New record of moss and thermophilic bacteria species and physico-chemical properties of geothermal soils on the northwest slope of Mt. Melbourne (Antarctica)

Four samples of surface soils, one with shoots of an unidentified moss species, were collected from a geothermal site on the northwest slope of volcanic Mt. Melbourne (northern Victoria Land, continental Antarctica) to determine physico-chemical properties, isolate existing strains of heterotrophic microorganisms, and identify the moss species through molecular genetic techniques. Surface soil features such as temperature, grain-size, pH, moisture content, and isolated genera of bacteria, generally corresponded to those previously reported for other geothermal sites in Victoria Land. However, when compared with chemical characteristics of warm substrata from these sites, soils from the northwest slope of Mt. Melbourne showed lower contents of total N and water-extractable PO₄^3- and K⁺, and relatively higher concentrations of Na, Fe, Mn, and of potentially toxic elements such as Cd and Pb. Preliminary results indicate that a new species of thermophilic bacteria growing in Fe-enriched medium was isolated. Although the study area lay only about 1.5 km from "Cryptogam Ridge", a geothermal site in the rim of the Mt. Melbourne summit crater with a well-developed population of the moss Campylopus pyriformis, molecular genetic analyses showed that the moss on the volcano slope is Pohlia nutans, a species closely related to populations some 110 km to the north in the Mt. Rittmann fumaroles. It was concluded that physico-chemical features of geothermal grounds may affect the colonisation history and dispersal of microorganisms and mosses.