Determining diatom ecotones and their relationship to terrestrial ecoregion designations in the central Canadian Arctic Islands

• Published in: Journal of Phycology
• Main Authors: Antoniades, Dermot, Douglas, Marianne S. V., Michelutti, Neal, Smol, John P.
• Other Authors: Wood, M., Natural Sciences and Engineering Research Council of Canada
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2014
• Subjects: Plant Science; Aquatic Science; Arctic
• Online Access: http://dx.doi.org/10.1111/jpy.12195; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fjpy.12195; https://onlinelibrary.wiley.com/doi/pdf/10.1111/jpy.12195

Ecotones are key areas for the detection of global change because many are predicted to move with shifts in climate. P rince of W ales I sland, in the C anadian A rctic A rchipelago, spans the transition between mid‐ to high‐ A rctic ecoregions. We analyzed limnological variables and recent diatom assemblages from its lakes and ponds to determine if assemblages reflected this ecotone. Limnological gradients were short, and water chemistry explained 20.0% of diatom variance in a redundancy analysis (RDA), driven primarily by dissolved organic carbon, Ca and SO 4 . Most taxa were small, benthic forms; key taxa such as planktonic C yclotella species were restricted to the warmer, southern portion of the study area, while benthic S taurosirella were associated with larger, ice‐dominated lakes. Nonetheless, there were no significant changes in diatom assemblages across the mid‐ to high‐ A rctic ecoregion boundary. We combined our data set with one from nearby C ornwallis I sland to expand the study area and lengthen its environmental gradients. Within this expanded data set, 40.6% of the diatom variance was explained by a combination of water chemistry and geographic variables, and significant relationships were revealed between diatom distributions and key limnological variables, including pH, specific conductivity, and chl‐ a . Using principal coordinates analysis, we estimated community turnover with latitude and applied piecewise linear regression to determine diatom ecotone positions. A pronounced transition was present between P rince of W ales I sland and the colder, more northerly C ornwallis I sland. These data will be important in detecting any future northward ecotone movement in response to predicted A rctic climate warming in this highly sensitive region.