PARENT SESSION
Poster Session #10: UV-B.
Monday, August 6, 2001. Presentation from 3:30 PM to 5:00 PM. Exhibition Hall
29
Biodiversity of microfauna and fungal communities in a Sphagnum bog under two levels of solar UV-B.
ROBSON, THOMAS1, BALLARÉ, CARLOS2, SALA, OSVALDO2, SCOPEL, ANA2, CALDWELL, MARTYN1, 1 2
ABSTRACT- The Antarctic ozone hole raises levels of UV-B radiation in Tierra del Fuego, South America. The abundant peat bogs of Tierra del Fuego are of interest, because they previously received a very low dose of UV-B. The microorganisms that live in association with Sphagnum in the uppermost layers of the bog may be influenced by this increase in UV-B radiation. Long-term sample plots are under selective filters that either reduce UV-B radiation or allow near-ambient UV-B radiation to penetrate to the surface of a mineralotrophic Sphagnum bog. Samples of Sphagnum were taken from these plots on a monthly basis over two growing seasons (1999-2001), and fungal and microfaunal community composition was assessed. Testate amoebae of genera Assulina, Heleopera, Euglypha and Corythion were identified, rotifers, Nematoda, Cyanobacteria, Euglena and mites were counted, and an index of biodiversity was taken. The change in community structure and population size over the course of the growing season was monitored. Testate amoebae and rotifers were found to be significantly more abundant and to have a greater species diversity in plots under current dosage of UV-B than those receiving reduced UV-B radiation. However there was significant variability amongst genera in response to the treatments. Fungi inhabiting the Sphagnum surface layer were also seen to respond distinctly to the treatments, with an overall increase in biodiversity seen in 1999-2000 in those plots exposed to higher UV-B dose.
KEY WORDS: ozone depletion, long term ecosystem study, peat bog, biodiversity