If every plant grew as easily as Caulerpa taxifolia once did in the Agua Hedionda Lagoon, we’d all have green thumbs.
  • If every plant grew as easily as Caulerpa taxifolia once did in the Agua Hedionda Lagoon, we’d all have green thumbs.
  • Image by KYLE DEMES, SMITHSONIAN TROPICAL RESEARCH INSTITUTE
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Agua Hedionda Lagoon Discovery Center

1580 Cannon Road, Carlsbad

It’s a mild, breezy afternoon at Agua Hedionda Lagoon. From the vantage of the visitors center, I can see small boats and jet-skis carving whitewater trails off to the west. Right above me are massive towers and transmission lines snaking up the ridge to the Encina Power Station and its 400-foot landmark stacks. Loud buzzing and crackling tell me there’s enough electromagnetic energy here to fry Chuck McGill’s foil suit. But instead of calling Saul, I call Eric Muñoz. I wouldn’t say it’s paradise, but according to Muñoz, it was almost paradise lost, courtesy of a monster mutated seaweed that all but shuttered the lagoon a decade and a half ago.

If every plant grew as easily as Caulerpa taxifolia once did in the lagoon, we’d all have green thumbs. But, exults Muñoz, who worked as a planner for the City of Carlsbad, thanks to anti-Caulerpa activists, we’ve all been spared the Big Green Nightmare. Muñoz is so stoked about the death of a mutated seaweed that he decided to write a book about it: Caulerpa Conquest: A Biological Eradication on the California Coast. He thinks it should be on every bookshelf. When it comes to Agua Hedionda, Muñoz exhibits what might be characterized as pride of ownership. It’s not that Muñoz has a piece of the aquatic pie or was spawned in the shallows of the lagoon; it’s just that he views the aquatic triptych as something of a local treasure. “People need to understand that, between Oceanside Harbor and Mission Bay, the only place where you can actually get into the water in a lagoon or wetland is Agua Hedionda. That would have been lost.”

Muñoz has the history of the not-quite-sleepy lagoon down pat.

“In 1769, Spanish missionaries and soldiers, led by Gaspar de Portola, smelled the debris and decaying fish, so they named it ‘Agua Hedionda,’ or ‘stinky waters.’” Fast-forwarding a couple of centuries, Muñoz says, “I’m sure you’ve seen all the people jet-skiing and waterskiing. The present configuration isn’t natural, but instead, was created so the water entering the lagoon could cool the turbines of the power plant that was built in 1954. Before dredging, it used to be sloughs, not the lagoon you see today. Prior to building the plant, they dredged three different, connected basins: one which opens to the Pacific and extends to the railroad tracks [western], one between the tracks and the freeway [central] and a third, farthest inland [eastern].”

It’s in the eastern basin that the marine menace manifested, bearing fruit to a “green” tableaux welcomed by no one.

Muñoz sets the scene for what he views as a megadebacle narrowly avoided: “It’s technically an estuary, the western terminus of a watershed. Depth, which is tide-dependent, can be as much as 20 feet but is typically 8 to 12 feet. Rainfall has minimal effect.”

The lagoon, which, according to Muñoz, contains about 390 acres of water surface, has the same salinity as ocean water, with a touch of brackishness at the eastern end where it’s fed by the confluence of Agua Hedionda and Calavera creeks. Water temperatures, 58–70 degrees, are identical to those of the ocean.

It’s not all Eden, of course, because for most San Diegans, Agua Hedionda is overshadowed, at least visually, by the ginormous tower of the power plant that uses lagoon water to cool its turbines. There’s also dredging.

“Cooling requires full circulation of the water flowing from the ocean under the Tamarack bridge,” Muñoz says. “However, when tides and wave action cause sediment build-up at the mouth of the lagoon, cooling is impeded. As a result, the lagoon has to be dredged every two to three years, with the sand placed on the nearby Carlsbad beaches. Last winter, large waves moved a lot of sand back into the lagoon.”

Agua Hedionda Lagoon

Agua Hedionda Lagoon

Revealing that he’s no kook, Muñoz adds, “‘Warmwater Jetties’ [named for the warm outflow via discharge pipes] is the name of a surf spot, a really good wave that breaks off the edge of the jetties.”

