Aerial dispersal of lichen soredia in the maritime Antarctic

An aerobiological monitoring programme was carried out for over a year on Signy Island, South Orkney Islands, Antarctica. Collections were made using arrays of rotorod samplers at three sites. Lichen soredia were found to be the most abundant air borne propagules, more so than ascospores, the sexual propagules of lichen fungi. The dominance of soredia over ascospores appeared to decrease with increasing maturity of fellfield sites. No correlations were found with temperature, relative humidity or wind speed. Collections at 1 m above ground level were shown not to be significantly different to those at 0·15 m at two of the sites. Size range distribution also differed at two of the sites. Soredial clumps in excess of 100 μm in diameter were collected at 1 m above ground level and at some distance from potential source plants, though most fell in the range 30–60 μm. Peaks in numbers of air borne soredia were found after winter snow melt, demonstrating that soredial production continues at subzero temperatures