Marine biologist Nancy Caruso has a plan to help giant kelp grow in the ocean waters off Orange County – again.
Kelp, the ocean’s forest and critical to a healthy ecosystem, made a comeback after Caruso, with help from more than 2,000 Orange County students and volunteer divers, replanted areas from the Newport Jetty to Dana Point in 2009. After her project, there was more kelp along the section of coastline than there had been in 30 years. At the time, Caruso worked for Orange County Coastkeeper.
Laguna Beach had kelp washing up onto its sands, which hadn’t happened in 25 years.
But, then from 2013 to 2017, a blob of warm water coupled with El Nino disrupted the kelp’s success and the forest started to die off again.
Recently, an annual report that studies kelp growth off San Diego and Orange County, said that while ocean conditions – more nutrients and cooler water –have improved in the past few years, kelp is not rebounding as quickly as scientists who study it would hope.
Data from 2019 shows that the region’s kelp population has declined by 53% and that all kelp beds with visible canopies in 2018 decreased in size in 2019. Ten kelp beds have entirely disappeared.
Data is collected four times a year by aerial surveys followed by visual inspections for kelp canopies by boats. The surveys are done in March, July, September and December. Some areas are also inspected by divers, including locations off Dana Point and further south off San Diego County.
Mike Lyons, a senior scientist with MBC Aquatic Sciences, has compiled the reports for the last four years. Kelp has been studied off Orange and San Diego counties since 1967.
“I’ve never seen so many kelp beds disappear, that’s very unusual,” Lyons said.
Caruso, among other ocean scientists, has reviewed the findings and she believes she has a remedy: the ocean floor needs a good weeding.
While she agrees the ocean climate for kelp still isn’t ideal, she said she thinks an invasive species known as sargassum horneri, also known as devil weed, is a bigger problem.
The plant is native to the ocean waters off Korea, China and Japan. It was first discovered in Long Beach Harbor, and likely brought over on ships.
Caruso said she first encountered it off Divers Cove in Laguna Beach in 2006. The plant is an annual that grows from July to April. In its early stages, it looks like a fern, but turns into a massive, brown bush so dense that fish and other ocean creatures can’t pass through it.
“Normally, waters turn colder in December, January and February, which is when kelp starts reproducing,” Caruso said. “But, by that time, sargassum is reproducing. It crowds out the kelp and since nothing eats it and destroys it, it keeps growing, taking away all real estate on the reefs.”
Caruso’s plan is to weed the sargassum and create opportunities for the kelp forests to take over.
The winter would be the right time to get to work. Kelp typically grows in the colder months starting in November through February, the ocean’s coldest month. Kelp prefers an ocean temperature of about 57 degrees to thrive.
“Sargassum is everywhere now,” said Caruso. “It’s off San Diego and on five of the Channel Islands along with Catalina.”
One area Caruso would like to focus on is off Thousand Steps Beach in Laguna Beach where kelp typically grows giving a home to marine life.
Decades of over-fishing diminished much of California’s marine life and prompted a massive effort in the late 1990s to establish a statewide network of marine protected areas. A group of ocean activists in Laguna Beach convinced scientists and the California Department of Fish & Wildlife to create the Laguna Beach Marine Protected Area – the largest protected area in Southern California and the only citywide reserve in the state.
Mike Beanan, a longtime ocean advocate and co-founder of Laguna Bluebelt Coalition, said he has seen the success of protecting the coastline off Laguna Beach, which has “allowed key fish species to recover,” some of which in turn helped keep the population of sea urchins under control that had previously been grazing on kelp and adding to the destruction of the beds.
Recently, Caruso asked the Fish & Wildlife agency if she could do some restorative work to further help the kelp along.
She proposes to establish four 10-square-meter sites, and a fifth control site, about 200 yards off Thousand Steps Beach. There, she’ll dive 20 feet to 30 feet down and do a survey to assess the different species, including the sargassum.
One plot, she proposes to weed entirely and remove all of the invasive species, returning weekly to make sure it’s completely clear. In a second spot, she would pull the sargassum once the water temp drops below 59 degrees. In the third plot, Caruso said she would remove the sargassum starting in January when the water is continuously cold and the kelp usually begins to grow. In the fourth plot, she would remove the sargassum in February. The plan is to catch all the phases of sargassum development.
“The test season would end in May,” she said. “I would look at where is the most kelp, where is the most sargassum and why? I assume the control plots would be covered in kelp.”
To do her project, she needs sign-off from the wildlife agency, which recently answered that because of restrictions on restoration work in the marine protected areas, legislative action is required.
She has approached Assemblywoman Cottie Petrie-Norris, D-Laguna Beach, for help.
Petrie-Norris said she recognizes the kelp forests’ value to the California coast and their ability to protect against erosion, storm surges and sea-level rise.
“Nancy Caruso and her team have been doing tremendous work for coastal erosion,” Petrie-Norris said. “I am working with Nancy, the Ocean Protection Council and the Department of Fish & Wildlife to enable critical restoration work along our vulnerable coastlines.”
Lyons and other scientists agree that Caruso’s plan could be a good one.
“It’s a good theory,” Lyons said, adding that another researcher, Ed Ed Parnell at Scripps in La Jolla, has seen the invasive plants near the much larger kelp beds off La Jolla.
“In La Jolla, it would take a catastrophic event like a big storm with a lot of waves to tear some of the sargassums out,” Lyons said. “In Laguna, it could work.”
