Dataset: 18S rRNA amplicon sequencing of microbial eukaryotes from the Mid-Cayman Rise acquired Jan-Feb, 2020

Samples and experiments were collected and executed during cruise AT42-22 aboard the RV Atlantis with ROV Jason in January-February 2020 at the Von Damm (2300 m; 18°23’N, 81°48’W) and Piccard (5000 m; 18°33’N, 81°43’W) hydrothermal fields located along the Mid-Cayman Rise.

Fluids for shipboard grazing experiments and biogeochemistry were obtained in 10L volume bags (Kynar, Keika Ventures; polyvinylidene fluoride) using the Hydrothermal Organic Geochemistry (HOG) sampler mounted on ROV Jason. Between 4-10 L of vent fluid was collected and filtered through a 47 mm polyethersulphone (PES) filter (Millipore) with a pore size of 0.2 µm and preserved with RNAlater (Ambion) at the seafloor for molecular analysis of microbial communities. 

Non-vent samples were collected from within the overlying non-buoyant hydrothermal plume at each site and from background seawater via CTD-mounted Niskin bottles. Plume samples were identified using in situ CTD sensors to detect the presence of hydrothermal influence in real-time (back-scatter and temperature) above each vent field. Background seawater samples were collected outside of the influence of the hydrothermal vent at approximately the same depth as the vent sites (~2350 m and ~4950 m).