The boundary layer between sea ice and the water column with special abiotic (e.g. temperature, salinity) and biotic (e.g. food resources) factors, which also vary with season and region. This habitat is colonized by autochthonous under-ice amphipods (Apherusa glacialis, Onisimus spp., Gammarus wilkitzkii), which live directly at the ice underside and complete their entire life-cycle here, and allochthonous sub-ice fauna, organisms originating either from the ice interior or the pelagic realm, which are found in this boundary layer temporarily, e.g. for feeding or during certain life stages. There is some evidence that the first metres below the ice are strongly stratified, particularly during the melt period in summer. Source: http://www.awi-bremerhaven.de/Climate/WorkingGroups/ofis/ARK-19-1/sea-ice-biology.htm.