Nuisance Blooms Hit Chilean Rivers

An extensive bloom of the invasive diatom known as “didymo” (Didymosphenia geminata) has been identified in South America for the first time. Didymo is a significant concern because it can erupt into massive “nuisance blooms” that cover stream and river bottoms. These dense masses substantially alter the habitat of invertebrates, fish and other aquatic life. A USGS scientist confirmed that this bloom, found on 35 miles of two remote Chilean rivers near Esquel, Argentina, was caused by didymo. Because didymo can survive in damp conditions for more than 30 days, it is easily transported from one stream to another on the gear of anglers and boaters — the suspected cause of most occurrences, including the one in Chile. More information on didymo is available online, or contact USGS ecologist Sarah Spaulding at sarah.spaulding@usgs.gov