Evolution, abundance, diversity and trophodynamics of mixotropic protists in Antarctic waters

• Applicant: Dr. Elanor Margaret Bell
• Subject Area: Oceanography
• Term: from 2004 to 2005
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5427170

Mixotrophy is a strategy by which organisms combine autotrophy and heterotrophy, Mixotrophy is widespread in freshwater and marine habitats, but little is known about mixotrophic protists in Antarctic waters. Existing studies suggest that mixotrophy, in particular phagotrophy by phototrophys, is advantageous in extreme environments such as Antarctica. Therefore, it is reasonable to assume that mixotrophs play a vital role in Antarctic, aquatic microbial food webs. Indeed, the first documented instance of phagotrophy for a green alga. Pyramimonas gelidicola (Chlorophyta: Prasinophyceae) was from an Antarctic lake. All Prasionphystes share a similar ultrastructure to P. gelidicola, implying that mixotrophy may be common in this genus but is "switched off" unless conditions are sufficiently extreme. The proposed research aims to further investigate the incidence of phagotrophy in P. gelidicola, look for evidence of mixotrophy in other green algae, characterise the abundance, diversity and trophodynamics of mixotrophic protists in Antarctic lacustrine and marine ecosystems, and determine which factors cause mixotrophy to be "switched on". These aims will be achieved through laboratory and in situ field experiments during the period December 2003 to June 2005.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1158: Infrastructure area - Antarctic Research with Comparative Investigations in Arctic Sea Ice Areas
• International Connection: Australia
• Participating Person: Dr. Andrew T. Davidson