Effects of enhanced mid-ultraviolet radiation (290-315 NM) on development and survival of Boreal toad (Bufo boreas boreas) tadpoles

More than 3700 fertilized toad eggs were used in a series of studies designed to determine the effects of UV-B radiation (290- 315 nm) on temporal developmental patterns, systematic development and viability prior to metamorphic climax. The eggs were exposed to radiation from either "white-light" fluorescent lamps (Vita-Lite, Duro-Test Corporation, North Bergen, New Jersey) or "white-light" fluorescent lamps plus fluorescent sunlamps (Westinghouse- FS40). Several radiation exposure schedules were utilized (chronic or varied, daily exposures) and, in all but one study, filters were utilized - Kodacel cut-off filters to transmit wavelengths longer than 290 nm and Mylar cut-off filters to transmit wavelengths longer than 315 nm. These filters provided a transmission "window" in the UV-B region. Exposure of the developing tadpoles on a daily basis to eleven or more Sunburn Units of UV-B radiation per day resulted in the development of tadpole populations with lordotic posture, hyperplasia in the presumptive cornea and other dorsal epithelial tissue, increased pigmentation in the presumptive cornea, desquamation of areas of the dorsal surface, and increased mortality. Exposure of the tadpoles on a daily basis to 4.4 Sunburn Units of UV-B radiation per day resulted in a significant lengthening of the time periods required to achieve metamorphic climax. Biological photoreactivation of ultraviolet damage was demonstrable with three groups of tadpoles exposed to comparable daily exposures of UV-B radiation (11.0 Sunburn Units per day) at a comparable rate (1.1 Sunburn Units per hour) from similar sources. The critical differences between the groups was the duration of exposure to UV-A and visible radiation (0, 2 and 4 hours) following the termination of the UV-B exposure

Response of estuarine diatom assemblages to ultraviolet-B radiation (290-320 nm)

Artificial substrates colonized by diatoms from Yaquina Estuary, Oregon, were exposed to solar visible radiation and three levels of ultraviolet radiation (UV-B, 290-320 nm). Flow-through microcosms were constructed inside a glasshouse to serve as chambers for the artificial substrates. The artificial substrates were sampled during three spring/summer experiments. Chlorophyll a concentration, biomass (ash-free dry weight), primary productivity (radiocarbon uptake), and community composition were the parameters measured biweekly for each four-week experimental period. The results indicated that daily exposure to enhanced levels of UV-B radiation was associated with a decrease in species diversity of benthic diatom assemblages during all experiments after four weeks of growth. However, changes in taxonomic structure were not accompanied by a significant depression in chlorophyll a concentration, biomass, or radiocarbon uptake. In fact, in some experiments enhanced levels of UV-B radiation appeared to have a stimulatory effect on the latter parameters

Effects of UV radiation on aquatic ecosystems and interactions with other environmental factors

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.Fil: Häder, Donat P.. Universitat Erlangen-Nuremberg; AlemaniaFil: Williamson, Craig E.. Miami University; Estados UnidosFil: Wängberg, Sten Åke. University of Gothenburg. Department of Biological and Environmental Science; SueciaFil: Rautio, Milla. Université du Québec à Chicoutimi. Département des Sciences Fondamentales and Centre for Northern Studies; CanadáFil: Rose, Kevin C.. University Of Wisconsin; Estados UnidosFil: Gao, Kunshan. Xiamen University. State Key Laboratory of Marine Environmental Science; ChinaFil: Helbling, Eduardo Walter. Fundación Playa Unión. Estación de Fotobiología Playa Unión; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Sinha, Rajeshwar P.. Banaras Hindu University. Centre of Advanced Study in Botany; IndiaFil: Worrest, Robert. Columbia University; Estados Unido

Ozone depletion, ultraviolet radiation, climate change and prospects for a sustainable future

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.Peer reviewe

Stratospheric ozone reduction solar ultraviolet radiation and plant life

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Aquatic ecosystems: effects of solar ultraviolet radiation and interactions with other climatic change factors

Aquatic ecosystems are a key component of the Earth's biosphere. A large number of studies document substantial impact of solar UV radiation on individual species, yet considerable uncertainty remains with respect to assessing impacts on ecosystems. Several studies indicate that the impact of increased UV radiation appears relatively low when considering overall ecosystem response, while, in contrast, effects on individual species show considerable responses. Ecosystem response to climate variability incorporates both synergistic and antagonistic processes with respect to UV-related effects, significantly complicating understanding and prediction at the ecosystem level. The impact of climate variability on UV-related effects often becomes manifest via indirect effects such as reduction in sea ice, changes in water column bio-optical characteristics, changes in cloud cover and shifts in oceanographic biogeochemical provinces

Effects of increased solar ultraviolet radiation on aquatic ecosystems

Aquatic ecosystems supply humans with vast amounts of food, primarily in the form fo finfish, shellfish and seaweed. More than 30 of the world's animal protein for human consumption comes from the sea, and in many countries, particularly the developing countries, this percentage is significantly higher. As a result, it is important to know how increased levels of exposure to solar UV-B radiation (280-315 nm) might affect the productivity of aquatic systems. In addition, the oceans plan a key role with respect to global warming. Marine phytoplankton are a major sink for atmospheric carbon-dioxide, and they have a decisive role in the development of future trends of carbon dioxide concentrations in the atmosphere. The relative importance of the net uptake of carbon dioxide by the biological pump in the ocean and by the terrestrial biosphere is a topic of much current research. Phytoplakton for the foundation on which the very survival of aquatic food webs depends. Marine phytoplancton are not uniformly distributed throughout the oceans of the world. The highest concentrations are found at high latitudes while, with the exception of upwelling areas on the continental shelves, the tropics and subtropics have 10 to 100 times lower concentrations. In addition to nutrients, temperature, salinity and light availability, the high levels of exposure to solar UV-B radiation that normally occur within the tropics and subtropics may play a role in phytoplankton distribution

The interactive effects of stratospheric ozone depletion, UV radiation, and climate change on aquatic ecosystems

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

Environmental effects of ozone depletion and its interactions with climate change: progress report, 2011

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 increased 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 believed previously. As a result of this, human health and environmental problems will be longer-lasting and more regionally variable. Like the other panels, the EEAP produces a detailed report every four years; the most recent was published in 2010 (Photochem. Photobiol. Sci., 2011, 10, 173-300). In the years in between, the EEAP produces less detailed and shorter progress reports, which highlight and assess the significance of developments in key areas of importance to the parties. The next full quadrennial report will be published in 2014-2015