Abstract:
The potential importance of dried cyanobacterial mats as sources of propagules for local dissemination was studied at Bratina Island (McMurdo Ice Shelf), Lake Fryxell (Taylor Valley) and Cape Crozier (Ross Island). The McMurdo Ice Shelf is an area covered by pools, lakes, streams and rivers, many of which contain abundant growths of algae and cyanobacteria mats. Often the pools dry out when pond
... water levels fall leaving behind dried mats. Viable propagules were found in this material even after air exposure for 3 years. The dispersal mechanisms of propagules to and within the continent were investigated by sampling for propagules and measuring meteorological variables. The importance of aerial transport in the distribution of algae and cyanobacteria was determined by sampling the air and deploying Tauber traps for propagules. The contents were subjected to three media created to mimic three of the MIS ponds with contrasting water chemistries (fresh, brackish and salty water). Meteorological information (wind speed and direction at Lake Frxyell and Bratina Island and temperature (air and ground), humidity, net radiation, solar radiation, UV-A and UV-B at Bratina Island only) was collected in conjunction with spore trap deployment at different heights above ground level (0, 100, 300, 800, 1600mm). At Bratina Island the ability of cyanobacterial mats to survive prolonged aerial exposure was investigated by determining the time course changes in pigment content, photosynthetic and respiratory potential and carbon, nitrogen and ash content after aerial exposure from cores of mat from two ponds. The potential of mats which had been dried for 3 years to initiate new growth when wetted (fresh, brackish and salty water) was determined. Transect surveys were undertaken to classify terrain type (bare ice, pond, seepage or soil with or without salt crust or vegetation). At 50 or 100m intervals, soil temperatures were recorded and samples taken for analysis of water content, salt content and chlorophyll a (as a measure of biomass). Small scale surveys of these parameters were undertaken in areas providing environmental gradients including transects across moss stands and drainage gulleys. Cyanobacterial mat cores (3mm diam) were incubated at different salinities with 14C as a tracer and analysed to understand the effects of salinity. To investigate the importance of layer, cyanobacterial mats were isolated from different layers within mats and their pigment content, photosynthetic responses to a range of light intensities and potential to form new mats was determined. 
