in live animals but not visible in preserved material they are classified into five groups. Further investigations will reveal whether these groups are distinct species, or merely variants of B. rubipunctatus.

Epimeria rubrieques sp. n., belonging to the cold water family Paramphithoidae, occurred relatively often in Agassiz and bottom trawls taken during several German Antarctic Expeditions into the eastern Weddell Sea since 1983. Although this species is very conspicuous because of its long mid-dorsal teeth, bright pink-red colour and large size (up to 70 mm), it has only been recorded in the Weddell Sea. The new species is compared to its closest relatives Epimeria macrodonta and E. similis, and an updated key to the 14 species of Antarctic Epimeria is provided. Observations on the general and feeding behaviour of living specimens of Epimeria rubrieques sp. n. in aquaria showed the species to be an ambush predator and a weakly motile epibenthic walker, which swims only rarely.

Marine mud volcanoes are significant source locations contributing to the marine methane cycle. Enhanced heat flow, unique chemoautotrophic communities, occurrence of massive gas hydrates and large gas plumes are direct evidences of elevated methane concentrations and the dynamic environment of mud volcanoes. Related to the high concentrations and large inventories of CH4 in surface sediments only a fraction of the methane is exported to the bottom water. This is mainly due to chemoautotrophic communities oxidizing methane and proving a “microbial filter” reducing CH4 fluxes. Although these processes were studied for several mud volcanoes still little is known about the spatial pattern and the areas covered by chemoautotrophic communities or by present mud flows. For this purposes the Hakon Mosby Mud Volcano (HMMV), which is located at the continental slope of the Barents Sea, was studied by several dives with the Remotely Operated Vehicle Victor6000. During these dives a high resolution microbathymetric map, with a footprint of 25×25 cm and a vertical resolution of better than 10 cm was derived. Furthermore, video streams of the bottom camera were converted into georeferenced mosaics, providing a detailed image about the spatial distribution of seafloor features as bacterial mats, pogonophorans, both indicating methane oxidation, or mud flows. Based on visual inspection of 2310 georeferenced mosaics covering an area of 46,160 m 2 , different biogeochemical habitats were identified and quantified on a m 2 basis. By application of geostatistic techniques as indicator kriging the distribution of different biogeochemical habitats was quantified and mapped for the entire HMMV. Considering the flat and hummocky area of HMMV, approximately 16% (115,165 m 2 ) of the flat centre is nearly void of any benthic communities. This area is considered as a region of high methane discharge into bottom water. An area of 5% (38,244 m 2 ), located in the south-eastern part, is densely inhabited by Beggiatoa. The hummocky outer part is colonised dominantly by pogonophoran tube worms (37.3%; 276,121 m 2 ) and only occasional by Beggiatoa. Source locations and drainage directions for current mud flows were identified by computation of trend surfaces and consideration of temperature data. This suggests that present mud flow ascend close to the northern edge of the flat unit of HMMV, and that the drainage pattern of mud flows shifted from a westward to a south-south-eastern direction. © 2007 Elsevier B.V. All rights reserved.

Mud volcanism is an important natural source of the greenhouse gas methane to the hydrosphere and atmosphere(1,2). Recent investigations show that the number of active submarine mud volcanoes might be much higher than anticipated ( for example, see refs 3 - 5), and that gas emitted from deep-sea seeps might reach the upper mixed ocean(6-8). Unfortunately, global methane emission from active submarine mud volcanoes cannot be quantified because their number and gas release are unknown(9). It is also unclear how efficiently methane-oxidizing microorganisms remove methane. Here we investigate the methane-emitting Haakon Mosby Mud Volcano (HMMV, Barents Sea, 72 degrees N, 14 degrees 44' E; 1,250 m water depth) to provide quantitative estimates of the in situ composition, distribution and activity of methanotrophs in relation to gas emission. The HMMV hosts three key communities: aerobic methanotrophic bacteria (Methylococcales), anaerobic methanotrophic archaea (ANME-2) thriving below siboglinid tubeworms, and a previously undescribed clade of archaea (ANME-3) associated with bacterial mats. We found that the upward flow of sulphate- and oxygen-free mud volcano fluids restricts the availability of these electron acceptors for methane oxidation, and hence the habitat range of methanotrophs. This mechanism limits the capacity of the microbial methane filter at active marine mud volcanoes to

