FIX08 cruise at the East Pacific Rise

FIX08: An interdisciplinary and international collaboration to study autotrophic carbon fixation and fluid chemistry at 9ºN and 13ºN EPR

An international group of scientists representing five different countries, i.e., USA, Germany, France, Italy, and China, was recently on board R/V Atlantis on cruise AT15-28, named FIX08. They were conducting work on in-situ chemistry of high- and low temperature hydrothermal vent fluids and the characterization of microbial communities carrying out autotrophic carbon fixation.

High temperature fluids are studied by the group of Bill Seyfried and Kang Ding from the University of Minnesota (USA) in collaboration with Chinese colleagues Bo Jin and Shijun Wu (Zhejiang University) by using in situ sensors (pH, H2, H2S) as well as sampling of fluids using isobaric samplers. A newly developed auto-calibrating pH cell was deployed for the first time at a diffuse flow site near the Ty-Io vent structure during the cruise. Analyses of fluids being conducted on board ship already reveal distinct differences in fluids sampled at 9ºN compared to 13ºN.

The microbial studies lead by Stefan Sievert from the Woods Hole Oceanographic Institution (WHOI, USA) are focusing on free-living and attached microbial communities associated with diffuse flow venting as well as physiological and proteomic studies of the endosymbiont of Riftia pachyptila. Invited collaborators include Horst Felbeck (Scripps Institution of Oceanography, USA), Michael Hügler (IfM-Geomar, Kiel, Germany), Stephanie Markert (University of Greifswald, Germany), and Kathleen Scott (University of South Florida, USA) studying the Riftia endosymbiont, as well as Costantino Vetriani (Rutgers University, USA), Karyn Rogers (WHOI/University of Missouri, USA), Sara Borin (University of Milan, Italy), and Kristina Beblo (PhD student in Harald Huber’s lab, University Regensburg, Germany) working on free-living and surface/chimney associated microbial communities. These studies are complemented by characterizing the physicochemical environment in situ by using chemical sensors as well as shipboard analyses carried out by the group of Nadine Le Bris (Ifremer, France). By performing analyses and incubations utilizing 14C- and 13C-labelled substrates in conjunction with determining microbial diversity and quantifying different groups of microbes as well as physicochemical measurements, these studies will comprehensively address the question of how much carbon is produced in diffuse flow areas and which organisms are responsible for it. This cruise follows directly after a workshop and Theoretical Institute of the InterRidge working group on ‘Biogeochemical Interactions at Deep-Sea Vents’ held in September 2007 in Woods Hole, which was co-organized, among others, by Nadine Le Bris and Stefan Sievert and attended by a number of participants of this cruise.

The cruise was made possible by US National Science Foundation (NSF) grants OCE-0452333 awarded to Stefan Sievert (PI), Craig Taylor (Co-PI, WHOI, USA) and Roger Summons (Co-PI, MIT, USA) and OCE-0525907 awarded to Bill Seyfried/Kang Ding. Support for individual projects came from NSF grants MCB 04-56676 and OCE 03-27353 (Costantino Vetriani), the German Aerospace Center (Kristina Beblo), Ifremer (Nadine Le Bris), and a WHOI postdoctoral scholarship and the University of Missouri (Karyn Rogers). The scientific party thanks the captain, crew, WHOI shipboard scientific services group, and Alvin group for their dedication and hard work that made this cruise a success.

Photo legend:
Nadine Le Bris, Alvin pilot Mark Spear, and Stefan Sievert pose in front of Alvin before their dive to the vent sites at 13ºN on the East Pacific Rise. While the focus of the cruise was initially solely on 9ºN, impeding weather made the scientific party to decide to launch four dives at 13ºN before coming back to 9ºN. This was the first extensive visit to the vents at 13ºN since the French expedition PHARE in 2002, providing interesting data for comparative analyses. While some of the vents were found to be still active, quite a few sites have become inactive since then.