Traditional DSFI analysis and conversion to ecological status
classes
Sampling of 53 Danish stream ecosystem sites using the kick-sampling
method (Bradey & Ormerod, 2002) and subsequent DSFI analysis was
performed by the Laboratory of Fish Ecology (Fiskeøkologisk
Laboratorium, Helsingør, Denmark) in accordance with the Danish
standardised DSFI protocol (Skriver, 1999). The samples used for the
DSFI analysis was stored in 96 % ethanol at 4 °C until further
analysis. After DSFI analysis, the scores were converted to ecological
quality classes using a previously proposed distribution
(Baattrup-Pedersen et al., 2004). An overview of all samples, their DSFI
quality category and ecological quality class is shown in Table 1.
Sample homogenisation and DNA
extraction
Prior to DNA extraction, samples were decanted using a mesh sieve (0.5
mm) and homogenised with a blender (JB 5160 BK, Braun GmbH, Germany)
using 10 second cycles at speed setting 3. Total genomic DNA was
extracted from 0.25 g of homogenised material using the QIAamp
PowerFecal DNA kit (Qiagen, USA) according to manufacturer’s
recommendations. Extracted DNA was eluted to 50 µL elution buffer from
the kit. Concentration of the extracted DNA was determined using
Quant-IT Broad Range DNA assay kit (Thermo Fisher Scientific, USA) and
an M200 Infinite PRO plate reader (TECAN, Switzerland).