Devil weed threatens kelp off Orange County

Aubre Alvarez, 6, of Garden Grove examines sea urchins, starfish, and sea anemones up-close at a touch tank located at the "Why is Kelp Important?" booth, organized by Boy Scout Troop 695. The touch tank gave Kelpfest visitors a chance to interact with an array of marine life and to learn about the importance of protecting their oceanic habitat.
Aubre Alvarez, 6, of Garden Grove skims her fingers across the underside of a sea slug at a marine life touch tank during the fourth annual Kelpfest in Laguna Beach on Saturday afternoon.
Noah Lubbers, 3 of Dana Point poses for a photo with professional mermaid, Linden Wolbert, of Los Angeles as part of the fourth annual Kelpfest on Main Beach.
Marine biologist Nancy Caruso restored the kelp forests near Crystal Cove in Newport Beach and then placed mature abalone, like the 10-year-old one she holds, in the ocean to study their outcome.
A stand up paddle boarder makes his way through the waters off Laguna Beach and the kelp beds that were there a few years ago.
Some of the kelp living in the waters off Laguna Beach takes on a golden beauty while back lit in the morning sun.

By Erika I. Ritchie | eritchie@scng.com | Orange County Register

April 16, 2016 at 2:05 p.m.

LAGUNA BEACH – While the tropical waters of El Nino have brought a bountiful variety of sea creatures to local beaches, its effect on growing kelp beds recently on the rebound off Orange County has been less enriching.

That’s a bit disheartening to Nancy Caruso, a marine biologist who in 2002 launched a kelp restoration project with the help of students from 37 Orange County high schools.

“The warm water has stunted the kelp growth and it’s died back in many places,” Caruso said. “It has no nutrients. The kelp is almost completely gone on the west end of Catalina.”

Caruso started Kelpfest in Laguna Beach in 2010 following the success of the kelp restoration. She’ll be back at Main Beach Saturday for the 7th annual event to talk about the importance of kelp for the marine environment and for marine life, such as the recently-discovered sea otter living off Crystal Cove State Beach and the growing abalone community.

She and others from Laguna Ocean Foundation will demonstrate the many uses of kelp in day-to-day life.

In Caruso’s project, students grew kelp attached to tiles. Divers planted tens of thousands of the quarter-inch plants into five acres of underwater habitat off Laguna Beach and Newport Beach.

By 2009, there was more kelp in Orange County than there had been in 30 years. Laguna had kelp washing onto the beach, which hadn’t happened in 25 years.

But for the past two years the warmer water has been a problem – but not the only one.

There’s a new threat – Sargassum horneri, an invasive species known as devil weed that is native to Korea, China and Japan. It was first discovered in Long Beach Harbor by Michael Curtis, a senior scientist at MBC Applied Environmental Sciences in Costa Mesa, and likely brought over on ships, Caruso said.

She spotted it during recent dives off Laguna and Catalina Island. It typically grows in 10 – 60 feet of water and is brown and very dense. It keeps the kelp beds from getting the light they need to grow.

Sargassum usually dies off during summer and grows back slowly in fall, Caruso said. If the recent cooler ocean temperatures stay around, kelp may get a head start this winter.

“If that’s the case, I believe in two seasons the kelp will take over again,” she said.

Contact the writer: 714-796-2254 or eritchie@ocregister.com or Twitter:@lagunaini