LONG BEACH, California — A recreational scuba diver discovered an invasive species of Asian seaweed growing in the Channel Islands National Marine Sanctuary for the first time this year. Now scientists are asking for help from boaters to help halt its spread, and from other divers to continue searching for it. The Marine Sanctuary Advisory Council invited a prominent ocean researcher from UC Santa Barbara to discuss Sargassum horneri during a recent meeting at Channel Islands National Park Visitor Center in Ventura.
Associate Research Biologist Jack Engle works for the university's Marine Science Institute, and says the plant already had a foothold along parts of the mainland coast, and surrounded Catalina Island, before it was discovered near Anacapa this year. It was first found in California near Long Beach during 2003. "Since the first record was in Long Beach Harbor, it seems the circumstantial evidence is pretty good for it coming over on ships," says Engle. Scientists are concerned that newly introduced species might affect nature's balance and crowd out important native species like giant kelp, which makes the sanctuary a world class scuba diving destination. "A near relative of Sargassum arrived in California in the late '60s and we monitored its spread, too, and there have been a number of papers published on it. We know that when it grows thickly it can block out the light and take up space that native species can be using," says Engle. "It can also reduce the flow of water in the areas near the bottom. It can increase the amount of sediment that could come in, and it basically could outcompete some of the native species." A scuba diver first noticed it off the west end of Anacapa last spring and took a picture of it. Engle says they're hoping divers can contribute to science by helping monitor its spread. "We're going to be sending out posters and information forms that can be utilized to have everybody help us out and figure out what's going on with it," says Engle. "We could use your help to actually help document it by learning what it looks like and taking photographs and sending us GPS coordinates for sites where you find it. That would be a tremendous help." Boaters and fishing enthusiasts are also urged to keep the hulls of vessels clean to help prevent its spread, and to make sure it's not attached to mussels transported to the islands for use as bait. | | It might be too late to stop the spread of Sargassum horneri, an invasive species in the Channel Islands National Marine Sanctuary since just one plant can produce up to a billion embryos but scientists are asking for help from divers and boaters. Sargassum horneri varies greatly in how it looks over its lifespan. "In the early stages, it's more fernlike in appearance, and as it gets taller it develops small oval air bladders that buoy it up, and then it can grow up to two meters tall and will develop reproductive structures that are very small cigar-shaped structures from which it releases the embryos for the next generation," says Engle. It might be too late to stop the spread of this particular species since just one plant can produce up to a billion embryos, but researching its spread might help scientists prevent future plant invasions and develop plans for quick eradication. "The best thing we can do is try to study it, and learn from it, and develop ways to try and minimize the chances of the next kind of introduction from occurring," says Engle. "I think the most important thing is to treat something like this the way you would an oil spill. There should be a rapid response capability developed to try and deal with it when something is first discovered." by ALEX WILSON |
