Estimating the Impact of Invasive Spartina densiflora on Primary Productivity in Humboldt Bay

Start/End: July, 2010 to March, 2012

Four species of non-native Spartina, commonly called “cordgrass,” are found along the West Coast of the United States and Canada. Where established, these invaders convert estuarine mudflats and salt-marsh ecosystems into uniform expanses of dense grass. Aggressive control efforts in San Francisco Bay and elsewhere on the West Coast have demonstrated the feasibility of eradication (or near eradication) with adequate funding, political will and coordinated efforts. But eradication is costly and at some sites, particularly those that face other severe threats, restoration funds might be better spent elsewhere or on other things. This question is being asked for sites within Humboldt Bay in Northern California, where the price tag of removing Spartina has been estimated at up to $20 million. Scientists are now attempting to quantify the effects of removing the most problematic of the cordgrasses, Spartina densiflora, from the bay’s tidal marshes, on above-ground net primary productivity. The methods and design of the study were presented at the 2010 Spartina Summit, hosted by the Coastal Conservancy. Findings will be shared with the U.S. Fish and Wildlife Service, which is in the process of removing cordgrass in the Humboldt Bay National Wildlife Refuge to recreate the diversity of native vegetation that sustains native wildlife.