Glass Sponge Reefs
Beneath the waters of the Pacific North Coast lies a globally-unique biological phenomenon: glass sponge reefs. These sponge reefs are made from tiny glass spicules (needle-like skeletal elements), and were thought to have gone extinct millions of years ago during the Cretaceous period (145.5 to 65.5 million years ago). Scientists were very surprised when sponge reefs were discovered in Hecate Strait in 1987.
These "living fossils" are found in only a few other places on the west coast of North America and the largest specimens live in North Pacific Coastal waters. These reefs here are up to 9,000 years old and often take the shape of large mounds, some of which have grown to the height of a five-storey building (18 metres). The full range of these reefs cover about 1,000 square kilometres on the North Pacific Coast. Sponge reefs provide structure, habitat, and nurseries for many species. Rockfish appear to benefit greatly from the habitat created by the sponge reefs: they are 10 times more abundant in the sponge reefs than in nearby areas.1
Glass sponge reefs are vulnerable to fishing gear such as bottom trawling. When scientists proved that the ground fish trawl fishery was damaging the reefs, the fishermen voluntarily stopped fishing in the area. In 2002 DFO used the Fisheries Act to make the closure enforceable.
Source:
1 Sarah Cook. (1999) Ecology of the Hexactinellid sponge reefs on the western Canadian continental shelf. Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science in the Department ofBiology, University of Victoria. 127p.
