The diagram indicates the number of species in each FEC for the North Atlantic region of the Arctic (circular outline) and the overlap between the five CBMP–Terrestrial Plan FECs and the additional ‘predators’ FEC. The link width indicates the number of species linking two FECs. The larger the link the more species that are found in linking FECs. Modified from Gillespie et al. 2020a. STATE OF THE ARCTIC TERRESTRIAL BIODIVERSITY REPORT - Chapter 3 - Page 38 - Figure 3.8

Long-term monitoring programs on benthic fauna are missing for large areas of the Arctic. In areas where repeated monitoring has occurred, it is difficult to compare data due to different sampling approaches and different targets of monitoring efforts. There is a need for an international standardization of long- term benthic monitoring. The CBMP Benthos Expert Network has identified potential ways to improve benthic monitoring coverage, and has come up with a map showing a Pan Arctic station map.

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.

Global catches of polar cod from 1950 to 2011 (FAO 2015); 95% of the catches are from the Barents Sea. STATE OF THE ARCTIC MARINE BIODIVERSITY REPORT - <a href="https://arcticbiodiversity.is/findings/marine-fishes" target="_blank">Chapter 3</a> - Page 116 - Figure 3.4.4

Number of megafauna species/taxa in the Arctic (7,322 stations in total), based on recent trawl investigations. Stations with highest species/taxon number are sorted to the top, meaning that dense concentrations of stations (e.g. Eastern Canada, Barents Sea), with low species numbers are hidden behind stations with higher species numbers. Also note that species numbers are somewhat biased by differing taxonomic resolution between studies. Data from: Icelandic Institute of Natural History, Iceland; Marine Research Institute, Iceland; University of Alaska, Fairbanks, U.S.; Greenland Institute of Natural Resources, Greenland; Zoological Institute of the Russian Academy of Sciences, St. Petersburg, Russia; Université du Québec à Rimouski, Canada; Fisheries and Oceans Canada; Institute of Marine Research, Norway; and Polar Research Institute of Marine Fisheries and Oceanography, Murmansk, Russia. STATE OF THE ARCTIC MARINE BIODIVERSITY REPORT - <a href="https://arcticbiodiversity.is/findings/benthos" target="_blank">Chapter 3</a> - Page 91 - Box figure 3.3.2 Several regions of the Pan Arctic have been sampled with trawl. Even though the trawl configurations and the taxonomic level are different from area to area, we choose to consider the taxonomic richness as relatively comparative.

Biogeographic borders in the Barents Sea based on species distributions of bryozoans. Average position of the border with 50:50% of Atlantic boreal and Arctic species numbers is indicated by the pink line, and the red and green lines indicate the extreme positions of the border in cold and warm periods respectively. Area III between them is the transitional zone between the Atlantic boreal and the Arctic regions. Thus, area I always has > 50% Atlantic boreal species, and area II always > 50% Arctic species (after Denisenko 1990).

Trends in biomass or diversity of benthic Focal Ecosystem Components across each Arctic Marine Area. STATE OF THE ARCTIC MARINE BIODIVERSITY REPORT - Chapter 4 - Page 179 - Figure 4.3

Alpha diversity (± standard error) of river (a) diatoms from benthic samples, (b) benthic macroinvertebrates, and (c) fish within hydrobasins in western and eastern North America plotted as a function of the average latitude in each hydrobasin. Alpha diversity is rarefied to 10 stations per hydrobasin, using size level 5 hydrobasins for all panels. State of the Arctic Freshwater Biodiversity Report - Chapter 5 - Page 85 - Figure 5-2

Figure 4-7 Circumpolar assessment of lake diatoms, indicating (a) the location of lake diatom stations, underlain by circumpolar ecoregions; (b) ecoregions with many lake diatom stations, colored on the basis of alpha diversity rarefied to 40 stations; (c) all ecoregions with lake diatom stations, colored on the basis of alpha diversity rarefied to 10 stations; (d) ecoregions with at least two stations in a hydrobasin, colored on the basis of the dominant component of beta diversity (i.e. species turnover, nestedness, approximately equal contribution, or no diversity) when averaged across hydrobasins in each ecoregio. State of the Arctic Freshwater Biodiversity Report - Chapter 4 - Page 35 - Figure 4-7

Results of circumpolar assessment of river diatoms, indicating (a) the location of river diatom stations, underlain by circumpolar ecoregions; (b) ecoregions with many river diatom stations, colored on the basis of alpha diversity rarefied to 40 stations; (c) all ecoregions with river diatom stations, colored on the basis of alpha diversity rarefied to 10 stations; (d) ecoregions with at least two stations in a hydrobasin, colored on the basis of the dominant component of beta diversity (species turnover, nestedness, approximately equal contribution, or no diversity) when averaged across hydrobasins in each ecoregion. State of the Arctic Freshwater Biodiversity Report - Chapter 4 - Page 36 - Figure 4-8