Scientists evaluate the impact of ultraviolet radiation on marine life
- An international research team evaluates the impact of increased UV radiation on marine biota, globally untested to date
Mallorca, 25 de julio de 2012. An international team involving the Spanish National Research Council (CSIC), evaluates the magnitude of impacts caused by increased ultraviolet B radiation (UVB), and determines the degree of relative sensitivity between marine organisms and these processes, in an article published in the latest issue of the journal Global Ecology and Biogeography. The analysis of this paper is based on 1,784 experimental evaluations performed with natural radiation and organisms from different geographical areas, as well as artificial radiation and cultured organisms in many laboratories around the world.
The continuous emission of fluorocarbon compounds (known as CFCs, a group of gases used in multiple applications, which are primarily responsible for the reduction of the ozone layer), into the atmosphere, particularly during the 1970s and 80s, eroded ozone levels and increased the effects of UVB on marine biota (living marine organisms). However, the role of UVB radiation (with a wavelength between 280 - 315 nm) as a possible cause of the global decline in the health of marine ecosystems has not yet been quantified.
The results of this study show that increased levels of UVB radiation have caused a significant increase in mortality rates of marine organisms; being groups of protists, corals, crustaceans and fish larvae and eggs the most sensitive. In addition, the data reveals a significant correlation between the intensity of UVB radiation and mortality rates. This may assist in the determination of the possible impacts of changes in UVB radiation on marine organisms.
Moira Llabrés, author of the article and CSIC researcher at the Mediterranean Institute for Advanced Studies (CSIC-UIB), explains that "the work expands on previous UVB radiation studies, in an effort to achieve a more robust database which quantifies the relationship between responses such as physiological and metabolic diseases and doses of UVB. As Llabrés explains, "The effects of ultraviolet radiation detailed in this study mainly affect the organisms growing near the surface of the ocean, such as the eggs and larvae of invertebrates and fish, which are exposed to very high UVB levels." Additionally, continues the author, "these impacts vary according to season, and would be higher in spring, when UVB levels are higher.”
The experiments included in this research involve organisms and species that have survived after the erosion of the ozone layer caused by CFCs. Therefore, the results suggest that an increase in UVB radiation could have a heavy impact on marine biota. A clear evidence of this impact is the reduction of mortality rates of up to 81% when reducing exposure to UVB present in larvae of commercial fish such as cod, anchovies and other organism.
“The relationship between the responses of organisms to increased levels of UVB observed in this study, and the rate of increase in UVB values ??allows us to predict that an increase in UVB radiation by 15% would result in the deterioration of marine taxa by 59%”, argues Llabrés. The results indicate that marine biota has been strongly affected by high levels of UVB radiation from the 1970s, "particularly in high latitudes of the Southern Hemisphere where the increase in UVB was greater, suggesting selection processes or adaptation of organisms in response to high UVB radiation,” concludes Llabrés.
The significant increase observed in mortality rates of organisms, together with high levels of UVB that exist today, suggest UVB radiation as a clear threat to marine biota. The recent widespread decline in abundance of many marine organisms, from corals to fish and krill, which are highly vulnerable to increased UVB radiation, may also be explained by current levels. Krill is a biologically strategic crustacean native to the Antarctic, which acts as one of the most important links in the marine food web. Its abundance decreased by 60 times within the Southern Ocean between 1970 and 2003, concurrent with a considerable increase in UVB radiation.
The decline of corals in the tropics and subtropics is consistent with increased levels of UVB. As the results presented in this paper show corals to be among the most vulnerable organisms to UVB exposure, we can deduce that increased temperature may not be the sole cause of their decline. In recent years, much attention has been given to global warming, eutrophication, and more recently, ocean acidification, which have all increased in parallel with increasing levels of UVB. The focus on each of these specific issues may have prevented more in-depth exploration of the role of UVB radiation in the accelerated declines of marine biota. As indicated by Susana Agustí, research professor in the Spanish National Research Council, “We believe that this neglect stems from the widespread perception that the Montreal Protocol solved the problem of increased UV radiation.” The Montreal Protocol, which was entered into on January 1st, 1989, aimed to prevent further deterioration of the ozone layer and set the stage for recovery. However this recovery, as stated by several investigations, has not happened. “This misconception is particularly surprising given the evidence that high levels of UV continue to impact human health,” continues Agustí, who argues that “If high levels of UVB continue reaching the biosphere in the coming decades, it will be necessary to understand the impacts on marine biota associated with those levels.”
This research is the result of collaboration between Latin American and Spanish researchers in the field of global change, and framed within the objectives set by the International Global Change Laboratory (LINCGlobal), promoted by the Spanish National Research Council (CSIC) and the Pontifical Catholic University of Chile (PUC).
Citation: Moira Llabrés, Susana Agustí, Miriam Fernández, Antonio Canepa, Felipe Maurin, Francisco Vidal & Carlos M. Duarte. Impact of Elevated UVB Radiation on Marine Biota: a Meta-Analysis. Global Ecology and Biogeography. (2012)
Fuente: Comunicación LINCGlobal / Departamento Comunicación CSIC
Imagen: CSIC