Biogeographic distributions and environmental controls of stream diatoms in the Canadian Arctic Archipelago

Abstract

Streams are amongst the most sensitive ecosystems in Arctic regions to environmental change. Although diatoms are excellent indicators of environmental change, little information is available about stream diatom distributions across the vast Canadian High Arctic. We sampled 42 streams from nine islands in the Canadian Arctic Archipelago to study their diatom floras and evaluate the influences of biogeographic and environmental variables on species distributions. Highly divergent diatom communities were identified, with 100% species overturn between the most dissimilar communities. Taxa including Hannaea arcus (Ehrenberg) Patrick were characteristic of streams from all regions; other common taxa included Nitzschia perminuta (Grunow) Peragallo, Rossithidium petersenii (Hustedt) Round & Bukhtiyarova, Achnanthidium minutissimum (Kützing) Czarnecki, and Eucocconeis laevis (Østrup) H. Lange-Bertalot. Canonical correspondence analysis indicated that diatom assemblages were significantly related to differences in pH, temperature, latitude, and longitude, which together explained 14.7% of species variability. Analysis of similarities indicated that communities did not differ significantly between epilithic and epiphytic samples and that there were weak but significant differences between the diatom communities in our three regions. These data provide important baseline information for future biomonitoring efforts as well as for paleolimnological studies of past stream hydrology.