Sub-ice colonial Melosira arctica in Arctic first-year ice

Abstract

As one of the three main algal communities associated with polar sea ice, the occurrence of a sub-ice community has been recorded during a May 2012 field campaign conducted in the central Canadian High Arctic around Cornwallis Island, Nunavut. The sub-ice community was only observed once at the nearshore station in Wellington Channel (water depth: 85 m; ice thickness: 1.3 m; snow depth:<4 cm), forming short strands< 10–15 cm in length. The community was dominated by the northern cold water centric diatom, Melosira arctica Dickie, which formed very dense aggregates of several parallel, vertically aligned chains of cells, held tightly together by a secretion of mucilage from the rimoportulae on the valve face within the limit of the carina. In addition, three epiphytic diatom taxa were present, Chaetoceros sp., Synedropsis hyperborea (Grunow) Hasle, Medlin & Syvertsen and Pseudogomphonema arcticum (Grunow) Medlin. Surprisingly, and in addition to these epiphytes, some raphe-bearing diatoms were also part of this sub-ice community, gliding over the colonial filamentous cells of M. arctica.

Keywords:

• Arctic
• Melosira arctica
• sub-ice community
• epiphytes
• colony

Acknowledgements

This study was supported by funding support from Fisheries and Oceans Canada (International Governance Strategy), the Natural Sciences and Engineering Research Council of Canada and the Polar Continental Shelf Program (PCSP) of Natural Resources Canada to C. Michel, the U.K. Natural Environment Research Council Grant NE/E016251/1 to G. Underwood, and the Canadian Museum of Nature to M. Poulin. We are especially indebted to Steve Duerksen, Nathalie Fortin, Duane Jordan, Guillaume Meisterhans and Anke Reppchen for assistance in the field and laboratory, Paul Hamilton for producing the figure plates, the Resolute Bay Hunters and Trappers Association, and PCSP for logistical support during the expedition.