Diversity and composition of molecular biome profiles in Danish
freshwater streams
Diversity and distribution of the obtained biome profiles was assessed
using the estimated richness as calculated per domain by alpha diversity
index Chao1 (Figure 1). The lowest average number of bacterial ZOTUs was
observed in the samples from good ecological status (4,243 ± 1,414
ZOTUs) (Figure 1a), while the highest was seen in the samples of poor
ecological status (5,790 ± 1,777 ZOTUs). No immediate relationship
between the bacterial diversity and ecological status of the sampled
locations was apparent (p > 0.05), and a similar pattern of
diversity was observed for the Archaea ZOTUs. A trend towards
increased diversity with better ecological status was observed for the
Eukaryotic ZOTUs (Figure 1b), where an average 54 ± 3 ZOTUs were
observed in the samples representing bad ecological quality, opposite 93
± 25 ZOTUs in samples of high ecological status. However, statistical
testing revealed no significant differences (p > 0.05) in
the estimated number of ZOTUs across all 5 ecological status categories
in all three domains. Bacterial and Eukaryotic ZOTUs had a
relatively low variation between samples of the same groups, compared toArchaea , where a larger variation was observed.
The composition of the molecular biome profiles across ecological status
categories was further examined per domain (Figure S2-S4). Prior to
analysis, all ZOTUs associated to Chloroplasts were filtered from the
dataset. The majority of the abundant bacterial community members were
observed across all ecological status groups (Figure S2), including
multiple representatives of Rhodoferax, Nitrospira,
Comamonadaceae and Anaerolineaceae . Representatives of the genusBacillus , as well as one ZOTU representing Nitrospira were
almost exclusively detected in samples representing good and high
ecological quality. Representatives of the domain Archaea were
detected sparsely in samples across all five ecological status
categories (Figure S3). The majority of abundant archaeal ZOTUs were
associated to the class Bathyarchaeia and the familyNitrososphaeraceae . For the Eukaryota , several abundant
organisms were observed across all ecological status groups, including
representatives of the insect order Diptera and the plant
division Magnoliophyta (Figure S4). Other eukaryotic ZOTUs were
more sparsely detected in the sampled locations, and included
invertebrates, fungi and annelids. Representatives of the flatworm groupContinenticola were primarily observed in samples of good and
high ecological status.