Keeping the seaweed in your bowl and out of your bay

When we’re not visiting dramatic change upon the natural world, we’re trying to keep the natural world in stasis, and the latter act, while necessary, is even less natural than the first. Visiting change upon the world is what we do naturally, after all, and exploiting change is what other species do naturally.
We must create less change, and we must try to mitigate some of the doom-teasing change we’ve created; there’s no question about that. But there is ample irony to be found in the panic humans feel when some other species succeeds dramatically because of us: mosquitoes in Hawaii, kudzu in the South, Asian carp in the Mississippi, zebra mussels in the Great Lakes, and, now, wakame in San Francisco Bay. Delicious in your miso soup, wakame is destructive in your local bay:
SAN FRANCISCO — Chela Zabin will not soon forget when she first glimpsed the golden brown tentacle of the latest alien to settle in the fertile waters of San Francisco Bay.
The broad-leaf kelp is used in miso soup.
“I had that moment of ‘Oh God, this is it, it’s here,’ ” said Dr. Zabin, a biologist with the Smithsonian Environmental Research Center. “I was really hoping I was wrong.”
The tentacle in question was that of an Asian kelp, Undaria pinnatifida, a flavorful and healthful ingredient in miso soup and an aggressive, costly intruder in waters from New Zealand to Monterey Bay.
The kelp, known as wakame (pronounced wa-KA-me), is on a list of “100 of the World’s Worst Invasive Alien Species,” compiled by the Invasive Species Specialist Group. Since her discovery in May, Dr. Zabin and colleagues have pulled up nearly 140 pounds of kelp attached to pilings and boats in the San Francisco Marina alone.
Every year the damage wrought by aquatic invaders in the United States and the cost of controlling them is estimated at $9 billion, according to a 2003 study by a Cornell University professor, David Pimentel, whose research is considered the most comprehensive. The bill for controlling two closely-related invasive mussels — the zebra and the quagga — in the Great Lakes alone is $30 million annually, says the United States Federal Aquatic Nuisance Species Task Force.
Many scientists say that San Francisco Bay has more than 250 nonnative species, like European green crab, Asian zooplankton and other creatures and plants that outcompete native species for food, space and sunlight.
On the bright side, your corner sushi joint doesn’t have to travel as far to find wakame. On the dark side, wakame might threaten the vitality of California’s native kelp forests, a dream seascape as gorgeous and vital as any surface forest, splashed with iridescent fish who weave between the swaying stalks. Save the native kelp forest: eat wakame.