Artificial reefs help bring giant kelp back to Southern California

by on May 7, 2011 · 0 comments

in California, Environment

By Tony Barboza / Los Angeles Times / May 7, 2011

It was a gamble when Southern California Edison crews pushed basketball-size chunks of rock from a barge off San Clemente three years ago.

Eventually, the utility company hoped, the artificial reef it had assembled 50 feet below the waves would support a new kelp forest and fulfill state-imposed requirements to offset the damage its nearby nuclear power plant causes to marine life.

But no one expected the 174-acre Wheeler North Reef would thrive the way it has. Or as quickly.

Edison just happened to build its reef during the greatest giant kelp resurgence in decades, one that has brought an impressive buildup of floating green foliage to long-depleted waters near the Southern California shore.

“The last few years have been the most fantastic years for giant kelp in the last 30 years at least,” said Nancy Caruso, a marine biologist who organized last month’s Kelpfest in Laguna Beach, a festival celebrating the return of the underwater forests. “We had some excellent ocean conditions and the kelp started to spread, so they couldn’t have timed it better.”

More than a mere seaweed, giant kelp — a fast-growing algae — is the foundation for an entire ocean ecosystem, towering up from the seafloor to tangled canopies on the surface and offering nutrients and shelter to fish like sheepshead and perch as well as crabs, spiny lobsters and marine mammals.

Yet in recent decades, Southern California’s kelp forests have been on the decline, reduced by up to 80% of their historic range.

Pollution from sewage and storm runoff has made it harder for sunlight to reach the leafy algae. As the kelp beds withered and the fish declined, sea urchins invaded the seafloor and crowded out the surviving kelp. Off San Onofre, the decline was accelerated by the warm, cloudy water discharged by the nuclear power plant.

Conservation groups have worked up and down the coast to try to restore kelp forests, planting seedlings and scattering spores in places such as Laguna Beach, Crystal Cove and Malibu, where there is a rocky seafloor for them to clamp onto. The results were initially disappointing as warm-water climate patterns such as El Niño continued to devastate the kelp.

Now, giant kelp has bounced back in the last few years, not because of made-man reefs but largely in response to a series of mild summers and an influx of cool, nutrient-rich water.

Recent aerial surveys show the spread of kelp forests at “near historical highs” not seen since the 1950s, said Ed Parnell, a marine ecologist with the Scripps Institution of Oceanography.

“If you look at the records in terms of the canopies, they’re doing phenomenally well,” he said, noting a similar revival at two of the region’s largest kelp forests off the San Diego County coast.

Once a giant kelp takes hold on the ocean bottom, it can grow up to 2 feet a day. So it doesn’t take long to mature into a sprawl of translucent greenery that sustains populations of fish and invertebrates and drops nutrients onto the seafloor.

Last year, kelp growing from Edison’s artificial reef broke the ocean surface for the first time, revealing a grid of dark-green patches of foliage much sooner than the project’s managers anticipated.

“Within the second year, we had a full-blown kelp forest canopy,” said David Huang, a research scientist for UC Santa Barbara and one of the project’s independent monitors. “The real long-term question is whether the kelp forest will sustain itself.”

Huang and a team of researchers with the university work five days a week in the summer diving into the reef, documenting the forest’s progress and meticulously counting the creatures living among the kelp. They report their findings to the California Coastal Commission, which ordered the energy company to build the reef.

On a recent morning, Huang and his team set out from Dana Point Harbor in a motorboat for their first series of dives of the year.

Huang and fellow diver Denise Weisman struggled into dry suits, put on air tanks, masks and flippers and leaped into the water. Though the water is murky below, they could see fish swimming through the kelp’s columns, sea stars stuck to its blades and crabs and snails crawling about where it clings to chunks of rock on the seafloor. A few minutes later, the divers emerged from the frigid ocean, tangled in slimy green kelp fronds.

To comply with its permit from the Coastal Commission, Edison’s reef must meet a list of scientific standards for 40 years. Since the reef isn’t expected to meet all the requirements each consecutive year, it could take decades longer for the company to meet its obligations.

Last year, the reef met 10 of 14 standards, including kelp abundance, and fish density and diversity. A report by UC Santa Barbara last month said giant kelp “increased dramatically” to fill the entire 174-acre reef, up from just 19 acres the year before. But the reef has yet to attract as many creatures to the seafloor as natural reefs.

The gains kelp has made in San Clemente and across Southern California could be short-lived because its prosperity waxes and wanes with climate conditions.

The algae starve when warm ocean conditions cut off their source of deep-water nutrients. They can be torn from the seafloor and washed ashore when the next big storm rolls through. Parnell, the marine ecologist, said kelp is “constantly in a state of responding to ocean climate conditions, human disturbances and predators.”

For Edison, which has invested $39 million in the reef, there is hope its design will make up for the ups and downs of the ocean environment.

The company, for instance, used rock quarried from Catalina Island and broken into chunks small enough to be knocked around by ocean currents, said David Kay, Edison’s head of environmental projects. That motion is important because it can dislodge organisms like sea fans that compete with kelp for space on the rock.

“We’re trying to re-create a complex marine ecosystem on a very large scale and get it perfectly right by very stringent measures,” Kay said. “We have no delusions that we’re going to get everything right. Mother Nature will have its effects on this reef and on natural reefs in the area, and we’ll be watching and adapting to them.”



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