Summary
Over recent decades, Antarctic plants have been exposed to the largest relative increase in UV-B exposure as a result of ozone depletion. Open-sided plexiglass screens were used to reduce UV levels by 77% over turves of the endemic Antarctic bryophyte, Grimmia antarctici, and the effect on pigment concentrations, surface reflectance and physiological and morphological parameters was investigated over 14 months. G. antarctici was affected negatively by ambient levels of UV radiation. Chlorophyll content was significantly lower in plants grown under near ambient UV, whilst the relative proportions of photoprotective carotenoids, especially ß-carotene and zeaxanthin, increased. No evidence for accumulation of UV-B absorbing pigments in response to UV radiation was observed. Although photosynthetic rates were not affected, there was evidence of UV effects on morphology. Given that other Antarctic bryophytes possess UV-B absorbing pigments that should offer better protection under ambient UV-B radiation, these findings suggest that G. antarctici may be disadvantaged under a climate with continuing high levels of springtime UV-B radiation.