Fast-growing kelp invades San Francisco Bay

(AP) -- A fast-growing kelp from the Far East has spread along the California coast from Los Angeles to San Francisco Bay, worrying marine scientists and outpacing eradication efforts.

In May, scientists for the first time found the invasive seaweed called Undaria pinnatifida clinging to docks at a yacht harbor in San Francisco Bay, fouling boat hulls and pier pilings.

"I was walking in San Francisco Marina, and that's when I saw the kelp attached to a boat," said Chela Zabin, a biologist at the Smithsonian Environmental Research Center in Tiburon, Calif.

"It was six-foot long, and there is nothing here in the bay that gets to that size," Zabin said. "I didn't want to believe what it was, it's depressing."

Before Zabin's discovery, scientists believed the northward spread of the invasive kelp had been stopped at Monterey Bay. But funding for eradication dried up last year, forcing federal officials to rely on volunteers.

The seaweed - known as wakame by Japanese food lovers and used in miso soup - was first discovered in Los Angeles Harbor in 2000.

A year later the kelp, which can grow an inch a day as it creates dense underwater forests, showed up at Catalina Island, off the Los Angeles coastline, and Monterey Bay.

Studies have concluded the kelp was likely introduced to California by accidental transport on shipments of oysters, vessel hulls and people who cultivated it in the region for cooking.

On Thursday, four divers spent hours at Pier 40 on San Francisco's Fisherman's Wharf peeling pieces of kelp off of the docks, yachts and pier pilings. But few believe the effort removed all traces of the seaweed. Scientists will be checking monthly for signs of further spread.

"If it's restricted to two docks in the marinas in San Francisco Bay, we'll have a chance," Zabin said. "If it's spread beyond those places, it may be a lost cause."

The seaweed concerns because it can damage fragile by choking off the sunlight needed by native kelps. The native kelp forests provide key habitat for otters, fish and other marine life.

The seaweed spreads by releasing millions of spores that are dispersed by currents and can travel miles. While it is native to Japan, China and Korea, studies have found the kelp in the Mediterranean Sea, the Atlantic Coast of Europe, New Zealand and Argentina.

Because of its wide range, it has been nominated as among 100 of the world's worst invaders, according to the Global Invasive Species Database.

Scientists say the waters from Baja California to British Columbia are the perfect temperature for Undaria to spread even further up the Pacific Coast of the United States.

For about six years, the National Oceanic Atmospheric Administration has organized monthly volunteer diving efforts to yank the stubborn kelp out of Monterey harbor to help root out the kelp.

The program helped, but failed to stop the kelp from entering San Francisco Bay, scientists say.

"This is not well studied enough, and we're really quite nervous about it getting out in the ecosystem," Zabin said. "It will attach to about anything."

©2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.


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Jul 10, 2009
I'm sure that someone has considered that it could be harvested for biomass energy production.

Jul 10, 2009
We could also eat it. I mean, it grows itself!

Jul 10, 2009
"Studies have concluded the kelp was likely introduced to California by accidental transport on shipments of oysters, vessel hulls and people who cultivated it in the region for cooking."

So, how does that make the kelp invasive? I see so much of this kind of pseudoscientific drivel, hype posing as science. If people have, or are spreading, it, the kelp is not the invasive organism here. Humans are the invasive organism. Plants and animals just do what is in their genes: try to survive in whatever niche they happen to find themselves.

Jul 11, 2009
With nearly 60% of its people considered as obese or overweight, California should feel fortunate that nature has finally sent the bankrupt state a cure: wakame kelp. Wakame is rich in compound known as fucoxanthin that can help burn fatty tissue. In addition, it is a good source of lignans that are thought to reduce the chance of breast cancer in women and prostate enlargement in men. Thus, instead of complaining about yet another immigrant invasion problem that they have no chance of solving, Californians should learn to harvest the kelp and eat it.

