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Climate and Environment

It's Back! Bioluminescent Algae Glows Again Off Southern California's Coast

Laguna Beach, March 2021.
((Courtesy Mark Girardeau / Orange County Outdoors))
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These days, if you gaze into the ocean off Laguna or Newport Beach, you may notice the water looking a little brown and ruddy. Take a look again after the sun sets, and you'll see a glowing blue-green light show in the waves, all thanks to a bioluminescent algae that is now in bloom in Orange County waters.

Clarissa Anderson is Executive Director of the Southern California Coastal Ocean Observing System located at Scripps Institution of Oceanography and is always keeping an eye on the tide. As a guest on our newsroom's local news and culture show Take Two, which airs on 89.3 KPCC, she explained the glow is triggered when the waves crash, or when something (or someone) swishes through the algae.

"The turbulence that's stirring up those cells is what's turning on a chemical reaction that gives you a light show," she said.

But Why The Glow?

The top theory is that it's a defense mechansim. "It is thought that it has something to do with scaring off predators like other microscopic organisms that feed on them," explained Anderson.

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The glowing algae can appear at different times throughout the seasons, but has been popping up every spring the last few years. (Remember last year, at the height of the stay at home order, when bioluminescence watch parties gathered at the beach every night cause there was nothing else to do?)

Laguna Beach, March 2021. (Courtesy Mark Girardeau/Orange County Outdoors)

"This time of year, we see a lot of circulation in the coastal ocean that brings nutrients to the surface, and those nutrients are important for the growth of this organism," said Anderson. "It can do well with some of the colder water that we're seeing right now. It also likes to bloom in warm water so you'll see it fall, in summer, it's pretty flexible."

Newport Beach, April 2020 (Courtesy of Mark Girardeau / Orange County Outdoors)

Last spring, a lot of rain followed by a lot of warm weather created the perfect conditions for a prolonged bioluminescent algae bloom. Some surfers did report skin and respiratory irritation when coming into contact with the algae and some marine animals appeared harmed by the last season's abundance. There's limited medical data on reactions to the glowing plankton, but Anderson says this year's bloom shouldn't produce anything like that.

Visible From Space

Bioluminescent algae can be so bright that it's detectable from Earth's orbit. Anderson says the latest satellite technology allows scientists to track the glowing plankton because the creatures absorb UV light.

"We have this ability now with some of the new, ocean color, remote sensing satellites that are in space to look at that part of the electromagnetic spectrum," she said, "and actually detect these blooms from space just based on that."

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See The Glow With For Yourself

Scientists have a tough time predicting when and where the bioluminescent algae will appear. In the last week, it's been spotted from Orange County down to San Diego.

"It could just be that we have these short lived blips every two weeks along the coast and then the season is over," said Anderson. "And that's typical."