During their most recent dive at Agamemnon Channel, near Egmont, British Columbia the B.C. Waters dive team discovered one of two gorgonian coral fans that had been tagged and returned to the ocean in 2002.
“It’s like finding a buried treasure,” says Senior Aquarium Biologist David Caughlan who found and collected the coral last week.
In 2002, Aquarium divers returned two gorgonian coral fans (commonly called sea fans) to the dive site in Agamemnon Channel. These particular specimens had been on display at the Aquarium and in order to better understand their growth patterns and life history they were re-located back to Agamemnon Channel with proper transplant permitting. Prior to being re-located they were measured, photographed and tagged, which is why Caughlan was able to make this exciting discovery.
This recovered specimen will provide a wonderful opportunity to compare the state of the coral 14 years later. Initial casual observations indicate that the coral, although healthy, has grown very little — which may indicate a very slow growth rate for these animals. If this is the case, large specimens may be hundreds of years old.
What is a gorgonian coral?
Commonly known as sea fans, gorgonian corals are soft corals familiar to divers and snorkelers in tropical waters. But, in the cold, dark waters of British Columbia they are rarely seen because of the depth at which they live. Gorgonian corals get their name from the protein gorgonin that provides a flexible yet strong structural scaffolding for these fan-shaped, colonial animals. They are similar to stony, reef-building corals in that each colony is made up of many individual polyps. But, unlike hard corals they do not form reefs — instead they form large, intricate fan-shaped skeletons. Like a tree trunk, these skeletons are strong enough to withstand the force of the ocean’s tides, but flexible enough to bend with the current. Gorgonian corals can live at much deeper depths —since they are not photosynthetic the corals are not restricted to shallow water like reef-building corals are.
Vancouver Aquarium marine biologists have been visiting the Agamemnon Channel for decades. The waters around Egmont are famous for their depth (over 600 metres in Jervis Inlet) and their high tidal current. The nearby Skookumchuk Narrows produces some of the fastest tidal currents in the world, sometimes reaching over 30 km/hour. These cold, deep and fast-moving waters provide the perfect habitat for the soft corals and a multitude of other marine life.
Although relatively abundant in very deep water, gorgonian corals at safe dive-able depths in B.C. are rare. Rarer still are corals on small stones that can be hand-collected by divers for study and display — these are usually found anchored to sheer cliff walls or slabs of bedrock. In the 1990s biologists started diving on a peak of rock jutting up from the bottom of the Agamemnon Channel. This unique pinnacle, with its flat, rubble-covered top about the size of a soccer field, provides the perfect habitat for gorgonian corals conveniently growing on small rocks, as well as safe diving depth during very low tides.
Irreplaceable marine microcosms such as the coral pinnacle in Agamemnon Channel demonstrate the beauty and fragility of the aquatic environment — it would take but one errant trawl to sweep the site clean of coral. Knowing these places exist is the first step in protecting them.
Blog post by Jeremy Heywood, Vancouver Aquarium Marine Science Centre diving safety officer.