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Microplastics (MP) are recognized as a growing environmental hazard and have been identified as far as the remote Polar Regions, with particularly high concentrations of microplastics in sea ice. Little is known regarding the horizontal variability of MP within sea ice and how the underlying water body affects MP composition during sea ice growth. Here we show that sea ice MP has no uniform polymer composition and that, depending on the growth region and drift paths of the sea ice, unique MP patterns can be observed in different sea ice horizons. Thus even in remote regions such as the Arctic Ocean, certain MP indicate the presence of localized sources. Increasing exploitation of Arctic resources will likely lead to a higher MP load in the Arctic sea ice and will enhance the release of MP in the areas of strong seasonal sea ice melt and the outflow gateways. Microplastic (MP) pollution in polar regions is a growing environmental concern, yet little is known regarding the role of sea-ice as a sink and transport vector of MPs. Here, the authors show that MPs in sea-ice have no uniform polymer composition and observe unique MP patterns in different sea-ice horizons.

The seafloor covers some 70% of the Earth’s surface and has been recognised 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 modelling techniques. Knowledge gaps that need to be tackled, data needs for modelling, and data comparability and harmonisation are also discussed. In addition, it shows how research on seafloor macrolitter can inform international protection and conservation frameworks to prioritise efforts and measures against marine litter and its deleterious impacts.

Plastic debris is ubiquitous in all ecosystems and has even reached locations that humans will hardly reach such as the deep ocean floor and the atmosphere. Research has highlighted that plastic debris is now pervasive even in remote Arctic regions. While modeling projections indicated local sources and long-distance transport as causes, empirical data about its origin and sources are scarce. Data collected by citizen scientists can increase the scale of observations, especially in such remote regions. Here, we report abundance and composition data of marine debris collected by citizen scientists on 14 remote Arctic beaches on the Spitsbergen archipelago. In addition, citizen scientists collected three large, industrial sized canvas bags (hereafter: big packs), filled with beached debris, of which composition, sources and origin were determined. A total debris mass of 1,620 kg was collected on about 38,000 m 2 (total mean = 41.83 g m -2 , SEM = ± 31.62). In terms of abundance, 23,000 pieces of debris were collected on 25,500 m 2 (total mean = 0.37 items of debris m -2 , SEM = ± 0.17). Although most items were plastic in both abundance and mass, fisheries waste, such as nets, rope, and large containers, dominated in mass (87%), and general plastics, such as packaging and plastic articles, dominated in abundance (80%). Fisheries-related debris points to local sea-based sources from vessels operating in the Arctic and nearby. General plastics could point to both land- and ship based sources, as household items are also used on ships and debris can be transported to the north via the oceans current. Overall, 1% of the items (206 out of 14,707 pieces) collected in two big packs (2017 and 2021), bore imprints or labels allowing an analysis of their origin. If the categories ‘global’ and ‘English language’ were excluded, most of identifiable items originated from Arctic states (65%), especially from Russia (32%) and Norway (16%). But almost a third of the items (30%) was of European provenance, especially from Germany (8%). Five percent originated from more distant sources (e.g. USA, China, Korea, Brazil). Global measures such as an efficient and legally binding plastic treaty with improved upstream measures and waste management are urgently needed, to lower the amount of plastic entering our environments and in turn lifting the pressure on the Arctic region and its sensitive biota.

The ocean moderates the world’s climate through absorption of heat and carbon, but how much carbon the ocean will continue to absorb remains unknown. The North Atlantic Ocean west (Baffin Bay/Labrador Sea) and east (Fram Strait/Greenland Sea) of Greenland features the most intense absorption of anthropogenic carbon globally; the biological carbon pump (BCP) contributes substantially. As Arctic sea-ice melts, the BCP changes, impacting global climate and other critical ocean attributes (e.g. biodiversity). Full understanding requires year-round observations across a range of ice conditions. Here we present such observations: autonomously collected Eulerian continuous 24-month time-series in Fram Strait. We show that, compared to ice-unaffected conditions, sea-ice derived meltwater stratification slows the BCP by 4 months, a shift from an export to a retention system, with measurable impacts on benthic communities. This has implications for ecosystem dynamics in the future warmer Arctic where the seasonal ice zone is expected to expand. The North Atlantic biological pump has the most intense absorption of C globally, but how this will fare in light of climate changes (especially sea-ice melting) is poorly understood. Here the authors present a 24-month continuous time series of physical, chemical, and biological observations in the Fram Strait.

