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

Summary of the taxa accounting for 85% of the river benthic macroinvertebrates collected in each of several highly-sampled geographic areas, with taxa grouped by order level or higher in pie charts placed spatially to indicate sampling area. Pie charts correspond to (1) Alaska, (2) western Canada, (3) southern Canada, south of Hudson Bay, (4) northern Labrador, (5) Baffin Island, (6) Ellesmere Island, (7) Greenland high Arctic, (8) Greenland low Arctic, (9) Iceland, (10) Svalbard, and (11) Fennoscandia. State of the Arctic Freshwater Biodiversity Report - Chapter 4 - Page 70 - Figure 4-34

Figure 3-5 Changes in alpha diversity (red line), predator body size (blue dashed line), and ecosystem metabolism (blue solid line) with a shift in glacial cover from high (left) to low (right). Redrawn from Milner et al. (2017). State of the Arctic Freshwater Biodiversity Report - Chapter 3 - Page 22 - Figure 3-5

Figure 3-3 Long-term trends in total phosphorus water concentrations (μg/L) in four major, unregulated rivers that drain the subarctic Arctic/alpine ecoregion of the Scandinavian peninsula, the Kalix river, The Lule river, the Råne river, and the Torne river. Slopes and p-values are given in the different panels. Boxes indicate medians and 25th and 75th percentiles, while whiskers give the 10th and 90th percentiles. State of the Arctic Freshwater Biodiversity Report - Chapter 3 - Page 21 - Figure 3-3

Temporal patterns in % abundance of Atlantic salmon, brown trout, and anadromous Arctic charr from catch statistics in northern Norway rivers monitored from 1993 to 2016, including basins dominated by (a) rivers and (b) lakes. State of the Arctic Freshwater Biodiversity Report - Chapter 4 - Page 81- Figure 4-42

Figure 4-13 Number of deep lakes (red), shallow lakes (blue), and ponds (brown) in each geographical zone (BF, T, LA, HA). BF = Boreal Forest, T =Transition Zone, LA = Low Arctic, HA = High Arctic. State of the Arctic Freshwater Biodiversity Report - Chapter 4 - Page 40 - Figure 4-13

Figure 3-6. The hypothesized effects of rising mean water temperature on biodiversity (as total species number) of Arctic freshwater ecosystems. A pulsed increase in gamma biodiversity (a) results from the combination of high eurythermal invasion and establishment and low stenothermic loss with increasing water temperature. A pulsed decrease in gamma biodiversity (b) results from the combination of low eurythermal invasion and establishment and high stenothermic loss. Rapid increases (c) and slow increases (d) in species diversity occur, respectively, with high eurythermal invasion and establishment coupled with high stenothermic loss or low eurythermal invasion and establishment and low stenothermic loss as temperatures increase. For simplification, barriers to dispersal have been assumed to be limited in these models. State of the Arctic Freshwater Biodiversity Report - Chapter 3 - Page 23 - Figure 3-6

Taxa accumulation curves for (left) lake surface sediment samples, and (right) stream scrapes across the sub-Arctic (blue), Low Arctic (green) and High Arctic (red) ABA Arctic zones. Dashed lines represent the bounds of the 95% confidence interval of the estimate. State of the Arctic Freshwater Biodiversity Report - Chapter 4 - Page 38 - Figure 4-11

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 6-2 Current state of monitoring for river FECs in each Arctic country State of the Arctic Freshwater Biodiversity Report - Chapter 6 - Page 94 - Figure 6-2

Figure 3-1 Long-term trends in ice duration (as days) in the River Torne (upper plot) and Lake Torneträsk (lower plot) at 68° north on the Scandinavian peninsula. Lines show smooth fit. Data source: Swedish Meteorological and Hydrological Institute. State of the Arctic Freshwater Biodiversity Report - Chapter 3 - Page 19 - Figure 3-1