Life, decay and fossilisation of endolithic microorganisms from the Ross Desert, Antarctica

The adaptation and survival of the endolithic microorganisms that colonise the near-surface layer of porous sandstone rock in the Ross Desert (Antarct ica) depend upon a precarious equilibrium of biological, geological and cli matic factors. Any unfavourable change in external conditions can result in the death and disappearance of microscopic organisms, and this may be foll owed by trace microfossil formation. The sequence of events leading to the extinction of life in the Antarctic desert is considered to be a terrestria l analogue of the disappearance of possible life on early Mars. The present paper reviews the current state of knowledge on the endolithic microorgani sms of the Ross Desert with particular reference to their decay and fossili sation processes. Ideas for in situ further research on this microbial ecos ystem are also proposed, including several new microscopy techniques such a s CLSM, LTSEM, SEM-BSE and EDS. Preliminary images are presented and it is proposed that, for the first time, such techniques will permit the in situ study of the ecology of Antarctic lithobiontic microorganisms and the ident ification and characterisation of fossilised traces of past life.