EFFECTS OF UV RADIATION ON ANTARCTIC BENTHIC ALGAE - WITH EMPHASIS ON EARLY SUCCESSIONAL STAGES AND COMMUNITIES

In field experiments the interactive effects of UVR and grazing on early life stages of a hard bottom algal community were studied. In a two-factorial design, experimental units (1. ambient radiation, >280 nm; 2. ambient minus UV-B, >320 nm; 3. ambient minus UVR, >400 nm vs. grazer - no grazer) were installed for 2.5 and 3.5 months in the field. In conclusion, the results showed that the ambient UVR do not seem to be a threat to benthic marine Antarctic diatoms while grazers acted as important drivers on the complete intertidal algal community structure. In contrast, UV-B radiation significantly shaped macroalgal diversity and species composition. Limpets could mediate negative effects of ambient UVR on species richness and diversity to a certain level. On the basis of these results we hypothesise that ambient UV-B radiation, and a potential further increase of these wavelengths has the ability to affect the zonation, composition and diversity of Antarctic intertidal macroalgae altering trophic interactions in this system.