Coastal Services Center

Humboldt Bay and the nearby Eel River Estuary on California’s north coast comprise an ecosystem of nearly 50 square miles that nurtures hundreds of bird, fish, and invertebrate species. Until two years ago, resource managers were frustrated by a scarcity of low-tide photo imagery that could shed light on the conditions of the ecosystem’s mudflats, salt marsh, eelgrass meadows, and other features. High-quality baseline information on the bay’s habitats had not been collected since 1970.

By early 2010, that frustration had turned into anticipation with the release of full-color, digital aerial photographs and benthic habitat maps of the bay and estuary.

With funding from the NOAA Coastal Services Center, in partnership with California Sea Grant, the California Coastal Conservancy, Humboldt Bay Harbor District, and the National Weather Service Forecast Office in Eureka, California, a geosciences company was hired to collect GIS-compatible images in June 2009, creating the first detailed (.5-meter resolution) inventory of the area’s intertidal and subtidal bottom habitats.

“With this information we can monitor habitat trends and changes, adapting our management strategies with different scenarios and conditions in mind,” says Susan Schlosser, a marine advisor with California Sea Grant, who led the imagery and mapping project spearheaded by the multi-partner Humboldt Bay Initiative.

More than 20 organizations, academic institutions, businesses, and government agencies have used the images and maps to conserve habitat, monitor rare species, craft aquaculture plans, and devise ways to minimize the effects of sea level rise. The imagery is also being used to update National Wetlands Inventory maps.

One of those using the images is Paula Golightly, a biologist and coordinator for the U.S. Fish and Wildlife Service’s Coastal Program and a participant in the Humboldt Bay Initiative.

“Work conducted by Humboldt Bay National Wildlife Refuge has shown that the invasive plant species Spartina densiflora has expanded onto mudflats around Humboldt Bay, which may impact the bay’s use by migratory shorebirds and other species,” Golightly says. “The photo imagery, combined with work in the field, will help our coastal program, the refuge, and other local partners to better monitor the species, as efforts to eradicate it have been initiated.”

Schlosser foresees other benefits, too. The mapped sloughs and drainage network will aid those making restoration plans or assessing water control structures. And the habitat maps, she notes, allow for trend analysis and a better understanding of the mechanisms of change.

To obtain these benthic data, visit www.csc.noaa.gov/digitalcoast/data/benthiccover/download.html. For the photo imagery, visit www.csc.noaa.gov/digitalcoast/data/highresortho/download.html. To learn more, contact Susan Schlosser at (707) 443-8369 or sschlosser@ucsd.edu.