18S rDNA from lake water (GFC filter)
Water samples were filtered (1.5  2 L) through previously autoclaved glass fiber filters (GF/C) using low vacuum filtration. DNA was extracted using the the DNeasy Power Water Kit from GFC filters. Amplification of  18S rDNA V4 region was done using the two standard primers V4F-18S_ILL (CCAGCASCYGCGGTAATTCC) and V4R-18S_ILL (ACTTTCGTTCTTGATYRATGA), (28 cycles).