Updated distribution of the diatom Didymosphenia geminata (Lyngbye) Schmidt in Tierra del Fuego, Patagonia

In this study, we report new observations on the distribution of the invasive diatom Didymosphenia geminata on the island of Tierra del Fuego, southern Patagonia. We present new findings as well as data collected by the monitoring programme of the Government of the Tierra del Fuego. Didymosphenia geminata was first reported from the island in 2013, in the watershed of the Rio Grande, northeast of the island. In 2017, it was found in the Lapataia River, within the Tierra del Fuego National Park. More recently, we detected its presence at two more sites; one in Lake Fagnano, and in the Arroyo Grande, near the city of Ushuaia. Hence, in eight years, this invasive diatom has spread and reached the southern part of the island despite prevention measures applied in protected areas since 2014. Although D. geminata is already in Tierra de Fuego, the island is home to many water bodies with high conservation value. Monitoring the range expansion of this invasive diatom should continue since prevention is the only tool to prevent further expansion. This is particularly important because Ushuaia, in the southern part of the island, is a port from which many tourist companies depart for Antarctica, a continent not yet impacted by D. geminata.