A Slimy Invader Blooms in the Rivers of Patagonia

摘要

Biochemist William Horvath was the first to sound the alarm. A Patagonian guide to kayakers from all over the world, Horvath was taking U.S. clients on the pristine Futaleufu River in Chile last year when he saw something that stopped him cold. In the water there "appeared to be toilet paper," he says. Afraid of hepatitis, the kayakers turned back. Horvath decided to investigate. After ruling out pollution from a local water-treatment plant, he sent samples to the U.S. Geological Survey (USGS) in Fort Collins, Colorado. USGS ecologist Sarah Spauld-ing determined that it was natural material: the mucilaginous stalks of the algae known as Didymosphenia geminata, or Didymo. The discovery caused a stir, as Didymo is unwelcome wherever it blooms. It forms large colonies of brownish slime that cling to vegetation and streambeds, extending leathery trailers into the current.