California's sensitive marine estuaries will be studied under a $3.8 million grant awarded to University of California, Davis, researchers by the National Science Foundation to study the effects of an invading plant species on a complex ecosystem.
The project will provide one of the first rigorous studies of the value of ecosystems, including human, economic and environmental benefits, says principal investigator Alan Hastings.
The 51³Ô¹ÏºÚÁÏ Davis team, together with colleagues at the Scripps Oceanographic Institute, 51³Ô¹ÏºÚÁÏ San Diego and the San Francisco Estuarine Institute, will use Atlantic cordgrass (Spartina alterniflora) as an example of an invasive species. Native to the East Coast of the United States, cordgrass is a big problem in estuaries on the West Coast such as San Francisco Bay, says Hastings. The invading plant changes the ecology of the estuary, with far-reaching effects on native plants and animals, and an impact on people who live, work and play along the coast.
"Our estuaries lack large land plants which grow in salt water," explains ecologist Don Strong, "so they have evolved as mudflats." The cordgrass has no competitors or enemies in this environment, so it spreads rapidly. The plants slow down water flow and increase sedimentation, changing mudflats into intertidal meadows as the high-water line moves to the middle of the estuary.
"This plant violates the law in the Pacific states," jokes Strong, pointing out that land reclamation is illegal in California. "This is among the most profound changes you can impose on these estuaries."
Most of the West Coast is rocky shore, says Strong, and humans have damaged most of the few natural estuaries. What remains is home for a unique collection of migratory birds, he says, but these habitats are threatened by cordgrass invasion.
Cordgrass also threatens harbor seals, which need tidal mud islands as nurseries for their pups, says Strong.
Cordgrass encroachment decreases the value of river estuaries to humans -- both in financial terms, and in non-commercial and esthetic values. The research will look at all these different impacts of cordgrass on the ecosystem.
"It's an example of trying to understand an invasion," says Hastings. "Complex enough to see the effects of a species on the environment, simple enough for us to understand completely."
The team will create a dynamic model of cordgrass invasion, using extensive historical records and data collected by aerial and satellite photography. Resource science specialist Susan Ustin will lead the remote sensing part of the project. They will then compare the results of the model with detailed observations of West Coast estuaries, including San Francisco Bay and Willapa Bay, Washington.
The project integrates a variety of approaches, says Hastings. In addition to computer models and remote sensing, there will be measurements of water flow, sediment accumulation, and surveys of mammals, insects and birds. The impact of cordgrass on food webs will be studied by Ted Grosholz from 51³Ô¹ÏºÚÁÏ Davis, and Lisa Levin from the Scripps Institute.
These observations will be used to refine the model, which will then be used to predict the effects of cordgrass invasion on bird populations in estuaries.
An important aspect will be to look at the effect of cordgrass invasion on the value of the affected area to humans. Estuaries have a dollar value from activities such as navigation, fishing and sailing, but also have non-commercial and esthetic values that are affected by cordgrass invasion. Analysis of the economic effects of cordgrass invasion will be led by David Layton of the Department of Environmental Science and Policy.
Community outreach activities will play a major role in the project. "The aim is to educate the public on invasive species, like Spartina," says Grosholz, who will coordinate the outreach activities. A series of workshops will begin in the first year of the project, says Grosholz. All kinds of estuary users affected by cordgrass, such as birders, fishers, recreational boat users, as well as representatives of regulatory authorities are expected to attend.
Grosholz hopes that as well as education, the outreach program will help to prevent the unintentional spread of invasive cordgrass.
The 51³Ô¹ÏºÚÁÏ Davis grant is one of the largest awarded as part of $52.5 million awarded by NSF for biocomplexity research. Studies of biocomplexity aim at the "big picture," combining ecology and biology with disciplines as diverse as physics, geology, engineering and economics.
NOTE: Color images showing cordgrass invasion in estuaries are available. Contact Andy Fell, News Service, for details.