Animation of "Giant Reed" Plant May Speed Its DemiseBy Marcia Wood
August 19 2009
Along streams and irrigation canals in 16 states, a wily weed called giant reed, or Arundo donax, can grow a remarkable 3 to 6 inches a day. This intruder crowds out native plants like cottonwoods and willows, and can block water flow to farms and cities.
In research designed to stop arundo's advance, Agricultural Research Service(ARS) ecologist David F. Spencerand co-investigators have developed a computerized, science-based animation that shows precisely how a real-world arundo plant grows. The animation???apparently a first for an invasive weed???is intended for researchers, streamkeepers, students and others.
During this brief clip, a reality based "virtual arundo" goes through its first year of growth, emerging from a single, thick, underground stem, or rhizome, to reach its maximum height of about 30 feet.
The animation is derived from studies led by Spencer. In some of those studies, thousands of digitized measurements were taken by magnetic sensors of dozens of arundo plants. Using commercially available software, the measurements were analyzed to create L-DONAX, a computer-based model of arundo's growth, with optional 3-D animation.
Work to improve the first (2007) version continues. Meanwhile, the animation has been newly posted on the web. To view it, scroll down toward the bottom of www.ars.usda.gov/arundo.htm
Researchers can use L-DONAX and its animations to gauge???and see on-screen???the predicted effects of tactics to control arundo. For example, the model could help scientists determine the best times in the weed's growth to unleash helpful insects that attack arundo's leaves, stems or rhizomes.
Spencer, who works at the ARS Exotic and Invasive Weeds Research Unitin Davis, Calif., created L-DONAX with David Thornby, formerly at the University of California-Davis; Jim Hanan of the University of Queensland, Australia; and Anna Sher of the University of Denverand Denver Botanic Gardenin Colorado.
Lars Anderson of the U.S. Department of Agriculture's Agricultural Research Service removes the invasive kelp from a boat docked at Pier 40. (Below)
(07-09) 17:30 PDT -- Four divers led by a land-based ecologist hunted the turbid waters of San Francisco's South Beach marina Thursday for a nasty, invasive seaweed that is taking over harbors and estuaries all along the Pacific coast.
Although their prey didn't seem to have a chance, the divers could hardly keep up with the abundant infestation of what in more benign coastal environments is a tasty ingredient of miso soup.
At Pier 40 along the marina's concrete dock for visiting yachts and from the hulls of the boats themselves, the divers stripped off yards of the kelp in small chunks. They harvested 2-inch-long golden brown juvenile algae, and long strands of the dark brown mature kelp, their broad rippling leaves holding clusters of reproductive spores ready to spread through the water and give birth to still more invaders.
Steve Lonhart, a senior scientist and diver from the Monterey Bay National Marine Sanctuary, has been battling the invasion in the bay since the alien kelp species was discovered on boat hulls in the San Francisco marina in May.
"It's still there and no one thinks it will be completely eradicated, but hopefully we can keep it from spreading," said Lonhart as he put on scuba gear before his first dive.
The invading kelp is called Undaria pinnatifida, a seaweed species known popularly in Japan as wakame. Believed to have arrived on the hulls of commercial ships, the kelp has plagued harbors in Southern California since 2000 and arrived in the bay more recently.
"The kelp is a serious threat to our native species because it crowds them out and deprives them of oxygen, so it ruins the natural habitat for native species of fish, shellfish, sea otters and other marine organisms," said Chela Zabin, an ecologist with the Smithsonian Environmental Research Center in Tiburon who with her assistants keeps meticulous records of every alien cluster the divers harvest.
"What we want to do is to alert boat owners - particularly those sailing into the bay from southern harbors - to watch for the seaweed fouling their hulls and get rid of it. But not in the water!" she said.
Although the kelp is tasty food in Asia, it is dangerous to eat here, Zabin said, because it gathers up all the toxins in the murky, polluted waters of harbors along the California coast - including the bay.
Other divers in the project that will continue until the South Beach marina is clear include Chad King, a biologist from the Marine Sanctuary, Gail Ashton of the Smithsonian Center, and Christopher Scianni of the California State Lands Commission.
E-mail David Perlman at email@example.com.
This article appeared on page D - 1of the San Francisco Chronicle
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