Fig 1.
The average chlorophyll a (A) and cell abundances of autotrophic (B) and heterotrophic picoplankton (C) were determined via flow cytometry at each time point. Error bars show standard deviations for triplicate treatments: control (C), thiamin (Thi), nitrogen (N), and thiamin + nitrogen (N_Thi). For significant differences in response to treatments, see the text.
Fig 2.
Stacked bar graph of the average relative abundance and the taxonomical identification in the 16S rRNA (A) and 18S rRNA (B) gene amplicon libraries for each time point (Day 0, 3, 6, 10, 12 and 16) for triplicate treatments; Control (C), Thiamin (Thi), Nitrogen (N), and Thiamin + Nitrogen (N_Thi). The remaining ASVs have been grouped in the category “Other”, and ASVs with the same identification have been given indices in the legend.
Fig 3.
Phytoplankton abundance (103 units m-3) (A) and biomass (mg C m-3) (B) for the dominant taxonomic groups in the Control (C), Thiamin (Thi), Nitrogen (N), and Thiamin + Nitrogen (N_Thi) treatments. There were overall higher abundances following N addition but no effects of thiamin addition (see statistics in the text). However, there were no significant differences among treatments in either abundance or biomass within each sampling occasion, i.e., on Days 3, 6 or 16 (Mann‒Whitney U test, multiple comparisons, p>0.05)).
Fig 4.
Total zooplankton abundance (103 individuals m-3) (A) and biomass (mg C m-3) (B) for the dominant taxonomic groups in the Control (C), Thiamin (Thi), Nitrogen (N), and Thiamin + Nitrogen (N_Thi) treatments. There were overall higher abundances following N addition and a tendency toward higher abundances in response to thiamin addition (see statistics in the text). There were no significant differences among treatments in either abundance or biomass within each sampling occasion, i.e., on Days 3, 6 and 16 (Mann‒Whitney U test, multiple comparisons, p>0.05).
Fig 5.
Nonmetric multidimensional scaling (NMDS) plot of the community composition of phytoplankton (A) and zooplankton (B). Each symbol represents the median community composition (Bray‒Curtis dissimilarity) for each replicate and time point (0, 3, 6, 16), while the color represents treatment; Control (C), Thiamin (Thi), Nitrogen (N), and Thiamin + Nitrogen (N_Thi). Dashed lines connect replicates within a time point and treatment. Arrows illustrate fitted vectors.
Fig 6.
Total thiamin content (nmol (g C)-1) in phytoplankton (A) and zooplankton (B) in the Control (C), Thiamin (Thi), Nitrogen (N), and Thiamin + Nitrogen (N_Thi) treatments. Phytoplankton thiamin content is presented for separate size fractions (90–200 μm, 20–90 μm, 3.0–20 μm, and 0.7–3.0 μm). The error bars show the standard deviation of the total thiamin content. Different letters indicate significant differences among treatments within time points, while symbols indicate significant differences among time points within treatments.
Fig 7.
Total thiamin content (log; nmol gC-1) in phytoplankton, zooplankton, planktivorous fish, piscivorous fish and omnivorous fish (drawings modified from [52]).
Data collected in a literature search (black dots) on the concentrations of thiamin in different organisms (phytoplankton, zooplankton, planktivorous fish, piscivorous fish, and omnivorous fish). The grey dots represent mesocosm concentrations of phytoplankton and zooplankton.
Table 1.
Summary of the median, average, maximum and minimum concentrations of total thiamin in phytoplankton (or seston), zooplankton, planktivorous fish, piscivorous fish and omnivorous fish.