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, eastern Antarctica. 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 a highly seasonal, rapidly variable and often extreme climate with frequent sub zero temperatures, an intermittent water supply and almost continuous sunlight. Additionally, recent ozone depletion has resulted in elevated levels of potentially damaging ultraviolet-B radiation early in the growing season. Moss samples were collected from late November through to mid March. Pigments were extracted and analysed using high pressure liquid chromatography and spectroscopy. Chlorophyll, xanthophyll cycle, anthocyanin and UV-B absorbing pigments were measured for each of the moss species over the season. All three species had photosynthetic and photoprotective pigment levels similar to ÔsunÕ 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. Pigment and climate data were combined to build models for the association between moss pigment parameters and environmental variables. Water content was the strongest environmental variable affecting moss pigmentation, particularly in G. antarctici. Total ultraviolet radiation, which was used to represent sunlight, and air temperature also contributed significantly to these pigment models. This work represents a novel study of a neglected group of plants which represent a key component of Antarctic biodiversity and are important indicators for climate change research in this region.