The invasive species is being cleared from Santa Barbara Harbor.

SANTA BARBARA - Six divers and support teams worked together Oct. 31 to remove a nonnative kelp species from docks, pilings and boat hulls at Marina Four in Santa Barbara Harbor.

Organized by Mick Kron-man, harbor operations manager, this was the third attempt to remove the invading kelp, known as Undaria pinnatifida, since it was first discovered in the harbor in 2002. Kronman's plan is to clear the kelp in phases throughout the remainder of the year.

Commonly called Asian kelp, the species is native to Japan, Korea and parts of China. Called wakame in Japan, this fast-growing kelp is farmed as a popular food source. The kelp has fronds that grow 6 ft. long and more than a foot wide. It was discovered in the 1980s in New Zealand, where it stretched over a large part of the shoreline in Wellington Harbour. Its appearance there was unwelcome, as it changed the structure and composition of native marine communities in a short period of time.

Since then, it's also been found in Australia, at Catalina and in Monterey, in addition to Santa Barbara Harbor.

"Our concern is that the plant will take over the native species," Kronman said. "Our plan is to keep it in check so it doesn't displace the giant kelp (Macrocystis pyrifera) native to our coast."

Though no one knows for certain, it's believed that the kelp was spread by bilge water from foreign vessels. Also, since it attaches itself easily to boat hulls, boat maintenance is critical to reduce the kelp's ability to spread.

"Preventing it from getting beyond the harbor and affecting the natural reefs is our goal," said diver Jessie Alstatt, a member of Santa Barbara Channel Keepers (a nonprofit organization working to protect and restore the Santa Barbara Channel). "We don't really know what the extent of damage or change to the local ecosystem and natural reefs would be. We want to prevent a problem from occurring."

Divers and dockside helpers from the Channel Islands National Marine Sanctuary, Santa Barbara Harbor Patrol and Channel Keepers worked together to remove the weed. Equipped with a map prepared by Harbor Patrol Officer Monica Broumand (who had surveyed the area beforehand) teams worked on Marina Four pilings, docks, boat hulls and the bait barge, collecting about 80 lbs. of the weed in less than four hours.

"As the holdfast (root structure) is small, it's easy to remove," sanctuary manager Chris Mobley said. "We don't know how it might affect the channel, so by keeping it in check, we won't give it a chance to have a negative impact."

• The Log