Deep in the ocean off of BC’s Hecate Strait and Queen Charlotte Sound live rare and delicate glass sponge reefs. While glass sponges are found all over the world, it is mainly on our coasts that they form intricate reefs.
Canadian Parks and Wilderness Society, or CPAWS-BC, has been advocating for the protection of glass sponge reefs since 2001. In 2017, the Government of Canada established the Hecate Strait and Queen Charlotte Sound Glass Sponge Reefs Marine Protected Area Marine Protected Areas (MPAs) to safeguard these fragile features from harmful human activities. But new research published in the journal Marine Ecology Progress Series suggests that these current protections may not be enough to prevent glass sponge reefs from harm.
Most marine sponges are soft and squishy, feeling much like the sponges we use to clean our kitchens and bathrooms. However, glass sponges absorb silica from the water to form their glass skeletons, giving them hard bodies but making them extremely fragile.
The earliest fossils of glass sponge reefs are 220 millions years old, spread out over a 7,000 kilometre stretch of Central Europe. However, 40 millions years ago they disappeared from the fossil record and were thought to be extinct.
But in 1987, a team of Canadian scientists mapping the seafloor discovered living glass sponge reefs 200 metres below the ocean surface of Hecate Strait. For them, this discovery was like finding a herd of living dinosaurs.
Besides being beautiful and rare, glass sponges are also integral parts of the ocean ecosystem. Glass sponge reefs provide shelter for bottom-dwelling creatures such as rockfish and prawns.
Fishing activity can cause severe harm to these fragile habitats. Prawn and crab traps drop down and crush glass sponge reefs. Bottom trawling of heavy nets dragged along the seafloor destroy everything in their path while kicking up clouds of disturbed sediment. The Marine Protected Area regulations protect the reefs themselves from bottom-contact activities such these. However, nearby fishing activity kilometres away can still be deadly.
Glass sponges are filter feeders. They do this so efficiently that 95% of bacteria are filtered out, cleaning the water. In fact, a single small reef can filter enough water to fill an Olympic-sized swimming pool in less than 60 seconds! Furthermore, the nitrogen waste they excrete acts as a fertilizer for
plankton. When these storms of sediment kicked up be bottom trawling roll over glass sponge reefs, they are triggered to stop filter feeding and absorbing oxygen. The glass sponges choke and can even starve to death.
The Hecate Strait and Queen Charlotte Sound Glass Sponge Reefs Marine Protected Area currently provides a one kilometre buffer zone around each reef where no bottom contact activity is allowed.
This new research proves that these restrictions are not enough to protect these global treasures. Although the glass sponge reefs found in Howe Sound and the Georgia Strait have been found to have a stronger tolerance to sediment, their buffer zones are only a paltry 150 metres wide and drastically insufficient.
New regulations are needed to increase the Hecate Strait and Queen Charlotte Sound Marine Glass Sponge Reefs Protected Area buffer zones to at least three kilometres and as much as six kilometres.
This will only increase restricted bottom fishing areas in B.C.’s ocean by 0.6% while ensuring the health of the valuable marine species supported by these reefs for generations to come.