EUKARYOTIC MICROBIOTA IN THE SURFACE WATERS AND SEA-ICE OF THE SOUTHERN-OCEAN - ASPECTS OF PHYSIOLOGY, ECOLOGY AND BIODIVERSITY IN A 2-PHASE ECOSYSTEM

The Southern Ocean provides a habitat for microplankton which is stron gly influenced by physical factors. Of these, one of the most importan t and striking is the formation of sea ice. Organisms in the ice form a unique community with specific properties and adaptations. Material and organisms are exchanged between the water column and the ice durin g the annual cycle, and ice is an important factor in modifying biogeo chemical processes and exchange between ocean and atmosphere. The coup led system, in which a range of organisms alternate between a fluid an d a solid medium, provides an interesting exercise in community ecolog y, and has implications for the assessment of biodiversity in understa nding large-scale change.