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- Wängberg, Sten-Åke, 1955, et al.
(författare)
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Inhibition of primary production by UV-B radiation in an arctic bay - model calculations
- 2006
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Ingår i: Aquatic Sciences. - : Springer Science and Business Media LLC. - 1015-1621 .- 1420-9055. ; 68:2, s. 117-128
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Tidskriftsartikel (refereegranskat)abstract
- Inhibition of primary production by UV-B radiation (UVBR) in Kings Bay, western Spitsbergen, was modelled using measured physical and biological data. The underwater radiation regime was modelled using continuous measurements of incoming radiation and repeated measurements of underwater attenuation of Photosynthetic Active Radiation (PAR) and UVBR. By using attenuation measurements, P/I curves and UVBR sensitivity measurements, we modelled the reduction of primary production in the photic zone for 14 days. We also calculated how the estimate was dependent on the different factors. The model showed that, on average, 2.9 % of the primary production was inhibited by UVBR, assuming that the inhibition is a function of the UVBR irradiance. If the ozone layer were reduced to 200 DU, the inhibition would increase to 4.4% using unweighted UVBR values. The model indicated that at ambient ozone levels the inhibition was practically independent of the chosen weighting function, but the choice was critical when predicting the effects of a depleted ozone layer. At 200 DU, using DNA weighting, the inhibition was 14.4% but using erythema weighting it was 6.5%. Different P/I curves did not change the estimate while changes in water attenuation gave results in the range 1.6-5.2%. The most uncertain factor in the model was the estimate of the sensitivity of primary production. Using four different in situ incubations, the estimated integrated reduction in primary production caused by UVBR ranged from 0.05-4.1%.
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- Wängberg, Sten-Åke, 1955, et al.
(författare)
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UV-B effects on microplankton communities in Kongsfjord
- 2008
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Ingår i: Journal of Experimental Marine Biology and Ecology. - 0022-0981. ; 365, s. 156-163
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Tidskriftsartikel (refereegranskat)abstract
- The effect of ambient ultraviolet radiation on microplankton communities in an Arctic fjord was measured in mesocosms incubated for 9 days at 2 or 5 meters depth. The mesocosms were either shielded from UV-B radiation by Mylar foil or received full radiation. The parameters measured were: microscopic counts of phytoplankton and micro-zooplankton, photosynthetic capacity, the wavelength-dependent inhibition of photosynthesis, and bacterial biomass and production. The results showed that UV-B radiation increased the photosynthetic capacity of the community but that the overall biomass of the plankton community was reduced. This indicates that UV-B exposure results in a net impairment of the plankton community in that it reduces the potential to allocate the photosynthetic product into new biomass or that the grazing pressure is higher in the UV-B exposed mesocosms. There were no differences in the wavelength dependence between communities exposed to UV-B versus not, but we observed a significantly lower dependence in communities from 2 m depth compared to those from 5 m, indicating that an acclimation of the photosynthetic apparatus to high radiation also reduces the wavelength dependence. A general effect was an increase in nanoflagellate and choanoflagellate biomass and a decreased in the biomass of ciliates and bacteria. The increase nanoflagellates was significantly larger in mesocosms shielded from UV-B, while choanoflagellates increased more in UV-B exposed mesocosms.
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