Glen Dennison worries every time he ventures out into the waters of Howe Sound outside West Vancouver. This is because he is concerned about the health of the prehistoric creatures he found nearby.
“I discovered them, so, you know, right away they’re my kids,” Dennison said with a laugh of his small boat, which he’s filled with custom-made equipment to monitor the rare glass sponge reefs out there under.
Dennison was writing a book about diving in Howe Sound in 1984 when he made an important discovery of massive glass sponge reefs. They look like something from another world, with beige and brown tubes that delicately intertwine like a fish dart with each other.
Although individual glass sponges are not uncommon, scientists believed that their reefs, also known as bioherms, which can grow 20 to 30 meters tall, had died out 40 million years ago.
“When I saw it, I was totally shocked. I didn’t understand what I was looking at,” Dennison said. “It is nature’s own work of art.”
These reefs are as fragile as the most delicate crystal, since they are made of silica, the main component of glass. They can be wrecked instantly by things like crab and shrimp traps, anchors, fishing line and downriggers.
Not only are these sponges rare, scientists say they contribute to the health of the Howe Sound.
Glen Dennison has been fighting to protect glass sponge reefs since he first discovered them in Howe Sound near Vancouver in 1984. (Dillon Hodgin/CBC)
“They filter the water, about every 90 days, from the whole sound,” Dennison said. “They’re feeders for bacteria, they’re habitat for the rockfish here. So it’s an ecosystem that’s not only beautiful, but incredibly useful.”
But their fragility leaves them susceptible to damage from commercial and recreational fishing. Dennison describes seeing large square holes in reefs where traps have been dropped, damage that can lead to the death of nearby sponges. Dropped steel balls from downriggers are another example, he says.
Cartography of the reefs
Dennison’s accidental discovery started a decades-long struggle to protect the reefs, with Dennison almost single-handedly funding most of the dives to document them. He used his skills as an engineer to create a special camera that can be dropped tens of meters to capture live images of the reefs and map every inch of them.
Their work helped push the Department of Fisheries and Oceans (DFO, now Fisheries and Oceans Canada) to establish protections that prohibit bottom fishing. This prohibits any activity that comes into contact with the ocean floor, such as launching traps or downriggers.
But Dennison, now president of the Marine Life Sanctuaries Society, says it’s not uncommon to find new damage.
“DFO enforcement officers are doing the best job they can,” Dennison suggested. “But they’re so understaffed that they can’t protect the sound properly.”
On a recent Monday, Dennison took divers Tori Preddy and Greg McCraken into the water to check the health of the reefs.
This is an example of a custom 3D map created by Glen Dennison to capture all the glass sponge reefs, shown here in red. (Glen Dennison/Marine Life Sanctuary Society)
Last fall, Preddy went on a dive and discovered damage from a shrimp trap that had shattered the delicate tubes on a reef.
“Honestly, I thought we were dropped off at the wrong place,” he said. “I said, what is this? Where’s the reef? What’s going on? So it was really daunting.”
Greg McCraken owns a dive shop and offers a course on reef diving. It teaches the necessary technical skills, as some reefs are 60 meters below the surface and require advanced deep-water diving skills. It also tries to teach divers the importance of protecting reefs.
“To see what the reefs looked like even 10 years ago,” he said. “It’s very sad to see the images we see when we go down there [now].”
The punishments have increased
The Department of Fisheries and Oceans says it patrols regularly, adding that after the initial protections were put in place, violations dropped dramatically. But fisheries officer Eric Jean says the pandemic brought a whole new group of people to the water and violations jumped.
“There was a whole new cohort of individuals playing and recreating in these areas and maybe under the guise that they don’t know there are reefs,” Jean said.
He said new legislation in April 2021 created higher fines and possible bans for recreational and commercial fishermen.
“These new tickets are hundreds of dollars more than the tickets we had to use just a year ago,” Jean said. Officers also encourage people to report violations and ask for information before going out on the water.
But Dennison says more enforcement and education is needed.
“We cannot enforce destruction,” he said. “That means you can’t wait until someone drops a trap down there and hope you’re going to ticket them or take their gear. The reefs will go away.”
Although bottom contact fishing is prohibited, many of the reefs do not prohibit anchor dropping, a problem DFO reports to Transport Canada.
A rockfish is seen taking refuge inside the glass sponge reef. (Greg McCraken)
Speaking to CBC, Transport Canada said: “Anchorage has long been recognized as an accessory to the common law public right of navigation. Although Transport Canada has not legally prohibited anchorage in these areas, in there are practically no commercial anchorages.”
A statement also said: “Recreational boat operators who may anchor over the reefs should seek local information from marinas in the area they will be sailing through.”
Another threat
Another type of human activity is also threatening reef survival: warming and more acidic waters due to climate change can also damage and kill the glass sponge.
Researcher Angela Stevenson was one of the only people to have been able to keep tiny sponges in an aquarium to study their effects.
He said warmer, more acidic water reduces their ability to filter water and eventually damages them.
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“It means they’re filtering a lot less microbes and particles out of the water,” he said. In his research, he found that in warmer water “they could withstand less pressure. So they broke more easily.”
In today’s dive, the news isn’t all bad. There doesn’t seem to be much new damage, at least on this reef.
“There are still a lot of good sponges, but I definitely saw damaged sponges as well,” McCraken said. “Pretty much the same as it was the last time I was here.”
But Dennison worries next time, that might not be the case.
“If it’s damaged or destroyed, it may not come back,” he said. “We don’t have the science yet to show that these things will regenerate again. In fact, they may disappear from the planet.”