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Antarctic Research Series

 

Keywords

  • Marine biology—Antarctic Ocean
  • Marine ecology—Antarctic Ocean
  • Sea ice—Antarctic Ocean

Article

ANTARCTIC RESEARCH SERIES, VOL. 73, PP. 45-83, 1998

Ice colors '93: Spectral UV radiation effects on Antarctic frazil ice algae

B. B. Prézelin, M. A. Moline, and H. A. Matlick

We assessed and monitored the polychromatic effects of solar ultraviolet B (UVB, 280–320 nm), ultraviolet A (UVA, 320–400 nm) and photosynthetically available radiation (PAR, 400–700 nm) on frazil ice algal communities. These team studies were conducted in pack ice communities that flowed into the vicinity of Palmer Station, Antarctica, between August and November, 1993. Pack ice provided incomplete protection to frazil ice algae from the damaging effects of incoming UV radiation. In vivo DNA damage, solely attributable to recent exposure to UVB radiation within the ice community [Jovine et al., 1996], was routinely evident. DNA damage occurred in spite of elevated levels of the mycosporine-like amino acid porphyra-344 within the algal community. Action spectra for UV inhibition of primary production indicated that carbon fixation was very sensitive to UVB radiation and that the relative UVB sensitivity became more pronounced at low light levels. We showed that UVB specifically targets photosystem II in ice algae and that the damage could account for most of the UVB-specific inhibition of carbon fixation occurring at the whole cell level [Kroon et al., 1994; Schofield et al.. The effects of UVB and UVA inhibition of carbon fixation varied over time and appeared dependent upon the photophysiological state of the community, the length of exposure, and pattern of light field fluctuations over the day. Seasonal monitoring of in situ pigmentation and photosynthesis-irradiance parameters revealed that in situ ice algae were responding to changes in PAR on time scales of a few days and becoming adapted to higher light levels by late spring (Ik values > 80 μE m−2 s−l). Present data may not be sufficient to accurately model the dose-dependent effects of UV radiation on in situ sea ice communities over larger time and space scales. Much better knowledge of UV optics (especially scalar irradiances) within sea ice is required and the magnitude and sources of variability in UV action spectra or biological weighting functions (BWFs) need to be defined for diverse sea ice communities.

Citation: Prézelin, B. B., M. A. Moline, and H. A. Matlick (1998), Ice colors '93: Spectral UV radiation effects on Antarctic frazil ice algae, in Antarctic Sea Ice: Biological Processes, Interactions and Variability, Antarct. Res. Ser., vol. 73, edited by P. Lizotte and R. Arrigo, pp. 45–83, AGU, Washington, D. C., doi:10.1029/AR073p0045.

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