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Arctic marine organisms act as a reservoir for CO ₂ , according to research published in the international journal Geophysical Research Letters .

The study , co-authored by Professor Susana Agusti and Dr Lara Silvia Garcia-Corral, from The University of Western Australia's Oceans Institute , suggests increased levels of Ultraviolet B (UV-B) radiation support the capacity of Arctic marine organisms to sequester CO ₂ .

UV-B radiation is a band of high energy that reaches the Earth's surface after being filtered out by the ozone layer. Increasing UV-B radiation, resulting from the erosion of the ozone layer, has greatly impacted marine life, and research shows that UV-B can penetrate clear, oceanic waters to depths of up to 60 meters.

The study, undertaken in Arctic waters, examined the response of plankton communities to UV-B exposure.  Data was collected from several oceanographic expeditions over the past two decades.  In the absence of a night recovery period during the Arctic summer, the UV-B suppressed bacterial activity, which improved the production of these communities. Of the 77 per cent of communities sampled, there was a 38.5 per cent net increase in Arctic plankton production. These results suggest that UV-B radiation triggers plankton to act as a reservoir to sequester CO ₂ , directly combating the impacts of increased Arctic warming.

Lead author, Dr Lara Silvia Garcia-Corral said the natural UV-B radiation seemed to be an important energy source for communities in the Atlantic, Pacific and Indian oceans. "Communities in these oceans are able to recover from cell damage during the night, but during summertime in the Arctic Ocean with up to 24 hours of sunlight, these recovery processes are inhibited," Dr Garcia-Corral said. "This means the bacterial activity is lower which results in increased production of Arctic plankton communities."

Professor Agusti said the results were unexpected and knowledge of the effects of UV-B radiation on the ocean was still limited.

"At the surface of the Indian, Pacific and Atlantic Oceans, UV-B radiation had the opposite effect," Professor Agusti said.  "UV-B radiation acts on both chemical and biological processes, and generates complex interactions.

"The balance between photosynthesis and respiration resulted in the net emission of CO ₂ , due to the increased bacterial respiration at night."

She said that while Arctic warming was previously expected to lead to an overall decline in plankton communities, the research suggested a much more positive future, with exciting possibilities for production and availability to the food web in the Arctic Ocean.

The paper Ultraviolet radiation enhances Arctic net plankton community production has been published in the journal Geophysical Research Letters .

Professor Agusti will discuss the impacts of UV-B radiation on ocean ecosystems at The University of Western Australia on Tuesday, 21 October.  The lecture, co-sponsored by the UWA Institute of Advanced Studies, is open to the public and registration details are available on the web.

Media references

Anna-lee Harry (UWA Oceans Institute)  (+61 8) 6488 7314
David Stacey (UWA Media Manager)  (+61 8) 6488 3229 / (+61 4) 32 637 716