BC’s waters are home to a multitude of little known deep-sea
corals and sponges. Corals are large colonies of tiny animals that can create
structures more than three metres tall. Sponges are the simplest multicellular
animals on Earth. These persevering animals have thrived for millennia attached
to BC’s dark, cold ocean floor.
Unlike tropical sponges and coral reefs, coldwater corals and sponges do not rely on photosynthetic algae and are able to live deep in the ocean and in northern waters. They can live for hundreds or even thousands of years. They provide homes, shelter and nursing grounds for a diverse array of sea life including rockfish, crabs and shrimp.
BC’s 9,000-year-old glass sponge reefs were discovered in Hecate Strait in 1989. Before then, glass sponge reefs were thought to be extinct and were known only through the fossil record. Smaller sponge reefs have recently been discovered off the Sunshine Coast and in the Strait of Georgia, including one located off Galiano Island.
Although the four sponge fields in Hecate Strait are the only known living examples of glass sponge reefs on Earth, they still do not have permanent protection. Half the sponges have been destroyed by bottom trawling and those sections of the reefs may never regenerate. Since 2002, the federal government has closed the reefs to trawling, but these closures do not provide permanent, legislated protection.
Benthic organisms like corals and sponges have been heavily
damaged by human activities in BC and around the world. A 2004 United Nations
Environment Program (UNEP) report warned, “Many of the most spectacular examples
[of coldwater corals] discovered so far could be gone in less than a generation.”
Why should we care about primitive, sedentary, uncharismatic bottom-dwellers? Aside from the great diversity of corals and sponge themselves, the three-dimensional structures of these animals provide complex habitat on the otherwise flat and featureless seabed. These benthic “islands” harbour food and shelter for many species of fish and other animals, creating areas of rich biological diversity and contributing to the sustainability of local fisheries, including redfish, rockfish, lingcod, and warbonnet. Invertebrates such as sponges, hydroids, scallops, octopuses, shrimps, bryozoans and basket stars have been observed among coldwater corals and sponge reefs are proving to be vital habitat for BC’s juvenile rockfish.
Bottom trawling, offshore oil and gas exploration and development,
cable laying, gravel extraction, and ocean dumping are the most serious threats
to corals, sponges and other benthic organisms. These animals are vulnerable
to physical damage because they grow extremely slowly and are fragile and immobile.
One way to effectively protect coldwater corals and sponge reefs is with marine protected areas (MPAs). Corals and sponge reefs are ideal candidates for MPA zoning, since they live in stationary groupings with distinct boundaries containing high biodiversity.
This November, Canadian Parks and Wilderness Society (CPAWS) is presenting a public speaking tour to highlight the need for coral and sponge reef conservation on the BC coast. International sponge specialist Dr. Manfred Krautter will be speaking in Vancouver, Victoria, Galiano Island, Nanaimo, Port Hardy, Prince Rupert, Queen Charlotte City and Sechelt.
For more information about sponge reefs and CPAWS efforts to protect them, go to www.cpawsbc.org/marine/sites/hecate_strait.php
Karen Blinkhorn is the communications coordinator at CPAWS BC chapter.