Fig. 1

Depth profiles of microbial community clustering and key biological and chemical characteristics of the sediment cores taken from 30-m depth in Lake Stechlin. Microbial communities were clustered by similarity (average clustering) into three groups (a, b, c) corresponding to different depth horizons (upper-left panel). Dates (y-axis) were calculated using ¹³⁷Cs measurements. Values are means (±1 SE) from four replicate cores. Parameters and units: FI = fluorescence index; cells [ 10⁶ ml⁻¹]; BPP-C = bacterial protein production in carbon [ μg C ml⁻¹d⁻¹]; DNA extract [ng μ l ⁻¹]; the shared chao index (R vegan package, [106]); low sim. = proportion of sequences with no close relative [% of sequences]; SRP [ mg l⁻¹]; NH₄ [ mg l⁻¹]; SO\(_{4}^{2-}\) [ mg l⁻¹]; DOC [ mg l⁻¹]; CH₄ [ μmol l⁻¹]; CO₂ [ mmol l⁻¹]; P [ mg g⁻¹ dry weight]; Fe [ mg g⁻¹ dry weight]; Pb [ mg g⁻¹ dry weight]. Additional information for all measured variables per individual core are provided in the Additional files 2 and 12