| 1. |
- Abrahamsson, Katarina, 1957, et al.
(författare)
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Air-sea exchange of halocarbons: the influence of diurnal and regional variations and distribution of pigments
- 2004
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Ingår i: Deep-Sea Research Part Ii-Topical Studies in Oceanography. - : Elsevier BV. - 0967-0645. ; 51:22-24, s. 2789-2805
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Tidskriftsartikel (refereegranskat)abstract
- Diurnal cycles of halocarbons, except methyl bromide and methyl chloride, were observed at six 24-h stations occupied in three different regions, the Summer Ice Edge, the Winter Ice Edge, and the Antarctic Polar Front, in the Atlantic sector of the Southern Ocean during a Swedish-South African expedition in 1997/1998. The diurnal cycles contained three phases; a productive phase, a phase of losses and a phase with steady state. The duration of the different phases varied for the different stations as well as for individual compounds. The measured production and losses of organo-halogens in the Antarctic Ocean based on values from each station, were in the order of a few to hundreds of Tg yr(-1). Bromochloromethane, tribromomethane, trichloroethene and diiodomethane were the four compounds found in highest concentrations throughout the investigation, and they were found to be the major contributors of organohalogens. Only the presence of the photosynthetic pigment 19'-hexanoyloxyfucoxanthin, biomarker pigment of haptophytes, could explain some of the variations in the distribution and production of halocarbons, and then only for iodinated compounds. The flux of organo-halogens from the oceans to the atmosphere was estimated in two ways, either based on calculations according to models or based on the measured concentrations. Large discrepancies were found, which could not be explained by chemical or biological degradation or adsorption to particles. This investigation, therefore, shows the need for assessing the rates of degradation and the air-sea exchange more accurately. (C) 2004 Elsevier Ltd. All rights reserved.
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| 2. |
- Andrady, A, et al.
(författare)
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Environmental effects of ozone depletion and its interactions with climate change: progress report, 2015
- 2016
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Ingår i: Photochemical and Photobiological Sciences. - 1474-905X .- 1474-9092. ; 15:2, s. 141-174
-
Tidskriftsartikel (refereegranskat)abstract
- The Environmental Effects Assessment Panel (EEAP) is one of three Panels that regularly informs the Parties (countries) to the Montreal Protocol on the effects of ozone depletion and the consequences of climate change interactions with respect to human health, animals, plants, biogeochemistry, air quality, and materials. The Panels provide a detailed assessment report every four years. The most recent 2014 Quadrennial Assessment by the EEAP was published as a special issue of seven papers in 2015 (Photochem. Photobiol. Sci., 2015, 14, 1-184). The next Quadrennial Assessment will be published in 2018/2019. In the interim, the EEAP generally produces an annual update or progress report of the relevant scientific findings. The present progress report for 2015 assesses some of the highlights and new insights with regard to the interactive nature of the effects of UV radiation, atmospheric processes, and climate change.
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| 3. |
- Andrady, Anthony, et al.
(författare)
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Environmental effects of ozone depletion and its interactions with climate change: Progress report, 2016
- 2017
-
Ingår i: Photochemical and Photobiological Sciences. - : Springer Science and Business Media LLC. - 1474-9092 .- 1474-905X. ; 16:2, s. 107-145
-
Tidskriftsartikel (refereegranskat)abstract
- The Parties to the Montreal Protocol are informed by three Panels of experts. One of these is the Environmental Effects Assessment Panel (EEAP), which deals with two focal issues. The first focus is the effects of UV radiation on human health, animals, plants, biogeochemistry, air quality, and materials. The second focus is on interactions between UV radiation and global climate change and how these may affect humans and the environment. When considering the effects of climate change, it has become clear that processes resulting in changes in stratospheric ozone are more complex than previously believed. As a result of this, human health and environmental issues will be longer-lasting and more regionally variable. Like the other Panels, the EEAPproduces a detailed report every four years; the most recent was published as a series of seven papers in 2015 (Photochem. Photobiol. Sci., 2015, 14, 1–184). In the years in between, the EEAP produces less detailed and shorter Progress Reports of the relevant scientific findings. The most recent of these was for 2015 (Photochem. Photobiol. Sci., 2016, 15, 141–147). The present Progress Report for 2016 assesses some of the highlights and new insights with regard to the interactive nature of the direct and indirect effects of UV radiation, atmospheric processes, and climate change. The more detailed Quadrennial Assessment will bemade available in 2018.
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| 4. |
- Andreasson, Kristin I. M., 1963, et al.
(författare)
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Biological weighting functions as a tool for evaluating two ways to measure UVB radiation inhibition on photosynthesis
- 2006
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Ingår i: Journal of Photochemistry and Photobiology B-Biology. - : Elsevier BV. - 1011-1344. ; 84:2, s. 111-118
-
Tidskriftsartikel (refereegranskat)abstract
- To estimate the inhibitory effect of the changing UVB radiation (UVBR, 280-315 nm) on earth's ecosystems, an understanding of its wavelength dependency is needed. The tool used for these estimations is the biological weighting function (BWF), whereby the inhibition of different wavelengths is calculated. B\WFs were determined for three algae species from different classes, Phaeodactylum tricornutum (Bacillariophyceae), Dunaliella tertiolecta (Chlorophyceae) and Rhodomonas sp. (Cryptophyceae), using polychromatic irradiation, where the UVBR spectra were varied with cut-off filters. For each alga, BWFs were determined for two photosynthetic parameters; the quantum yield measured as fluorescence from Photo System II in a pulse-amplitude-modulation (PAM) fluorometer, and the fixation of C-14-labelled carbon dioxide. The BWFs were calculated with the Rundel method, using the radiation data between 270 and 360 nm with 1 nm resolution. The results show that the UVBR damages were generally higher when using the carbon fixation measurements than when measuring with the PAM technique. When using PAM, P. tricornutum in particular had a sensitivity intermediate between the sensitive Rhodomonas sp. and the more tolerant D. tertiolecta, but was as sensitive as, or even more sensitive, than Rhodomonas sp. when using carbon fixation. D. tertiolecta was shown to be less sensitive when using both techniques and the inhibition of its photosynthesis was almost as high when using PAM as when using carbon fixation. We concluded that, although the PAM technique has advantages such as being cleaner and easier to use, it is unable to Substitute the carbon fixation measurements. Not only are the algae less sensitive when measured with PAM than they are when measured as carbon fixation, the relationship between the effects on the algae measured with the two techniques also differs. As fixation of carbon dioxide integrates a larger part of the photosynthetic machinery, it should be favoured as a measure of photosynthesis. (c) 2006 Elsevier B.V. All rights reserved.
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| 5. |
- Andreasson, Kristin I. M., 1963, et al.
