SEA ICE MICROBIAL COMMUNITY
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The fish Pagothenia
borchgrevinki is perched on a grounded iceberg just south of Cape Evans on
Ross Island. The surface of the ice is covered with a sea ice microbial
community comprised of diatoms and other microalgae, bacteria and protozoans.
The brown coloration is due to photosynthetic pigments in the microalgae.
Crustaceans and molluscan pteropods graze on the microalgae and fish prey on the
crustaceans. Antarctica in the area of McMurdo Sound is continuously dark for
four months in the winter and continually light for four months in the summer;
these are separated by two-month transition periods in which the light increases
or decreases by twenty minutes per day [1]. To the human
eye, lighting can be dim under the sea ice. The sea ice reduces light as does
its overlying snow cover and the organisms living on its underside. At noon
during McMurdo Sound summer, the sea ice undersurface receives less than 1% of
the sun's irradiance [2]. This isn't much light to use for
photosynthesis yet the sea ice microalgae have adapted. Called cryophiles for
their ice lifestyle, the sea ice microalgae live in low light intensity and make
a significant contribution to primary productivity under the ice [2].
| Text ©Peter Brueggeman. Photographs
©Norbert Wu. Photographs may not be used in any form without the
express written permission of Norbert Wu.
Norbert Wu no longer grants permission for uncompensated use of his photos under any circumstances whatsoever;
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