Red Tide Could Persist for Months, Contain Low-Level Toxins

Originally published 1:08 p.m. Aug. 14.

Tests conducted late last week detected a dinoflagellate bloom better known as red tide in south San Diego waters, a Scripps Institution of Oceanography researcher announced Monday.

The results of testing conducted at the Imperial Beach Pier last Friday found the dinoflagellate Lingulodinium polyedrum, which can glow shades of neon blue at night when disturbed by wave action or movement in the water.

Scripps has observed red tide blooms in the San Diego-area since the 1980s. Based on observations of the Lingulodinium polyedrum the red tide could persist for weeks or months or see a sharp decline and disappear.

"This bloom began around the 1st of August and could last for several weeks to a couple of months," Carter said in a statement released on the Southern California Coastal Ocean Observatory System (SCCOOS) website.

Coronado, Silver Strand State Beach and Imperial Beach lifeguards first told Coronado Patch about red tide observations last week.

"This isn't something new for California. This isn't something new for the area," she told Coronado Patch during a phone interview.

Lingulodinium polyedrum are the most common species in Southern California, Carter said, and can turn water brown or red during the day. The National Institute of Health also note that this particular dinoflagellate species can create "a peculiar, strong odor."

Though the term red tide is often attached to dinoflagellate blooms, discoloration of water could be yellow, red, brown or green depending on the protist species.

What causes dinoflagellates to bloom is still unknown, Carter said.

"I wish i could say it's exactly this or that but we don't know," she said. Species of dinoflagellates like Karenia brevis can bloom and produce toxic red tides in Florida which can lead to asthma-like symptoms, skin irritation and even death.

Lingulodinium polyedrum produce mild toxins.

"It's like you can eat apple seeds but you can't eat 100 of them. It's kind of like a low-level toxin," Carter said.

Blooms are broken down by bacteria so a red tide can mean a higher presence of bacteria in the water, which may lead to more ear infections or things of that nature.

"Most people that are at the beach, we have people constantly swimming and going in the water and a majority of people are not complaining about those issues," she said. " We can't say for sure no they're no risk, but in general the majority of people are not impacted by the red tide."

To learn more about red tides, visit the SCCOOS website.

Correction: The original version of this article stated that testing took place in Imperial Beach and Coronado. Hours after this story was published Coronado Patch learned that testing only occurred in Imperial Beach. Coronado Patch apologizes for any inconvenience this may have caused.