Jul 13, 2009
I think everyone is missing the point. Yes, it is delicious and we should eat a more plant-based diet, but this is akin to an insanely fast-growing weed in your garden. It will be difficult and time-consuming to just harvest this seaweed without also destroying the native kelp beds. Allowed to grow unchecked, this seaweed could potentially significantly alter or destroy the incredible ecosystem that already exists off the CA coast.

"Studies have concluded the kelp was likely introduced to California by accidental transport on shipments of oysters, vessel hulls and people who cultivated it in the region for cooking."
This is ridiculous! Yes, humans could fairly be considered a virus or the most invasive species the planet has ever seen. That doesn't give you an argument against THIS being an invasive species. Most invasive species [b]are[/b] inadvertently transported by humans. What makes them invasive is the fact that when they get their, they destroy or significantly disrupt the native ecosystem. See: Rats on Easter Island. [/blockquote]

Jul 13, 2009
Sorry, looks like my quoting got messed up. The part in quotes was LariAnn's, this was my reply:

This is ridiculous! Yes, humans could fairly be considered a virus or the most invasive species the planet has ever seen. That doesn't give you an argument against THIS being an invasive species. Most invasive species [b]are[/b] inadvertently transported by humans. What makes them invasive is the fact that when they get their, they destroy or significantly disrupt the native ecosystem. See: Rats on Easter Island.

Jul 13, 2009
So, how does that make the kelp invasive?


An invasive is a species that had a given barrier (biological, geological, etc.) that indefinitely prevented it's "natural" progression (as is possible defined by it's current developmental capabilities) into a given ecosystem. When it arrives in that ecosystem via the "unnatural" mechanism of human-facilitated (protected, long distance) transport, a trip that was otherwise not within it's biological capability, whether intended or not, that makes it invasive.

Human activity brought the species here. The fact it didn't die and is now displacing other flora and fauna is why it is an invasive species.


There are parameters that are used to define invasives. They are based on the relationship between all species' developmental biology in a given ecosystem (itself defined by physical and biological parameters) as they relate to each other at a given temporal evolutionary modernality, when a new species is introduced.

An invasive species does not always out perform native species... but that does not make it any less an invasive, that species is still an invasive to that ecosystem. Sometimes they die, sometimes they exploit an empty niche, sometimes they disrupt the "native" ecosystem negatively.

It could certainly be argued that once an invasive is in a new ecosystem it is de facto now "native", but this does not occur without altering that ecosystem by definition as well.

Basically it's a descriptive tool which is part of the whole of this thing we use called language to relate things to one another to others, arguing the absolute semantic accuracy of it is pointless and sophomoric.

Jul 13, 2009
I should also probably add that invasive species can also be referred to, probably more accurately but not nearly as sensationally, as exotic species.

Jul 14, 2009
There are several species that adapt specifically for human transport.


If that human transport is not an absolutely necessary part of these several species' life-history and successful reproduction, then it falls under the category of unnatural transport.

If such transport is an absolutely necessary and integral part of these several species' life-history, then it'd just be referred to as an exotic academically, as that just means it didn't originate from where it is now.

But while we're at it, I'd love to hear what these several species are. I'm sure you already know parasites, bacteria and viruses and the like don't count, as the host is then the ecosystem, right?

The sophomoric part was saying that there isn't truly such a thing as an invasive species.

Jul 14, 2009
So how exactly is it sophomoric?


That really got under your skin didn't it... Vel, you are arguing the validity of an adjective being used as a descriptor meant to give context to another word in a given set of assumptions.

All you are going on about is the absolution of these context and the assumptions, when no one ever claimed they were absolute. That's sophomoric. I already acknowledged everything you're saying before you said it.

I let the anthropocentric context of invasive go in my OP because I don't find it particularly useful, so that was a misrepresentation, but that wasn't the point of my OP. I just wanted to outline the very concrete parameters to LariAnn and whoever else cared, to show it isn't a wholly arbitrary delineation from invasive or exotic to a native.

It's a term that is useful and only used in a given context with given assumptions, you arguing that it is junk because of the context is just sophomoric.

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