Heat cooks up foam on local beaches

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The yellow goo is not dangerous to people.

By Vicky Newman/Special to the Malibu Times

Yellow foam seen on local beaches the past few weeks has alarmed residents, thinking that it might be due to some form of pollution.

However, it is a natural occurrence and not dangerous to people, authorities said.

Summer heat, rather than a more sinister origin, seems to have caused the froth, although excessive fertilizer nutrients might also be to blame.

“The foam is most likely caused by a bloom of diatoms, a type of algae found in phytoplankton, or plant plankton,” said Hallie Jones, public affairs manager of Heal the Bay. “The unusually warm water we’ve been having probably encourages these blooms. Cooler temperatures cause the plankton die, leaving organic matter decomposing on the surf.”

Waves pick up sand, causing the distinctive yellow color.

“It’s a natural occurrence, nothing that comes from the creek or the canyons,” county lifeguard Chuck Moore said about the foam.

Except for a couple of days last week, the ocean at the Zuma lifeguard station has been pretty clear, he noted.

Rather than being excessively polluted, Malibu beaches, with the exception of Surfrider at the breach location, received high marks for water quality from Heal the Bay last week. Even Surfrider Beach at the Malibu Colony fence received an A+.

The environmental organization’s rating scale, which ranges from A to F, is based on daily and weekly fecal bacterial pollution levels in the surf zones. The higher the grade a beach receives, the lower the risk of illness for ocean users.

Some people thought that the foam might have been a repeat of last year’s domoic acid (a neurological biotoxin) poisoning, which sickened scores of marine animals and caused the state health department to issue a warning on eating certain types of seafood.

“There is no evidence of domoic acid poisoning,” Pepperdine University biology professor Karen Martin said. “As far as I know, it hasn’t been a big issue this year.”

As long as the foam dissipates, there’s nothing to worry about, Martin added. However, large chunks of foam indicate pollution from a “point source.”

In that case, septic systems or other possible pollution sources should be checked, Martin said.

Mayor Ken Kearsley attributes the foam to excessive amounts of minerals, nitrates and phosphates found in fertilizers, which end up in the ocean. Triggered by warm water, these nutrients cause algae to bloom, which creates bacteria that destroys life in the ocean and infects swimmers.

The water reclamation project the city is proposing as part of its development agreement with the Malibu Bay Company will stop the flow of contaminants into the ocean, he said.

Upstream communities such as Agoura and Calabasas should implement a similar project, Kearsley added. He also suggested organic gardening.