Summary
Seasonal changes in the photosynthetic and photoprotective pigment content of three species of Antarctic moss; Grimmia antarctici, Bryum pseudotriquetrum and Ceratodon purpureus were explored in relation to a range of environmental variables over the growing season in the Windmill Islands region on the east coast of the Antarctic continent. Climate data for this region was collected over the 1999/2000 summer and related to the ecophysiology of the local moss plants. These Antarctic moss are exposed to the highly seasonal, rapidly variable and often extreme climate of the region with frequent sub zero temperatures, an intermittent water supply and almost continuous sunlight. These conditions are physiologically stressful to the moss. Additionally, recent ozone depletion has resulted in elevated levels of damaging ultraviolet-B radiation early in the growing season. Moss samples were collected from late November through to mid March and pigments were extracted and analysed using high pressure liquid chromatography and spectroscopy. Chlorophyll, ß-carotene, xanthophyll cycle and UV-B absorbing pigment contents were measured for each of the moss species over the season. All three species had photosynthetic and photoprotective pigment levels similar to ‘sun’ type higher plants, particularly G. antarctici and C. purpureus, indicating high light acclimation. Conversely, B.pseudotriquetrum was comparatively well protected from damaging UV-B by a high UV-B absorbing pigment content. Seasonal trends in pigment levels were discussed in relation to photosynthetic acclimation to the climate and also possible photodamage. This pigment data was combined with the climate data to build a model for the association between each of the six moss pigment parameters and environmental variables. Water content was the strongest environmental variable affecting moss pigmentation, particularly in G. antarctici. Total ultraviolet radiation was used to represent sunlight and along with