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The colonisation of hard substrata (HS) by epibenthic megafauna was studied by photographic surveys along the Ardencaple Canyon
in the deep western Greenland Sea in 2000. Seven transects at 2,700–3,200m water depth showed generally low densities of
dropstones, sunken wood, and other substrata including anthropogenic material (range: 2–11HSkm−1). Ov...
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Context 1
... of the seafloor were taken by the towed Ocean Floor Observation System (OFOS) during the expedition ARK XVI/1 of RV Polarstern (July 2000) at *2,700-3,000 m water depth. The OFOS was towed along five transects crossing the channel, and two transects along the channel axis (Table 1). The OFOS frame was equipped with a still camera (Benthos), which was triggered manu- ally or at 30-s intervals, allowing for up to 800 shots per track (Kodak Ektachrome 100 ASA slide film). ...
Context 2
... for ground-truthing were collected Fig. 1 Study sites in the proximal part of the Ardencaple Canyon east off Greenland; location of the sampling stations (numbers in the circles represent abbreviated station numbers, e.g. 71 = PS57-71; see also Table 1) Polar Biol nearby by a small Agassiz trawl in 2002 (for details see Krause and Schauer 2000;Fahrbach 2002). ...
Citations
... An experiment conducted in the LTER (long-Term Ecological Research) area of HAUSGAR-TEN, Meyer-Kaiser et al. (2019) showed that on abandoned steel structure the number of comatulid crinoids attributed to Poliometra prolixa was significantly higher than at the bottom surface. In Fram Strait where the hard substrate is limited, P. prolixa has been frequently observed on stones and as an epibiont on sponges (Meyer et al. 1984(Meyer et al. , 2014(Meyer et al. , 2016Schulz et al. 2010). Bottom currents are essential for benthic organisms to disperse, reproduce, and feed (Eléaume et al. (Schander et al. 2010). ...
This publication presents an unusual behavior of a comatulid crinoid that was tentatively attributed to Heliometria glacialis (Echinodermata, Crinoidea, Heliometrinae). This unstalked crinoid was observed clinging on Hyas sp. crabs in the inner part of the Spitsbergen fjords heavily loaded with suspension runoff. In situ observations were made using a 16-h and 45-min time-lapse sequence showing the decompositions of Atlantic cod. During the exposure, apart from typical organisms such as carrion crustaceans, crabs, and starfish, three individuals of crinoids were observed. One of the crinoids was clinging to the edge of the platform for most of the exposure. The remaining two individuals were observed attached to the carapace of Hyas sp. crabs for 6 h 55 min. It was also found, based on analysis of the video material from 202 locations examined in the summer season between 2015 and 2020 using a drop camera, two additional locations showing comatulid crinoids. Both locations in the Ekmanfjorden and in the interior of the Vanmijenfjorden are areas under the strong influence of a glacier meltwater plum or a glacial river runoff. So far, comatulid crinoids have been found mainly in locations outside of the influence of turbid waters from fjords. We interpret this new behavior within comatulid crinoids as an adaptation that help colonize new regions gradually exposed by the retreating glaciers.
... In an experiment conducted in the LTER (long-Term EcologicalResearch) area of HAUSGARTEN, Meyer-Kaiser, K. et al. 2019 showed that on the previously abandoned steel structure on the panels mounted above, the number of P. prolixa was signi cantly higher than at the bottom surface. In Fram strait where the hard substrate is limited, P. prolixa has been frequently observed on stones and as an epibiont on sponges(Schulz et al. 2010;Meyer et al. 2014Meyer et al. , 2016. Bottom currents are essential for benthic organisms to disperse, reproduce and feed(Eléaume et al. 2011). ...
