But you’d be wrong. That expanse of tall cordgrass reaching out into the mudflats is an alien invader, a nightmare for those working to protect and expand tidal marshlands. “It’s all nonnative, everything you see,” says Debra Smith, coordinator of the Invasive Spartina Project, which was launched last year to rid the Bay of this pest, or at least to control it.

Ironically, Spartina alterniflora, commonly known as smooth or Atlantic cordgrass, was introduced to the Bay in the 1970s as part of an effort to restore degraded wetlands (see the previous story). It has been spreading inexorably ever since. In many places, including the bird sanctuary, it has all but wiped out the native Pacific cordgrass (Spartina foliosa). It menaces salt marshes in much of San Francisco Bay and in estuaries up and down the West Coast. Restored marshes are especially vulnerable. Even as millions of dollars are being committed to restoration, it threatens to undermine virtually all efforts to bring back some of the lost marsh habitat. Several other nonnative invasive species of Spartina—S. densiflora, S. anglica, and S. patens—are also making headway. “There’s definitely a sense of urgency here,” says Smith.

The eradication effort is funded by CALFED, a federal-state water policy partnership; the National Fish and Wildlife Foundation; and the Coastal Conservancy. An immediate goal is to prevent the spread of nonnative cordgrass in the north and south Bay and to keep it out of Suisun Bay.

I follow Smith to the upper edge of the marsh, where we can get a close look at some Spartina. For me, an amateur, it’s difficult to distinguish the native species from the nonnative. Both grow in the intertidal zone and look nearly identical. Both have tough, narrow leaves that taper to a point. (Both look like lemon grass to me.) Smith says Atlantic cordgrass tends to grow taller and thicker than its Pacific counterpart, and if you peel away the outer leaves of the nonnative plant you may find a purplish pink coloring that is absent in the native. She picks a couple of plants at random. Both show the trace of purple. Then she pulls a foot-tall plant from the mud, revealing a thick, almost mandrake-like root structure.

But why do their differences matter? Local and state agencies may commit millions of dollars and untold hours of work to get rid of nonnative Spartina. Why? Smith has often been asked that question, especially by folks from the East Coast who are using Atlantic cordgrass in efforts to rebuild their own wetlands. “They’re floored that we think it’s a problem,” she says.

Well, east is east and west is west, and what’s good in the smooth cordgrass’s natural habitat—which stretches from New England to the Gulf Coast—can be deadly to the estuaries on this side of the continent. Here the alien species of Spartina “actually re-form the terrain,” says Peter Baye, a botanist with the U.S. Fish and Wildlife Service Endangered Species Program, who has studied cordgrass on both coasts.

Pacific cordgrass tends to grow in small clumps, allowing wetlands to drain through numerous channels. When Atlantic cordgrass arrives, usually in the form of seeds that wash in, it sends out numerous rhizomes, forming massive clones that can coalesce into vast meadows. The thick roots and stems accrete sediment, and in subsequent seasons new Spartina grows on top of the old, building a mass of plant material several yards deep. Atlantic cordgrass also hybridizes with the S. foliosa, so that within a few years almost all the pure native cordgrass is gone. Meanwhile, the clones merge and build up, sometimes raising the level of the marsh by several feet and effectively “paving over” the channels that allowed the marsh to drain. Tidal flows diminish. Marsh creatures lose channel habitat and foraging areas. The endangered clapper rail, for one, forages on the open mud in the channels. Without these pathways, the birds are forced into more open spaces, where they are more vulnerable to predators.

Atlantic cordgrass also extends farther into the tidal zone than the native grass does, invading the pickleweed habitat of the endangered salt marsh harvest mouse, and it spreads far into the mudflats. Smith says she’s seen the Alameda mudflats shrink dramatically as S. alterniflora has taken over. If it’s not controlled, she says, Atlantic cordgrass could eventually fill in the mudflats between Alameda and Bay Farm Isle, about a quarter of a mile away, leaving open just the narrow deep-water channel between them.

Mudflats along the California coast are crucial stopover points for shorebirds migrating along the Pacific Flyway. Long-billed birds that hunt for small critters in wet sand would not likely be able to forage in a dense stand of alien Spartina. Gary W. Page, director of coastal
and estuarine research at the Point Reyes Bird Observatory, says that birds that overwinter in the Bay could be especially affected, such as dunlins, which arrive from nesting grounds in the Arctic, and marbled godwits, which nest in the Great Plains.

