The biota and environment of fumaroles on Mt Melbourne, northern Victoria Land

Abstract

The aim of this investigation was to provide a general description of the biota and environment of fumarolic ground close to the summit (2733 m) of Mt Melbourne. Heat flow through the ground was examined and analyses made of the physico-chemical properties of the soil. Bryophyte vegetation comprisedCampylopus pyriformis (K.F. Schultz) Brid. andCephaloziella exiliflora (Tayl.) Steph. The former is a new antarctic record. These grew as scattered and confluent cushions where surface ground temperatures ranged between 14°–31°C. Algae were epiphytic on bryophytes and formed crusts over most other areas of warm ground. Six species of cyanophytes and five unicellular chlorophytes are described. The majority were mesophilic butMastigocladus laminosus showed a strong preference for soil temperatures >30°C. A loosely lichenised chlorophyte was also encountered. The only soil fauna was a testate amoeba,Corythion dibium. Heterotrophic microorganisms included thermotolerant fungi, actinomycetes and bacteria as well as typical mesophilic microflora. Nitrogen fixation, analysed using both C2H2 reduction and15N2 enrichment, occured in bryophyte cushions and surface algal crusts containingM. laminosus and in sub-surface samples lacking cyanophytes. The biota are compared with those found at other thermal localities in Antarctica and the dispersal of propagules to these areas is discussed.