Planktonic diatom communities in High Arctic lakes (Store Koldewey, Northeast Greenland)

This contribution documents with light micrographs the planktonic diatom flora in seven high arctic lakes on Store Koldewey, an island off Northeast Greenland. The lakes have maximum water depths between 6.1 and 72.0 m. Basic limnological analyses indicate that all lakes are cold, monomictic, clear, oligotrophic, and alkaline. Planktonic diatoms and chrysophyte statospores were present in all but one lake. Eight planktonic diatom taxa were identified in the phytoplankton samples: Aulacoseira islandica (O. Müller) Simonsen, Aulacoseira tethera Haworth, Aulacoseira sp. 1, Cyclotella antiqua W. Smith, Cyclotella pseudostelligera Hustedt, Cyclotella rossii Håkansson, Fragilaria tenera (W. Smith) Lange-Bertalot, and Stephanodiscus minutulus (Kützing) Cleve et Möller. Fragilaria tenera was present in two morphotypes; the "normally shaped" type and a type with abnormally shaped valves, which has mostly been recorded in metal-polluted lakes. The diatom communities were generally dominated by only one or two species. The water columns of the lakes with a water depth greater than 10 m accomodate a moderate to high proportion of primarily benthic diatoms.Key words: Greenland, High Arctic, limnology, diatoms, valve morphology.

Terrain Geochemistry Surveys, Permafrost Studies, and Arctic Limnology, District of Keewatin, N.W.T.: Implications for Water Quality Monitoring in the North

Geochemical studies and surveys conducted by the Geological Survey of Canada have provided considerable information about the natural geochemical variations in glacial drift, lake sediments, and lake waters in south-central District of Keewatin. In addition to their intended contribution to mineral exploration, these activities yielded much basic background data that may be applied to the planning of water quality monitoring programs in the region. Studies of permafrost features, and arctic limnology have furnished knowledge about natural geomorphic and diagenetic processes that influence surface water quality. Cryoturbation, on land and in the shallow areas of lakes underlain by permafrost, plays a major role in the transfer of particulate and dissolved drift constituents to surface waters. In spite of the abundance of mineral detritus on shore, profundal lake sediments are typically highly diatomaceous and possess conspicuous oxic surface layers that likely have a strong capacity to sequester both nutrients and trace metals.