Anthropogenic litter is present in all marine habitats, from beaches to the most remote points in the oceans. On the seafloor, marine litter, particularly plastic, can accumulate in high densities with deleterious consequences for its inhabitants. Yet, because of the high cost involved with sampling the seafloor, no large-scale assessment of distribution patterns was available to date. Here, we present data on litter distribution and density collected during 588 video and trawl surveys across 32 sites in European waters. We found litter to be present in the deepest areas and at locations as remote from land as the Charlie-Gibbs Fracture Zone across the Mid-Atlantic Ridge. The highest litter density occurs in submarine canyons, whilst the lowest density can be found on continental shelves and on ocean ridges. Plastic was the most prevalent litter item found on the seafloor. Litter from fishing activities (derelict fishing lines and nets) was particularly common on seamounts, banks, mounds and ocean ridges. Our results highlight the extent of the problem and the need for action to prevent increasing accumulation of litter in marine environments.

Plastic production and plastic waste have increased to such an extent that it has become globally ubiquitous. Recent research has highlighted that it has also invaded remote Polar Regions including the Arctic, where it is expected to accumulate over time due to transport from distant sources, rising local anthropogenic activities and increasing fragmentation of existing ocean plastics to microplastics (plastic items <5 mm). While a growing body of research has documented microplastics in the atmosphere, cryosphere, sea surface, water column, sediments and biota, contamination levels on Arctic beaches are poorly known. To fill this knowledge gap, we engaged citizen scientists participating in tourist cruises to sample beach sediments during shore visits on Svalbard, Norway. Following drying, sieving, and visual inspection of samples under a binocular microscope, putative plastic particles ≥1 mm were analysed by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Plastic particles ≥1 mm were found in two out of 53 samples from 23 beaches (mean: 196.3 particles kg −1 and 147.4 particles L −1 ). These pollution levels could be due to our focus on plastic particles ≥1 mm as well as the relatively small sample sizes used during this initial phase of the project. In addition, the coarse substrate on most beaches might retain fewer plastic particles. The two samples with plastic particles ≥1 mm contained six polyester-epoxide particles and 4920 polypropylene fibres. The latter likely originated from a fishing net and points to possibly accelerated plastic fragmentation processes on Arctic beaches. Since fisheries-related debris is an important source of plastic on Svalbard, a build-up of microplastic quantities can be expected to burden Arctic ecosystems in addition to climate change unless efficient upstream action is taken to combat plastic pollution.

Megafauna play an important role in benthic ecosystem function and are sensitive indicators of environmental change. Non-invasive monitoring of benthic communities can be accomplished by seafloor imaging. However, manual quantification of megafauna in images is labor-intensive and therefore, this organism size class is often neglected in ecosystem studies. Automated image analysis has been proposed as a possible approach to such analysis, but the heterogeneity of megafaunal communities poses a non-trivial challenge for such automated techniques. Here, the potential of a generalized object detection architecture, referred to as iSIS (intelligent Screening of underwater Image Sequences), for the quantification of a heterogenous group of megafauna taxa is investigated. The iSIS system is tuned for a particular image sequence (i.e. a transect) using a small subset of the images, in which megafauna taxa positions were previously marked by an expert. To investigate the potential of iSIS and compare its results with those obtained from human experts, a group of eight different taxa from one camera transect of seafloor images taken at the Arctic deep-sea observatory HAUSGARTEN is used. The results show that inter- and intra-observer agreements of human experts exhibit considerable variation between the species, with a similar degree of variation apparent in the automatically derived results obtained by iSIS. Whilst some taxa (e. g. Bathycrinus stalks, Kolga hyalina, small white sea anemone) were well detected by iSIS (i. e. overall Sensitivity: 87%, overall Positive Predictive Value: 67%), some taxa such as the small sea cucumber Elpidia heckeri remain challenging, for both human observers and iSIS.

