Orange water in Vancouver Island bay likely harmless phytoplankton bloom

Plankton turns bay orange

Water the colour of cream of tomato soup on the shore near Duncan is catching the attention of visitors to the waterfront.

Sarah Merriam shared images to social media showing the shore in Maple Bay Marina covered in bright orange water on Saturday.

“It was thick. You couldn’t even see the water, like under the water. It was just straight orange,” Merriam said.

Merriam thought it looked like red tide, an algae bloom that has toxic effects on people, fish, shellfish, marine mammals and birds.

But the colour is likely the result of a phytoplankton bloom called noctiluca, said Maycira Costa, a University of Victoria geography professor.

The blooms occur in spring and summer, when the weather warms and there are increased nutrients in the water, sometimes as a result of the discharge of sewage or fertilizer, she said.

It’s not harmful and likely will only last a few days, Costa said.

While it’s safe to swim in, it might not be the most pleasant experience, she said.

At night, the phytoplankton shines like bioluminescence in the water, and during the day, if you look really close, you might be able to see individual organisms with the naked eye, Costa said.

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