(författare)
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Reduction in growth rate in Phaeodactylum tricornutum (Bacillarlophyceae) and Dunaliella tertiolecta (Chlorophyceae) induced by UV-B radiation
- 2007
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Ingår i: Journal of Photochemistry and Photobiology B-Biology. - : Elsevier BV. - 1011-1344. ; 86:3, s. 227-233
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of UV-B radiation (UVBR, 280-315 nm) on growth rate during 72 h of incubation, was measured for two marine microalgae - Dunaliella tertiolecta (Chlorophyceae) and Phaeodactyhan tricornutum (Bacillariophyceae). The resulting inhibition of growth rate was analysed by calculating biological weighting functions (BWFs). The growth rate of D. tertiolecta was slightly more inhibited by UVBR (over the whole range of the spectrum) than was the growth rate of P. tricornutum, but the wavelength dependencies were the same. Our results were compared with results from photosynthesis experiments of Andreasson and Wangberg [1], where two methods, pulse amplitude modulation (PAM) fluorescence and carbon fixation, were measured for these same algae. The BWF for the growth rate, here, showed more wavelength dependency than the BWF for the previous two photosynthesis measurements - except for the carbon fixation BWF in P. tricornutum, which was closer to the BWF for growth rate. The wavelength dependency of the growth rate inhibition showed less variation between the species than the inhibition of the photosynthesis. (c) 2006 Elsevier B.V. All rights reserved.
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| 6. |
- Bais, A. F., et al.
(författare)
-
Environmental effects of ozone depletion, UV radiation and interactions with climate change: UNEP Environmental Effects Assessment Panel, update 2017
- 2018
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Ingår i: Photochemical & Photobiological Sciences. - : Springer Science and Business Media LLC. - 1474-905X .- 1474-9092. ; 17:2, s. 127-179
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Tidskriftsartikel (refereegranskat)abstract
- The Environmental Effects Assessment Panel (EEAP) is one of three Panels of experts that inform the Parties to the Montreal Protocol. The EEAP focuses on the effects of UV radiation on human health, terrestrial and aquatic ecosystems, air quality, and materials, as well as on the interactive effects of UV radiation and global climate change. When considering the effects of climate change, it has become clear that processes resulting in changes in stratospheric ozone are more complex than previously held. Because of the Montreal Protocol, there are now indications of the beginnings of a recovery of stratospheric ozone, although the time required to reach levels like those before the 1960s is still uncertain, particularly as the effects of stratospheric ozone on climate change and vice versa, are not yet fully understood. Some regions will likely receive enhanced levels of UV radiation, while other areas will likely experience a reduction in UV radiation as ozone- and climate-driven changes affect the amounts of UV radiation reaching the Earth's surface. Like the other Panels, the EEAP produces detailed Quadrennial Reports every four years; the most recent was published as a series of seven papers in 2015 (Photochem. Photobiol. Sci., 2015, 14, 1-184). In the years in between, the EEAP produces less detailed and shorter Update Reports of recent and relevant scientific findings. The most recent of these was for 2016 (Photochem. Photobiol. Sci., 2017, 16, 107-145). The present 2017 Update Report assesses some of the highlights and new insights about the interactive nature of the direct and indirect effects of UV radiation, atmospheric processes, and climate change. A full 2018 Quadrennial Assessment, will be made available in 2018/2019.
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| 7. |
- Barnes, P. W., et al.
(författare)
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Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2021
- 2022
-
Ingår i: Photochemical & Photobiological Sciences. - : Springer Science and Business Media LLC. - 1474-905X .- 1474-9092. ; 31, s. 275-301
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Tidskriftsartikel (refereegranskat)abstract
- The Environmental Effects Assessment Panel of the Montreal Protocol under the United Nations Environment Programme evaluates effects on the environment and human health that arise from changes in the stratospheric ozone layer and concomitant variations in ultraviolet (UV) radiation at the Earth’s surface. The current update is based on scientific advances that have accumulated since our last assessment (Photochem and Photobiol Sci 20(1):1–67, 2021). We also discuss how climate change affects stratospheric ozone depletion and ultraviolet radiation, and how stratospheric ozone depletion affects climate change. The resulting interlinking effects of stratospheric ozone depletion, UV radiation, and climate change are assessed in terms of air quality, carbon sinks, ecosystems, human health, and natural and synthetic materials. We further highlight potential impacts on the biosphere from extreme climate events that are occurring with increasing frequency as a consequence of climate change. These and other interactive effects are examined with respect to the benefits that the Montreal Protocol and its Amendments are providing to life on Earth by controlling the production of various substances that contribute to both stratospheric ozone depletion and climate change. © 2022, The Author(s).
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| 8. |
- Barnes, Paul W., et al.
(författare)
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Ozone depletion, ultraviolet radiation, climate change and prospects for a sustainable future
- 2019
-
Ingår i: Nature Sustainability. - : Springer Science and Business Media LLC. - 2398-9629. ; 2:7, s. 569-579
-
Forskningsöversikt (refereegranskat)abstract
- © 2019, Springer Nature Limited. Changes in stratospheric ozone and climate over the past 40-plus years have altered the solar ultraviolet (UV) radiation conditions at the Earth’s surface. Ozone depletion has also contributed to climate change across the Southern Hemisphere. These changes are interacting in complex ways to affect human health, food and water security, and ecosystem services. Many adverse effects of high UV exposure have been avoided thanks to the Montreal Protocol with its Amendments and Adjustments, which have effectively controlled the production and use of ozone-depleting substances. This international treaty has also played an important role in mitigating climate change. Climate change is modifying UV exposure and affecting how people and ecosystems respond to UV; these effects will become more pronounced in the future. The interactions between stratospheric ozone, climate and UV radiation will therefore shift over time; however, the Montreal Protocol will continue to have far-reaching benefits for human well-being and environmental sustainability.
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| 9. |
- Bergkvist, Johanna, 1980, et al.
(författare)
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Grazer-induced chain length plasticity reduces grazing risk in a marine diatom
- 2012
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Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590. ; 57:1, s. 318-324
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Tidskriftsartikel (refereegranskat)abstract
- We show that Skeletonema marinoi suppresses chain formation in response to copepod cues. The presence of three different copepod species (Acartia tonsa, Centropages hamatus, or Temora longicornis) significantly reduced chain length. Furthermore, chain length was significantly reduced when S. marinoi was exposed to chemical cues from caged A. tonsa without physical contact with the responding cells. The reductions in chain length significantly reduced copepod grazing; grazing rates on chains (four cells or more) were several times higher compared to that of single cells. This suggests that chain length plasticity is a means for S. marinoi to reduce copepod grazing. In contrast, chain length was not suppressed in cultures exposed to the microzooplankton grazer Gyrodinium dominans. Size-selective predation may have played a key role in the evolution of chain formation and chain length plasticity in diatoms.
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| 10. |
- Bernhard, G. H., et al.
(författare)
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Environmental effects of stratospheric ozone depletion, UV radiation and interactions with climate change: UNEP Environmental Effects Assessment Panel, update 2019
- 2020
-
Ingår i: Photochemical and Photobiological Sciences. - : Springer Science and Business Media LLC. - 1474-905X .- 1474-9092. ; 19:5, s. 542-584
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Tidskriftsartikel (refereegranskat)abstract
- © 2020 The Royal Society of Chemistry and Owner Societies. This assessment, by the United Nations Environment Programme (UNEP) Environmental Effects Assessment Panel (EEAP), one of three Panels informing the Parties to the Montreal Protocol, provides an update, since our previous extensive assessment (Photochem. Photobiol. Sci., 2019, 18, 595-828), of recent findings of current and projected interactive environmental effects of ultraviolet (UV) radiation, stratospheric ozone, and climate change. These effects include those on human health, air quality, terrestrial and aquatic ecosystems, biogeochemical cycles, and materials used in construction and other services. The present update evaluates further evidence of the consequences of human activity on climate change that are altering the exposure of organisms and ecosystems to UV radiation. This in turn reveals the interactive effects of many climate change factors with UV radiation that have implications for the atmosphere, feedbacks, contaminant fate and transport, organismal responses, and many outdoor materials including plastics, wood, and fabrics. The universal ratification of the Montreal Protocol, signed by 197 countries, has led to the regulation and phase-out of chemicals that deplete the stratospheric ozone layer. Although this treaty has had unprecedented success in protecting the ozone layer, and hence all life on Earth from damaging UV radiation, it is also making a substantial contribution to reducing climate warming because many of the chemicals under this treaty are greenhouse gases.
