Impact of UV-B radiation on microalgae and bacteria: a mesocosm study with computer modulated UV-B radiation addition

Wängberg, Sten-Åke; Wulff, Angela; Nilsson, Claes; Stagell, Ulrica

doi:10.3354/ame025075

Cited by 13 publications

(9 citation statements)

References 39 publications

(61 reference statements)

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“…The absence of significant differences in chl a concentrations between the NUVBR and HUVBR treatments in the present study has previously been reported (Mousseau et al 2000, Wängberg et al 2001 and attributed to the fact that diatoms are more resistant to UVR exposure than other phytoplankton groups (Karentz et al 1991, Helbling et al 1996. However, significant differences were observed between both UVBR treatments in the total abundance of cells < 20 μm.…”

Section: Mechanisms and Relevance Of Enhanced Uvbr To Plankton Assembcontrasting

confidence: 55%

Non-synergistic effects of water-soluble crude oil and enhanced ultraviolet-B radiation on a natural plankton assemblage

Sargian¹,

Mostajir²,

Chatila³

et al. 2005

Mar. Ecol. Prog. Ser.

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The present study demonstrates the effects of the water-soluble fraction (WSF) of a crude oil, enhanced ultraviolet-B radiation (UVBR: 280 to 320 nm), and the combination of WSF and enhanced UVBR on a natural plankton assemblage (<150 μm) isolated from the lower St. Lawrence Estuary. To study the separate and dual effects of WSF and UVBR, 12 microcosms (9 l) were immersed in the water column of larger mesocosms (polyethylene bags; 1800 l), providing 4 treatments, each in triplicate: (1) NUVBR + WSF (natural UVBR with WSF), (2) HUVBR + WSF (enhanced UVBR with WSF), (3) NUVBR (natural UVBR without WSF), and (4) HUVBR (enhanced UVBR without WSF). During 5 d we monitored the incident radiation, WSF and nutrient concentrations, abundance and production of heterotrophic bacteria and phytoplankton. Strong deleterious effects of WSF and lower effects of UVBR were observed on the phytoplankton assemblage, with a decrease in growth rates accompanied by an increase in mean cell size which reflected a perturbation of the cell division cycle. Using the NUVBR treatement as reference conditions, the above effects resulted in a reduction of 84, 79 and 60% of total abundance of the phytoplankton fraction < 20 μm in the HUVBR + WSF, NUVBR + WSF and HUVBR treatments, respectively. Significant higher values of bacterial abundances were observed in the WSF-added treatments compared to NUVBR without WSF. However, bacterial thymidine incorporation exhibited diel variations, suggesting cumulative UVBR-induced DNA and/or PAHinduced DNA damages, and possible repair mechanisms with the co-occurrence of more available growth substrates from stressed phytoplankton. The absence of significant differences between both WSF-added treatments under the 2 different UVBR conditions suggests that there is no additive interaction between WSF and UVBR. This study provides therefore the first evidence of a non-synergistic interaction between both stresses, and suggests that UVBR-induced effects on marine microorganisms can be completely masked by the strong deleterious effects of soluble petroleum hydrocarbons.KEY WORDS: Ultraviolet radiation · Dissolved hydrocarbons · Non-synergistic effect · Phytoplankton · BacteriaResale or republication not permitted without written consent of the publisher

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Section: Mechanisms and Relevance Of Enhanced Uvbr To Plankton Assembcontrasting

confidence: 55%

Non-synergistic effects of water-soluble crude oil and enhanced ultraviolet-B radiation on a natural plankton assemblage

Sargian¹,

Mostajir²,

Chatila³

et al. 2005

Mar. Ecol. Prog. Ser.

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“…The outdoor model ecosystem was modified from the setup described in Wängberg et al (2001), see Fig. 2.…”

Section: Methodsmentioning

confidence: 99%

Effects of changes in ambient PAR and UV radiation on the nutritional quality of an Arctic diatom (Thalassiosira antarctica var. borealis)

Leu

Wängberg

Wulff

et al. 2006

Journal of Experimental Marine Biology and Ecology

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Polyunsaturated fatty acids (PUFAs) are essential macromolecules that are synthesized by phytoplankton during spring bloom, and they play a key role in the Arctic food web. They are, however, considered to be sensitive to oxidation by UV radiation (280-400 nm). Changes in the food quality of primary producers may affect the transport of biomass and energy in the whole ecosystem. Using a common Arctic diatom, we looked at the effect of ambient and increased UV radiation on its nutritional quality, specifically, the fatty acid composition and elemental ratios. In May 2004, in the archipelago of Svalbard (79° N), a unialgal culture of Thalassiosira antarctica var. borealis was subjected to a 17-day experiment in outdoor aquaria. The diatoms were kept in semi-continuous culture (40 1) and exposed to three treatments with different levels of UV radiation: none (UV-shielded), ambient, and enhanced. Fatty acid composition, C:N:P ratios, photosynthetic pigment composition, optimum quantum yield of PSII, and cell numbers were analysed over the experimental period. An initial increase in PAR (photosynthetically active radiation, 400-700 nm) intensities profoundly affected the fatty acid composition and substantially inhibited the synthesis of PUFAs, but the relative amounts of PUFAs were not reduced by UV radiation. Enhanced UV radiation did, however, cause a significant reduction in optimum quantum yield of PSII and affected some fatty acids, mainly 18:0 and 16:1 n-7, during the first week of the experiment. Both ambient and enhanced UV radiation caused significantly lower C:P and N:P ratios. At the same time, these treatments elicited a higher relative content of the photoprotective pigments diadinoxanthin and diatoxanthin. After acclimation to the new light levels these effects faded off. Thus, brief periods with high light exposure may cause significant changes in photosynthetic activity and food quality, but the capacity for photo-acclimation seems high. The impact of UV radiation seems to be less important for food quality than that of PAR during a sudden rise in total light intensity.

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“…Smith et al, 1992;Bracher and Wiencke, 2000;Villafane et al, 2004;Eilertsen and Holm-Hansen, 2000;Wängberg and Gustavson, 1988), and is correlated with sampling depth, blooms and frontal systems and also if PP is inhibited by PAR or UVAR. It has also been shown that the UVBR exposure during the development of plankton communities in model ecosystems changes the sensitivity to UVBR (Wängberg et al, 2001;Wängberg and Wulff, 2004). Proposed reasons for these differences in sensitivity includes adaptation to UVBR or high light intensities in general and changes in species composition and cell sizes during different ecological situations not directly connected to high radiation, e.g.…”

Section: Discussionmentioning

confidence: 99%

Inhibition of primary production by UV-B radiation in an arctic bay – model calculations

Wängberg¹,

Andreasson²,

Garde

et al. 2006

Aquat. Sci.

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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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Impact of UV-B radiation on microalgae and bacteria: a mesocosm study with computer modulated UV-B radiation addition

Cited by 13 publications

References 39 publications

Non-synergistic effects of water-soluble crude oil and enhanced ultraviolet-B radiation on a natural plankton assemblage

Non-synergistic effects of water-soluble crude oil and enhanced ultraviolet-B radiation on a natural plankton assemblage

Effects of changes in ambient PAR and UV radiation on the nutritional quality of an Arctic diatom (Thalassiosira antarctica var. borealis)

Inhibition of primary production by UV-B radiation in an arctic bay – model calculations

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