Fig. 2

Environmental factors affecting species abundance in Ace Lake. dbRDA ordination plot showing the relationship between species abundance variations and changes in season and lake depth. The x-axis (dbRDA1) explains 77% of the fitted and 21% of the total variation. The y-axis (dbRDA2) explains 13% of the fitted and 4% of the total variation. The data points representing the three filter fractions from each depth and time point, overlap in the plot thereby reducing the 120 metagenomes to 40 data points (i.e. each data point represents the three filter fractions for a specific sampling date and depth). Included are vector overlays showing the contribution of lake depth (depth), salinity (salinity), monthly average day length (daylength), monthly average sunlight hours (sunlight), and monthly average air temperature (temperature) to variance. The season-based variations are highlighted by grouping samples from: December (white circle), January (white square), and February (white triangle) as summer (red shading); July (black triangle) and August (black square) as winter (blue shading); and October (grey circle) and November (grey triangle) as spring (green shading). The depth-based variations are highlighted by grouping samples from upper 1, 2, and 3 as Upper (thick dotted line); interface as Interface (solid line); and lower 1, 2, and 3 as Lower (thin dotted line)