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| 11. |
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| 12. |
- Chen, Deliang, 1961, et al.
(författare)
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Attenuation of biologically effective UV doses under overcast skies: a case study from the eastern Atlantic sector of the Southern Ocean
- 2004
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Ingår i: Deep-Sea Research Part Ii-Topical Studies in Oceanography. - : Elsevier BV. - 0967-0645. ; 51:22-24, s. 2673-2682
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Tidskriftsartikel (refereegranskat)abstract
- This study deals attenuation of ultraviolet solar radiation measured during the SWEDARP 1997/1998 expedition in the eastern Atlantic sector of the Southern Ocean. Experimental data were measured on board a ship and theoretical computation of radiative transfer has been applied. Focus has been placed on biologically effective UV-B doses using three commonly applied biological weighting functions based on: inhibition of carbon dioxide fixation (Science 258 (1992) 646); Generalized plant effects (Stratospheric Ozone Reduction, Solar Ultraviolet Radiation and Plant Life 1986, Springer, Berlin) and DNA lesions (Proc. Nat. Acad. Sci. USA 71 (1974) 3363). The ratio of measured dose to that under clear sky condition, calculated by a model, was defined as transmittance which was studied in relation to other information. Further, the interrelationship between the biologically effective UV doses and various broadband irradiance in the UV-A, UV-B and PAR was established. It shows that the UV-B doses based on the three weighting functions are closely linked to each other and their cloud transmittances are nearly the same. The biologically effective UV-B doses can be estimated with reasonable accuracy from the broadband irradiance in the UV-A, UV-B and PAR regions, with UV-B giving the best results. Univariate analysis between the transmittance and zenith angle, total cloud cover and cloud base height was performed. It is found that attenuation is almost independent of zenith angle. Transmission is reduced by 7.7% if the cloud cover is increased by one octa. The average transmittance of the UV-B doses is 0.40, indicating that clouds have played an important role in reducing the UV radiation. (C) 2004 Elsevier Ltd. All rights reserved.
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| 13. |
- Dave, Göran, 1945, et al.
(författare)
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Ecosystem health of Lake Vanern: Past, present and future research
- 2015
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Ingår i: Aquatic Ecosystem Health & Management. - : Michigan State University Press. - 1463-4988 .- 1539-4077. ; 18:2, s. 205-211
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Tidskriftsartikel (refereegranskat)abstract
- The large lakes of Sweden (Vanern, Vattern, Malaren and Hjalmaren) have been monitored for more than four decades for water quality conditions to assess the impact of eutrophication from anthropogenic activities. Lake Vanern is basically an oligotrophic lake that showed signs of eutrophication, notably the emergence of algal blooms in the coastal areas (1967-1968). The lake was also contaminated, due to the discharge of pulp and paper effluents including metals such as mercury. However, ecosystem-based information is lacking for Lake Vanern. Consequently a symposium was organized in 2012 by the University of Gothenburg, Motesplats Vanersborg and the Aquatic Ecosystem Health and Management Society to: assess the current status of the health of Lake Vanern's ecosystem, identify knowledge gaps and develop a road map for the future. In this regard, Lake Vanern was compared with the North American Great Lakes to learn from their extensive, long-term data sets. A special issue devoted to the State of Lake Vanern Ecosystem symposium was published in Aquatic Ecosystem Health and Management (AEHM, Vol. 17, no. 4) including keynotes and contributed papers. The conclusions shown in the appendix (available in the online supplementary information) summarize the authors' contributions. Most of the articles covered Lake Vanern, but some were directed towards monitoring and management of Great Lakes in general, and others addressed co-operation under the auspices of international agreements and directives. Based on the background information provided by the State of Lake Vanern Ecosystem symposium and its publication in the special issue, the conveners decided that a synthesis of the symposium with recommendations for the future would be useful in boosting ecosystem research in Lake Vanern.
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| 14. |
- Drotz, Marcus, 1968, et al.
(författare)
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Forskning och kunskapsproducenter runt Vänern. Kunskapsunderlag inom Vänersamarbetet
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rapporten är en kunskaps- och forskningsinventering av befintlig och avslutad forskning, samt kunskapsproducenter med anknytning till Vänern. Geografiskt har inventeringen begränsats till kommunerna i anslutning till Vänern samt vattnet och dess tillflöden, utflöde och kanaler. Ämnesmässigt har inventeringen fokuserat på forskning och kunskapsproduktion som direkt rör Vänerområdet inom såväl natruvetenskap, samhällsvetenskap som humaniora, speciellt det som rör arbetet inom Vänersamarbetet som är relaterat till hållbar utveckling socialt, ekonomiskt och ekologiskt. Tidsmässigt har arbetet fokuserats på att sammanställa projekt som pågår eller är avslutade under de senaste fem åren. Genom denna avgränsning har vi i mindre utsträckning tagit med forskning, kunskapsproduktion, nätverk och myndighetsdokumentation som rör större regionala områden eller Sverige i stort. Målgruppen är forskare, tjänstemän och beslutsfattare inom den offentliga sektorn. Projektet har genomförts i samarbete med Västra Götalandsregionen och Region Värmland. Till rapporten hör en referenssamling i form av en bilaga, ISBN: 91-88048-18-7.
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| 15. |
- Drotz, M.K., et al.
(författare)
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Lake Vänern: A historical outline
- 2014
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Ingår i: Aquatic Ecosystem Health and Management. - : Michigan State University Press. - 1463-4988 .- 1539-4077. ; 17:4, s. 323-330
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Tidskriftsartikel (refereegranskat)abstract
- © 2014, Copyright © AEHMS. Although Lake Vänern is the largest freshwater reservoir in Western Europe, it remains relatively unknown to the scientific community outside of Scandinavia. Therefore, we aim to give a brief outline of the lake and its geological history, in particular the landscape transformation, resource utilization, pollution history, and environmental development of the region. The landscape around Lake Vänern was shaped into its present form during the latest glaciations some 10,000years ago. Large variation exists in its tributaries, with forest in the north and agricultural areas in the south. Human influence on the landscape was relatively small until the mid-18th century. Later, in the mid-19th century, the agriculture, forestry and shipping industries underwent large transformations as the towns around the lake grew and the economy changed. Development of fishing equipment, processes and changes in catching methods industrialized the fishing industry after mid-20th century. In the 1960s the lake was considered to be one of the most heavily mercury-polluted lakes in the world. After the passing of the first national environmental protection law in Sweden the lake turned into a success story: It has been declared to be healthy. However, old pollution still affects the fishing industry. With this new focus on the environment, the scientific community started to be interested in the lake. The lake has also played a very important role as the largest hydropower reservoir in Sweden. Here, too, the environmental question is in focus and the effects of the water regulation are still under debate. The result has been loss of biodiversity and an increased risk of an inflow of invasive species from international shipping. However, still many questions remain to be answered regarding the lake and effect of ongoing climate change on the sustainable development of the lake region.
