If you go for a nighttime ocean swim on Vancouver Island during the summer, you might be lucky enough to experience the magic of bioluminescent organisms.
“The bioluminescence looks like 100 sparkles or glitter around your paddle stroke or around your arm if you’re swimming through it. It’s not a big, solid light. It’s tons of tiny, little lights,” said E-J Frederiksen, owner and manager of Pacifica Paddle Sports in Brentwood Bay.
The bioluminescent glow is consistent in the Saanich Inlet near Brentwood Bay between May and October, said Frederiksen, who runs kayak tours three nights a week to observe the phenomenon.
“The bay is quiet and dark until you dip your paddle into the water and then it lights up,” she said.
The inlet’s warm, sheltered water and dark shoreline create the perfect conditions to see a trail of sparkles in the water as you pull a paddle through it, she said.
While many organisms are capable of emitting bioluminescence, the most likely culprit is dinoflagellates, a form of microscopic phytoplankton, said Diana Varela, a University of Victoria professor in biology and earth and ocean science.
A chemical reaction in the cell triggered by a mechanical force — moving your arms as you swim or pulling a paddle through the water — creates the glow, she said.
Varela said the purpose of the bioluminescence isn’t quite certain, but many believe it to be a defence mechanism to deter predators.
“So they flash and they will deter a predator from eating them,” she said. Another theory that Varela believes is a bit “far-fetched” is that the light is like a “burglar alarm,” attracting a second predator to feed on a predator of the dinoflagellates.
The one-celled dinoflagellates are too small for the naked eye to see, but when bound together in a chain or colony and triggered, they become visible as small flashes of light, she said.
Dinoflagellates exist in all of the world’s oceans and are more abundant in warmer waters, said biologist Patrick Walshe.
Warm temperatures in summer lead to plankton blooms around Vancouver Island, increasing the concentration of dinoflagellates and improving the likelihood of seeing the glow, he said.
Walshe recommends finding a dark location without light pollution. The best time is at least an hour after sunset during a new moon or before the moon has risen, he said. Shallow or sheltered water may make the light easier to see, but the organisms can be found pretty much anywhere, he said.
“Even on the ferries, you can see it at night. Look at the wake behind the ferry and it’s lit up,” he said.
Using a scuba mask or goggles is “even more spectacular” because it reduces reflected light, Walshe said.
“You can see little fairy trails behind the fish when you’re snorkelling.”
While Frederiksen has had many magical nights on the water swirling her paddle around to create sparkly lines in the water, one evening on a multi-person paddleboard with friends sticks out.
A curious seal came close, swimming under the board and around it.
“You could see a sparkling outline of the seal around our board,” Frederiksen said. “And it’s really neat, because seals usually disappear as soon as they go underwater. But the opposite was true that evening, because it was hard to see the seal when he popped his head up, but you could see the body underwater, sparkling.”
