Temporal changes in effects of ambient UV radiation on natural communities of Antarctic marine protists

Abstract

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 52:131-147 (2008) - DOI: https://doi.org/10.3354/ame01201 Temporal changes in effects of ambient UV radiation on natural communities of Antarctic marine protists Paul G. Thomson1,2,*, Andrew T. Davidson1,2, Nina Cadman1 1Department of the Environment and Water Resources, Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia 2Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC), University of Tasmania, Private Bag 80, Hobart, Tasmania 7001, Australia *Email: paul.thomson@aad.gov.au ABSTRACT: The effects of ambient solar UV radiation (280 to 400 nm) were determined using 3 natural marine protist communities incubated in 650 l tanks (minicosms) for 13 to 14 d over the summer of 2002–2003 at Davis Station, Antarctica. Minicosms were exposed to ambient light that was variously attenuated to give treatments of photosynthetically active radiation (PAR, ≥385 nm wavelength), PAR + UV-A radiation (315 to 385 nm), and PAR + UV-A + 4 different treatments of UV-B radiation (280 to 315 nm) that simulated a range of equivalent depths (ED) in the water column from 4.43 to 7.15 m. Results showed a seasonal progression in the response of microbial communities to UV radiation exposure. The first experiment in November showed that the microbial community was significantly inhibited in the PAR + UV-A-exposed treatment but this inhibition declined with increasing addition of UV-B radiation. The second experiment in December showed that UV-A or UV-B radiation had few significant effects. Like in Expt 1, some taxa were inhibited by PAR + UV-A or promoted by UV-B, but most were inhibited at the highest UV-B irradiances (≤4.43 m ED). The last experiment in January showed UV-B induced inhibition of all but one of the dominant taxa. The seasonal transition in UV wavelengths responsible for inhibition of protists may be due to ozone reduction, the light history of protists, and/or changes in species composition. The increasing UV-B-induced inhibition we observed over the summer corresponded to a decline in ozone concentrations over Davis. This recurrent decline in ozone over Antarctica between January and April coincides with blooms of diatoms that appear to have low UV-B tolerance but are responsible for ~47% of annual primary production in Antarctic waters. KEY WORDS: Antarctic · Marine protists · UV-A · UV-B · Ozone · Diatoms · Flagellates · Dinoflagellates Full text in pdf format Supplementary appendix PreviousNextCite this article as: Thomson PG, Davidson AT, Cadman N (2008) Temporal changes in effects of ambient UV radiation on natural communities of Antarctic marine protists. Aquat Microb Ecol 52:131-147. https://doi.org/10.3354/ame01201Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 52, No. 2. Online publication date: July 24, 2008 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2008 Inter-Research.