The specialized, sympagic (i.e. ice-associated) community within the sea ice is found in the tiny (mostly <1mm diameter) liquid filled network of pores and brine channels or at the ice-water interface.
Locally and seasonally occurring at several hundred individuals per square meter, they are important mediators for particulate organic matter from the sea ice to the water column.
While previous studies of coastal and offshore sea ice provided a glimpse of the seasonal and regional abundances and the diversity of the ice-associated biota, biodiversity in these communities is virtually unknown for all groups, from bacteria to metazoans.
"[4] Experts apparently agree that the age of the perennial ice cover exceeds 700,000 years but disagree about how much older it is.
[1] However, some research indicates that a sea area north of Greenland may have been open during the Eemian interglacial 120,000 years ago.