3.1 Effect of sampling day, sampling position, and environment
Sampling day affected the detection of both species (F = 5.933, p-value
= <0.001, ndf = 4.055, ddf = 90.945) and OTU (F = 2.765,
p-value = 0.030, ndf = 3.32, ddf = 91.68) richness. In contrast, neither
temperature, discharge, nor sampling position had an effect on species
or OTU richness. Highest species and OTU richness was detected in spring
with lowest numbers in the summer months for all three sampling
positions (Figure 2 and Figure S3). Conversely, sampling positions
exhibited little difference in read richness, with 99 % of reads shared
among the different positions in the stream and only a small fraction of
reads being exclusively detected per sampling position (≤0.1 %) (Figure
2). The sampling positions showed high overlap of reads for shared
species (99.14 %) and only a small fraction of reads was assigned to
the exclusively detected species per sampling position (≤0.1 %) (Figure
2). Although some species were exclusively found at one of the three
sampling positions (Figure 2), relative occurrence of these species was
low in contrast to shared species (Figure S4). We found no significant
differences between surface, riverbed or riverbank samples based on OTU
richness (Kruskal-Wallis rank sum test: chi-squared = 0.085, p-value =
0.957, ndf = 2, ddf = 97) or read abundance (Kruskal-Wallis rank sum
test: chi-squared = 0.774, p-value = 0.679, ndf = 2, ddf = 97).