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Non-native species colonize San Francisco Bay

Julia Scott

Take a trip to the bottom of San Francisco Bay, and you’d find a lot of critters that aren’t supposed to be here at all. Hundreds of tiny, exotic organisms now live there, too.

“It’s unfortunately on the rarer side to find those things that should be here,” says Chris Brown, a biologist with the Smithsonian Environmental Research Center, based in Marin. His lab works to locate and identify foreign marine life. Brown says the Bay is like an underwater zoo, with species from all over the world.

He pulls up a rope attached to a piece of plastic that’s been sitting on the Bay floor, growing species like a rock and explains, “So here you can see lots of different little barnacles growing on it, possibly eburneus, the introduced acorn barnacle.”

Earlier this year, the Department of Fish and Game’s Marine Invasive Species Program announced that four new exotic aquatic species had been identified in San Francisco Bay. The acorn barnacle was one of them.

“You can see this little bright orange blob here; this is a colonial tunicate, actually from the east coast of the U.S. as well,” Brown continues.

DNA experts at the Moss Landing Marine Laboratories’ Genomics Lab identified some of these new species, which include a tiny shrimp from Japan; an acorn barnacle from the North Atlantic Ocean; red algae native to Korea; and a little orange worm that was first found in San Diego Bay 12 years ago.

With these new species, no one really knows what the effects will be. It’s too early to tell whether they may turn out to be as destructive as the quagga mussel, which clogs intake pipes along the Colorado River Aqueduct and has cost water agencies millions of dollars to remove, or the Asian clam, which has been partly blamed for the decline of Delta smelt.

One species has raised some red flags, says Randy Imai, Environmental Program Manager with the Department of Fish and Game.

“The most worrisome is the red algae. It can reproduce quickly, and it can spread quickly, like a weed. And it competes for light and space with native pop of marine algae, plants and animals.”

San Francisco Bay is already one of the most invaded estuaries in the world; with at least 280 foreign species here already, Imai says four more may not make much of a difference.

The bigger issue is that officials can’t seem to stop the migration because these animals are stowaways. Most foreign invaders get here by hitching a ride on the hulls of yachts and cargo vessels. Then they work their way up the coast with the shipping traffic.

Examining a nearby boat, Chris Brown explains, “You can see this boat that we’re right next to, here. It is literally covered from bow to stern with muscles and algae, and everything else that you find here on the docks. And if this boat travels to another location, all these things growing on it have the potential to colonize in new environments.”

California leads the country with strict new rules on filtering ballast water ships pick up at sea, water that often carries foreign species from other ports of call. But there are no regulations pertaining to the hulls themselves, which can be very hard to clean.

That’s why Chris Brown believes more species than we know of may have already snuck in the back door – though he may not find them right away. Once it joins the party, it’s usually here to stay.