show Abstracthide AbstractThe case study is focused on the crenogenic meromictic Lake El Tobar (Spain), a continental karstified system formed by the sink and solution of a combination of Cretaceous dolomites and Triassic salt-rich Keuper. One of the peculiarities of this system is the formation of a salinity gradient from 0.6 to > 200 mS cm-1, that generates an anoxic saline monimolimnion starting at 13-14 m and reaching the bottom at 18 m of depth. Samples were obtained from 2, 12, 12.5, 13, 13.5, 14, integrated 15.5-16.5 and 18 m of depth to study the microbial vertical zoning and stratification patterns of the lake. Water samples were filtered through a series of 20, 5 and 0.22 micron filters. The 0.22 micron filters were sequenced with high-throughput Shotgun sequencing. We provide 8 metagenomic datasets and MAGs derived from these samples.