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| 16. |
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| 17. |
- Hader, D. P., et al.
(författare)
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Effects of UV radiation on aquatic ecosystems and interactions with other environmental factors
- 2015
-
Ingår i: Photochemical & Photobiological Sciences. - : Springer Science and Business Media LLC. - 1474-905X .- 1474-9092. ; 14:1, s. 108-126
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Tidskriftsartikel (refereegranskat)abstract
- Interactions between climate change and UV radiation are having strong effects on aquatic ecosystems due to feedback between temperature, UV radiation, and greenhouse gas concentration. Higher air temperatures and incoming solar radiation are increasing the surface water temperatures of lakes and oceans, with many large lakes warming at twice the rate of regional air temperatures. Warmer oceans are changing habitats and the species composition of many marine ecosystems. For some, such as corals, the temperatures may become too high. Temperature differences between surface and deep waters are becoming greater. This increase in thermal stratification makes the surface layers shallower and leads to stronger barriers to upward mixing of nutrients necessary for photosynthesis. This also results in exposure to higher levels of UV radiation of surface-dwelling organisms. In polar and alpine regions decreases in the duration and amount of snow and ice cover on lakes and oceans are also increasing exposure to UV radiation. In contrast, in lakes and coastal oceans the concentration and colour of UV-absorbing dissolved organic matter (DOM) from terrestrial ecosystems is increasing with greater runoff from higher precipitation and more frequent extreme storms. DOM thus creates a refuge from UV radiation that can enable UV-sensitive species to become established. At the same time, decreased UV radiation in such surface waters reduces the capacity of solar UV radiation to inactivate viruses and other pathogens and parasites, and increases the difficulty and price of purifying drinking water for municipal supplies. Solar UV radiation breaks down the DOM, making it more available for microbial processing, resulting in the release of greenhouse gases into the atmosphere. In addition to screening solar irradiance, DOM, when sunlit in surface water, can lead to the formation of reactive oxygen species (ROS). Increases in carbon dioxide are in turn acidifying the oceans and inhibiting the ability of many marine organisms to form UV-absorbing exoskeletons. Many aquatic organisms use adaptive strategies to mitigate the effects of solar UV-B radiation (280-315 nm), including vertical migration, crust formation, synthesis of UV-absorbing substances, and enzymatic and non-enzymatic quenching of ROS. Whether or not genetic adaptation to changes in the abiotic factors plays a role in mitigating stress and damage has not been determined. This assessment addresses how our knowledge of the interactive effects of UV radiation and climate change factors on aquatic ecosystems has advanced in the past four years.
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| 18. |
- Hoffmann, L. J., et al.
(författare)
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Influence of trace metal release from volcanic ash on growth of Thalassiosira pseudonana and Emiliania huxleyi
- 2012
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 132-133, s. 28-33
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies demonstrate that volcanic ash has the potential to increase phytoplankton biomass in the open ocean. However, besides fertilizing trace metals such as Fe, volcanic ash contains a variety of potentially toxic metals such as Cd, Cu, Pb, and Zn. Especially in coastal regions closer to the volcanic eruption, where ash depositions can be very high, toxic effects are possible. Here we present the first results from laboratory experiments, showing that trace metal release from different volcanic ashes can have both fertilizing and toxic effects on marine phytoplankton in natural coastal seawater. The diatom Thalassiosira pseudonana generally showed higher growth rates in seawater that was in short contact with volcanic ash compared to the controls without ash addition. In contrast to that, the addition of volcanic ash had either no effect or significantly decreased the growth rate of the coccolithophoride Emiliania huxleyi. It was not possible to attribute the effects to single trace metals, however, our results suggest that Mn plays an important role in regulating the antagonistic and synergistic effects of the different trace metals. This study shows that volcanic ash can lead to changes in the phytoplankton species composition in the high fall-out area of the surface ocean.
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| 19. |
- Jansen, Marcel A. K., et al.
(författare)
-
Environmental plastics in the context of UV radiation, climate change, and the Montreal Protocol
- 2024
-
Ingår i: Global Change Biology. - : John Wiley & Sons. - 1354-1013 .- 1365-2486. ; 30:4
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Tidskriftsartikel (refereegranskat)abstract
- There are close links between solar UV radiation, climate change, and plastic pollution. UV-driven weathering is a key process leading to the degradation of plastics in the environment but also the formation of potentially harmful plastic fragments such as micro- and nanoplastic particles. Estimates of the environmental persistence of plastic pollution, and the formation of fragments, will need to take in account plastic dispersal around the globe, as well as projected UV radiation levels and climate change factors.image
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| 20. |
- Jansen, Marcel A. K., et al.
(författare)
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Plastics in the environment in the context of UV radiation, climate change and the Montreal Protocol : UNEP Environmental Effects Assessment Panel, Update 2023
- 2024
-
Ingår i: Photochemical and Photobiological Sciences. - : Springer Nature. - 1474-905X .- 1474-9092. ; 23, s. 629-650
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Tidskriftsartikel (refereegranskat)abstract
- This Assessment Update by the Environmental Effects Assessment Panel (EEAP) of the United Nations Environment Programme (UNEP) considers the interactive effects of solar UV radiation, global warming, and other weathering factors on plastics. The Assessment illustrates the significance of solar UV radiation in decreasing the durability of plastic materials, degradation of plastic debris, formation of micro- and nanoplastic particles and accompanying leaching of potential toxic compounds. Micro- and nanoplastics have been found in all ecosystems, the atmosphere, and in humans. While the potential biological risks are not yet well-established, the widespread and increasing occurrence of plastic pollution is reason for continuing research and monitoring. Plastic debris persists after its intended life in soils, water bodies and the atmosphere as well as in living organisms. To counteract accumulation of plastics in the environment, the lifetime of novel plastics or plastic alternatives should better match the functional life of products, with eventual breakdown releasing harmless substances to the environment.
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| 21. |
- Jenny, Jean Philippe, et al.
(författare)
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Scientists’ Warning to Humanity: Rapid degradation of the world's large lakes
- 2020
-
Ingår i: Journal of Great Lakes Research. - : Elsevier BV. - 0380-1330. ; 46:4, s. 686-702
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Forskningsöversikt (refereegranskat)abstract
- © 2020 The Authors Large lakes of the world are habitats for diverse species, including endemic taxa, and are valuable resources that provide humanity with many ecosystem services. They are also sentinels of global and local change, and recent studies in limnology and paleolimnology have demonstrated disturbing evidence of their collective degradation in terms of depletion of resources (water and food), rapid warming and loss of ice, destruction of habitats and ecosystems, loss of species, and accelerating pollution. Large lakes are particularly exposed to anthropogenic and climatic stressors. The Second Warning to Humanity provides a framework to assess the dangers now threatening the world's large lake ecosystems and to evaluate pathways of sustainable development that are more respectful of their ongoing provision of services. Here we review current and emerging threats to the large lakes of the world, including iconic examples of lake management failures and successes, from which we identify priorities and approaches for future conservation efforts. The review underscores the extent of lake resource degradation, which is a result of cumulative perturbation through time by long-term human impacts combined with other emerging stressors. Decades of degradation of large lakes have resulted in major challenges for restoration and management and a legacy of ecological and economic costs for future generations. Large lakes will require more intense conservation efforts in a warmer, increasingly populated world to achieve sustainable, high-quality waters. This Warning to Humanity is also an opportunity to highlight the value of a long-term lake observatory network to monitor and report on environmental changes in large lake ecosystems.
