Description: Epibenthic megafauna play an important role in the deep-sea environment and contribute significantly to benthic biomass, but their population dynamics are still understudied. We used a towed deep-sea camera system to assess the population densities of epibenthic megafauna in 2002, 2007, and 2012 at the shallowest station (HG I, ∼1300 m) of the deep-sea observatory HAUSGARTEN, in the eastern Fram Strait. Our results indicate that the overall density of megafauna was significantly lower in 2007 than in 2002, but was significantly higher in 2012, resulting in overall greater megafaunal density in 2012. Different species showed different patterns in population density, but the relative proportions of predator/scavengers and suspension-feeding individuals were both higher in 2012. Variations in megafaunal densities and proportions are likely due to variation in food input to the sea floor, which decreased slightly in the years preceding 2007 and was greatly elevated in the years preceding 2012. Both average evenness and diversity increased over the time period studied, which indicates that HG I may be food-limited and subject to bottom-up control. The community of HG I may be unique in its response to elevated food input, which resulted in higher evenness and diversity in 2012.

Description: During a survey of the H°akon Mosby mud volcano (HMMV), located on the Bear Island fan in the southwest Barents Sea at �1250m water depth, different habitats inside the volcano caldera and outside it were hotographed using a towed camera platform, an Ocean Floor Observation System (OFOS). Three transects were performed across the caldera and one outside, in the background area, each transect was �2 km in length. We compared the density, taxa richness and diversity of nonsymbiotrophic megafauna in areas inside the volcano caldera with different bacterial mat and pogonophoran tubeworm cover. Significant variations in megafaunal composition, density and distribution were found between considered areas. Total megafaunal density was highest in areas of dense pogonophoran populations (mean 52.9 ind.m−2) followed by areas of plain light-coloured sediment that were devoid of bacterial mats and tube worms (mean 37.7 ind.m−2). The lowest densities were recorded in areas of dense bacterial mats (mean �1.4 ind.m−2). Five taxa contributed to most of the observed variation: the ophiuroid Ophiocten gracilis, lysianassid amphipods, the pycnogonid Nymphon macronix, the caprellid Metacaprella horrida and the fish Lycodes squamiventer. In agreement with previous studies, three zones within the HMMV caldera were distinguished, based on different habitats and megafaunal composition: “bacterial mats”, “pogonophoran fields” and “plain light-coloured sediments”. The zones were arranged almost concentrically around the central part of the caldera that was devoid of visible megafauna. The total number of taxa showed little variation inside (24 spp.) and outside the caldera (26 spp.). The density, diversity and composition of megafauna varied substantially between plain lightcoloured sediment areas inside the caldera and the HMMV background. Megafaunal density was lower in the background (mean 25.3 ind.m−2) compared to areas of plain light-coloured sediments inside the caldera. So the effect of the mud-volcano environment on benthic communities is expressed in increasing of biomass, changing of taxa composition and proportions of most taxonomic groups.

Description: The purpose of the guidelines is to review existing knowledge and provide guidance for designing an Arctic monitoring program that will track litter and MP. The topics of litter, plastic pollution, and MP are addressed in many fora, including several of the Arctic Council working groups: Arctic Monitoring and Assessment Programme (AMAP; https://www.amap.no/documents/doc/amap-assessment-2016-chemicals-of-emerging-arctic-concern/1624), Protection of the Marine Environment (PAME, 2019), and Conservation of the Arctic Flora and Fauna (CAFF). The development of an Arctic monitoring program and its technical approaches will be based on the work that already exists in other programs such as those of OSPAR, the Helsinki Commission (HELCOM), the International Council for the Exploration of the Sea (ICES), the Organisation for Economic Co-operation and Development (OECD), and the United Nations Environment Programme (UNEP). Plastic pollution is typically categorized into items and particles of macro-, micro-, and nano-sizes. These guidelines address macrosized litter as well as MP (〈 5 mm), essentially including smaller size ranges (〉1 µm). However, determination of nanoplastic (〈 1 µm) particles is still hampered by technical challenges, as addressed in Section 4.3 Analytical methods, and thus not currently considered in the current recommendations. Although most studies have addressed marine litter and MP, these guidelines also comprise the Arctic’s terrestrial and freshwater environments. Thus, the objectives of the guidelines are to: 1) support litter and MP baseline mapping in the Arctic across a wide range of environmental compartments to allow spatial and temporal comparisons in the coming years; 2) initiate monitoring to generate data to assess temporal and spatial trends; 3) recommend that Arctic countries develop and implement monitoring nationally via community-based programs and other mechanisms, in the context of a pan-Arctic program; 4) provide data that can be used with the Marine Litter Regional Action Plan (ML-RAP) to assess the effectiveness of mitigation strategies; 5) act as a catalyst for future work in the Arctic related to biological effects of plastics, including determining environmentally relevant concentrations and informing cumulative effects assessments; 6) identify areas in which research and development are needed from an Arctic perspective; and 7) provide recommendations for monitoring programs whose data will feed into future global assessments to track litter and MP in the environment. To achieve these objectives, the guidelines present indicators (with limitations) of litter and MP pollution to be applied throughout the Arctic, and thus, form the basis for circumpolar comparability of approaches and data. In addition, the guidelines present technical details for sampling, sample treatment, and plastic determination, with harmonized and potentially standardized approaches. Furthermore, recommendations are given on sampling locations and sampling frequency based on best available science to provide a sound basis for spatial and temporal trend monitoring. As new data are gathered, and appropriate power analyses can be undertaken, a review of the sampling sizes, locations, and frequencies should be initiated. Plastic pollution is a local problem in Arctic communities, and thus, guidelines and references need to include community-based monitoring projects to empower communities to establish plastics monitoring with comparable results across the Arctic. Community-based monitoring is an integrated part of the objectives of this report. The monitoring program design and guidelines for its implementation are the necessary first steps for monitoring and assessment of litter and MP in the Arctic. The work under the AMAP LMEG is taking a phased approach under this new expert group. The first phase (which included the development of these Monitoring Guidelines) focuses on a monitoring framework and set of techniques for physical plastics. Later phases of the work will extend to assessments of levels, trends, and effects of litter and MP in the Arctic environment. The guidelines strictly cover environmental monitoring of litter and MP. This does not include drinking water or indoor air quality tests. Additionally, although there is an emphasis on examining litter and MP in biota that are consumed by humans, and thus of interest to human-health questions, the guidelines do not consider MP ingestion by humans.

Description: 〈jats:p〉 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, ROVs 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. 〈/jats:p〉

Description: Litter and microplastic assessments are being carried out worldwide. Arctic ecosystems are no exception and plastic pollution is high on the Arctic Council’s agenda. Water and sediment have been identified as two of the priority compartments for monitoring plastics under the Arctic Monitoring and Assessment Programme (AMAP). Recommendations for monitoring both compartments are presented in this publication. Alone, such samples can provide information on presence, fate, and potential impacts to ecosystems. Together, the quantification of microplastics in sediment and water from the same region produce a three-dimensional picture of plastics, not only a snapshot of floating or buoyant plastics in the surface water or water column but also a picture of the plastics reaching the shoreline or benthic sediments, in lakes, rivers, and the ocean. Assessment methodologies must be adapted to the ecosystems of interest to generate reliable data. In its current form, published data on plastic pollution in the Arctic is sporadic and collected using a wide spectrum of methods which limits the extent to which data can be compared. A harmonised and coordinated effort is needed to gather data on plastic pollution for the Pan-Arctic. Such information will aid in identifying priority regions and focusing mitigation efforts.