Central Coast beachcombers could soon be in for a bioluminescence light show

A plankton plume developed in the Southern California Bight last week and created glowing electric-blue colored waves as they crashed on the beaches in the San Diego area. This phenomenon is called bioluminescence and occurs when dinoflagellate plankton that emit flashes of blue or green light in response to agitation. We may be able to see the same light show develop along the Central Coast on Monday or Tuesday, and here is why.

Over the past few weeks, the northwesterly “spring” winds have kicked in along the Northern and Central Coast, which has produced a lot of fog-free afternoons and huge amounts of upwelling. This, in turn, has as brought frigid, clear and nutrient-rich water from the ocean’s depths to the surface along the immediate shoreline to replace the shallow water that is pushed out to sea. On Friday, seawater temperatures at the Diablo Canyon Intake Cove dropped to a bone-chilling 48 degrees.

This type of upwelling can provide the nutrients that allow kelp and other tapes of algae that are anchored to the sea floor or intertidal zone to grow rapidly. In fact, California giant kelp (Macrocystis) can grow up to 24 inches in just one day, ultimately reaching more than 150 feet in length.

Well, a significant change in the weather pattern occurred this weekend as an upper-level low-pressure system is dropping southward into Nevada and toward California while a Catalina eddy (not someone you don’t want to meet in a dark alley) developed. Forecasting a Catalina eddy — a circular counterclockwise air flow — can be difficult because it usually covers a small area in the Southern California Bight, the coast from Point Conception to just south of San Diego.

But when a Catalina eddy does form, it can quickly stop the relentless northwesterly winds and allow extensive marine low clouds to develop over the coastal regions. The formation of the Catalina eddy is still not completely understood but happens most often from May through July during the peak of the spring winds.

During periods of gale-force northwesterly winds, coastal eddies seem to develop as these winds travel down the rugged California coast past Point Conception and interact with the topography of the Southern California shoreline.

That interaction causes the winds to flow in a counterclockwise direction and creates an area of low pressure in the vicinity of Santa Catalina Island. When coastal eddies develop, the winds will shift out of the south and usually produce a rapid increase in the depth of the marine layer, resulting in a thick blanket of fog, drizzle and cooler temperatures. That condition also allows seawater temperatures to increase, as upwelling diminishes and warmer water from the south moves north along the shoreline.

Toward the end of these events, the marine layer can rise to over 7,000 feet and eventually dissipates, leaving behind clear skies with plenty of sunshine. If there’s enough sunlight, the bioluminescent plankton can multiply rapidly with the abundant nutrient-rich water acting like fertilizer, especially with the longer days of late spring. Even though plankton blooms, and especially bioluminescence, are extremely difficult to predict, there’s a good chance that we may see bioluminescence during the overnight hours on Monday and Tuesday.

Bioluminescence acts like light sticks at Halloween; it’s the production of light by living organisms through an internal chemical reaction. This can be seen in fireflies back East or even in glow worms that live in canyons along the Central Coast, like Poly Canyon the Cal Poly campus.

Almost all marine bioluminescence is blue-green, probably because blue-green light travels farthest in water. On the other end of the light spectrum, red and yellow hues are quickly absorbed by the water column as you descend. Bioluminescent plankton inhabits all the world’s oceans but not its freshwater lakes.

The light of just a single dinoflagellate can be seen at night. When millions upon millions of tiny plankton give off their light at the same moment, the ocean can turn into a nearly indescribable light show.

One night, we were diving off San Clemente Island during a period of high bioluminescence activity, and a pod of Pacific white-sided dolphins came swimming by. The dolphins resembled a gaggle of fast- moving, brilliant blue torpedoes with trails of glowing bubbles corkscrewing toward the surface.

One moonless night, while serving in the U.S. Navy and traveling through the Strait of Hormuz — situated between the Persian Gulf and the Gulf of Oman — on the guided-missile frigate U.S.S. Estocin back in the early 1980s, the bioluminescence was frightfully strong. The greenish wake of our ship could be seen from miles away as an ever-expanding chevron on the surface of a flat and calm sea as billions of agitated plankton gave off their light.

Along the Central Coast, one of the best places to see bioluminescence activity is along Avila Beach and Port San Luis.

▪ ▪ ▪

Back in 1993, PG&E partnered with the California Coastal Commission and the Port San Luis Harbor District to open up part of its Diablo Canyon Power Plant property as a public hiking trail, now known as the Pecho Coast Trail, which takes visitors to the Port’s historic Point San Luis Lighthouse.

To celebrate the 25th anniversary of one of the most beautiful spots along the Central Coast, PG&E and the Point San Luis Lighthouse Keepers, the nonprofit organization dedicated to the preservation of the lighthouse, partnered with Just Looking Gallery to commission a unique piece of artwork by Steve Thomas. This artwork can be purchased at the lighthouse or at Just Looking Gallery in downtown San Luis Obispo. A portion of all sales will be donated to the Point San Luis Lighthouse Keepers. If you’re interested in hiking along the Pecho Coast Trail and visiting this beautiful lighthouse, please visit pge.com for information and open the “in your community” tab.

This story was originally published May 11, 2018 at 6:55 PM with the headline "Central Coast beachcombers could soon be in for a bioluminescence light show."