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| 22. |
- Leu, E., et al.
(författare)
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Effects of changes in ambient PAR and UV radiation on the nutritional quality of an Arctic diatom (Thalassiosira antaretica var. borealis)
- 2006
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Ingår i: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981. ; 337:1, s. 65-81
-
Tidskriftsartikel (refereegranskat)abstract
- 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 degrees 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. (c) 2006 Elsevier B.V. All rights reserved.
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| 23. |
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| 24. |
- Munawar, M., et al.
(författare)
-
Preface
- 2014
-
Ingår i: Aquatic Ecosystem Health and Management. - : Michigan State University Press. - 1463-4988 .- 1539-4077. ; 17:4, s. 321-322
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 25. |
- Neale, P. J., et al.
(författare)
-
The response of aquatic ecosystems to the interactive effects of stratospheric ozone depletion, UV radiation, and climate change
- 2023
-
Ingår i: Photochemical & Photobiological Sciences. - : Springer. - 1474-905X .- 1474-9092. ; 22:5, s. 1093-1127
-
Tidskriftsartikel (refereegranskat)abstract
- Variations in stratospheric ozone and changes in the aquatic environment by climate change and human activity are modifying the exposure of aquatic ecosystems to UV radiation. These shifts in exposure have consequences for the distributions of species, biogeochemical cycles, and services provided by aquatic ecosystems. This Quadrennial Assessment presents the latest knowledge on the multi-faceted interactions between the effects of UV irradiation and climate change, and other anthropogenic activities, and how these conditions are changing aquatic ecosystems. Climate change results in variations in the depth of mixing, the thickness of ice cover, the duration of ice-free conditions and inputs of dissolved organic matter, all of which can either increase or decrease exposure to UV radiation. Anthropogenic activities release oil, UV filters in sunscreens, and microplastics into the aquatic environment that are then modified by UV radiation, frequently amplifying adverse effects on aquatic organisms and their environments. The impacts of these changes in combination with factors such as warming and ocean acidification are considered for aquatic micro-organisms, macroalgae, plants, and animals (floating, swimming, and attached). Minimising the disruptive consequences of these effects on critical services provided by the world's rivers, lakes and oceans (freshwater supply, recreation, transport, and food security) will not only require continued adherence to the Montreal Protocol but also a wider inclusion of solar UV radiation and its effects in studies and/or models of aquatic ecosystems under conditions of the future global climate. [GRAPHICS]
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| 26. |
- Neale, R. E., et al.
(författare)
-
Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2020
- 2021
-
Ingår i: Photochemical & Photobiological Sciences. - : Springer Science and Business Media LLC. - 1474-905X .- 1474-9092. ; 20, s. 1-67
-
Tidskriftsartikel (refereegranskat)abstract
- This assessment by the Environmental Effects Assessment Panel (EEAP) of the United Nations Environment Programme (UNEP) provides the latest scientific update since our most recent comprehensive assessment (Photochemical and Photobiological Sciences, 2019, 18, 595-828). The interactive effects between the stratospheric ozone layer, solar ultraviolet (UV) radiation, and climate change are presented within the framework of the Montreal Protocol and the United Nations Sustainable Development Goals. We address how these global environmental changes affect the atmosphere and air quality; human health; terrestrial and aquatic ecosystems; biogeochemical cycles; and materials used in outdoor construction, solar energy technologies, and fabrics. In many cases, there is a growing influence from changes in seasonality and extreme events due to climate change. Additionally, we assess the transmission and environmental effects of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is responsible for the COVID-19 pandemic, in the context of linkages with solar UV radiation and the Montreal Protocol.
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| 27. |
- Odmark, S, et al.
(författare)
-
Effects of UVB radiation in a microbenthic community of a marine shallow-water sandy sediment
- 1998
-
Ingår i: Marine Biology. - 0025-3162. ; 132:2, s. 335-345
-
Tidskriftsartikel (refereegranskat)abstract
- The role of ambient and enhanced ultraviolet-B radiation (UVB; 280 to 315 nm) in a natural sand-associated microbenthic community was studied in a 3-week experiment by incubating intact sediment cores from a shallow bay in an outdoor flow-through system with 27 aquaria. After sampling of initial cores, the remaining cores tone per aquarium) were given one of three treatments: no, ambient, and moderately enhanced UVB, and sampled, nine at a time, after 5, 12, and 19 d. The response of the community was studied by analysing algal and meiofaunal composition and biomass, chlorophyll a content, composition of pigments and fatty acids, and content of UV-absorbing compounds (state variables), as well as carbon fixation and allocation, and bacterial productivity (rate variables). Among rate variables, significant effects of UVB-treatments were found for carbon fixation and allocation, while bacterial productivity was not affected. For state variables, a significant response was observed for the composition of microalgae and fatty acids, and for chlorophyll a content. The effect of treatments was mainly observed as differences in development with time (two-way analysis of variance, treatment x time interaction). Towards the end of the experiment, the no-UVB treatment most often differed from one or both of the two treatments with UVB exposure, the latter showing lower values. There were marked successional changes in the community, irrespective of treatment. The microalgal community changed from being dominated by coccoid cyanobacteria and epipsammic diatoms to a dominance of epipelic diatoms and filamentous cyanobacteria. The pattern of carbon allocation, as well as an increased C/N ratio of the sediment, suggested limitation of growth, perhaps by nutrients, at the end of the experiment. This may possibly have acted synergistically with UVB exposure to create the treatment effects. The new knowledge gained from our experiment is that ambient UVB can exert a stress on the function of sand-associated microbenthic communities in shallow waters and that this effect coincides with structural differences in the community.,More experiments in natural or semi-natural systems are needed to allow better prediction of microbenthic community-level responses to UVB.
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| 28. |
- Paul, C., et al.
(författare)
-
Diatom Derived Polyunsaturated Aldehydes Do Not Structure the Planktonic Microbial Community in a Mesocosm Study
- 2012
-
Ingår i: Marine Drugs. - Basel : MDPI AG. - 1660-3397. ; 10:4, s. 775-792
-
Tidskriftsartikel (refereegranskat)abstract
- Several marine and freshwater diatoms produce polyunsaturated aldehydes (PUA) in wound-activated processes. These metabolites are also released by intact diatom cells during algal blooms. Due to their activity in laboratory experiments, PUA are considered as potential mediators of diatom-bacteria interactions. Here, we tested the hypothesis that PUA mediate such processes in a close-to-field mesocosm experiment. Natural plankton communities enriched with Skeletonema marinoi strains that differ in their PUA production, a plankton control, and a plankton control supplemented with PUA at natural and elevated concentrations were observed. We monitored bacterial and viral abundance as well as bacterial community composition and did not observe any influence of PUA on these parameters even at elevated concentrations. We rather detected an alternation of the bacterial diversity over time and differences between the two S. marinoi strains, indicating unique dynamic bacterial communities in these algal blooms. These results suggest that factors other than PUA are of significance for interactions between diatoms and bacteria.
