Sampling, isolation and cultivation

Epilithic samples were collected by brushing rocks in the littoral of Lake Van in July 2021, in the vicinity of Erciş Municipality (Fig. ​(Fig.1).1). Samples were re-suspended in surface water from the lake in 50 ml tubes before being brought to the University of Szczecin for subsequent analyses. Samples were then transferred into Petri dishes containing sterile f/2 medium (Guillard 1975) modified to 18‰ salinity. Single cells were isolated by micropipette under an inverted Nikon Eclipse light microscope. Successive re-isolations were performed (at least 3 times) before the culture was considered monoclonal. Strains were later transferred into 250 ml Erlenmeyer flasks with modified f/2 medium. Cultures were maintained in active growth under a light intensity of 60 µmol photons m^–2 s^–1 and a photoperiod of 14 h light/10 h darkness). Two morphologically distinct clones with different cell sizes were registered in the Szczecin Culture Collection as SZCZEY2172 and SZCZEY2262.

Map of the sampling location A location of Lake Van in Turkey. The red frame indicates the position of Lake Van B general view of the lake. The pin indicates the position of the sampling area C photo of the epilithic sampling area on the rock (Esri. (2023). ArcGIS Pro 3.1.0. Environmental Systems Research Institute).