Metabarcoding reveals potentially mixotrophic flagellates and picophytoplankton as key groups of phytoplankton in the Elbe estuary

Picophytoplankton dominate phytoplankton communities in the Elbe estuary in terms of cell counts

“…a) -c) refer to cell counts from flow cytometry, d) -e) to reads from metabarcoding. Data in d) is obtained from a former study (Martens et al, 2024b). Regression lines were added with geom_smooth() from ggplot2 and the method "gam" (see also tab.…”

“…Stephanodiscus, Cyclotella) were dominant in most seasons and areas of the Elbe estuary. For the spatial dataset, 16S rRNA metabarcoding as well as 18S rRNA metabarcoding from another study (see further information in (Martens et al, 2024b)) were included to add information about picophytoplankton taxa in the Elbe estuary (fig. 2d-e, fig.…”

“…S3). Samples for 16S rRNA sequencing were processed in the same way as shown for the 18S data (Martens et al, 2024b), however, reads were assigned using the BLAST database (carried out by biome-id Dres Barco & Knebelsberger GbR). In both datasets, we selected taxa that are in general considered picophytoplankton or can be < 3 µm (e.g.…”

“…a) - c) refer to cell counts from flow cytometry, d) - e) to reads from metabarcoding. Data in d) is obtained from a former study (Martens et al, 2024b).…”

“…Here, we applied flow cytometry and metabarcoding (partially from (Martens et al, 2024b), in the context of new metabarcoding data) to (1) investigate spatial and seasonal patterns in picophytoplankton abundance and composition in the Elbe estuary, (2) identify dominant taxa and (3) assess under which conditions (with respect to abiotic factors, season, location) picophytoplankton and different players within (e.g. picocyanobacteria) might be particularly dominant.…”