Recently the web has been buzzing about bioluminescent waves in San Diego. This isn’t their first appearance in So Cal, and it won’t be their last. While they may not be rare, they do give an Otherworldly touch to surf footage. Check out this video from Man’s Best Media:
What’s responsible for the neon blue glow? In the ocean, there are these tiny organisms called dinoflagellates. Neither plant nor animal, dinoflagellates are protists comprised of a single cell with two appendages called flagella that they whirl around to propel them across the surface of the ocean. In fact their name comes from the Greek word for “whirling” (dinos) and the Latin for “whip” (flagellum). The species of dinoflagellate that causes the bioluminescent waves in So Cal is Lingulodinium polyedrum.
When a dinoflagellate population explodes as a result of increased nutrients in the water and optimized growing conditions, it causes an algal bloom, also known as a “red tide” for the color that it changes the water. Not all blooms are red nor are they associated with the tide. Algal blooms can deplete the oxygen in the water, and certain dinoflagellates produce neurotoxins that kill fish and end up in the shellfish we eat. L. polyedrum was found to contain toxins, but the fact that surfers and beach-goers have no effect from the being in the water suggests that the toxins are at a low concentration.
Bioluminescent dinoflagellates can produce short flashes of light or a sustained glow in response to being disturbed by waves, boats, or predators. When a dinoflagellate sense a disturbance along its cellular membrane, the pH inside the cell drops, causing particles called scintillons to trigger a chemical reaction that produces the bioluminescence. The blueish-white areas in the picture of L. polyedrum above are the scintillons emitting light (the red is from chlorophyll). The flashes of light are used to distracts creatures that feed on dinoflagellates and attracts the attention of bigger predators. Not a bad defense mechanism for a single-celled organism, right?