San Diego beaches are lighting up blue due to a phenomenon called a red tide.
People have been sharing photos of the blue light, called bioluminescence, in waves crashing on to beaches. On this occasion, it is caused by a bloom of phytoplankton brought by the natural phenomenon known as the red tide.
My friend Rafaela and I took a trip down the coast and saw the pretty tides tonight! I wish the pics showed what we saw better, but here is what I got. #Blessed #Bioluminescence #SanDiego pic.twitter.com/PZ5qQRgibk
— 🐦Whitney🐦 (@WhitneyChirps) May 10, 2018
Bioluminescence expert Michael Latz, a scientist at Scripps Institution of Oceanography at UC San Diego, explained the red tide phenomenon.
“The red tide is due to aggregations of dinoflagellates including Ceratium falcatiforme and Lingulodinium polyedra, the latter of which is well known for its bioluminescent displays, with waves or movement in the water causing the phytoplankton to glow neon blue at night.”
Phytoplankton are microscopic, single-celled plants that occur naturally in some coastal waters.
Mother Nature's stunning light show in San Diego tonight #bioluminescence #Encinitas #MoonlightBeach pic.twitter.com/q30qLqXHDo
— Abby (@RogueAbby) May 10, 2018
During the day, the phytoplankton rise to the surface to capture sunlight for growth and reproduction. As they contain a reddish pigment, they make the sea appear red during daylight hours.
Latz says the best time to view the blue display is from a dark beach at least two hours after sunset.
The last red tide in this area occurred in September 2013 and lasted one week. The one before that, in October 2011, lasted a month.