Impact of changes in natural ultraviolet radiation on pigment composition, physiological and morphological characteristics of the Antarctic moss, Grimmia antarctici

The impact of ambient ultraviolet (UV)-B radiation on the endemic bryophyte, Grimmia antarctici, was studied over 14 months in East Antarctica. Over recent decades, Antarctic plants have been exposed to the largest relative increase in UV-B exposure as a result of ozone depletion. We investigated the effect of reduced UV and visible radiation on the pigment concentrations, surface reflectance and physiological and morphological parameters of this moss. Plexiglass screens were used to provide both reduced UV levels (77%) and a 50% decrease in total radiation. The screen combinations were used to separate UV photoprotective from visible photoprotective strategies, because these bryophytes are growing in relatively high light environments compared with many mosses. G. antarctici was affected negatively by ambient levels of UV radiation. Chlorophyll content was significantly lower in plants grown under near-ambient UV, while the relative proportions of photoprotective carotenoids, especially beta-carotene and zeaxanthin, increased. However, no evidence for the 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. Plants that were shaded showed fewer treatment responses and these were similar to the natural variation observed between moss growing on exposed microtopographical ridges and in more sheltered valleys within the turf. Given that other Antarctic bryophytes possess UV-B-absorbing pigments which should offer better protection under ambient UV-B radiation, these findings suggest that G. antarctici may be disadvantaged in some settings under a climate with continuing high levels of springtime UV-B radiation.

Some like it wet - biological characteristics underpinning tolerance of extreme water stress events in Antarctic bryophytes

Antarctic bryophyte communities presently tolerate physiological extremes in water availability, surviving both desiccation and submergence events. We investigated the relative ability of three Antarctic moss species to tolerate physiological extremes in water availability and identified physiological, morphological, and biochemical characteristics that assist species performance under such conditions. Tolerance of desiccation and submergence was investigated using chlorophyll fluorescence during a series of field- and laboratory-based water stress events. Turf water retention and degree of natural habitat submergence were determined from gametophyte shoot size and density, and delta C-13 signatures, respectively. Finally, compounds likely to assist membrane structure and function during desiccation events (fatty acids and soluble carbohydrates) were determined. The results of this study show significant differences in the performance of the three study species under contrasting water stress events. The results indicate that the three study species occupy distinctly different ecological niches with respect to water relations, and provide a physiological explanation for present species distributions. The poor tolerance of submergence seen in Ceratodon purpureus helps explain its restriction to drier sites and conversely, the low tolerance of desiccation and high tolerance of submergence displayed by the endemic Grimmia antarctici is consistent with its restriction to wet habitats. Finally the flexible response observed for Bryum pseudotriquetrum is consistent with its co-occurrence with the other two species across the bryophyte habitat spectrum. The likely effects of future climate change induced shifts in water availability are discussed with respect to future community dynamics.

The credentialing of counselling in Australia

Counselling is an unregulated activity in Australia. No statutory regulation currently exists. As a result, different counselling organizations are promoting different voluntary standards for the practice of counselling. This has led to a credentialing dilemma in which counsellors and the public are confronted with a number of counselling qualification choices. This dilemma poses a number of questions: Should counselling become more regulated in Australia? At what level should counselling be regulated? Should there be various levels of counsellor regulation? This article provides an overview of the credentialing dilemma facing counselling in Australia, compares and contrasts two main Australian accreditation efforts, and proposes cooperation as a way of navigating said dilemma. The implications for counselling as a profession are discussed along with suggestions for its development as a profession. This includes a discussion regarding the relative advantages and disadvantages of greater regulation of counselling as a professional activity in Australia. Specifically, what is and is not generally considered a profession is reviewed, different forms of credentialing are outlined, and general arguments for and against accreditation efforts are presented. The efforts of the Australian Counselling Association (ACA) and the Psychotherapy and Counselling Federation of Australia (PACFA) are compared and are shown to have common ground. Consequently, ways in which the main counselling organizations may best work in conjunction to promote counselling as a profession in Australia are proposed. These suggestions include good communication, collaboration, and the avoidance of turf wars. Specifically, that the ACA and PACFA collaborate on developing a combined independent registration list that is supported by both organizations or, minimally, that both organizations have mutual recognition on each other's register lists.