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Sea Ice Algae. The Polar Regions. Antarctic ice pack Arctic ice pack The ice varies between the two hemispheres There are several different types of ice. Factors affecting ice algae growth. Salinity From hypersaline to hyposaline Dehydration and osmotic stress
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The Polar Regions • Antarctic ice pack • Arctic ice pack • The ice varies between the two hemispheres • There are several different types of ice
Factors affecting ice algae growth • Salinity • From hypersaline to hyposaline • Dehydration and osmotic stress • Adjustment of cellular concentrations of osmolytes restore the osmotic balance of the cell
Factors affecting ice algae growth • Temperature • Temperatures can reach –20 C • Form stress resistant cysts at specific stages in their life cycle • Maintenance of functional lipid membranes that regulates membrane fluidity
Factors affecting ice algae growth • Light Availability • Must adapt to low-light conditions • Have high photosynthetic efficiencies • Concentrated accessory pigment fucoxanthin
Life cycles • Algal blooms occur when water from snow and ice melt run into the porous surfaces of the ice and provide nutrients for the algae • Blooms occur multiple times per year
Ice algae: The backbone of the polar food web? • Ice algae provides food for adult krill and juvenile larvae • Concentrations of algae exceeding 1 mg per cubic meter, sometimes hundreds of mg per cubic meter • Algae production is highly underestimated
Ice algae: The backbone of the polar food web? • Krill provide main source of food for penguins, seals and whales • Strong relationship between algae production and krill production
Difficulties in ice algae research • Sea ice environ-ments are not always accessible • There are no long-term studies of ice algae life cycles • Research is expensive
Global Warming • Global warming could decrease amount of substrate available for the ice algae • This could in turn affect the food web, causing a decrease in the grazers that rely on the algae for food