The assessment of climate change factors includes a constraint of methane sources and sinks. Although marine geological Sources are recognized as significant, unfortunately, most submarine sources remain poorly quantified. Beside cold vents and coastal anoxic sediments, the large number of submarine mud volcanoes (SMV) may contribute significantly to the oceanic methane pool. Recent research suggests that methane primarily released diff-usively from deep-sea SMVs is immediately oxidized and, thus, has little climatic impact. New hydro-acoustic, Visual, and geochemical observations performed at the deep-sea mud volcano Hakon Mosby reveal the discharge of gas hydrate-coated methane bubbles and gas hydrate flakes forming huge methane plumes extending from the seabed in 1250 m depth up to 750 in high into the water column. This depth coincides with the upper limit of the temperature-pressure field of gas hydrate stability. Hydrographic evidence suggests bubble-induced upwelling within the plume and extending above the hydrate stability zone. Thus, we propose that a significant portion of the methane from discharged methane bubbles can reach the upper water column, which may be explained due to the formation of hydrate skins. As the water mass of the plume rises to shallow water depths, methane dissolved from hydrated bubbles may be transported towards the surface and released to the atmosphere. Repeated acoustic surveys performed in 2002 and 2003 suggest continuous methane emission to the ocean. From seafloor visual observations we estimated a gas flux of 0.2 (0.08-0.36) mol s(-1) which translates to several hundred tons yr(-1) under the assumption of a steady discharge. Besides, methane was observed to be released by diffusion from sediments as well as by focused outflow of methane-rich water. In contrast to the bubble discharge, emission rates of these two pathways are estimated to be in the range of several tons yr(-1) and, thus, to be of minor importance. Very low water column methane oxidation rates derived from incubation experiments with tritiated methane suggest that methane is distributed by currents rather than oxidized rapidly.

An overview of preliminary results from a series of recent Remotely Operated Vehicle (ROV) dives on the deep-water coral provinces of the Porcupine Bank, Irish continental margin, NE Atlantic is presented. The Porcupine Bank exhibits numerous giant carbonate mounds (up to 100s of metres in height) that occur predominantly, although not exclusively, on topographic ridges. The results revealed that, although these ridges have a tectonic origin, contemporaneous activity is typified by erosion due to strong hydrodynamic controls. The carbonate mounds are colonized by a variety of suspension feeders and associated fauna including framework-building corals (e.g., Lophelia pertusa and Madrepora oculata) although dense coral reef-like fauna coverage is not evident at present. The ecology of the carbonate mounds varied widely. Sessile megafauna, such as sponges, gorgonians and framework-building corals (e.g., Lophelia pertusa), were abundant on some of the carbonate mounds. Other mounds were relatively barren and appeared to be undergoing a natural senescence, with a much lower biomass of megafauna than is typical of shallow-water coral reefs. Some mounds had been damaged by demersal trawls, with smashed coral and lost gear common, whereas others appeared relatively pristine with occasional evidence of man-made litter.

The Belgica Mound province is one of three provinces where carbonate mounds are associated with cold-water coral species in Porcupine Seabight, west of Ireland. Building upon extensive existing datasets, the Polarstern ARK XIX/3a cruise, deploying the robotic submersible VICTOR6000 (ROV), was undertaken in June 2003. This paper presents an overview of preliminary results from a reconnaissance video survey over and between several steep-flanked Belgica Mounds (giant mounds) and from a microbathymetric survey over some smaller mounds (Moira Mounds). Visual evidence for a strong hydrodynamic regime in the vicinity of the carbonate mounds is found with the interaction between currents and sedimentation having an important role in mound growth and development. Only some mounds show a high percentage of live coral coverage although there is a clear increase of megafaunal concentrations and species on mounds. One area of the province (the eastern ridge of aligned mounds) revealed very little live coral cover, asymmetrical drift accumulations burying the eastern sides and sediment-clogged dead coral frameworks at the western sides. This is in contrast to other areas (e.g., the western alignment of mounds) that show abundant live coral cover at present. In nearly all parts of the survey area the impact of fisheries, especially demersal trawling, is noted.

