Composition, Buoyancy Regulation and Fate of Ice Algal Aggregates in the Central Arctic Ocean
Figure 6
Conceptual model of the mechanisms responsible for the formation and fate of the different types of algal aggregates.
(1) In early spring sea-ice algal growth starts before that of phytoplankton. (2) In summer as the sea ice melts and nutrients become limiting, some sea-ice algae are released to the water column or grow into the water column. Due to their stickiness and the under-ice turbulence they form aggregates. (3) In late summer melt ponds grow in depth and the sea-ice algae that are still in the ice are gradually exposed to very low salinities, high irradiances, and nutrient depletion making them accumulate and degrade in the pond. Depending on the environmental conditions, some sub-ice aggregates sink and others remain floating. (4) In early autumn, the melt ponds can either open completely allowing some phytoplankton species to come into the melt pond, or they can refreeze again, becoming second year ice. (5) In autumn those melt ponds that were open to the seawater freeze again, trapping the floating aggregates that were not grazed in the newly formed ice.