Assessing different components of biodiversity across a river network using eDNA

We studied a river network in a 740 km2 catchment containing 61 sampling sites in the upper river Thur in north-eastern Switzerland. The catchment comprises three main river-stems: Thur, Glatt, and Necker, the latter two draining into the Thur. In a sampling campaign conducted from June 11 to June 22 2016, we collected eDNA. At each site, we sampled three times 250 mL of river water, each on a separate filter. We used an Illumina MiSeq dual-barcoded two-step PCR amplicon sequencing protocol