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You are here: Cruise News » Drake Passage 2010 » Background » Ice algae
Ice algae in melt pools
Photo: Gwyn Griffiths
Layers of ice with different algae
Photo: Kevin Saw
Algae on the underside of sea ice
Photo: Gwyn Griffiths
Sea ice pocked by ice alage
Photo: Gwyn Griffiths
Ice algae are microscopic plants that live in sea-ice. When numerous they colour the ice green - even yellow, brown or red. Like phytoplankton, ice algae are at the bottom of the food chain. Primary production by ice algae plays an important part in polar ecosystems.
The tiny plants are attached to ice crystals, or live in pockets of salty water between them. Often they stick to the underside of the ice, where marine animals can reach them and scrape them off.
When sunlight first returns in spring, it reaches the ice algae through the ice, and photosynthesis can begin. The floating ice ensures that the tiny plants stay in the sunlit zone.
Krill scraping ice algae
Photo: Uwe Kils
Zooplankton
When the sea ice melts, the algae are released into the ocean, where they find extra nutrients and continue to bloom. Such ice edge blooms occur earlier than the open ocean blooms. They may even 'seed' some of the later oceanic blooms of diatoms and other phytoplankton.
Ice algae and oceanic phytoplankton are the at the bottom of the Antarctic food chain. Ultimately all Antarctic animals depend on the growth of algae for their survival.
Ice algae do not contribute as much to Antarctic primary production as oceanic phytoplankton, but they are very important for the survival of krill and other tiny animals. Because they bloom at different times and in different locations from the main plankton blooms, they are a source of food when little else is available.
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Last update: 18 December 2010 |
Contact: o4s@noc.soton.ac.uk |