Ultraviolet (UV) radiation, the latest threat to seas and oceans besides global warming and atmospheric carbon, is causing an alarming spike in deaths of marine animals and plants, according to an international research team.
The team, which included researchers from the Oceans Institute of the University of Western Australia (UWA), synthesised 1,784 published experiments on marine organisms around the world to evaluate the magnitude of impacts caused by increased ultraviolet B radiation (UVB).
Until now, the role of UVB radiation as a possible cause of the global decline in the health of marine ecosystems had not been quantified, the journal Global Ecology and Biogeography reported.
The marine life most affected by UVB are protists (such as algae), corals, crustaceans and fish larvae and eggs, thereby affecting marine ecosystems from the bottom to the top of the food web, according to a university statement.
Since the 1970s, a continuous emission of fluorocarbon compounds (CFCs) has led to the depletion of ozone layer and consequent elevated levels of UVB, particularly in the southern Hemisphere.
Carlos Duarte, professor and director of the Oceans Institute and co-author, said the impact of increased UVB radiation had not been fully addressed to date because of two key misconceptions – that the Montreal Protocol (first signed in 1987) “fixed” the ozone layer and that UVB does not penetrate to significant depths in ocean waters.
“Whereas the Montreal Protocol was effective in preventing further deterioration of the ozone layer, this has not yet recovered, and now we know that damaging UVB radiation can penetrate to considerable depths in clear ocean waters,” Duarte said.
Today’s study builds on evidence of considerable impacts of UVB radiation on marine plankton and ocean processes. The research was coordinated by Susana Agusti, UWA professor.
“The effects of ultraviolet radiation detailed in this study mainly affect organisms growing near the ocean surface, such as eggs and larvae of invertebrates and fish, which are exposed to very high UVB levels,” Agusti said.