The effects of ultraviolet-b radiation on Antarctic sea-ice

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TitleThe effects of ultraviolet-b radiation on Antarctic sea-ice algaeAbstractThe impacts of ultraviolet-B radiation (UVB) on polar sea-ice algal communities have not yet been demonstrated. We assess the impacts of UV on these communities using both laboratory experiments on algal isolates and by modification of the in situ spectral distribution of the under-ice irradiance. In the latter experiment, filters were attached to the upper surface of the ice so that the algae were exposed in situ to treatments of ambient levels of PAR and UV radiation, ambient radiation minus UVB, and ambient radiation minus all UV. After 16d, significant increases in chl a and cell numbers were recorded for all treatments, but there were no significant differences among the different treatments. Bottom-ice algae exposed in vitro were considerably less tolerant to UVB than those in situ, but this tolerance improved when algae were retained within a solid block of ice. In addition, algae extracted from brine channels in the upper meter of sea ice and exposed to PAR and UVB in the laboratory were much more tolerant of high UVB doses than were any bottom-ice isolates. This finding indicates that brine algae may be better adapted to high PAR and UVB than are bottom-ice algae. The data indicate that the impact of increased levels of UVB resulting from springtime ozone depletion on Antarctic bottom-ice communities is likely to be minimal. These algae are likely protected by strong UVB attenuation by the overlying ice and snow, by other inorganic and organic substances in the ice matrix, and by algal cells closer to the surface. â"' 2011 Phycological Society of America.AcknowledgementsFinancial assistance for this study was provided by FRST contracts no CO8817 and VICX0706 for the New Zealand component and an ASAC grant and a University of Tasmania ARC grant for the Australian contribution. We thank Ian Hawes for the loan of the PUV500 radiometer. We are particularly grateful to Antarctic New Zealand and the Scott Base staff, especially Shul Gordon and Brian Staite, for logistic and field support for Events K136 and K043. UV data from McMurdo was provided by the NSF UV Monitoring Network, operated by Biospherical Instruments Inc. under a contract from the United States National Science FoundationÅ› Office of Polar Programs via Raytheon Polar Services Company.

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1st AuthorRyan, K.AuthorRyan, K.Mcminn, A.Hegseth, E.Davy, S.Year2012JournalJournal of PhycologyVolume48Number1Pages74-84DOI10.1111/j.1529-8817.2011.01104.xURLhttps://www.scopus.com/inward/recor.....7f74ab0ff712dedb4597c5f90KeywordsalgaeBacillariophytaDinophyceae, rank5Author KeywordsAntarcticDiatomDinoflagellateSea iceSea-ice algaeUVUVB

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TypeArticleCitationRyan, K., Mcminn, A., Hegseth, E. and Davy, S. (2012) The effects of ultraviolet-b radiation on Antarctic sea-ice algae. Journal of Phycology, 48(1): 74-84 doi:10.1111/j.1529-8817.2011.01104.x