Changes in diatom assemblages in Lake C2 (Ellesmere Island, Arctic Canada): response to basin isolation from the sea and to other environmental changes

摘要: Diatoms preserved in the sediments of Lake C2 (82°50′ N, 76°00′ W), a high arctic meromictic lake, track changes lake's salinity which have occurred as basin was isolated from sea. An assemblage dominated by marine taxa, such Chaetoceros species, Nitzschia cylindrus and Diploneis spp., replaced Cyclotella kuetzingiana var. planetophora freshwater flora. A brief brackish period separates two assemblages. Relatively little floristic change within either or periods, indicating rather stable environmental conditions, except that rheophilous diatoms fluctuated relative abundance during lacustrine phase, perhaps tracking past discharge inflowing streams. These may reflect periods warmer, wetter conditions.