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| 29. |
- Rasmus, K. E., et al.
(författare)
-
Optical studies in the Southern Ocean
- 2004
-
Ingår i: Deep-Sea Research Part Ii-Topical Studies in Oceanography. - : Elsevier BV. - 0967-0645. ; 51:22-24, s. 2583-2597
-
Tidskriftsartikel (refereegranskat)abstract
- During the Austral summer of 1997-1998, measurements of absorption, attenuation, downwelling and upwelling irradiance were made in the Southern Ocean along a S-N transect at 6degreesE. Measurements were made to quantify the penetration of ultraviolet B radiation (UVBR) in the water column and daily doses of UVBR at different water depths, to study the attenuation of photosynthetically active radiation (PAR), and to judge if in the investigated areas of the Southern Ocean phytoplankton are light limited. The results show that the UVBR affects a substantial portion of the upper mixed layer. The diffuse attenuation coefficients (K-PAR) for PAR were found to vary between 0.03 and 0.09 m(-1). Using the values for KPAR and the definition of the Sverdrup critical depth, the studied Southern Ocean plankton systems were found not to be light limited. (C) 2004 Elsevier Ltd. All rights reserved.
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| 30. |
- Rothschild, Miriam, et al.
(författare)
-
Cannabis sativa: volatile compounds from pollen and entire male and female plants of two variants, Northern Lights and Hawaian Indica
- 2005
-
Ingår i: Botanical Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4074 .- 1095-8339. ; 147:4, s. 387-397
-
Tidskriftsartikel (refereegranskat)abstract
- Sixty-eight compounds were identified by coupled gas chromatography and mass spectrometry (GC-MS) in the chemosphere of Cannabis sativa L. pollen and entire male and female plants of two cultivated varieties, Northern Lights and Hawaian Indica. Twenty-one and 28 substances, respectively, were present in pollen of the two forms. To conserve the natural composition of volatiles a delicate headspace method was employed. The two varieties represent different chemotypes which distinguish themselves, in the main quantitatively, in the setup of volatiles from pollen and entire male and female plants. Twenty compounds were monoterpenes, including the five major components: beta-myrcene (E)-beta-ocimene, terpinolene, beta-pinene and limonene; 25 were sesquiterpenes, and the other 23 were of mixed biogenetic origin, including 3-methyl-1-butanol and benzylalcohol which occurred only in pollen; two pyrazines occurred only in Northern Lights females. Besides being of interest in natural products chemistry, the results should have relevance for plant systematics and for the pharmaceutical and technical applications of Cannabis. We demonstrate that the pollen has a distinct chemical character in possessing two exclusive volatiles, while lacking seven compounds occurring in males and females of both variants. (c) 2005 The Linnean Society of London, Botanical Journal of the Linnean Society.
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| 31. |
- Sundbäck, Kristina, 1949, et al.
(författare)
-
Effects of enhanced UVB radiation on a marine benthic diatom mat
- 1997
-
Ingår i: Marine Biology. - 0025-3162. ; 128:1, s. 171-179
-
Tidskriftsartikel (refereegranskat)abstract
- In order to study the ecophysiological response of a natural diatom-dominated microbial mat to an enhanced level of ultraviolet-B radiation (UVBR), intact sediment cores from a shallow microtidal bay on the Swedish west coast were incubated in an outdoor flow-through system and exposed to either no UVBR or to an artificially enhanced level of UVBR. The microbial mat was cohesive and dominated by the large (approximate to 400 mu m) motile diatom Gyrosigma balticum. Functional response to UVBR was assessed by measuring carbon fixation (C-14) and allocation of photosynthetic products. Sediment oxygen microprofiles were measured as indicators of the balance between the photosynthetic and respiratory activity of the community. Structural variables included biomass and composition of microalgae, pigment composition (HPLC), content of UV-absorbing compounds, and composition of fatty acids. An enhanced level of UVBR resulted in significant functional changes in the microalgal community. Significantly decreased carbon fixation and lower net oxygen production (as calculated from oxygen microprofiles) suggest that primary productivity in the type of microbial mat studied is potentially sensitive to an enhanced level of UVBR. The pattern of carbon allocation hinted a change as to the photosynthetically active part of the community when exposed to UVBR, indicating a differential sensitivity among algal cells. Despite significant functional effects, pigment or algal composition were not significantly affected by enhanced UVBR. The concentration of UV-absorbing compounds was low and did not increase at UVBR exposure. Due to the short duration of the experiment (4 d), a change in algal biomass or composition was not to be expected. Moreover, the thickness of the sampled sediment layer, may have contributed to the lack of observed structural effects of enhanced UVBR. Visual observations suggested that UVBR affected the motility of G. balticum. This study, as well as other experiments with a similar diatom mat, suggest that vertical migration is a key mechanism to be further studied in relation to UVBR exposure of diatom-dominated microbial mats.
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| 32. |
- Taylor, Rebecca L, et al.
(författare)
-
SEASONAL VARIABILITY IN POLYUNSATURATED ALDEHYDE PRODUCTION POTENTIAL AMONG STRAINS OF SKELETONEMA MARINOI (BACILLARIOPHYCEAE)
- 2009
-
Ingår i: Journal of Phycology. - : Wiley. - 0022-3646 .- 1529-8817. ; 45:1, s. 46-53
-
Tidskriftsartikel (refereegranskat)abstract
- The cosmopolitan bloom-forming diatom Skeletonema marinoi Sarno et Zingone is known to produce toxic polyunsaturated aldehydes (PUAs) in response to cell damage that can affect a diverse suite of organisms, including grazing species and competitor plankton species. The production of PUAs in nine different S. marinoi strains isolated at three different times of the year (spring, summer, and autumn) was assessed in relation to the predominant conditions at the time of isolation from Gullmar Fjord, Skagerrak. During the initial stages of growth, PUA production potential of S. marinoi was generally the highest in summer strains, although there was a substantial variation among strains isolated at the same time. Spring strains, however, showed a strong capacity for increased PUA production potential in later stage cultures with diminishing nutrient levels, reaching amounts similar to those observed in summer strains. In contrast, PUA production potentials of summer and autumn strains did not change significantly from the original values. There is negligible grazing pressure during the spring bloom in Gullmar Fjord, but a potential for high competition for resources, such as nutrients, toward the later stages of the bloom. In contrast, grazing pressure is much greater during summer and autumn, and there may also be nutrient limitation at this time. The PUA production potentials of S. marinoi appear to reflect the ecological conditions at the time of isolation with higher production potentials in strains isolated when conditions were likely to be less beneficial for survival.
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| 33. |
- Williamson, Craig E., et al.
