Moss diatom communities from Ile de la Possession (Crozet, Subantarctica) and their relationship with moisture

More than 190 taxa, belonging to 33 genera, were observed on mosses collect ed on Ile de la Possession, Crozet Archipelago, Antarctica. Six assemblages could be identified. Habitat type and moisture content of the samples appe ared to be the major factors in separating the communities. It was clear th at diatom communities growing on mosses found in rivers and brooks are diff erent from assemblages on rocks and in stagnant pools. The Diadesmis conten ta assemblage was bound to dry mosses growing on rocks whereas the Eunotia paludosa var. paludosa community preferred acid stagnant pools, situated in the larger valleys. The other four assemblages are typical for circumneutr al waterbodies, with the Fragilaria maillardii and the Fragilaria vaucheria e-Fragilaria in germainii assemblages found in running water and the Fragil aria pinnata var. pinnata and the Achnanthes confusa-Achnanthes aueri assem blages in more stagnant water. Weighted averaging and calibration were used to develop a statistical transfer function to infer the moisture content o f moss samples from the diatom assemblages.