Righteous breaks aside, “What’s the deal with this evil seaweed?” I ask Muñoz. “Why should San Diegans give a slimy stolon about Caulerpa taxifolia?” And then it’s off to Marine Biology 101, a course I never took.

“Caulerpa is the genus, and taxifolia is the species, one of dozens; it’s a naturally occurring seaweed in tropical areas, where fish feed on it and keep it in check. But in the ’70s in Germany, the Stuttgart Zoo noticed a mutant strain and then cultivated it, ending up with a clone that was more robust than its natural counterpart. It was a neon-green. It was able to withstand much colder water as well as lower light conditions.” As a result, recounts Muñoz, it soon found its way into aquariums, where its bright color, ability to grow without maintenance, and lack of palatability to fish were positive attributes.

By 1980, taxifolia had been distributed to several European countries, including Monaco, where it was housed at the National Aquarium. In 1984, the Monacans released the seaweed into a cove in front of the facility, from which it rapidly spread in the open waters of the Mediterranean. “It was probably accidental,” opines Muñoz, “but nevertheless, we learned that you don’t want to dump the contents of an aquarium into the natural environment. Invasive species might find a niche where there are no predators, so they overtake and dominate.”

Such is the case with the Caulerpa taxifolia clone, which, once introduced, rapidly overwhelms its surroundings, forming masses dense enough to smother coral reefs. “Where there’s Caulerpa,” quips Muñoz, “there are no fish.”

In the interim, says Muñoz, humble Agua Hedionda Lagoon, already a destination for aquatic pleasures, had emerged as one of the birthplaces of wakeboarding, as well as a mecca for jet-skiing, and later, stand-up paddleboarding. It’s a nonpareil recreational realm, asserts Muñoz, along with an essential marine nursery that San Diego County stood to lose if the prolific seaweed had been allowed to run roughshod.

In 1998, the agencies who oversee the lagoon commissioned the plant owner, NRG Energy (pursuant to their periodic dredging), to replant eelgrass, which is the predominant naturally occurring vegetation of the lagoon bottom. Eelgrass, according to Muñoz, stabilizes the lagoon floor by inhibiting tidal scouring of sediment; it also serves as an integral part of the lagoon’s role as a nursery for marine life in the adjacent coastal waters. “You need to have eelgrass; it provides the baseline habitat for all the little critters — all the marine life — at the bottom of the food chain.” Revegetation (mitigation) programs undertaken by NRG required monitoring of the eelgrass several times a year. Scuba divers were dispatched to the lagoon, and reports were sent to the various agencies.

“It was during one of those routine inspections, in June of 2000, that Caulerpa taxifolia was first spotted in Agua Hedionda. One of the biologists, from Merkel & Associates, an environmental consulting firm, saw this bright green thing that really stood out, a little cluster of it. He said, ‘Wow — what is this? It doesn’t look right.’ They took a sample of it and contacted the lead researcher in the Mediterranean, who confirmed that we had Caulerpa taxifolia in our lagoon.” When the alarm was sounded, says Muñoz, “Some scientists wanted to study the seaweed in an open lab setting, but it was urgent; we didn’t have time for that. We actually had posters that read, ‘California coastline under threat.’”

During the second half of 2000, recalls Muñoz, “A multi-agency task team was formed with the acronym of ‘SCCAT’: the Southern California Caulerpa Action Team.” No relation to “scat” of animal feces fame (“everyone’s gotta’ work through that,” jokes Muñoz), it was comprised of an alphabet soup of bosky bureaucracies — the Regional Water Quality Control Board; the California Department of Fish and Game (nowadays the more PC “Wildlife”); the U.S. Department of Agriculture; and the National Marine Fisheries Service. Other “stakeholders,” as Muñoz terms them, included the City of Carlsbad, the Agua Hedionda Lagoon Foundation, and NRG.

When the task force appeared before the Carlsbad City Council in late 2001, says Muñoz, “Not only did they ask us for a million dollars, but they told us we needed to shut down the lagoon.”

