Summary We present data on the co‐registered geochemistry ( in situ mass spectrometry) and microbiology (pyrosequencing of 16 S rRNA genes; V 1, V 2, V 3 regions) in five fluid samples from I rina II in the L ogatchev hydrothermal field. Two samples were collected over 24 min from the same spot and further three samples were from spatially distinct locations (20 cm, 3 m and the overlaying plume). Four low‐temperature hydrother...

Summary This study examines the representativeness of low‐temperature hydrothermal fluid samples with respect to their chemical and microbiological characteristics. Within this scope, we investigated short‐term temporal chemical and microbial variability of the hydrothermal fluids. For this purpose we collected three fluid samples consecutively from the same spot at the Clueless field near 5°S on the southern Mid‐Atlantic Ridg...

Summary Lilliput was discovered in 2005 as the southernmost known hydrothermal field along the Mid‐Atlantic Ridge. It is exceptional in that it lacks high‐temperature venting probably because of a thickened crust. The absence of thermophilic and hyperthermophilic prokaryotes in emissions supports the argument against the presence of a hot subsurface at Lilliput, as is typically suggested for diffuse emissions from areas of hig...