(författare)
-
The interactive effects of stratospheric ozone depletion, UV radiation, and climate change on aquatic ecosystems
- 2019
-
Ingår i: Photochemical and Photobiological Sciences. - : Royal Society of Chemistry. - 1474-905X .- 1474-9092. ; 18:3, s. 717-746
-
Tidskriftsartikel (refereegranskat)abstract
- This assessment summarises the current state of knowledge on the interactive effects of ozone depletion and climate change on aquatic ecosystems, focusing on how these affect exposures to UV radiation in both inland and oceanic waters. The ways in which stratospheric ozone depletion is directly altering climate in the southern hemisphere and the consequent extensive effects on aquatic ecosystems are also addressed. The primary objective is to synthesise novel findings over the past four years in the context of the existing understanding of ecosystem response to UV radiation and the interactive effects of climate change. If it were not for the Montreal Protocol, stratospheric ozone depletion would have led to high levels of exposure to solar UV radiation with much stronger negative effects on all trophic levels in aquatic ecosystems than currently experienced in both inland and oceanic waters. This “world avoided” scenario that has curtailed ozone depletion, means that climate change and other environmental variables will play the primary role in regulating the exposure of aquatic organisms to solar UV radiation. Reductions in the thickness and duration of snow and ice cover are increasing the levels of exposure of aquatic organisms to UV radiation. Climate change was also expected to increase exposure by causing shallow mixed layers, but new data show deepening in some regions and shoaling in others. In contrast, climate-change related increases in heavy precipitation and melting of glaciers and permafrost are increasing the concentration and colour of UV-absorbing dissolved organic matter (DOM) and particulates. This is leading to the “browning” of many inland and coastal waters, with consequent loss of the valuable ecosystem service in which solar UV radiation disinfects surface waters of parasites and pathogens. Many organisms can reduce damage due to exposure to UV radiation through behavioural avoidance, photoprotection, and photoenzymatic repair, but meta-analyses continue to confirm negative effects of UV radiation across all trophic levels. Modeling studies estimating photoinhibition of primary production in parts of the Pacific Ocean have demonstrated that the UV radiation component of sunlight leads to a 20% decrease in estimates of primary productivity. Exposure to UV radiation can also lead to positive effects on some organisms by damaging less UV-tolerant predators, competitors, and pathogens. UV radiation also contributes to the formation of microplastic pollutants and interacts with artificial sunscreens and other pollutants with adverse effects on aquatic ecosystems. Exposure to UV-B radiation can decrease the toxicity of some pollutants such as methyl mercury (due to its role in demethylation) but increase the toxicity of other pollutants such as some pesticides and polycyclic aromatic hydrocarbons. Feeding on microplastics by zooplankton can lead to bioaccumulation in fish. Microplastics are found in up to 20% of fish marketed for human consumption, potentially threatening food security. Depletion of stratospheric ozone has altered climate in the southern hemisphere in ways that have increased oceanic productivity and consequently the growth, survival and reproduction of many sea birds and mammals. In contrast, warmer sea surface temperatures related to these climate shifts are also correlated with declines in both kelp beds in Tasmania and corals in Brazil. This assessment demonstrates that knowledge of the interactive effects of ozone depletion, UV radiation, and climate change factors on aquatic ecosystems has advanced considerably over the past four years and confirms the importance of considering synergies between environmental factors.
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| 34. |
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| 35. |
- Wulff, Angela, 1963, et al.
(författare)
-
Effects of UVB radiation on a marine microphytobenthic community growing on a sand-substratum under different nutrient conditions
- 2000
-
Ingår i: Limnology and Oceanography. - 0024-3590. ; 45:5, s. 1144-1152
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of ultraviolet-B radiation (UVBR) on a microphytobenthic community, dominated by diatoms, was studied under different nutrient conditions in a 9 day outdoor experiment on the Swedish west coast. The microalgal assemblage was isolated from the sediment and resettled onto acid-cleaned sand placed in petridishes. The experimental treatments were: "ambient" or "enhanced" UVBR with no nutrient addition, "ambient" or "enhanced" UVBR with nutrient addition (N, P, Si). Enhanced UVBR (+15%) was provided by a computer-controlled system. Primary productivity, carbon allocation, chlorophyll a (Chl a) concentrations, composition of algae and pigments and intra- and extracellular carbohydrate fractions were measured. Most UVBR effects were seen in treatments without nutrient addition. Exposure to enhanced UVBR resulted in statistically significant decreases in primary productivity, Chl a and in the biomass of Haslea ostrearia and Nitzschia spp. The relative amount of carbon allocated to proteins increased when exposed to enhanced UVBR. The effect of enhanced UVBR on microalgae subjected to nutrient addition was less pronounced, and observed for Chl a, algal intracellular storage of carbohydrates (glucans) and concentration of extracellular "colloidal" carbohydrates. Enhanced UVBR + nutrients resulted in a significantly greater ratio between glucan and total carbohydrates and a decreased concentration of colloidal carbohydrates compared to the ambient UVBR + nutrients treatment. These results indicate that availability of inorganic nutrients acts to mitigate the negative effects of UVBR on microphytobenthic communities and that UVBR acts as a selective force during early growth and succession.
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| 36. |
- Wulff, Angela, 1963, et al.
(författare)
-
Spatial and vertical distribution of phytoplankton pigments in the eastern Atlantic sector of the Southern Ocean
- 2004
-
Ingår i: Deep-Sea Research Part Ii-Topical Studies in Oceanography. - : Elsevier BV. - 0967-0645. ; 51:22-24, s. 2701-2713
-
Tidskriftsartikel (refereegranskat)abstract
- The spatial and vertical distribution of phytoplankton pigments was analysed during the Scandinavian/South African Southern Ocean JGOFS expedition of the S.A. Agulhas from 31 December 1997 to 26 January 1998. In total, seawater from 12 different stations along a transect at 6degreesE from 60.38 to 49.82degreesS were sampled at water depths of approximately 2, 10, 20, 30, 50, 75 and 100 m. Pigment concentrations were analysed using high-performance liquid chromatography. The highest chlorophyll a (chl a) concentrations were found within the Spring Ice Edge (SIE) at water depths of 2-30 m (1.5-2.0 mug l(-1)). The lowest phytoplankton biomass (chl a) was found within the Winter Ice Edge (WIE) with typical values around 0.3 mug l(-1). While the chl a concentrations decreased with depth within the SIE, no apparent difference between depths was found within WIE. The same trend with similar chl a concentrations (0.8-1.2 mug l(-1)) at all depths was found for the northernmost part of the Antarctic Polar Front (APF) except for samples from 100 m. Principal component analysis (PCA) and the matrix factorisation program, CHEMTAX, were used to interpret the pigment data. The PCA indicated small differences between the samples in WIE and APF, while the SIE samples were separated into three groups. At the southernmost stations a clear separation was found between surface samples and deeper samples; this was not seen at the two northernmost stations within SIE. Along the whole transect, CHEMTAX suggested a dominance of diatoms and haptophytes. In general, the haptophytes contributed more to total chl a further south and the diatom contribution increased from south to north. Within WIE, CHEMTAX indicated that cyanobacteria were contributing approximately 3% to the total autotrophic biomass. In APF, a more diverse phytoplankton community was found compared with WIE and SIE. The pigment patterns interpreted by CHEMTAX showed that different phytoplankton assemblages were associated with distinct water masses along the transect. (C) 2004 Elsevier Ltd. All rights reserved.
