ABSTRACT: Sedimentological and paleoecological records from the Central and Western Canadian Arctic in relation to ice core paleoclimatic data.

CGRG Bibliography of Canadian Geomorphology
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Abstract

A series of lake sediment cores spanning the Holocene from across the central and western Canadian Arctic document ecosystem responses to climatic variations on several timescales. Sediment parameters (grain size, LOI, magnetic susceptibility) analyzed at very high resolution are used to quantify hydroclimatic variability at the watershed scale. Pollen, diatom, biogenic silica and chironomid series measured at high resolution show that the responses of terrestrial and aquatic organisms to millennial-scale climate variations are coeval with those variations interpreted from Greenland and Canadian ice core records. Climatic change caused large fluctuations in terrestrial production, as measured by pollen influx and concentrations, although biodiversity changes were less significant. Diatom stratigraphies are more complex, and show not only production changes but also diversity changes. These fluctuations are ultimately controlled by climate, but the direction and magnitude of changes in diatom assemblages are often determined by local factors such as habitat availability, lake size and nutrient status. Interpretation of chironomid records in relation to diatom-derived proxies for primary production indicate the combined impact of food source and climate on chironomid populations. Climate variations during the Holocene and the associated ecological impacts are sometimes comparable in rate and magnitude to those occurring now, suggesting paleoecological records from Arctic lakes can be used to better predict future impacts of climatic change.

Bibliography of Canadian Geomorphology