Boaters and jet-skiers (whose activities could potentially spread the Caulerpa) were on the lagoon while the scuba divers were mapping the infestation. The City of Carlsbad wanted to ban all recreational activities. According to Muñoz, there was some dissent.

“It was a source of bewilderment; a lot of scientists said, ‘Don’t touch it, leave it right there.’ But there was another school of thought: ‘If you’re gonna restore the lagoon, you need to get rid of that stuff and bring it back to the way it was.’”

Although Carlsbad has the ability to issue recreational permits for surface water use, Agua Hedionda, unlike most of the other lagoons in San Diego County, sits on privately owned land. Muñoz says that private-sector involvement played an unusual role in ousting the seaweed.

“The power plant was an early and important player,” states Muñoz. “They gave a bunch of money upfront to the agencies and to Merkel [something like a half a million dollars] to help.”

The power plant’s interest in eradicating the Caulerpa stemmed from the fact that dredging, vital to the plant’s cooling scheme, would likely have been curtailed due to the potential for exacerbating the spread of the seaweed.

When it comes to his role, Muñoz is hardly reticent. “I was the designated liaison between [the task force] and the community. And when I’m talking about the community, I mean not just the public at large but the Carlsbad City Council, city management, and staff. I was in the eye of the hurricane, and it was an amazing experience. I had to be a kind of referee. We ended up creating a complicated interim plan with different zones in the lagoon which were opened and closed on a rotating basis based on water quality, tides, and the surveillance and eradication work going on.”

I asked Muñoz, “How do you get rid of monster seaweed?”

“We learned from the Mediterranean situation that you can’t just take a vacuum cleaner to it, because the exhaust spreads it. Caulerpa propagates through fragmentation. If you take a piece and deposit it at another location, it’ll find sediment and start growing a new colony there. In the Mediterranean, people would spread it by going from one location to another, dropping an anchor or using scuba gear that hadn’t been cleaned. Small pieces of the seaweed would fall off, sink to the bottom, and start growing.”

Eric Muñoz holding Caulerpa taxifolia in France last year

Eric Muñoz holding Caulerpa taxifolia in France last year

In the case of Agua Hedionda, the first patch spotted was underneath a storm drain near Hoover Street. Muñoz speculates that someone in the neighborhood had dumped the contents of a saltwater aquarium at the curb, which in turn led to the drain, and then the eastern basin of the lagoon.

The initial assessment of the scale and scope of the infestation, calculated to be around 11,500 square feet, fell to Merkel and Associates. Next, the order of the day was, in Muñoz’s parlance, “intensive eradication,” which took place from 2000 through 2002.

Map it, zap it and watch it

When it comes to taxifolia- killing, Muñoz is effusive. “What Merkel and the task force did was unique. First, they needed to map out the Caulerpa; that was hard, because there’s poor visibility in Agua Hedionda. The scuba divers were guided by a rope system laid out in transects across the lagoon. They swam shoulder-toshoulder, and at times, the water was so murky that they had to hold hands and squeeze the hand of the adjacent diver when Caulerpa was found. They’d then mark it on their [global positioning devices], over time creating a map of the infestation.”

“Next,” says Muñoz, “they built what were essentially underwater tents, using dark-colored tarps framed with PVC pipe, in order to prevent sunlight from reaching the vegetation. The tarps were about two feet high, perimeters extending six feet farther out than the seaweed; the framing was anchored to the bottom with sandbags. After that, they pumped chlorine [from the shoreline or from boats] into the area, where it sank to the bottom and permeated the topmost layers of soil.”

The subsurface tent village stayed in place for several years, and Muñoz speculates that the chlorine, due to its density, did not migrate to untreated areas. Muñoz reflects, “The last actual sighting of Caulerpa in the lagoon was on September 11, 2002. The Merkel team spent the next couple of years making sure there were no remnants, using scuba divers [trained with pieces of fake Caulerpa] to monitor the lagoon.” Breathing an audible sigh of relief, he adds, “We’re lucky that we found it when we did, in the lagoon, none of it west of the freeway. Because if it had gone out into the ocean, we don’t know what might have happened, but you sure can’t build a tarp where there are ocean waves breaking.”

