COUPLED LANDSCAPE-LAKE EVOLUTION IN HIGH ARCTIC CANADA

Abstract

We profiled five ice-covered lakes and two ice-covered fiords of Ellesmere Island at the northern limit of High Arctic Canada to examine their environmental characteristics, and to evaluate the long-term limnological consequences of changes in their surrounding landscape through time (landscape evolution). All of the ecosystems showed strong patterns of thermal, chemical, and biological stratification with subsurface temperature maxima from 0.75 to 12.15 °C; conductivities up to 98.1 mS cm-1 (twice that of seawater) in some bottom waters; pronounced gradients in nitrogen, phosphorus, pH, dissolved inorganic and organic carbon, manganese, iron, and oxygen; and stratified photosynthetic communities. These ecosystems form an inferred chronosequence that reflects different steps of landscape evolution including marine embayments open to the sea, inlets blocked by thick sea ice (Disraeli Fiord, Taconite Inlet), perennially ice-capped, saline lakes isolated from the sea by isostatic uplift (Lakes A, C1, C2), and isolated lakes that lose their ice cover in summer. The latter are subject to entrainment of saline water into their upper water column by wind-induced mixing (Lake Romulus; Lake A in 2000), or complete flushing of their basins by dilute snowmelt (Lake C3 and Char Lake, which lies 650 km to the south of the Ellesmere lakes region). This chronosequence illustrates how changes in geomorphology and other landscape properties may influence the limnology of coastal, high-latitude lakes, and it provides a framework to explore the potential impacts of climate change. © 2006 NRC Canada.