Abstract
AbstractOver the past three decades, the 'ozone hole' has caused a transient increase in the levels of ultraviolet B radiation (UV-B, 280 to 320 nm) reaching Antarctic coastal marine ecosystems^1^. The direct effect of this enhanced UV-B on pelagic organisms remains unclear, for few studies have examined in situ the responses of Antarctic marine organisms in direct relation to the 'ozone hole'. Here we show that the presence of the 'ozone hole' over McMurdo Sound, Antarctica, during a two-week period in 2008 resulted in unequivocal increases in oxidative damage and developmental abnormality in embryos of the sea urchin Sterechinus neumayeri Meissner (Echinoidea: Echinidae) growing in open waters. We show that although embryos have a limited capacity to increase the activities of protective antioxidant enzymes, increased UV-B exposure caused a very large increase in oxidative damage to proteins and lipids. Importantly, we show that embryo damage, resulting from the presence of the 'ozone hole', is largely mitigated by sea ice, with embryos beneath the ice protected from UV-B and hence oxidative damage. As the ozone hole is now expected to persist for a further 80 years^2^, during which time significant reductions in sea ice coverage are expected around the Antarctic continent due to global warming^3^, our findings sound a warning that the coincidence of the two phenomena (high UV-B and open water conditions) will provide a window when significant damage to marine ecosystems may occur.
Highlights
Recent increases in biologically harmful UV-B radiation penetrating the waters surrounding Antarctica, as a result of stratospheric ozone depletion, are well documented[1]
Oxidative damage increased greatly in embryos exposed to UV-B (UV-T treatments) in the open water experiments compared to embryos protected from UV-B by artificial filters (UV minus (UV-O) and UV-B minus (UV-A)), or by sea ice (Fig. 2)
While the activities of protective antioxidant enzymes increased significantly in embryos exposed to full UV-B, the increases were relatively small and were insufficient to protect the embryos from oxidative damage (Fig. 3)
Summary
Recent increases in biologically harmful UV-B radiation penetrating the waters surrounding Antarctica, as a result of stratospheric ozone depletion, are well documented[1]. Our experiment was designed to test the interaction of ozone depletion and sea ice cover on oxidative stress and abnormal embryonic development.
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