The fear was that a piece would get detached, spread to the central basin, then the western basin, eventually affecting the Tamarack Reef and the kelp beds.

“We wanted to have the exact opposite of the Mediterranean experience, where they had 30,000 hectares of coverage, including the shores of Croatia, France, Greece, Italy, Malta, Spain, and Tunisia.”

What prevents it from happening again?

“There are some things in the legislative toolbox,” says Muñoz. “At first, it was just taxifolia, but now, all Caulerpa [the whole genus] has been outlawed by the State of California; there’s a $10,000 fine for possession. It’s also on the national list of ‘noxious weeds.’”

However, he concedes that if you still have the killer seaweed in your aquarium, there’s nothing stopping you from dumping it into a waterway. “It’s like getting a flu shot one year but getting the flu the next season.” Nonetheless, Muñoz views the eradication of Caulerpa taxifolia at Agua Hedionda as a stunning success.

“Carlsbad locals came to the realization that we were doing something that had never been done before anywhere else in the world — the removal of an invasive species from a saltwater environment.

There are not many success stories when it comes to getting rid of invasive species; I don’t know what would be number two after ours. Because it was genetic mutation with a great growth rate, it was much more challenging. There was no precedent for us to follow, so you have to be amazed that we were successful.... In scientific circles, we created a model for how to deal with invasive species. We always talk about saving the ocean, and if we want to start with one patch at a time, this is what happened at Agua Hedionda. That’s gotta count for something.”

Muñoz, though giving credit to many, extends ebullient praise to Merkel biologist Rachel Woodfield, who “took the lead in contacting the scientists who’d been studying the situation in the Mediterranean. Woodfield, who estimated that the Caulerpa had been growing there for a couple of years, came up with the eradication techniques.”

Referring to the Mediterranean outbreak, Muñoz speaks of ravaged fisheries, ruined recreation, and reduced tourism.

“No one wanted to come to scuba dive on the beautiful reefs of the Mediterranean Sea, because all they could see was a big, green carpet that looked like a golf course.”

He also pays homage to Alexandre Meinesz, a research biologist who’s played a seminal role in battling Caulerpa spread in Mare Nostrum.

“He wrote, Killer Algae. Go on Amazon.com and read the comments people have written about the book. I hung out with him; he was pretty inspirational. He wrote the forward to my book. In France and Monaco, when he raised the alarm, the other scientists told him, ‘Go pound sand.’ Part of the problem was that Jacques Cousteau was one of the directors of the Monaco Aquarium in the mid-’80s, and no one wanted to suggest that there was a problem under his watch.”

Beyond the facts of genus, species, clones, chlorine, tarps, and scuba divers, there’s Eric Muñoz the dedicated — maybe the obsessed.

“This story is my personal journey. The Caulerpa not only invaded a wetland, it invaded me — my heart, my mind. It challenged me incredibly, to understand it and explain it, and this book is my response to that challenge.

Over the past decade and a half, the battle against Caulerpa taxifolia has been, by Muñoz’s own admission, “the prevailing element in [his] actions and thoughts.”

I asked Muñoz, who served as president of the Agua Hedionda Lagoon Foundation for six years and remains a boardmember, whether the infestation angered him.

“I didn’t get angry, I got very sad. I remember one day when I literally wept for the lagoon. I hadn’t been a longtime boater or water skier — I’m mainly a surf guy — but thinking that our lagoon was going to get shut down, all because of an aquarium plant that got dumped in there…”

Muñoz’ Caulerpa Conquest was released on July 15. Will the proverbial man on the street have any interest in a book about eradicating seaweed in a lagoon? Muñoz answers in strident, almost messianic tones. “I tried to write it in such a manner that it has an international reach, showing people that a guy like me, who had just an undergraduate degree in geography and wanted to live near the ocean, could do this. A lot of science guys write only for a small audience in journals, but I wanted to bust beyond that realm. It was a case where policy, funding, and science all came together to solve an environmental problem, and that’s pretty rare. I’d like high school and university students to read it, as well as policy and planning people, elected officials and funding agencies. There’s almost no end to who might be interested in it.”

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