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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallYes—British Columbia has deep-water reefs built by glass sponges. “Glass” refers to silica in the animals’ tiny skeletal structures, not sheets or shards of manufactured glass. The living sponges grow on older sponge skeletons, while trapped sediment and generations of growth build up the reef mound.
What are glass sponge reefs?
Glass sponge reefs are large seafloor mounds formed by reef-building sponges in the class Hexactinellida. Unlike coral reefs, they are built by sponges. Fisheries and Oceans Canada (DFO) identifies the cloud sponge (Aphrocallistes vastus) and goblet sponge (Heterchone calyx) among the reef-building species found in British Columbia. Their skeletons contain silica spicules, which give the reefs their “glass” name. DFO’s overview of B.C. glass sponge reefs explains their location and formation.
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How the reef forms
When a sponge dies, its rigid skeleton can remain on the seafloor. New sponge generations settle on those skeletons; the growing sponges also trap fine sediment. Over centuries, sponge growth and accumulated sediment build large mounds, sometimes called bioherms. The reef is therefore a mixture of living sponges and older reef framework—not one solid mass of living animals or manufactured glass. DFO’s open-data description outlines the role of sediment trapping and sponge growth.
Where are they, and how deep?
DFO lists four regions off British Columbia where glass sponge reefs occur: Hecate Strait, Queen Charlotte Sound, the Strait of Georgia, and Howe Sound. The reefs typically occur at depths of 90 to 300 metres, according to DFO’s overview. They are offshore seafloor habitats, not places where visitors should assume they can see a reef from shore or join a public viewing trip.
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Why are these reefs unusual?
NOAA Ocean Service says Canadian scientists discovered living glass sponge reefs off British Columbia’s northern coast in 1987, after reefs of this kind had been thought extinct for about 40 million years. NOAA describes them as the only such reefs known to exist. Those details refer to NOAA’s account of the discovery and known distribution, rather than a claim that no other kind of sponge habitat exists. NOAA’s glass sponge fact page provides that history.
What lives in and around the reefs?
The reef framework offers habitat for fish and invertebrates, and the sponges filter water while contributing to the processing of carbon, nitrogen, and silica. These functions connect seafloor habitat with processes in the surrounding water column, as described in DFO’s open-data account.
A DFO announcement in 2019 said Howe Sound’s reefs supported more than 84 species of invertebrates and fish. That figure applies to the Howe Sound reefs covered by that announcement; it should not be read as a count for every reef or every region. The same announcement described eight refuges protecting nine newly discovered Howe Sound reefs. DFO’s 2019 Howe Sound announcement gives the scope of those figures.
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How are the reefs protected?
DFO’s Strait of Georgia and Howe Sound Glass Sponge Reef Conservation Initiative has established 17 marine refuges and proposed five additional refuges, according to its regulations page. The counts are specific to that initiative, not a national total. The measures are intended to protect reefs from bottom-contact fishing, which can damage the fragile reef structure. Established and proposed refuges are not interchangeable: a proposed refuge is not an established protection area. DFO’s regulations page lists the initiative’s refuge information; consult the applicable DFO notice or map for the rules and boundary of a particular area.
Reef condition can also vary from one surveyed area to another. A technical survey report for a Passage Island polygon found only dead reef habitat within the survey area; it cautioned that live sponges could be present beyond the boundary and noted that dead framework could allow future recovery. That is a finding about one survey polygon, not a description of all British Columbia reefs. The Passage Island survey report states those geographic limits.
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