Influence of solar UV-B radiation on peatland microbial communities of southern Argentinia

. Stratospheric ozone depletion occurs over Tierra del Fuego, Argentina, in the austral spring and summer due to the Antarctic 'ozone hole' and the ge neral erosion of the ozone layer. Thus, we investigated the responses of mi crobial communities to manipulations of solar UV-B radiation. . Results reported here are for field plots receiving either near-ambient o r reduced solar UV-B using plastic filters in a Sphagnum peatland and a Car ex fen during the second and third years of UV-B manipulations. . The total number of testate amoebae (Protozoa, Rhizopoda) inhabiting the upper centimeter of Sphagnum magellanicum was greater under near-ambient so lar UV-B than under reduced UV,B. No response to UV-B manipulation was appa rent for rotifers, nematodes, bacteria, microfungi, and a common microalga (Euglena mutabilis) inhabiting the S. magellanicum. on leaves of small Noth ofagus antarctica trees, the ratio of upper: lower leaf-surface fungal popu lations for the genus Aureobasidium and for total fungi indicated lower pop ulations on the upper, relative to the lower, surface under near-ambient so lar UV-B. . When responses to modifications of the solar UV-B flux were detected, the se involved both direct UV-B inhibition and indirect consequences of UV-B m anipulation.