On San Francisco Bay there are 1,000 acres or so of S. alterniflora south of the Bay Bridge, and new outlying populations in Marin County and Emeryville. On Humboldt Bay a small stand was discovered in the mid-1980s; it was eradicated before it could spread. But S. densiflora, a Chilean native, now covers 80 percent of Humboldt Bay’s 1,000 acres of salt marshes. Because it arrived way back in the 19th century, people had long assumed it was a native. “By the time anyone noticed [that it wasn’t], it was everywhere,” says Andrea Picard, a Fish and Wildlife Service ecologist at the Humbolt Bay National Wildlife Reserve.

In Washington State, S. alterniflora has spread over 5,000 acres of saltmarsh in 10 counties, and continues to outpace control efforts.

“Every estuary on the Pacific Coast could be vulnerable,” says biology professor Donald Strong of the University of California, Davis, Bodega Marine Laboratory. The nonnatives favor shorelines with shallow water and little wave action—common on the West Coast. Strong and his colleagues have identified 31 estuaries in California, Oregon, and Washington that could potentially be impacted, including several that could be dramatically changed by an influx of nonnative Spartina. They estimated that almost two-thirds of Bodega Harbor could be covered by S. alterniflora if the plant were introduced there. “It could go up the [San Joaquin–Sacramento] Delta,” Strong says. “It probably will.” Baye worries that as the areas covered with nonnative cordgrass expand within San Francisco Bay, seeds are more likely to be flushed through the Golden Gate, ending up on the mudflats of Point Reyes and Tomales Bay. Coastal areas to the south are likewise at risk, including Morro Bay, San Diego Bay, and the Tijuana River Estuary. “We need to do something now or learn to live with it,” says Wilcox. “If we don’t, it will be beyond control. It may be already.”

Newly restored wetlands seem to be especially vulnerable. In Cogswell Marsh at the Hayward Regional Shoreline, levees around a series of former salt ponds were breached in 1980. This marsh is now the site of one of the largest, densest S. alterniflora stands in the Bay, says Shoreline park supervisor Mark Taylor. At nearby Oro Loma Marsh, reopened in November 1997, the alien cordgrass came in right away, he says. “In some ways, future restorations in the Bay are being held hostage to these species.”

Controlling the invaders is not easy. Eradication efforts must be tailored to each individual site. If only a few plants have appeared, they can be removed by hand. Scattered individual clones can be destroyed by covering them with heavy black plastic fabric. But where the invasion is more widespread, the task is much more difficult.

The first attempt to eradicate clones at Cogswell Marsh by tearing out the plants was a failure. A group of Boy Scouts worked fiercely and filled a large truck with cordgrass pulled up by the roots, but the next spring the plants came right back. “It was a complete waste of time,” Taylor says. Laying on black plastic proved ineffective. “All it takes is just a couple of shoots coming out one side,” Taylor explains, and the trouble is back. He tried burning a stand with a propane torch, but “that failed miserably,” he says. “If anything, it came back stronger.” Much more successful was an experimental application of the herbicide Rodeo. It showed good results in Cogswell Marsh and the East Bay Regional Park District is now working to refine the spraying techniques and concentrations required.

Because San Francisco Bay is home to the endangered clapper rail, eradication efforts must take place after the rail’s nesting season ends on September 1 and before it resumes on February 1. Any attack must be quick and thorough, for the plants begin broadcasting seeds in autumn, and then the rainy season arrives.

Those wrestling with the problem are acutely aware that the public knows little about cordgrass, be it native or alien. Smith and her colleagues have begun to spread the word among public agencies and community groups. They hope that once people learn that these grasses could cancel out all the money and time already invested in restoration, they will support the efforts of the Invasive Spartina Team.

Bill O’Brien can frequently be found along the shores of the Bay, happily confusing godwits with avocets and curlews. He lives in Oakland. For more information, contact Debra Smith, coordinator of the Invasive Spartina Project, at (510) 526-4628 or dbrsmt@aol.com.