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Monterey Bay


Invasive Rockweed Returns to San Francisco Bay

May, 2008

While searching for evidence of an invasive snail, researchers from the Smithsonian Environmental Research Center (SERC) found large mats of the non-native alga Ascophyllum nodosum on the east side of San Francisco Bay at Bay Farm Island, Alameda, just a few miles north of Oakland International Airport.

In 2002 the same SERC scientists first discovered Ascophyllum nodosum on the western shore of San Francisco Bay. NOAA immediately organized a volunteer eradication effort, coordinating several state, federal, university and non-profit organizations and within two days the site was cleared of the alga. For more information on that successful eradication, see the 2004 paper published in Journal of Phycology (issue 40:1028-1031).

On May 5, 2008, the new population was discovered. This time, the area of infestation was larger in size and spanned approximately 400 meters of shoreline. Once again NOAA, and in particular the Restoration Center, Invasive Species Program and Southwest Region Fisheries office, coordinated the eradication effort. Volunteers participated in removals on July 7, 2008 and August 4, 2008, scouring the shoreline on hands and knees to remove the invader. The alga is easily removed by hand and does not require any special equipment. Collected material was placed in trash bags and wet weight was measured.

Less than 8 pounds of the invasive alga was removed in August, which was a significant drop from the 228 lbs. removed in July. Led by staff from the NOAA Fisheries Restoration Center, volunteers continue to scour the area initially invaded and also survey outlying areas. On-going surveys will continue for at least the next six months.

Volunteers are always welcome. If you are interested, please contact Andrew Chang at andrew.chang@noaa.gov or Natalie Cosentino-Manning at natalie.c-manning@noaa.gov at the NOAA Fisheries Restoration Center.

Invasive rockweed, Ascophyllum nodosum