The Contributions of Sea Ice Algae to Antarctic Marine Primary Production

The seasonally ice-covered regions of the Southern Ocean havedistinctive ecological systems due to the growth of microalgaein sea ice. Although sea ice microalgal production is exceededby phytoplankton production on an annual basis in most offshoreregions of the Southern Ocean, blooms of sea ice algae differconsiderably from the phytoplankton in terms of timing and distribution.Thus sea ice algae provide food resources for higher trophiclevel organisms in seasons and regions where water column biologicalproduction is low or negligible. A flux of biogenic materialfrom sea ice to the water column and benthos follows ice melt,and some of the algal species are known to occur in ensuingphytoplankton blooms. A review of algal species in pack iceand offshore plankton showed that dominance is common for threespecies: Phaeocystis antarctica, Fragilariopsis cylindrus andFragilariopsis curta. The degree to which dominance by thesespecies is a product of successional processes in sea ice communitiescould be an important in determining their biogeochemical contributionto the Southern Ocean and their ability to seed blooms in marginalice zones.