An eagle-eyed photographer caught a neat glimpse at a red tide along the coast of the Samsun Narrows off Salt Spring Island this week.

The tide is remarkably vivid from high up, more so than if you were to look at the water from sea level. But what’s the cause of this phenomenon? And should you be careful if you’re eating shellfish when the water looks like that?

Looks can be deceiving

In fact, the photo isn’t of a red tide at all, but rather of a non-toxic algae bloom called noctiluca scintillans, which is a species of dinoflagellate. 

“They are a single celled protist with large, spherical cells that range up to two millimetres in diameter, big enough to see with the naked eye,” says Elysha Gordon, Canadian Shellfish Sanitation Program coordinator.

“They emit light when disturbed—bioluminescence—and under certain conditions form greasy, fluorescent-orange blooms that coat the surface of the water.”

A high concentration of blooms like the one in the photo can occur due to a combination of warm ocean surface temperatures, low salinity (the level of salt in the water), high nutrient content, calm seas, and rain followed by sunny days during the summer months.

What about a real red tide?

As beautiful as it may be from high up, a real red tide is bad news if you want to eat any shellfish from an affected area. The algae in a red tide produces a potent natural toxin that is harmless to most fish and smaller grazing animals, but can accumulate and cause illness—or death—in larger mammals and even humans.

That’s why you should reconsider that plate of oysters if they came from an area affected by toxic algal bloom. 

Thankfully, this particular bloom is nothing to worry about. Nonetheless, maybe just enjoy the view from the safe vantage point of the beach—or a seaplane, if you’re feeling fancy.

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