This publication presents a possibly never-before-recorded new behaviour, adaptations of the filter feeder crinoid using Hyas crabs in the inner, heavily loaded with suspension runoff part of the Spitsbergen fjords. The work used a 16-hour and 45-minute time-lapse sequence showing the decompositions of Atlantic Cod . During the exposure, apart from typical organisms such as carrion crustaceans, crabs and starfish, several individuals of crinoids were observed. One of the crinoids attached its cirri to the edge of the platform for most of the exposure. The remaining individuals observed attached to the carapace of Hyas crabs for 6 hours 55 minutes. It was also found, basis on analysis of the video material from 202 locations examined in the summer season between 2015-2020 using a drop camera, additionally two locations with a positive occurrence of a comatulida. Both locations in the Ekmanfjorden and in the interior of the Vanmijenfjorden are areas under the strong influence of a glacier or a glacial river. So far, the occurrence of crinoids has been found mainly in locations outside of the influence of turbid waters from fjords. We believe that the new observation of the comatulida behaviour will allow it to colonize new regions gradually exposed by the retreating glaciers.
... Litter on the seafloor can cause anoxia to the underlying sediment, which could alter biogeochemistry and benthic community structure (Green et al. 2015). Simultaneously, it has the potential to serve as a substrate for the attachment of sessile biota in sedimentary environments and to thereby alter community structure and biodiversity (Schulz et al. 2010;Mordecai et al. 2011;Song et al. 2021). Debris from fisheries in particular represents a threat to mobile biota through processes such as ghost fishing, increasing benthic mortality (Matsuoka et al. 2005). ...
... Plastic litter has also been sporadically recorded off the East Greenland slope (Schulz et al. 2010). In 2002, the HAUSGARTEN observatory was established in the eastern Fram Strait with 21 stations located at depths between 250 and 5500 m and has provided time-series data for litter (Bergmann and Klages 2012;Tekman et al. 2017). ...
Marine litter in the Arctic Basin is influenced by transport from Atlantic and Pacific waters. This highlights the need for harmonization of guidelines across regions. Monitoring can be used to assess temporal and spatial trends but can also be used to assess if environmental objectives are reached, for example, to evaluate the effectiveness of mitigation measures. Seafloor monitoring by trawling needs substantial resources and specific sampling strategies to be sufficiently robust to demonstrate changes over time. Observation and visual evaluation in shallow and deep waters using towed camera systems, remotely operated underwater vehicles, and submersibles are well suited for the Arctic environment. The use of imagery still needs to be adjusted through automation and image analyses, including deep learning approaches and data management, but will also serve to monitor areas with a rocky seafloor. We recommend developing a monitoring plan for seafloor litter by selecting representative sites for visual inspection that cover different depths and substrata in marine landscapes, and recording the litter collected or observed across all forms of seafloor sampling or imaging. We need better coverage and knowledge of status of seafloor litter for the whole Arctic and recommend initiatives to be taken for regions where such knowledge is lacking.
... Macrofauna communities at SLOPE stations (1900-3500 m) was also dominated by deposit-feeders, accompanied by a higher proportion of sessile species compared to other depth zones. Large proportions of sessile filter feeders (e.g., Thenea abyssorum, Sycon sp.) can be related to occurrence of drop stones, which provide hard substrates to anchor at sea floor (Schulz et al., 2010;Zhulay et al., 2021). Temporal differences were mainly associated with 'Body form' and 'Living habit', with higher a proportion of tube-dwelling vermiform species before the WWA, and a higher proportion of attached globulose and free-living species after the WWA. ...
This is the first study presenting temporal changes of the macrofauna biodiversity along the bathymetric gradient from the shelf to abyssal depths in the eastern Fram Striat. In this region, between 2004 and 2008, a significant increase in surface water temperature was observed due to the transport of Atlantic water from lower latitudes and was defined as a Warm Water Anomaly (WWA). Effects of the WWA in the eastern Fram Strait were observed across the entire food web, from the pelagic to the deep seafloor. The material for our study was collected before (in 2000) and after the WWA (in 2010 and 2017) at station depths ranging from 203 m to 5561 m. Samples of macrofauna and surface sediments were collected with use of a box corer to analyze species composition and functional traits, and environmental characteristics in sediments. We explore the influence of environmental changes on the structure (species composition and diversity) and functioning (functional trait composition and diversity) of macrofauna communities. An increase of primary production in surface waters during and after the WWA was reflected in a higher food availability at the seafloor from shelf to abyssal depths. Warming induced environmental changes led to an increase of macrofauna density and taxonomic diversity at all water depths. Macrofauna species composition significantly changed after the WWA. At all study sites, macrofauna functional diversity increased after the warm period. Functional trait composition changed significantly along the bathymetric transect. Despite changes in the taxonomic composition, macrofauna communities at the shallowest stations showed high functional redundancy, i.e., trait composition remained unchanged after the WWA. At water depths below 1500 m, where functional redundancy was significantly lower, functional trait composition changed significantly after the WWA. Our results suggest that macrofauna communities on the shelves are more resistant to environmental changes compared to deep-sea assemblages in the eastern Fram Strait.
