Diatom species–environment relationships and inference models from Isachsen, Ellef Ringnes Island, Canadian High Arctic

Surface sediment diatom assemblages were examined from 26 freshwater sites near Isachsen (78 47 ¢ N, 103 32 ¢ W), Ellef Ringnes Island, a region of diverse and atypical water chemistry for high arctic sites. One hundred and sixty eight diatom taxa were identified from these samples, over 50 % of which had not previously been recorded in the Canadian High Arctic. Variations in diatom assemblages were related to changes in measured environmental variables using multivariate techniques. Canonical correspondence analysis (CCA) indicated that five variables contributed significantly to explaining patterns of diatom variation (i.e., COND, DIC, Mn, TPF, TPU). The first CCA axis (k 0.44) was primarily controlled by conductivity-related variables, while CCA axis 2 (k 0.21) was related to particulate concentrations. Diatom-based inference models were generated for the reconstruction of conductivity (RMSEPjack 0.32, r2jack 0.76) and pH (RMSEPjack 0.40, r2jack 0.69). The strengths of these models indicate that it will be possible to reliably infer past trends in conductivity and pH from diatom assemblages preserved in dated sediment cores from the Isachsen region