Biomonitoring survey of the hydrographical network in the MAB UNESCO Alpi Ledrensi and Judicaria Biosphere Reserve (Project AcquaViva)

Conventional taxonomic identifications based on the discrimination of diacritical morphological traits and culture based techniques have often proved inadequate in the study of microbial biodiversity (bacteria and protists) and biogeography of aquatic ecosystems. Moreover, investigations are generally focused on lakes and rivers that are also of interest for economic exploitation, therefore disregarding the small and/or ephemeral water bodies. Yet, due to their patchy and temporal habitat complexity, these neglected hydrographical elements can host a vast microbial diversity. In this work, we will report the results of a large survey of biodiversity carried out on water and sediments collected in the MAB UNESCO Alpi Ledrensi and Judicaria Biosphere Reserve (Project Acqua Viva) using high throughput sequencing (HTS) of 16S and 18S rDNA markers. The survey was carried out in 2019 in 20 sites of different sizes and characteristics. The study has allowed to disclose a high number of amplicon sequence variants (ASVs) belonging to a wide range of bacterial/cyanobacterial and protists groups. The presence of potentially toxigenic cyanobacteria was detected only in a few water bodies, including Lake Ledro, which showed the presence of Planktothrix rubescens and, for the first time, Tychonema bourrellyi in the pelagic sample