The birth and death of lakes on young landscapes

Ongoing land uplift caused by postglacial isostatic rebound creates strong landscape-age gradients alongside the Gulf of Bothnia, northern Scandinavia. Lakes are continuously generated on this dynamic landscape as the uplift isolates bays from sea inundation. However, concomitant with this process older lakes are lost as the basins are filled with sediments, creating a continuum of lake ages on the landscape. We studied the lake size and depth distributions and lake densities, along an age gradient covering 0-4500 years. Map data on the density, area, and elevation of lakes were combined with field-based measurements of maximum basin depth. We find that young lake populations are densely distributed and dominated by small and shallow lakes. Over time, small and shallow lakes are lost by complete sediment filling, resulting in lower lake density and a shift in size and depth distributions towards larger, deeper lakes. Since lake filling is a universal process, we propose that these findings can be generalized to other gradients in landscape age.