US EPA

8658828 

Journal Article 

Hexactinellid sponge reefs on the Canadian continental shelf: A unique "living fossil" 

Conway, KW; Krautter, M; Barrie, JV; Neuweiler, M 

2001 

Yes 

Geoscience Canada
ISSN: 0315-0941 

28 

2 

71-78 

WOS:000170098700006 

Globally unique hexactinellid (siliceous) sponge reefs, found in deep (200 m), glacially scoured troughs of the western Canadian continental shelf, have been explored by a manned submersible. Submersible observations 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 sl eet-like accumulations (biostromes) cover a low-angle, nondepositional, 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 km(2). 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.