Ellis-Evans, C. British Antarctic Survey, jcel@bas.ac.uk

 
FUNCTIONALLY SIGNIFICANT TOP-DOWN GRAZING AND PREDATION PRESSURE WITHIN MICROBIALLY DOMINATED ANTARCTIC FRESHWATER LAKE COMMUNITIES
 
Studies of Antarctic and peri-Antarctic lake environments have always emphasised restricted food webs and the dominant role of microbial components. It has been widely assumed that top-down pressures on microbial communities are restricted to herbivorous grazing and only functionally significant in peri-Antarctic environments. The possibility of predation of herbivorous plankton has been ignored or considered not functionally important to community dynamics. This paper considers four lake locations lying on a latitudinal gradient from inland continental Antarctica to the peri-Antarctic islands. Clear evidence of substantial grazing of microbial communities by copepods is demonstrated for certain sites. Significant predation of these copepods is identified at the peri-Antarctic site. Examples of re-definition of resource allocation, of microbial escape from herbivory and of a possibly alien species benefiting from regional warming to alter the food web balance are described.
 
Day: Tuesday, Feb. 2
Time: 12:00 - 12:15pm
Location: Sweeney Center
 
Code: SS27TU1215S