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| 37. |
- Wulff, Angela, 1963, et al.
(författare)
-
UV radiation effects on microbenthos - a four month field experiment
- 1999
-
Ingår i: Aquatic Microbial Ecology. - 0948-3055. ; 19:3, s. 269-278
-
Tidskriftsartikel (refereegranskat)abstract
- A 4 mo field experiment, covering the period May to September, was carried out in a shallow microtidal sandy bay on the Swedish west coast. To test whether the ambient UV radiation (UVR) had any effect on a marine microbenthic community, screens of Plexiglas, Plexiglas + Mylar-D film and polycarbonate were used. This gave 3 different treatments: Ambient (PAR+UVAR+UVBR), NoUVB (PAR+UVAR) and NoUV (PAR) plus Control (areas without screens to test the 'frame effect'). The response of the community was studied on 2 occasions (June, September) by measuring primary productivity (C-14), carbon allocation (C-14) and bacterial productivity (H-3-thymidine) (rate variables), as well as biomass and composition of microalgae and meiofauna, pigment composition (HPLC), content of mycosporine-like amino acids (MAA, HPLC) and composition of fatty acids (GC). The UVR maximum penetration depth (1%) in the sediment, measured by microsensors, was 800 mu m for UVAR and 600 mu m for UVB. No UVR effects were found for any structural variables but ostracodalbiomass, which doubled when exposed to WR compared with the UVR excluding treatments. Significant treatment effects were found for the rate variables primary productivity and carbon allocation. The effects on primary productivity and ostracods were observed in September only. All the treatment effects were found between exclusion of and exposure to UVR. Primary productivity increased in treatments shielded from UVR. For carbon allocation, significant effects on all fractions were found, however, with a partly different outcome in June and September. We conclude that the UVBR part of the spectrum exerted some stress on the microbenthic community, but this was almost exclusively found for rate variables in September, and that the ambient UVAR did not have any harmful effects. It is also concluded that the choice of time scales and experimental approach (laboratory vs field experiments) is crucial for the out come and interpretation of UVBR experiments.
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| 38. |
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| 39. |
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| 40. |
- Wängberg, Sten-Åke, 1955, et al.
(författare)
-
Effects of UV-B radiation on synthesis of mucosporine-like amino acids and growth in Heterocapsa triquetra
- 1997
-
Ingår i: Journal of Photochemistry and Photobiology B: Biology. ; 37:1-2, s. 141-146
-
Tidskriftsartikel (refereegranskat)abstract
- Unialgal cultures of the dinoflagellate Heterocapsa triquetra (Ehrenberg) Stein were exposed to artificial UV-B radiation and the growth and synthesis of mycosporine-like amino acids (MAAs) were compared with cultures shielded from UV-B radiation by sharp cut-off films. The UV-B radiation did not affect the growth (the increase in total cell volume of the culture) but resulted in an increase in the size of the individual cells and synthesis of MAAs. The synthesis of MAAs during UV-B radiation was synchronised with the cell cycle, being maximal during periods of increases in cell size without division. The absorbance spectra of the MAAs during UV-B radiation changed, showing higher absorption in the UV-B range as compared to the controls.
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| 41. |
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| 42. |
- Wängberg, Sten-Åke, 1955, et al.
(författare)
-
Impact of ultraviolet-B radiation on the development of phytoplankton communities in the eastern Atlantic sector of the Southern Ocean - results from on-deck model ecosystem experiments
- 2004
-
Ingår i: Deep-Sea Research Part Ii-Topical Studies in Oceanography. - : Elsevier BV. - 0967-0645. ; 51:22-24, s. 2731-2744
-
Tidskriftsartikel (refereegranskat)abstract
- Two model ecosystem experiments to assess the effects of UVB radiation (UVBR, 280-320 nm) on phytoplankton communities were performed on-deck during the SWEDARP 97/98 expedition to the eastern Atlantic sector of the Southern Ocean in January 1998. The first experiment was run in the Spring Ice Edge, around 60degreesS, and the second at the Antarctic Polar Front, around 50degreesS. The duration of the experiments were 12 and 10 days, respectively. Ambient UVBR was modified to three levels (i.e. treatments): NoUVB-shielded from UVBR (mylar foil); AMB-ambient UVBR; UVB+--enhanced UVBR. The development of the phytoplankton communities was followed by measuring primary production and composition of pigments and diatom species. At the start of the first experiment UVB+ had lower primary production per volume, but not when normalised to chlorophyll a. At the end there were no differences between treatments in primary production per volume but there were differences when normalised to chlorophyll a. In addition, a significant increase in the stimulation of primary production for UVB+ when excluding UVBR and in chlorophyll a concentration was found. These changes, together with changes in species composition, are assumed to be the result of an adaptation to the enhanced UVBR. During the second experiment, the effects from changes in UVBR were generally smaller but resembled to some extent the first experiment. The chlorophyll a concentration increased significantly in the UVB+ treatment at the end of the experiment and there was a strong tendency towards a reduction in primary production per chlorophyll a, but not per volume. The results are important when estimating the effects of increased UVBR as they show variability in short-term sensitivity, and also the capacity of phytoplankton communities to adapt to UVBR and retain primary production even in enhanced UVBR. (C) 2004 Elsevier Ltd. All rights reserved.
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| 43. |
- Wängberg, Sten-Åke, 1955, et al.
(författare)
-
Impact of UV-B radiation on microalgae and bacteria: a mesocosm study with computer modulated UV-B radiation addition
- 2001
-
Ingår i: Aquatic Microbial Ecology. - 0948-3055. ; 25:1, s. 75-86
-
Tidskriftsartikel (refereegranskat)abstract
- Effects of ambient and enhanced UV-B radiation (UVBR) on marine microbial plankton communities were assessed in a model ecosystem at Kristineberg Marine Research Station (KMRS) on the Swedish west coast. The system consisted of 16 aquaria (401) filled with surface seawater and semicontinuously run by replacing 101 of their contents with filtered seawater twice a day. The aquaria were placed outdoors and the ambient solar radiation was reduced by 70% using neutral screens. Four different levels of UVBR were applied, each in 4 replicates; nothing, ambient, ambient + 10% and ambient + 20%. The enhanced UVBR was supplied by fluorescent tubes whose intensity was modulated by the ambient radiation to give a constant percentage increase, Variables measured were nutrients (N, P, Si), composition of phytoplankton species and pigments, bacterial and primary productivity, and bacterial cell numbers. Statistically significant UVBR effects were found for carbon allocation, size distribution of primary productivity and phytoplankton species composition. It was also found that UVBR exposure during the development of the phytoplankton communities increased their sensitivity to UVBR in short-term carbon dioxide fixation measurements. We propose that this was due to an adaptation of the community to UVBR, including an increased production of components within the photosynthetic apparatus damaged by UVBR. The UVBR had no significant effect on the total biomass of phytoplankton and bacteria.
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| 44. |
- Wängberg, Sten-Åke, 1955, et al.
(författare)
-
Inhibition of primary production by UV-B radiation in an arctic bay - model calculations
- 2006
-
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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