| 21. |
- Jenny, Jean Philippe, et al.
(author)
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Scientists’ Warning to Humanity: Rapid degradation of the world's large lakes
- 2020
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In: Journal of Great Lakes Research. - : Elsevier BV. - 0380-1330. ; 46:4, s. 686-702
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Research review (peer-reviewed)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.
(author)
-
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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In: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981. ; 337:1, s. 65-81
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Journal article (peer-reviewed)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.
(author)
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Preface
- 2014
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In: Aquatic Ecosystem Health and Management. - : Michigan State University Press. - 1463-4988 .- 1539-4077. ; 17:4, s. 321-322
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Journal article (other academic/artistic)
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| 25. |
- Neale, P. J., et al.
(author)
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The response of aquatic ecosystems to the interactive effects of stratospheric ozone depletion, UV radiation, and climate change
- 2023
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In: Photochemical & Photobiological Sciences. - : Springer. - 1474-905X .- 1474-9092. ; 22:5, s. 1093-1127
-
Journal article (peer-reviewed)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.
(author)
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Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2020
- 2021
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In: Photochemical & Photobiological Sciences. - : Springer Science and Business Media LLC. - 1474-905X .- 1474-9092. ; 20, s. 1-67
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Journal article (peer-reviewed)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.
(author)
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Effects of UVB radiation in a microbenthic community of a marine shallow-water sandy sediment
- 1998
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In: Marine Biology. - 0025-3162. ; 132:2, s. 335-345
-
Journal article (peer-reviewed)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.
(author)
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Diatom Derived Polyunsaturated Aldehydes Do Not Structure the Planktonic Microbial Community in a Mesocosm Study
- 2012
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In: Marine Drugs. - Basel : MDPI AG. - 1660-3397. ; 10:4, s. 775-792
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Journal article (peer-reviewed)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.
(author)
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Optical studies in the Southern Ocean
- 2004
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In: Deep-Sea Research Part Ii-Topical Studies in Oceanography. - : Elsevier BV. - 0967-0645. ; 51:22-24, s. 2583-2597
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Journal article (peer-reviewed)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.
(author)
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Cannabis sativa: volatile compounds from pollen and entire male and female plants of two variants, Northern Lights and Hawaian Indica
- 2005
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In: Botanical Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4074 .- 1095-8339. ; 147:4, s. 387-397
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Journal article (peer-reviewed)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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