Glass Sponges of Halkett Reef & Bioherm, Howe Sound, British Columbia

Scuba Diving in the Glass Sponge Reef...

BC’s nutrient rich waters are famous for their abundance and diversity of colourful creatures great & small, that thrive due to the sheer quantity of food available.

One of the most truly remarkable sensitive marine habitats in our waters are the globally unique glass sponge reefs and bioherms of British Columbia. This video features Halkett Pinnacle and surrounding Bioherm located in Halkett Bay Provincial Marine Park.

In 1987 a remarkable discovery was made just off the BC coast. 200 metres below the surface, in the inky blackness of the deep sea, Canadian scientists found an underwater oasis exploding with life: gigantic reefs built by fragile glass sponges. The reefs cover hundreds of square kilometers of sea floor and in some places reach the height of an eight story building. British Columbia’s Sea of Glass is a Canadian national treasure.

Once thought long extinct, living glass sponge reefs are mainly found off BC’s coast.

While dinosaurs roamed the earth, huge glass sponge reefs thrived in prehistoric seas. The reefs were thought have gone extinct about 40 million years ago, leaving only giant fossil cliffs behind that stretch across parts of Portugal, Spain and France and Germany across Eastern Europe to Romania. That was until 1987 when a team of Canadian scientists discovered 9,000 year-old living glass sponge reefs on British Columbia’s north coast.

These ancient, delicate filter feeding animals not only help store carbon and fertilize the ocean, they also provide vital habitat to a wide range of marine animals including endangered rockfish. Fragile glass sponge reefs need protection from bottom contact fishing like prawn traps and trawls.

British Columbia’s glass sponge reefs are one of the great wonders of the world’s ocean. Although individual glass sponges are found across the world, glass sponge reefs were thought to have gone extinct 40 million years ago until living glass sponge reefs were discovered in Hecate Strait in 1987. Scientists have likened this discovery to finding a herd of dinosaurs on land.
The Hecate Strait and Queen Charlotte Sound Reefs are the largest reefs. They are 9,000 years old, cover 1,000 square kilometres, and reach the height of an eight-storey building. Since this discovery several smaller reefs have been identified in the Strait of Georgia, Howe Sound, and Chatham Sound. One small reef has been discovered in Alaska, but other than that they are found nowhere else in the world but BC.
Glass sponge reefs provide important habitat for other marine life, including spot prawns, rockfish, and sharks. They are very efficient filter feeders of bacteria. A single small reef can filter enough water to fill an Olympic-sized swimming pool in less than 60 seconds!

These sponges are exceptionally fragile, with skeletons made of silica, or glass. Sponges are easily broken on impact and increased suspended sediments can permanently smother or inhibit the filtration process.

The ocean conditions necessary to allow such large reefs to develop are rare, and the fragility of the reefs makes them vulnerable to damage from human activity.

They provide a link between benthic and pelagic environments, and play an important role in marine carbon and nitrogen processing.

Each sponge may live for over 200 years, and the slow growth and vulnerability of the sponges suggests that recovery from damage may take tens to several hundreds of years. If the skeletons of dead sponges are buried or destroyed, new sponges cannot grow to add stability to the reef.

Glass sponges don’t have eyes or a stomach or a mouth but they are in fact a living breathing animal! Adult sponges are “sessile” which means they don’t move. Their bodies have tiny holes or poles which water continuously flows through. They absorb all the food, oxygen and silica they need directly from the water that surrounds them. They get rid of their waste which they pump directly back into the water through their tube shaped “oscula”

Visiting these reefs and seeing them first hand as scuba divers is a privilege that can not be overstated. As a community what we do to both illustrate and educate ourselves as divers plays a critical role to ensure that the ability to visit these ancient reefs as recreational divers and citizen scientists is not lost.

To learn more about why protecting these reefs is so important visit the Marine Life Sanctuaries Society of BC website www.mlssbc.com

Video by: Deirdre Forbes McCracken
Director, Marine Life Sanctuaries Society of British Columbia

Special thanks to MLSSBC President, Glen Dennison for making this video possible.

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