He­cate Strait and Queen Char­lotte Sound Glass Sponge Reefs, Bri­tish Columbia

Canadian Geographic - - UNESCO -

SIG­NIF­I­CANCE The reefs com­prise colonies of glass sponges es­ti­mated to be 9,000 years old and are con­sid­ered the largest liv­ing ex­am­ple of glass sponge reefs that were abun­dant in the Juras­sic Pe­riod. The struc­ture of the reefs — sponges grow­ing on top of sponges for thou­sands of years — is not found any­where else in the world. SIZE 1,000 square kilo­me­tres and up to 240 me­tres deep. The sponges them­selves are up to 25 me­tres tall. LO­CA­TION Off the coast of Bri­tish Columbia be­tween Haida Gwaii and Van­cou­ver Is­land and the Cen­tral Coast CUR­RENT OF­FI­CIAL PRO­TEC­TION Be­came a Marine Pro­tected Area un­der the Oceans Act in 2017 RAR­ITY FAC­TOR It’s a unique ecosys­tem. Other coral reefs on the World Her­itage list are shal­low, warm-wa­ter reefs built from cal­cium car­bon­ate. The glass sponge reefs are only found in the cold wa­ters of Bri­tish Columbia and Alaska, where they ex­tract sil­ica to build their skele­ton and cre­ate an oa­sis of life on an oth­er­wise fea­ture­less seabed, which pro­vides shel­ter to nu­mer­ous species, in­clud­ing threat­ened rock­fish. THE LO­CAL’S TAKE Pro­fes­sor Sally Leys, a marine bi­ol­o­gist and sea sponge ex­pert at the Uni­ver­sity of Al­berta, says the He­cate Strait reefs are oases in the deep ocean that sup­port a re­mark­ably di­verse com­mu­nity of in­ver­te­brates and fish. “There is a mes­mer­iz­ing num­ber of in­ver­te­brates tucked in amongst the sponges, nes­tled into crevices, crawl­ing on their sur­faces, grab­bing at plank­ton, hid­ing from flow and preda­tors,” she says, adding that sponges are fil­ter feed­ers that are very ef­fi­cient at re­mov­ing bac­te­ria and ex­cret­ing am­mo­nia and car­bon diox­ide. “The sheer num­ber of fil­ter­ing tubes means they have an im­mense im­pact on the wa­ter col­umn prop­er­ties by re­cy­cling nu­tri­ents.”

He­cate Strait and Queen Char­lotte Sound Glass Sponge Reefs

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