George Krieger was worked up. His father had been hospitalised with a stroke the week before, so Krieger wanted to get out and shoot some photos in an attempt to relax. When he went out around 9 p.m. on February 5, he spotted something unusual coming from the direction of the Big Sur under California's Bixby Creek Bridge.
"The waves looked like someone had those blue headlights on the tops," Krieger says.
But when he got a closer look, he noticed there were no headlights. As his eyes adjusted to the darkness, he saw that a dim, blue glow was emanating directly from under the surf.
The glowing waves were a result of bioluminescence, a naturally luminescent phenomenon caused by a phytoplankton bloom. High concentrations of tiny organisms called dinoflagellates had flooded the coastal waters and were flashing light when agitated by encroaching predators.
The Big Sur waves had been emitting a dim glow since early January, says Steve Haddock, senior scientist at the Monterey Bay Aquarium Research Institute. The light given off by tiny dinoflagellates startles would-be predators, disrupting their feeding behavior and saving some of the phytoplankton from consumption. The glow could also act as a "burglar alarm" to attract predators that eat those that dine on dinoflagellates. (Watch: "Why Deep-Sea Creatures Glow")
"The species counts from Santa Cruz show low to moderate numbers of the 'usual suspects' of luminous species that we would expect to cause such a bloom," Haddock tells local outlet KSBW.
High nutrient rates in the water paired with relatively windless weather made the Big Sur the perfect place to host the glow. A dry, high-pressure system has been sitting on top of California for months, preventing regular storms and winds from blowing through and stirring up the area's waters.
Bioluminescence is only partially understood, but research is ongoing. The U.S. Navy is particularly interested in the natural phenomenon, since tiny glowing organisms can tip off submarines and Navy SEALs attempting to swim around unnoticed.
Krieger had witnessed the phenomenon in the past, before he became a photographer. During the recent sighting, he was out shooting for so long that the battery on his camera died. Even after he could no longer record, he remained staring at the dimly glowing water for the next half hour.
"It's just so amazing to see some of the things that happen naturally here," Krieger says. "[Seeing photographs is] not the same as when you see it in person."