Abstract
back to Publications Conway, K. W., Krautter, M., Barrie, J.V. & Neuweiler, M. (2001): Hexactinellid Sponge Reefs on the Canadian Continental Shelf: A Unique "Living Fossil". - Geoscience Canada, 28/2: 71-78, 8 figs.; St. Johns.
Hexactinellid Sponge Reefs on the Canadian Continental Shelf: A Unique "Living Fossil"
Abstract: Globally unique hexactinellid (siliceous) sponge reefs, found in deep (200m), glacially scoured troughs of the western Canadian continental shelf, have been explored by a manned submersible. Submersible observazion and geophysical data allow examination of the physical and biological processes that have shaped the sponge reefs, which began to form about 9 thousand years (k.y.) ago. The mounds (bioherms) and sheet-like accumulations (biostromes) cover a low-angle, non-depositional, iceberg-scoured seafloor, relict since the deglaciation of the region. Biohermal structures are up to 19 m in height, and are covered with hexactinosan sponges up to 1.5 m tall, creating a benthic habitat that discontinously covers roughly 700 km2. Similar to extinct siliceous sponge reefs, mud mounds, and reef mounds that were widespread during the Mesozoic, the modern reefs are like a "living fossil" and provide a unique modern analogue. Fishing activities, especially trawling or bottom dragging, have damaged the slow-growing reefs in some areas.