Depletion of ozone in the stratosphere increases
biologically damaging ultraviolet-Bradiation (UVBR)
at the Earth's surface, and there is overwhelming
evidence that UVBR damages marine organisms and penetrates
to biologically significant depths in the ocean.
This damage is likely to reduce the capacity of Antarctic
waters to act as a sink for atmospheric carbon dioxide
(CO2) and exacerbate global climate change due to
the greenhouse effect.
The research by scientists from the Australian Antarctic
Division (AAD) and Southern Cross University has been
outlined in a poster presentation at the 2004 Australian
Marine Sciences Association Conference in Hobart .
Dr Sharman Stone, Parliamentary Secretary with responsibility
for the Australian Antarctic Division said this research
demonstrated the importance the Australian Government
places on its Antarctic science program in advancing
our understanding of how global processes arise, their
interaction with the natural environment and their
AAD marine biologist Dr Andrew Davidson said that
increased UVBR had a damaging effect on microbes such
as phytoplankton. "Phytoplankton proliferates
around Antarctic coastal waters during spring and
summer, the time during which UVBR light is increased
by ozone depletion. These single-celled marine plants
mediate global climate: absorbing CO2 that is responsible
for global warming and, releasing compounds that aid
the formation of clouds and increase reflectance of
the sun's rays."
"Phytoplankton is the base of the food web and
support the wealth of marine life for which Antarctica
is renowned. Most studies have concentrated on the
effect of UVBR on phytoplankton, but phytoplankton
does not exist in isolation. Other microbes - the
protozoa, bacteria and viruses - can also be directly
damaged or killed by solar UVBR."
Most of us visualise Antarctic life as being penguins,
seabirds, seals and whales. However, marine microbes
comprise some 95% of the living matter in the Southern
Ocean and they consume most of the energy trapped
by phytoplankton. "Any UVB-induced impact at
one level can alter the entire community. To understand
the effect of UVBR, we need to consider both the effects
on each of the species and those on the whole community,"
Dr Davidson said.
"Results indicate that exposure to UVBR can
change the marine microbial community, thereby affecting
the abundance, size structure, palatability and nutritional
quality of food within the food web. "These changes
are likely to enhance global warming by reducing both
the uptake and storage of carbon in the ocean and
release of cloud-promoting substances to the atmosphere.
Though the effects of UVBR on natural microbial communities
are often subtle, the ramifications may be far-reaching,"