2.3 | Sampling and sample processing
Benthic invertebrates were collected using a kick net with a 25x25 cm frame and a mesh size of 0.25 mm. For each sample, an area of approximately 0.5 m2 was covered with a sampling duration of one minute. At each combination of sampling occasion and sampling station, five replicate samples were taken. The samples were preserved in 96% ethanol before subsequent subsampling of each sample (1/10) in the laboratory. All invertebrates in the subsample were sorted and identified to the lowest possible taxonomic unit using a stereo microscope and following Engblom (1996) for Ephemeroptera, Lillehammer (1988) for Plecoptera, Rinne & Wiberg-Larsen (2017) for Trichoptera, Holmen (1987) and Nilsson & Holmen (1995) for Coleoptera and Glöer (2002) for Gastropoda. The number of specimens from the sub sample were then multiplied by 10. All specimens of the remaining sample that differed morphologically from the specimens in the sub sample, were picked out, identified to lowest possible taxon and counted.