Carbonate mounds (up to 200 m high) formed from the accumulated remains of cold-water corals (principally Lophelia pertusa and Madrepora oculata), associated calcareous fauna and interstitial sediment are present at 500–1000 m water depths west of Ireland. Seabed mapping datasets (side-scan sonar, multibeam echosounder, sub-bottom profiler and underwater video imagery) are presented here from the Belgica Mound province on the eastern Porcupine Seabight margin. The data, integrated within a Geographic Information System (GIS), provide an environmental context to mound development. Analysis of this multidisciplinary dataset and resultant facies map highlight differing sedimentary processes (e.g., sediment wave, barchan dune, gravel lag and sand ribbon development) operating under strong northward flowing bottom currents with sandy sediment supply where the influence of mound topography on benthic currents and sediment pathways is evident. Correspondingly, benthic current pathways and associated sediment transport also exert an influence on carbonate mound surface morphology and growth. Giant mounds show a transition from sediment waves that, with increasing coral colonisation, give way to banks of coral towards the mound summits. Smaller mound features (Moira Mounds) show sand entrapment as an important mound-forming process.

The exploration of the Arctic Ocean has a long and multi-national history, but still we are only beginning to understand the role of the Arctic Ocean in the global carbon cycle. This chapter addresses the contribution of the Arctic benthos to organic carbon utilization, modification and sequestration. We review findings in benthic ecology and biogeochemistry of the Arctic Ocean from the past 15 years. Several older reviews on the Arctic benthos are available with a different focus: Zenkevitch’s (1963) thorough volume covering the entire Eurasian Arctic benthos remains outstanding in its description of species composition, biomass and biogeographic aspects. Reviews by Curtis (1975), Dayton (1990), and Carey (1991) cover general aspects of the Arctic benthos as well as distribution patterns, productivity, and the feeding ecology of different species. Many recent studies have emphasized processes at the sediment-water boundary layer including respiration of sedimentinhabiting communities or single species (Piepenburg et al. 1995), calculation of carbon utilization and remineralization rates of benthic communities and their correlation to primary production (Boetius and Damm 1998), but also measuring biomass of benthic populations (Seiler 1999; Jorgensen et al. 1999; Deubel 2000). Recent discoveries of cold seeps north of the polar circle (Vogt et al. 1999) and of hydrothermal activity on the Gakkel Ridge (Thiede 2002) suggest a more diverse deep-sea benthos than previously known, but these on-going investigations cannot be reviewed herein.

The evaluation of the first year of intensive scientific use of the French deep sea remotely operated vehicle (ROV) "Victor 6000" is presented. Victor was used in 2001 during five cruises on the continental margins. The Zairov 1 & 2, Biozaire 1 & 2 cruises were conducted offshore Western Africa and the Caracole cruise was conducted along the North East Atlantic margins (Porcupine and Rockall bank). Cold seep settings (up to 3000 m depth), coral mounds (400-1000 m), oil exploration rigs (1300 m) and the Zaire channel (about 4000 m) were explored. Victor carried out on site work during two cruises (IRIS & ATOS) on the hydrothermal vent areas in the Mid Atlantic Ridge (Menez Gwen 850 m, Lucky Strike 1650 m and Rainbow 2350 m). Finally, Victor was used by the Alfred Wegener Institute, through a French-German cooperation in the Arctic deep sea, to study the high diversity of species in the deep sea, at high latitude (AWI leg). Different strategies were tested during those cruises like survey and exploration or experimental work on small areas. The dive durations ranged between 8 to 28 hours on the bottom. The high potential of Victor was confirmed in both strategies with a high ability for the manipulation and. the trials of varied pieces of instrumentation. The status and recent evolution of Victor 6000 are presented showing the essential role of dynamic technical support oriented toward scientific objectives and operability.

Within the frame of a Franco-Germam co-operation between the German " Alfred Wegener Institut for Polar and Marine Research" (AWI) and the french "Institut Francais de Recherche pour l'Exploitation de la Mer" (IFREMER) the French Remotely Operated Vehicle (ROV) "VICTOR 6000" was successfully deployed from board R/V "POLARSTERN" during the polar expedition ARK XV/1 from 23.06 to 18.07.1999 to Fram Strait and the Greenland Sea.