EM122 Water Column Sonar Data Collected During AT26-10

AT26-10 Chemosynthetic Microbial Communities at Deep-Sea Vents (EM122). The cruise will include 16 dives with DSV Alvin or ROV Jason, to allow time for deployment and collection of experiments and for extensive sampling of discrete vents along the axis of the 9°46’N to 9°53’N segment of the East Pacific Rise (EPR). We propose to deploy experiments/sample a low temperature diffuse flow vent (e.g., Crab Spa; T: 10-30°C), and a higher temperature vent (e.g., L-vent; T: 30-60°C). Furthermore, we will carry out additional opportunistic sampling for a limited set of parameters (e.g., chemistry, 454- pyrotags, FISH, in situ carbon fixation) of vents that fall into these two categories, or that might have developed since the last visit to the site (May 2012). During the course of the cruise we will collect biomass from fluids and biofilms (deployment/recover experimental microbial colonizers) by utilizing a Large Volume Pump (LVP) (McLane WTS 6-1-142LV). We have successfully used this set up in previous cruises and were able to collect up to ~2,000 liters of hydrothermal fluids resulting in enough biomass (cell density is 2-5 x 105 cells per ml) for subsequent ‘omic’ analyses. During large volume filtration, the volume filtered is recorded by the LVP onboard computer and the vent fluid sampled is monitored with a time series temperature probe, H2S, and pH sensors. Fluid samples for chemical analyses will be collected at each deployment site using the isobaric gas-tight samplers, which will also be used to sample fluids from the two focus sites for the shipboard incubations. Finally, we will deployment/recover experimental microbial colonizers to collect microbial biofilms.We have successfully used these devices in previous cruises to collect sufficient biomass for metatranscriptomic analyses.