... At the West Antarctic Peninsula margin, for instance, dropstones contribute 20% to the total megabenthic species richness, though they cover less than 1% of the investigated seafloor 30 . They may also increase epifaunal density, for instance in the Ardencaple Canyon in the Greenland Sea, where epifaunal density is positively correlated with the size of hard substrate 31 . In fact, dropstones can even modify hydrodynamics that lead to increased food supply to parts of the surrounding sediment and affect trophic structure, diversity, and life-history traits of nematodes 26 . ...
Polymetallic nodule fields provide hard substrate for sessile organisms on the abyssal seafloor between 3000 and 6000 m water depth. Deep-seabed mining targets these mineral-rich nodules and will likely modify the consumer-resource (trophic) and substrate-providing (non-trophic) interactions within the abyssal food web. However, the importance of nodules and their associated sessile fauna in supporting food-web integrity remains unclear. Here, we use seafloor imagery and published literature to develop highly-resolved trophic and non-trophic interaction webs for the Clarion-Clipperton Fracture Zone (CCZ, central Pacific Ocean) and the Peru Basin (PB, South-East Pacific Ocean) and to assess how nodule removal may modify these networks. The CCZ interaction web included 1028 compartments connected with 59,793 links and the PB interaction web consisted of 342 compartments and 8044 links. We show that knock-down effects of nodule removal resulted in a 17.9% (CCZ) to 20.8% (PB) loss of all taxa and 22.8% (PB) to 30.6% (CCZ) loss of network links. Subsequent analysis identified stalked glass sponges living attached to the nodules as key structural species that supported a high diversity of associated fauna. We conclude that polymetallic nodules are critical for food-web integrity and that their absence will likely result in reduced local benthic biodiversity.
... In addition to direct impacts, icebergs sometimes release large dropstones as they melt, distributing additional hard substrates across the seafloor. Dropstones from previous calving episodes (e.g. during the past deglaciation) have been shown to provide habitat for sessile invertebrates in both the Antarctic and the Arctic (Starmans et al., 1999;Schulz et al., 2010). Dropstones can be associated with significant increases in the abundance and diversity of taxa (Ziegler et al. 2017) and could promote increased settlement of sessile invertebrates across areas of otherwise soft substrate (Dayton, 1990;Post et al., 2017). ...
Knowledge of life on the Southern Ocean seafloor has substantially grown since the beginning of this century with increasing ship-based surveys and regular monitoring sites, new technologies and greatly enhanced data sharing. However, seafloor habitats and their communities exhibit high spatial variability and heterogeneity that challenges the way in which we assess the state of the Southern Ocean benthos on larger scales. The Antarctic shelf is rich in diversity compared with deeper water areas, important for storing carbon (“blue carbon”) and provides habitat for commercial fish species. In this paper, we focus on the seafloor habitats of the Antarctic shelf, which are vulnerable to drivers of change including increasing ocean temperatures, iceberg scour, sea ice melt, ocean acidification, fishing pressures, pollution and non-indigenous species. Some of the most vulnerable areas include the West Antarctic Peninsula, which is experiencing rapid regional warming and increased iceberg-scouring, subantarctic islands and tourist destinations where human activities and environmental conditions increase the potential for the establishment of non-indigenous species and active fishing areas around South Georgia, Heard and MacDonald Islands. Vulnerable species include those in areas of regional warming with low thermal tolerance, calcifying species susceptible to increasing ocean acidity as well as slow-growing habitat-forming species that can be damaged by fishing gears e.g., sponges, bryozoan, and coral species. Management regimes can protect seafloor habitats and key species from fishing activities; some areas will need more protection than others, accounting for specific traits that make species vulnerable, slow growing and long-lived species, restricted locations with optimum physiological conditions and available food, and restricted distributions of rare species. Ecosystem-based management practices and long-term, highly protected areas may be the most effective tools in the preservation of vulnerable seafloor habitats. Here, we focus on outlining seafloor responses to drivers of change observed to date and projections for the future. We discuss the need for action to preserve seafloor habitats under climate change, fishing pressures and other anthropogenic impacts.