Floating marine debris is ubiquitous in marine environments but knowledge about quantities in remote regions is still limited. Here, we present the results of an extensive survey of floating marine debris by experts, trained scientists from fields other than pollution or non-professional citizen scientists. A total of 276 visual ship-based surveys were conducted between 2015 and 2020 in the Northeast (NE) Atlantic from waters off the Iberian Peninsula to the Central Arctic, however, with a focus on Arctic waters. Spatiotemporal variations among regional seas (Central Arctic, Barents Sea, Greenland Sea, Norwegian Sea, North Sea) and oceanic regions (Arctic waters and the temperate NE Atlantic) were explored. The overall median debris concentration was 11 items km -2 , with considerable variability. The median concentration was highest in the North Sea with 19 items km -2 . The Nordic seas, except the Central Arctic showed median concentrations ranging from 9 to 13 items km -2 . Plastic accounted for 91% of all floating items. Miscellaneous fragments, films, ropes and nets, packaging materials, expanded polystyrene and straps were the most frequently observed plastic types. Although the median debris concentration in the Central Arctic was zero, this region was not entirely free of floating debris. The variations between regional seas and oceanic regions were statistically not significant indicating a continuous supply by a northward transportation of floating debris. The data show a slight annual decrease and clear seasonal differences in debris concentrations with higher levels observed during summer. A correlation between debris concentrations and environmental and spatial variables was found, explaining partly the variability in the observations. Pollution levels were 500 times lower than those recorded on the seafloor indicating the seafloor as a sink for marine debris. The Arctic was characterised by similar pollution levels as regions in temperate latitudes highlighting that Arctic ecosystems face threats from plastic pollution, which add to the effects of rapid climate change.

Abstract Study Objectives To evaluate macro sleep architecture and characterize rapid eye movement (REM) sleep without atonia (RWA) by using the SINBAR excessive electromyographic (EMG) montage including mentalis and upper extremity muscles in early and advanced Parkinson’s disease (PD). Methods We recruited 30 patients with early- and advanced-stage of PD according to Movement Disorder Society (MDS) Clinical Diagnostic Criteria. Participants were classified as early-stage PD if they were treatment-naïve or had no motor complications and had been diagnosed with PD within the previous 6 years. Advanced PD was defined as a disease duration equal to or >6 years with or without motor complications. Results There was significantly shorter REM sleep latency in early as compared to the advanced stage of PD. We found that the sleep Innsbruck Barcelona (SINBAR) EMG index and tonic EMG activity of the mentalis muscle in advanced-stage PD were significantly higher than in early-stage PD with a trend in phasic EMG activity of the flexor digitorum superficialis muscles. The SINBAR EMG index, tonic and any EMG activity of the mentalis muscle, and phasic EMG activity of flexor digitorum superficialis muscles significantly correlated with disease duration. Conclusions This study analyzed RWA using the SINBAR EMG montage in early- and advanced-stage of PD and showed higher RWA in mentalis and flexor digitorum superficialis muscles and SINBAR EMG index in advanced-PD patients compared to patients in the early stage. Also, polysomnography-confirmed REM sleep behavior disorder was more common in advanced versus early-stage patients. Our findings suggest that RWA worsens or is more intense or more frequent with disease progression.

Plastic production and plastic waste have increased to such an extent that it has become globally ubiquitous. Several studies already have investigated the meso- and microplastic pollution along the German Baltic and North Sea coasts, but were all limited to a few locations. To obtain representative bulk samples from sandy beaches along the entire German coast, we initiated a citizen-science project entitled “Microplastic Detectives.” Here, we describe in detail 1) how we recruited, instructed, and engaged citizen scientists, 2) why we chose bulk sampling over reduced-volume sampling, and 3) the laboratory methods we used. The citizen scientists collected 1,139 samples from 71 locations along the German coast, totalling 2.2 tons of sand. After drying, sieving with a 1 mm sieve, and visual inspection of the retained fraction under a binocular microscope, all putative plastic particles ≥1 mm were analysed by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. 177 out of 1,139 samples (15.5%) contained a total of 260 plastic particles, with a large right-skewed variation among locations. Most of the particles were fragments, foils, foams, fibres, and pellets (96.2% in total), and 89.6% of the particles were made of polyethylene, polypropylene, polyester, and polystyrene. The unweighted mean pollution densities were 4.12 particles m −2 , 0.17 particles kg −1 and 0.27 particles L −1 , and the weighted mean pollution densities were 3.77 particles m −2 , 0.11 particles kg −1 and 0.18 particles L −1 . These densities are lower than in other similar studies, but previous studies had important methodological differences. We discuss how these differences could have influenced the results and make recommendations for improving future studies. Two important recommendations are 1) to use random or stratified random sampling and 2) to run transects perpendicular (rather than parallel) to the waterline. Our study highlights that large-scale, scientifically rigorous monitoring of meso- and microplastic pollution is possible at the national level, and possibly even at much larger spatial and temporal scales. With the help of local authorities, such a monitoring program could be established.