Arthropods (e.g., shrimps, crabs, sea spiders, amphipods, isopods) dominate taxon numbers in all Arctic regions, followed by polychaetes (e.g., bristle worms) and mollusks (e.g., gastropods, bivalves). Other taxon groups are diverse in some regions, such as bryozoans in the Kara Sea, cnidarians in the Atlantic Arctic, and foraminiferans in the Arctic deep-sea basins. This pattern is biased, however, by the meiofauna inclusion for the Arctic Basin (macro- and meiofauna size ranges overlap substantially in deep-sea fauna, so nematodes and foraminiferans are included) and the influence of a lack of specialists for some difficult taxonomic groups. STATE OF THE ARCTIC MARINE BIODIVERSITY REPORT - <a href="https://arcticbiodiversity.is/findings/benthos" target="_blank">Chapter 3</a> - Page 89 - Box figure 3.3.1 Each region of the Pan Arctic has been sampled with a set of different sampling gears, including grab, sledge and trawl, while other areas has only been sampled with grab. Here is the complete species/taxa number and the % distribution of species/taxa in main phyla, per region of the Pan Arctic.

Critical to the successful implementation of EBM in the Arctic is the existence of a cohesive circumpolar approach to the collection and management of data and the application of compatible frameworks, standards and protocols that this entails. STATE OF THE ARCTIC MARINE BIODIVERSITY REPORT - <a href="https://arcticbiodiversity.is/marine" target="_blank">Chapter 2</a> - Page 29 - Box Figure 2.2

Average September sea ice extent in 1979 (blue) compared with 2016 (white) and the median sea ice extent (yellow line) from 1981 to 2010 (Data: NSDIC 2016). STATE OF THE ARCTIC MARINE BIODIVERSITY REPORT - <a href="https://arcticbiodiversity.is/marine" target="_blank">Chapter 2</a> - Page 27 - Figure 2.4

Distributions of all capelin species (light green) and Pacific capelin (Mallotus catervarius; dark green pattern) based on participation in research sampling, examination of museum voucher collections, the literature and molecular genetic analysis (Mecklenburg and Steinke 2015, Mecklenburg et al. 2016). Map shows the maximum distribution observed from point data and includes both common and rare locations STATE OF THE ARCTIC MARINE BIODIVERSITY REPORT - <a href="https://arcticbiodiversity.is/findings/marine-fishes" target="_blank">Chapter 3</a> - Page 117 - Figure 3.4.5

Circumpolar map of known polynyas. Note that polynyas are dynamic systems and some may no longer exist in the form known from their recent history. Adapted from Meltofte (2013) and based on Barber and Massom (2007). STATE OF THE ARCTIC MARINE BIODIVERSITY REPORT - <a href="https://arcticbiodiversity.is/marine" target="_blank">Chapter 2</a> - Page 28 - Figure 2.5

Bacteria and Archaea across five Arctic Marine Areas based on number of operational taxonomic units (OTUs), or molecular species. Composition of microbial groups, with respective numbers of OTUs (pie charts) and number of OTUs at sampling locations (red dots). Data aggregated by the CBMP Sea Ice Biota Expert Network. Data source: National Center for Biotechnology Information’s (NCBI 2017) Nucleotide and PubMed databases. STATE OF THE ARCTIC MARINE BIODIVERSITY REPORT - <a href="https://arcticbiodiversity.is/findings/sea-ice-biota" target="_blank">Chapter 3</a> - Page 38 - Figure 3.1.2 From the report draft: "Synthesis of available data was performed by using searches conducted in the National Center for Biotechnology Information’s “Nucleotide” (http://www.ncbi.nlm.nih.gov/guide/data-software/) and “PubMed” (http://www.ncbi.nlm.nih.gov/pubmed) databases. Aligned DNA sequences were downloaded and clustered into OTUs by maximum likelihood phylogenetic placement."

In 2017 the SAMBR synthesized data about biodiversity in Arctic marine ecosystems around the circumpolar Arctic.. SAMBR highlighted observed changes and relevant monitoring gaps. This 2021 update provides information on the status of marine mammals in the Arctic from 2015–2020: More detail can be found in the Marine Mammals 2021 Technical report. STATE OF THE ARCTIC MARINE BIODIVERSITY REPORT

Numbers and taxonomic composition of five single-celled eukaryote groups for the regional divisions of the Arctic Marine Areas (pie charts), as well as the number of data sources reviewed across the Arctic (red circles). Total number of taxa is given in parenthesis after each region. Flagellates include: chlorophytes, chrysophytes, cryptophytes, dictyochophytes, euglenids, prasinophytes, prymnesiophytes, raphidophytes, synurales, and xanthophytes, and- for practical purposes though not flagellates - cyanophytes. Heterotrophs include: choanoflagellates, kinetoplastea, incertae sedis. Updated from Poulin et al. (2011). STATE OF THE ARCTIC MARINE BIODIVERSITY REPORT - <a href="https://arcticbiodiversity.is/findings/sea-ice-biota" target="_blank">Chapter 3</a> - Page 39- Figure 3.1.3 From the report draft: "For a pan-Arctic assessment of diversity (here defined as species richness), the first comprehensive assessments of this FEC from a few years ago (Poulin et al. 2011, Daniëls et al. 2013) have been updated for regions, with taxonomic names standardized according to the World Register of Marine Species (www.marinespecies.org). For the analysis of possible interannual trends in the ice algal community, we used a data set from the Central Arctic, the area most consistently and frequently sampled (Melnikov 2002, I. Melnikov, Shirshov Institute, unpubl. data). Multivariate community structure was analysed based on a presence-absence matrix of cores from 1980 to 2013. The analysis is biased by the varying numbers of analysed cores taken per year ranging widely from 1 to 24, ice thickness between 0.6 and 4.2 m, and including both first-year as well as multiyear sea ice. Locations included were in a bounding box within 74.9 to 90.0 °N and 179.9°W to 176.6°E and varied among years."

Circumpolar depiction of species richness based on the distributions of the 11 ice-associated Focal Ecosystem Components (according to the distributions reported in IUCN Red List species accounts). A maximum of nine species occur in any one geographic location. The Arctic gateways in both the Atlantic and Pacific regions have the highest species diversity. STATE OF THE ARCTIC MARINE BIODIVERSITY REPORT - <a href="https://arcticbiodiversity.is/findings/marine-mammals" target="_blank">Chapter 3</a> - Page 152 - Figure 3.6.1