First record of the invasive diatom Didymosphenia geminata (Lyngbye) Schmidt in a Patagonian Andean river of Argentina

Abstract

The Futaleufú River, Argentina, was monitored monthly from June 2010 to August 2011, in order to detect the invasive diatom Didymosphenia geminata, which was previously observed in Chile. Plankton and periphyton samples were taken from 10 sites. Didymosphenia geminata was not found until late winter. In August 2010, the species was first detected at isolated points of the river but in spring and summer the algal coverage extended along several kilometers. The coverage of blooms, spread to deeper areas (pools) with varying depths, reached more than 2 m, invading epiphytic and epilithic substrates. In autumn the bloom diminished its coverage area and there were only small isolated patches. During the next winter, blooms were not observed until late August, when it was recorded again. The observations showed that D. geminata appeared, colonized and invaded the bed of the river at low flow situations in spring and summer and its blooms declined in autumn - when the flows increase - after having been dried in summer when flows were the lowest.