The ecology of sublithic terrestrial algae at the Vestfold Hills, Antarctica

Abstract

Sublithic (hypolithic) algae were found to be widely distributed under quartz stones at the Vestfold Hills, Antarctica. More than 17 taxa were recognized but four were dominant: Chroococcidiopsis sp. and Plectonema sp. (Cyanophyta), cf. Desmococcus sp. A and Prasiococcus calcarius (Boye Pet.) Vischer (Chlorophyta). Niche selection by the different algae resulted in Chroococcidiopsis and cf. Desmococcus sp. A favouring dry, raw mineral soils, Plectonema sp moist, raw mineral soils and P. calcarius seal and bird-influenced soils. Chlorophyll a estimations showed sublithic algal growths to be considerably more abundant than growths in adjacent exposed soil surfaces but less abundant than superficial algal growths in favourable wet microenvironments. In an area of typical dry mineral soil there was a mean area of 66 cm² of sublithic algal growth m^-2 of the site. Most stones with algal growths were less than 30 g in weight. Algae were found at a maximum depth of 61 mm below the soil surface and under a maximum total thickness of 109 mm of quartz. Light transmission through stones from 13–80 mm thick varied between 0·9 and 2·7% of incident sunlight. Microclimate temperatures below stones showed diurnal fluctuations of up to 13 degrees. centigrade