... Rather, the large (several orders of magnitude) difference in densities between life stages suggests either patchy settlement of larvae of P. prolixa or high mortality during the early life history stages of this species. Hard substrata in the Fram Strait are isolated and island-like, and adults of P. prolixa are frequently observed resting on stones or as epibionts on sponges (Meyer et al., 2014(Meyer et al., , 2016Schulz et al., 2010). These adults may release competent larvae when they encounter a settlement substratum, resulting in patchy distributions. ...
Poliometra prolixa is a common species of comatulid crinoid in the Arctic deep sea. In this study, we characterize the ontogenetic development through the cystidean and pentacrinoid stages, using specimens from the LTER (Long‐Term Ecological Research) observatory HAUSGARTEN in the Fram Strait, Arctic Ocean. While embryos and early larval stages (e.g., the doliolaria) were not observed, both post‐settlement stages and adults of P. prolixa were observed on the same moored experimental platform at 2,500 m water depth, suggesting that larvae of P. prolixa do not disperse far from their mothers. This indicates that doliolariae may have an abbreviated pelagic duration period or may be brooded in this species. The cystidean has a short, translucent stalk with a star‐shaped attachment disc and a diamond‐shaped translucent head. Metamorphosis from the cystidean to the pentacrinoid is characterized by the formation of brachial ossicles from oral ossicles and by fusion of the basal and radial ossicles to form the calyx. The pentacrinoid stalk is opaque and first develops synarthrial joints at the distal end. Late pentacrinoids have a xenomorphic stalk, bifurcated arms with pinnules, and cirri. We discuss the reproductive and ecological niche of P. prolixa and also consider the question of whether cystidean and pentacrinoid stages undergo metamorphosis.
... Similar faunal characteristics, i.e. high proportions of sessile filterfeeding macrofauna, were also found at stations on the NE Greenland continental margin. Generally, coarser sediments and the increased occurrence of dropstones from sea-ice melting in this area might further promote filter-feeding organisms like the actiniarian Bathyphellia margaritacea and the poriferans Clathrina sp. and Sycon sp., which need hard-substrates to anchor to the seafloor (Barthel and Tendal, 1993;Schulz et al., 2010). Together with the sponge species Thenea abyssorum, these taxa show increased densities on the NE Greenland continental margin. ...
Deep-sea regions provide vast ecosystem services such as biological habitat and nutrient cycling. Even though being threatened by climate change and facing possible biodiversity loss, these deep-sea ecosystems are poorly understood. So are macrobenthic communities and their functions within these ecosystems. Biodiversity and ecosystem function relationships as well as their link to environmental drivers can be assessed with the biological trait analysis. We used this approach for the first time for macrofauna assemblages across the deep Fram Strait between Greenland and Svalbard (1000–5500 m water depth) to evaluate their community-specific function from the upper continental slope down to the deepest known Arctic depression, the Molloy Deep. We aimed to investigate whether there are changes in benthic functioning along the bathymetric gradient and if so, which environmental stressors may drive these changes.
In total, 16 stations were sampled with a giant box corer (0.25 m2) in 2016 and 2018. Sediments were sieved through a 0.5 mm mesh size sieve and fauna was identified to lowest possible taxonomic entity. Functions of species were characterized by using six traits split in 24 modalities gathered in a fuzzy coded species × traits array. Environmental parameters shaping the benthic habitat and reflecting food availability were gathered from remote sensing, mooring deployments, and sediment sampling.
