algae

A pungent, fishy rancid odor has been wafting through the coastal air in Los Angeles this week, an unfortunate consequence of beautiful bioluminescent algae that has graced local beaches for a fortnight.

Southern California beaches have recently experienced a “red tide” bloom of microscopic algae known as dinoflagellate, which give the ocean a rusty brown hue during the day and an electric blue glow when agitated by waves or other movement at night.

But now this bioluminescent algae is dying and releasing hydrogen sulfide gas, which causes a rotten egg smell, explained Laura Rink, associate director at Heal the Bay Aquarium in Santa Monica.

As bacteria feed on the decomposing algae, they consume oxygen, creating unbreathable patches of ocean known as dead zones, which can cause fish to die and worsen the smell, she said.

Neither the bioluminescent algae nor the odor it produces are harmful, said Rink.