Fig. 5: Bio-physical properties of single aggregates formed from non-infected and fungal-infected diatom cultures in rotating cylinders.

Bacterial abundances on whole aggregates (a) and single Synedra cells (b), infection prevalence (c), and relative abundances of different Synedra cell types within aggregates and in the ambient water (d). Bacteria in a were grouped based on their association with individual Synedra cell types within single aggregates. The letters a–e in b denote significantly different groups (Kruskal–Wallis, P < 0.05). N indicates the number of analyzed cells. Data in b are shown as single data points (white circles), the 25th, 50th, and 75th percentile (grey boxes), mean values (blue and red-filled circles), and distribution curves (kernel smoothing). Stacked bars in a, d represent individual replicates. Mass density (e), settling velocities (f), and respiration rates (g, h) of single aggregates. f Settling velocities were positively correlated with the aggregate diameter. Fitted curves (power function) were significantly different between both treatments (P = 0.04). Blue and red items represent data from the non-infected and fungal-infected aggregates, respectively. g Respiration rates given as nmol O₂ per µmol agg-POC × h define the oxygen consumption per mol aggregate-POC and hour. Rates of 0.1 d⁻¹ indicate that 10% of the aggregate-POC were respired per day. h Respiration rates per meter settled, estimated for differently-sized aggregates. Rates of 0.1% m⁻¹ indicate that 0.1% of the aggregate-POC were respired per meter settled. Data in c, e, g are shown as single data points (white circles), the 25th, 50th, and 75th percentile (white boxes), and mean values (black circles).