Patterns of geographical distribution of toxigenic cyanobacterial species and oligotypes in the perialpine lake district

Eco-AlpsWater (EAW) is a major European project co-financed by the European Regional Development Fund (ERDF) through the Interreg Alpine Space program (www.alpine-space.eu/projects/eco-alpswater). The aim of the initiative is to integrate traditional water monitoring approaches implemented in the Alpine region and in Europe (Water Framework Directive-WFD) with high throughput sequencing technologies (HTS). In this work we will present the rationale and results obtained in the Italian hydrographic network, with a focus on large subalpine lakes and cyanobacterial communities determined on samples collected in pelagic areas and rocky-shore biofilms (Lake Garda). Overall, the pelagic and biofilm samples showed distinct communities, with only a few shared species and oligotypes (amplicon sequence variants) mostly belonging to the Chroococcales. One of the most widespread pelagic species in the Italian district and the whole Alpine region was Planktothrix rubescens. In contrast, Tychonema bourrellyi showed consistent populations only in the southern subalpine lake district. The normalized DNA sequence abundances of these two species were highly correlated with the microcystin and anatoxin-a concentrations, demonstrating a high consistency of the results obtained by HTS and metabolomic profiling, and a high ability of HTS to predict the toxigenic potential due to the production of hepatotoxins and neurotoxins in inland waters.