Freshwater diatom biogeography of the Canadian Arctic Archipelago

Abstract

The biogeography of diatoms in 62 lakes across the Canadian Arctic Archipelago was studied. A total of 326 taxa was found, with up to 85 and as low as 8 taxa identified in any one lake. Rarefaction-estimated richness correlated with lake size. Although diatom assemblages showed regional patterns, between-lake variability in any region was high, indicating that local factors are important in determining the assemblages. Newly delineated genera showed interpretable geographic patterns and could be related to environmental factors, suggesting that this more natural grouping may enhance our understanding of diatom ecology. Some taxa showed southern and regionally limited distributions. Many taxa prefer colder temperatures while others were more influenced by lake water parameters. Assemblages with zero or low abundance of fragilaroid taxa tended to occur in larger lakes with higher silica. These lakes had more diverse assemblages including Gomphonema, Encyonema , and Encyonopsis taxa, suggesting a possible relationship between non-fragilaroid taxa and lake size and silica. Geographic, physical, and chemical factors are needed to explain diatom distributions in the Arctic.