Temporal patterns in % abundance of Atlantic salmon, brown trout, and anadromous Arctic charr from catch statistics in Iceland rivers monitored from 1992 to 2016, showing results from (a) west, (b) south, (c) north, and (d) east Iceland. State of the Arctic Freshwater Biodiversity Report - Chapter 4 - Page 81 - Figure 4-41

Warming in the Arctic has been significantly faster than anywhere else on Earth (Ballinger et al. 2020). Trends in land surface temperature are shown on Figure 2-2. STATE OF THE ARCTIC TERRESTRIAL BIODIVERSITY REPORT - Chapter 2 - Page 23 - Figure 2.2

Although the circumpolar countries endeavor to support monitoring programs that provide good coverage of Arctic and subarctic regions, this ideal is constrained by the high costs associated with repeated sampling of a large set of lakes and rivers in areas that often are very remote. Consequently, freshwater monitoring has sparse, spatial coverage in large parts of the Arctic, with only Fennoscandia and Iceland having extensive monitoring coverage of lakes and streams Figure 6-1 Current state of monitoring for lake FECs in each Arctic country. State of the Arctic Freshwater Biodiversity Report - Chapter 6 - Page 93 - Figure 6-1

Redundancy analysis of percentage species taxa share (taxa richness relative to richness of all taxa) among 5 FECs (phytoplankton, macrophytes, zooplankton, benthic macroinvertebrates and fish) in 13 Fennoscandian lakes (panels A and B) and among 3 FECs in 39 Fennoscandian lakes (panels C and D).The upper panels show lake ordinations, while the bottom panels show explanatory environmental variables (red arrows), as indicated by permutation tests (p < 0.05). Avg%Richness: average species taxa richness as a percentage of richness of all FECs (i.e., including benthic algae if present); %Richness BMI: relative taxa share in benthic macroinvertebrates; %EvergreenNLF: percentage cover of evergreen needle-leaf forests. State of the Arctic Freshwater Biodiversity Report - Chapter 5 - Page 87 - Figure 5-4

Spatial distribution of hillslope thermokarst across the circumpolar area, overlain with ecoregions used in the SAFBR analysis, showing no, low, moderate, and high thermokarst. Source for thermokarst layer: Olefeldt et al. (2016) State of the Arctic Freshwater Biodiversity Report - Chapter 4 - Page 90 - Figure 5-7

Results of circumpolar assessment of lake zooplankton, focused just on crustaceans, and indicating (a) the location of crustacean zooplankton stations, underlain by circumpolar ecoregions; (b) ecoregions with many crustacean zooplankton stations, colored on the basis of alpha diversity rarefied to 25 stations; (c) all ecoregions with crustacean zooplankton 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 58 - Figure 4-25

Fish species observations from Traditional Knowledge (TK ) literature, plotted in the approximate geographic location of observed record, with symbol colour indicating the number of fish species recorded and shape indicating the approximate time period of observation. Results are from a systematic literature search of TK sources from Alaska, Canada, Greenland, Fennoscandia, and Russia. State of the Arctic Freshwater Biodiversity Report - Chapter 4 - Page 75- Figure 4-37

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

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.

Sea ice meiofauna composition (pie charts) and total abundance (red circles) across the Arctic, compiled by the CBMP Sea Ice Biota Expert Network from 27 studies between 1979 and 2015. Scaled circles show total abundance per individual ice core while pie charts show average relative contribution by taxon per Arctic Marine Area (AMA). Number of ice cores for each AMA is given in parenthesis after region name. Note that studies were conducted at different times of the year, with the majority between March and August (see 3.1 Appendix). The category ‘other’ includes young stages of bristle worms (Polychaeta), mussel shrimps (Ostracoda), forams (Foraminifera), hydroid polyps (Cnidaria), comb jellies (Ctenophora), sea butterflies (Pteropoda), marine mites (Acari) and unidentified organisms. STATE OF THE ARCTIC MARINE BIODIVERSITY REPORT - <a href="https://arcticbiodiversity.is/findings/sea-ice-biota" target="_blank">Chapter 3</a> - Page 40 - Figure 3.1.4 From the report draft: "Here, we synthesized 19 studies across the Arctic conducted between 1979 and 2015, including unpublished sources (B. Bluhm, R. Gradinger, UiT – The Arctic University of Norway; H. Hop, Norwegian Polar Institute; K. Iken, University of Alaska Fairbanks). These studies sampled landfast sea ice and offshore pack ice, both first- and multiyear ice (Appendix 3.1). Meiofauna abundances reported in individual data sources were converted to individuals m-2 of sea ice assuming that ice density was 95% of that in melted ice. Due to the low taxonomic resolution in the reviewed studies, ice meiofauna were grouped into: Copepoda, nauplii (for copepods as well as other taxa with naupliar stages), Nematoda, Polychaeta (mostly juveniles, but also trochophores), flatworms (Acoelomorpha and Platyhelminthes; these phyla have mostly been reported as one category), Rotifera, and others (which include meroplanktonic larvae other than Polychaeta, Ostracoda, Foraminifera, Cnidaria, Ctenophora, Pteropoda, Acari, and unidentified organisms). Percentage of total abundance for each group was calculated for each ice core, and these percentages were used for regional averages. Maximum available ice core length was used in data analysis, but 50% of these ice cores included only the bottom 10 cm of the ice, 12% the bottom 5 cm, 10% the bottom 2 cm, and 11% the entire ice-thickness. Data from 617 cores were used."