Algal Colonization of Young Arctic Sea Ice in Spring (original) (raw)

Ecology of bottom ice algae: I. Environmental controls and variability

Over large ocean areas of the Arctic, Subarctic and Antarctic, which are covered by landfast sea ice during springtime, high concentrations of microalgae have been observed in the interstices of the lower margin of sea ice floes and, in some cases, in a thin layer of surface water immediately under the ice cover or associated with semi-consolidated frazil ice. Ice algal blooms enhance and extend biological production in polar waters by at least 1-3 months. Biomass accumulation of sea ice algal populations ultimately depends upon the duration of the growth season, which is largely a function of climatic and environmental variability. Growth seasons are shorter at lower latitudes because of abbreviated photoperiods, warmer air temperatures and earlier ablation and break up. Environmental factors, which regulate ice algal distributions and dynamics, display characteristic scales of time/space variance. Sea ice habitats are much more stable than planktonic environments, because ice is not subject to large vertical displacements in the irradiance field. Temperature and salinity are relatively constant over most of the growth period. However, nutrients must be supplied to relatively thin, dense layers of cells and fluxes are variable depending on ice growth and hydrodynamics. Although the occurrence of prolonged blooms of ice algae at the ice-water interface is a widespread phenomenon, there are important differences between the growth habits and environments of several well-studied sites. Recent observations from seasonal studies of these sites are compared and contrasted with an emphasis on how the dominant scales of environmental variability influence ice algal populations.