distributions20. We also measured major geochemical parameters
(temperature, specific conductivity, dissolved oxygen, nitrate, iron
and sulfate; Supplementary Figs 1–3).
The 16S rRNA gene survey showed that biogeochemistry had a
major influence on the bacterial community structure (Fig. 1).
Transitions in community structure lined up with the lake’s major
geochemical features: the thermocline, oxycline and nitrocline
(Fig. 1b). Cyanobacteria were most abundant near the surface
(Fig. 1a). Bacteroidetes, Actinobacteria and Proteobacteria were
abundant across all depths. Deltaproteobacteria, which include
most of the known sulfate-reducing bacteria, were abundant only