Recent spread of Raphidiopsis raciborskii in the lake district south of the Alps

Changing climate conditions and human-induced eutrophication could lead to an increase in harmful cyanobacterial blooms in freshwater environments. Furthermore, climate change may affect the geographic distribution of potentially toxigenic species and cyanobacteria, leading to the appearance of new threats in previously unexposed areas. Recently, the toxic cyanobacterium Raphidiopsis raciborskii, known for forming blooms, has increased its presence particularly in temperate regions. The objective of this work is to expand the knowledge about the distribution of R. raciborskii in Northern Italy. Specifically, we will include new observations recorded during the last decade based on investigations carried out in the framework of scientific and government monitoring, as well as large biogeographical surveys carried out on the whole Alpine Space area (Project Eco-AlpsWater). The detection of R. raciboskii in Northern Italy highlights the importance of an attentive monitoring of freshwater quality and the implementation of measures to prevent the spread of harmful organisms. 24