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Prehistoric Sponges

Winter diving weather along the British Columbia coast is not infrequently overcast but when the sun peaks through the clouds up there in the sky, divers can be rewarded with the best visibility of the year. This photo was taken during such a winter’s day in Agamemnon Channel, which is on B.C.’s Sunshine Coast (of course!), just north of Vancouver. As diver Barb Cox approached these gigantic Cloud Sponges (Aphrocallistes vastus) of the deep, clinging to the vertical rock wall of this fjord, water clarity was so amazing that I could see the surface from our depth of 115 feet (35m). Such are the diving days we live for!

These magnificent sponges provide habitat for a wide range of fish species, such as this Quillback Rockfish (Sebastes maliger), and for numerous other species, including crabs and many less familiar invertebrates. Growing over 12 feet (4m) in length in some cases, the cloud sponges encountered by sport divers here are generally found along these deep rocky slopes that often descend into abyssal regions well beyond our reach. Divers must take great care around these fragile glass sponges. One errant fin kick can destroy a sponge formation that may well have taken a hundred years to grow!

Recently deep-sea submersibles have discovered glass sponge reefs of truly gargantuan proportions along British Columbia’s continental slope.  Back in the days of the dinosaurs these immense reefs were common and rivaled the size of Australia’s Great Barrier Coral Reef. Scientists believed such reefs had been extinct for millions of years, until the late 1980s that is. It was then that a submersible discovered a living, growing, glass sponge reef several hundred meters deep in British Columbia’s Hecate Strait. Since that initial discovery, four of these immense reef structures have found in the region and are thought by scientists to be at least 9,000 years old. Even more impressive is that they cover a staggering total area of some 385 square miles (1,000 sq km) and in places the reef complex rises as high as an eight-story building from the sea floor.

Discovery came too late for many of the sponge structures. Investigation revealed that deep-sea trawler fishing nets carved huge swaths of destruction through many of the reefs. Government has since provided some protection, but not nearly enough to ensure the survival of these survivors of the ancient sea.  Though most of us will never see these wonders of nature with our own eyes, recreational divers can enjoy the next best thing viewing a dramatic wall of Cloud Sponges in a clear water BC fjord. Prehistoric reefs anyone? But, never say never. I’ll keep the faith that one day I’ll glimpse the deep sea reefs from the the viewing port of a submersible… a childhood dream come true!

Photograph taken in Agamemnon Channel on the Sunshine Coast of British Columbia, using a Nikonos III underwater Camera with a Nikkor 15mm UW f2.8 lens. Exposure about f5.6 or f8 at 1/30 second on Fuji Provia100 film pushed to ISO 200.  Fill light from a single Sea & Sea 120 underwater strobe.  Photo: © Dale Sanders – www.DaleSanders.info and www.dalesanders.photoshelter.com

 

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