SAN DIEGO (FOX 5/KUSI) — Scientists at UC San Diego’s Scripps Institution of Oceanography have identified a microscopic “ruthless predator” that could reshape how researchers understand Southern California’s glowing red tides.
In a study published last month in the Journal of Phycology, researchers examined Polykrikos kofoidii, a little-known species of plankton that hunts and consumes other plankton — including the toxic, bloom-forming organism responsible for red tide events.
Red tides occur when certain dinoflagellates rapidly multiply, creating dense blooms that can discolor ocean water and, at times, produce the bioluminescent waves seen along San Diego County beaches. One of the most common species behind these displays is Lingulaulax polyedra, which emits a bright blue glow when disturbed.
Bioluminescence seen near Crystal Pier in Pacific Beach on Nov. 10. (Photo by Jeff Lewis)
But scientists say that the species is not without predators.
Researchers found that P. kofoidii uses harpoon-like structures to capture prey, spearing individual cells before reeling them in and consuming them whole. Marine biologist and co-lead author of the study Michael Latz described the organism as “a ruthless predator,” noting that it has historically been difficult to study in laboratory settings.
Using seawater samples collected near the Scripps Pier, the team successfully cultivated the organism and analyzed its behavior using advanced microscopy, spectroscopy and genetic tools.
While many dinoflagellates are known for their bioluminescence, the study revealed that P. kofoidii produces light in a distinctly different way. Its flashes are slower, dimmer and longer-lasting than those of other glowing plankton, creating what researchers call a unique “light signature.”
At the cellular level, scientists also discovered that the molecule responsible for light production — luciferin — is distributed throughout the entire cell, rather than confined to specialized compartments as seen in other species.
“We made new discoveries into how Polykrikos kofoidii and other microorganisms emit light, which could lead to a better understanding of marine ecosystems, as well as the evolution, chemistry and potential functions of bioluminescence,” said co-lead author Brittany Sprecher.
Researchers say the findings could have important implications for understanding ocean ecosystems and the balance of predator-prey interactions that influence harmful algal blooms.
The study also raises new questions about ocean monitoring.
Because P. kofoidii consumes photosynthetic organisms whole, it may interfere with instruments that measure chlorophyll levels, potentially leading to overestimates of algae in the water.
Looking ahead, scientists say more research is needed to determine whether the species could play a role in naturally controlling harmful algal blooms — a possibility that could have environmental and economic significance for coastal communities.
“There is still much to discover when it comes to these organisms,” Sprecher said. “And even well-studied biological processes can hold unexpected surprises.”
The full study can be found here.