Why do California’s waters glow blue?
California seems to have gotten the year off to a good start — and we’re not just talking about Hollywood stars gathering for awards season. We are talking about bioluminescent algae.
Biolumi-what?
Bioluminescent algae. It’s not new, but this latest algae bloom in parts of Southern and Northern California is causing waves and parts of the water in the Pacific Ocean to glow fluorescent blue, bringing surfers and other enthusiasts out to take photos of a bright blue ocean view and share. . The water is so luminous when disturbed at night that it looks like surfers are riding the waves in “Avatar: The Way of Water.”
Bioluminescence is the emission of light by living organisms. It can be used “to warn or evade predators, to attract or detect prey, and for communication between members of the same species,” according to the National Ocean Service, an office within the National Oceanic and Atmospheric Administration. In the ocean the phenomenon is not rare: bacteria, fish, jellyfish, sharks and other animals and organisms can be bioluminescent.
The light emitted by a bioluminescent organism is produced by energy released by chemical reactions taking place within the organism. (For example, a firefly is a bioluminescent creature.)
The algae currently blooming in California are a type of marine phytoplankton called dinoflagellates, mostly one species in particular that is a very vibrant bioluminescence producer called Lingulodinium polyedra, said Dr. Clarissa Anderson, director of the Southern California Coastal Ocean Observing System. Dr. Anderson added that this algae is not related to the more harmful blue-green algae, or cyanobacteria, which can make animals sick, smother ecosystems and look much less magical.
The algae in California right now are related to the dinoflagellate that causes “red tides,” said Dr. Anderson, which gives water a rusty red hue during the day. Such red tides can be harmful: in 2022, large numbers of fish were killed in the San Francisco Bay Area. (The organism that causes red tides produces a toxin that can make animals and people sick, including respiratory symptoms.)
And while California’s glowing algae can produce a toxin, it is “not particularly potent or harmful to wildlife or to people,” said Dr. Anderson in an email.
The algae are vividly seen where the waves crash. The best way to find them is to search in warmer weather and when the water is calm.
Interest in night tours to see the phenomenon has grown. Some whale watching tour operators offer bioluminescent tours, and people have been posting luminous photos on social media lately.
Typically, bioluminescent algae are easiest to see between June and October. But it’s happening more and more year-round, says Dallas Smith, operations manager at Blue Waters Kayaking in Northern California. “It’s one of those questions,” he said: “Do we look for it more, or was it always there and getting stronger?”
Tours to see bioluminescence on the water have become increasingly popular, especially since about a decade ago, Mr Smith said.
The tours last about three hours, as guides take kayakers about a mile out into the water on calm nights with little moonlight.
Mr Smith and his colleagues take people out into the bay in kayaks to see the bioluminescence. There’s never a guarantee that glowing fish or algae will grace the horizon, but if it’s a bad night for bioluminescence, people can always look up instead of down to see a beautiful sky full of stars, he said.
Mr. Smith has been doing bioluminescence tours in the Bay Area for more than two decades, he said, but it doesn’t get old. “Every time you see one of them beneath you in bright bioluminescence,” he said of underwater creatures, “their bodies illuminate a glowing outline of what they look like that will stay with you forever.”