Siliceous sponge communities, biological zonation, and Recent sea- level change on the Arctic margin: Ice Island results

Bathymetric profiles, bottom-camera photographs, surface-sediment samples, and biological samples were obtained through a 44 m long hydrohole in the Canadian Ice Island as it drifted over the Canadian polar margin from western Ellesmere Island to Meighen Island. Continuous bathymetric profiles show a 300 km wide shelf with a narrow, dissected, shallow (<200 m) inner shelf and a deep (300-800 m), sloping outer shelf. Extensive areas of siliceous sponge, communities are present on the seafloor beneath the polar pack ice on the central shelf. A clear biological zonation is evident, this zonation may reflect a relative-sea-level depth increase of ~40-60 m during the past 1000 yr. Alternatively, the zonation may indicate a 20-30 m upward shift in the warm Atlantic water layer during the past 500-1000 yr, perhaps reflecting global climatic warming. -from Authors