A distance-based redundancy analysis indicated near-bottom water temperature, seabed inclination, water depth as well as phytodetritial matter at the sea surface and seafloor (indicating food availability) to be the best variables explaining the trait and station distribution. Stations clustered into three groups based on their trait composition. Shallower stations characterized by high chlorophyll a concentration with large organisms, living within the sediment as well as predating specimens clustered in one group. A second group was characterized by stations with low chlorophyll a concentration and medium-sized, suspension feeding, epifaunal living macrofauna. A third group comprised stations with water depths ≥ 3000 m and was dominated by medium sized, surface deposit feeding and infaunal living specimens.
Overall, the functional structure of macrofauna communities in the Fram Strait followed a food availability-driven gradient. Based on the relationship between sea ice, surface water primary production and food availability at the seafloor, these results point to macrobenthos being sensible to predicted anthropogenically generated environmental variations in polar regions. Alterations in benthic ecosystem functions might be expected when environmental conditions change.
... Despite the paucity of information, there is an increasing awareness that the seafloor and, in particular, the deep seafloor is a major sink for marine litter (Galgani 2015, Lebreton et Lenihan et al 1990, Nel and Nel 1999, Schulz et al 2010, Ivar Do Sul et al 2011, Bergmann and Klages 2012, Parga Martínez et al 2020 and also in the deepest ocean parts, such as the Mariana Trench where a plastic bag was filmed at ca. 10 900 m depth (Chiba et al 2018). Deep-water ROV surveys have shown that in some areas litter abundance numerically exceeds that of macrobiota (Tubau et al 2015, Pierdomenico et al 2019 whereas in other areas trawl surveys have found megafaunal biomass to be similar to the total litter weight (Cau et al 2018). ...
The seafloor covers some 70% of the Earth's surface and has been recognized as a major sink for marine litter. Still, litter on the seafloor is the least investigated fraction of marine litter, which is not surprising as most of it lies in the deep sea, i.e. the least explored ecosystem. Although marine litter is considered a major threat for the oceans, monitoring frameworks are still being set up. This paper reviews current knowledge and methods, identifies existing needs, and points to future developments that are required to address the estimation of seafloor macrolitter. It provides background knowledge and conveys the views and thoughts of scientific experts on seafloor marine litter offering a review of monitoring and ocean modeling techniques. Knowledge gaps that need to be tackled, data needs for modeling, and data comparability and harmonization are also discussed. In addition, it shows how research on seafloor macrolitter can inform international protection and conservation frameworks to prioritize efforts and measures against marine litter and its deleterious impacts.
... The Arctic region has long been considered a pristine environment, relatively undisturbed by humans. However, recent studies have shown that plastic debris has reached the Arctic oceanic and sea-ice environments, and its wildlife (Schulz et al. 2010;Obbard et al. 2014;Lusher et al. 2015;Trevail et al. 2015b;Bergmann et al. 2017a;Bergmann et al. 2017c;Buhl-Mortensen & Buhl-Mortensen 2017;Cózar et al. 2017). A suggested presence of an accumulation area in the Barents Sea was supported by Cózar et al. (2017) with recent field data and additional modelling indicating a peak accumulation of plastic in the vicinity of Svalbard and Novaya Zemlya. ...
In the framework of the EU JPI PLASTOX project, this PhD project focused on the effects of ingested plastic on marine wildlife and in particular the northern fulmar (Fulmarus glacialis). Plastic ingestion by fulmars was studied on Iceland and on Svalbard. Trophic transfer of plastic between predators and their prey was explored, by quantifying plastics ingested by prey fish from the Arctic Ocean and the North Sea. Ingested plastics were categorized according to their material characteristics. A mixture of relevant microplastics was created to be used in environmental impact studies. Experiments were conducted to investigate the transfer of chemicals from ingested plastic to northern fulmars. Furthermore an updated literature overview of species affected by plastics is provided.
