A red tide that developed off San Diego over the past few days is producing one of nature's small but grand spectacles: bioluminescent light in the ocean.
The algae bloom is filled with glowing phytoplankton that lights up when the microorganisms tumble down the face of waves at and near the shore.
At times, the light appears when a surfer paddles his or her board through the surf, or simply walks on the beach.
The phenomenon was first forecast on Monday by Michael Latz, an internationally known bioluminescence expert at UC San Diego's Scripps Institution of Oceanography.
"Based on analysis of a water sample provided by Scripps collector Phil Zerofski, the water contains dense numbers of dinoflagellates especially Ceratium falcatiforme and Lingulodinium polyedra. As L. polyedra (formerly Gonyaulax polyedra) is well known for its bioluminescent displays, there may be some nice light shows tonight," Latz said in an email.
"We're getting reports that the bioluminescence runs from La Jolla to Encinitas, but we don't know how big the red tide is," Latz told the San Diego Union-Tribune on Tuesday afternoon.
"The last time we had one was in September 2013, and the last big one was in October 2011."
Latz added, "We can't predict when these things occur, we don't know how long they will last, when they'll be here and we really don't understand the dynamics."
The Birch Aquarium at Scripps currently has a display called "Infinity Cube" that explains the phenomenon.