Iron localization in Acarospora colonizing schist on Signy Island
A small, inconspicuous lichen, Acarospora cf. badiofusca, was discovered colonizing ironstained
quartz mica schists on the lower slope of Manhaul Rock, a recently exposed nunatak on the McLeod
Glacier, Signy Island, South Orkney Islands. Thallus colour ranged from rust on exposed rock surfaces to
paler orange and green in shaded crevices. This study addressed the hypothesis that colour reflects element
localization, and considered substance localization within lichen tissues and responses to stress. Electron
microprobe analysis of specimens confirmed that Fe is localized principally in the outer rust-coloured part
of the cortex, confirming that the colour reflects Fe localization. Oxalates, widely reported as contributing
to tolerance mechanisms to environmental stress, were not detected using X-ray diffraction. The upper
thallus surface consisted of sub-micron particulate phases containing Fe, Al and O, suggesting mixed oxide/
hydroxide phases are present and play a role in photoprotection.
Authors: Purvis, O.W., Convey, P. ORCID record for P. Convey, Flowerdew, M.J., Peat, H.J. ORCID record for H.J. Peat, Najorka, J., Kearsley, A.