RV Atalante Fahrtbericht / Cruise Report HYDROMAR V (replacement of cruise MSM06/2) Toulon, France - Recife, Brazil 04.12.2007 - 02.01.2008 IFM-GEOMAR REPORT Berichte aus dem Leibniz-Institut für Meereswissenschaften an der Christian-Albrechts-Universität zu Kiel Nr. 22 September 2008 RV Atalante Fahrtbericht / Cruise Report HYDROMAR V (replacement of cruise MSM06/2) Toulon, France - Recife, Brazil 04.12.2007 - 02.01.2008 Berichte aus dem Leibniz-Institut für Meereswissenschaften an der Christian-Albrechts-Universität zu Kiel Nr. 22, September 2008 ISSN Nr.: 1614-6298 Das Leibniz-Institut für Meereswissenschaften The Leibniz-Institute of Marine Sciences is a ist ein Institut der Wissenschaftsgemeinschaft member of the Leibniz Association Gottfried Wilhelm Leibniz (WGL) (Wissenschaftsgemeinschaft Gottfried Wilhelm Leibniz). Herausgeber / Editor: Sven Petersen IFM-GEOMAR Report ISSN Nr.: 1614-6298 Leibniz-Institut für Meereswissenschaften / Leibniz Institute of Marine Sciences IFM-GEOMAR Dienstgebäude Westufer / West Shore Building Düsternbrooker Weg 20 D-24105 Kiel Germany Leibniz-Institut für Meereswissenschaften / Leibniz Institute of Marine Sciences IFM-GEOMAR Dienstgebäude Ostufer / East Shore Building Wischhofstr. 1-3 D-24148 Kiel Germany Tel.: ++49 431 600-0 Fax: ++49 431 600-2805 www.ifm-geomar.de Cruise Report HYDROMAR V (04.12.07 – 02.01.08) l’Atalante SUMMARY 1 1.1 Participants Atalante cruise Hydromar V ................................................................5 1.2 Research Program ........................................................................................................8 1.3 Daily Narrative ...........................................................................................................14 1.4 Preliminary Results....................................................................................................19 1.4.1 Oceanography.....................................................................................................19 1.4.2 Plume mapping with MAPR ............................................................................24 1.4.3 Gas Chemistry.....................................................................................................28 1.4.4 Logatchev Longterm Environmental Monitoring – LOLEM.......................33 1.4.5 Description of rocks and hydrothermal precipitates ....................................40 1.4.6 Fluid chemistry...................................................................................................42 1.4.6.1 Sampling and analytical methods................................................................42 1.4.6.2 Analytical procedures on‐board ..................................................................46 1.4.6.3 First results ......................................................................................................47 1.4.6.4 Sulfur Chemistry ............................................................................................52 1.4.6.5 Isotope ratios of oxygen, hydrogen, and carbon .......................................54 1.4.7 Microbiology from diffuse and hot hydrothermal fluids.............................55 1.4.8 Hydrothermal Symbioses..................................................................................62 1.4.9 Metagenomics .....................................................................................................67 1.4.10 ROV deployments during HYDROMAR V........................................................68 1.5 Achnowledgements ...................................................................................................76 1.6 References....................................................................................................................76 1.7 Appendix .....................................................................................................................78 1.7.1 Extended list of operations ...............................................................................79 1.7.2 Fluid chemistry results and subsamples.........................................................91 page ‐ 2 ‐ Cruise Report HYDROMAR V (04.12.07 – 02.01.08) l’Atalante Summary The overall goal of this leg – conducted under the auspices of the DFG SPP 1144 – is the investigation of causes for temporal and spatial compositional differences of hydrothermal fluids and their effect on the vent communities in the Logatchev hydrothermal field. To achieve this goal, the Logatchev field located at the Mid‐Atlantic Ridge at ~15°N and ~45°W has been, and will be, visited annually since 2004 during the HYDROMAR I‐IV expeditions in the last years and during this cruise in December 2007. The original scientific program was scheduled for 18 working days. The problems with the research vessel MARIA S. MERIAN resulted in a shortening of the working time for the 4 proposals that were rescheduled onto the French research vessel ATALANTE. We therefore anticipated 12 working days for our program. However, due to a heart attack of a crewmember at Christmas Eve the scientific program had to be stopped early after only 9 working days considerably affecting the scientific program. Taking the unexpected short time of 9 days of station work cruise HYDROMAR V with RV “L’Atalante” and ROV “Kiel 6000” was still successful. We had no downtime of the ROV due to repairs and were able to achieve 8 dives during 8 consecutive days totalling 53 hours of bottom time. Weather conditions (up to seastate 6‐7) precluded recovery of the instrument at night for the first couple of days limiting the time available at the seafloor for those first days. Problems with the Posidonia subpositioning systems on board the Atalante or between Atalante and the ROV Kiel 6000 prevented accurate positioning during most dives. However, localization was possible because of our precise knowledge of the hydrothermal field based on the excellent subpositioning during cruise MSM04/3 in January 2007 using the ROV Jason 2. Due to the overall time limitations of the cruise several geophysical monitoring instruments, previously deployed during MSM04/3 could not be recovered due to time limitations. Also instruments and an additional mooring that should have been installed during this cruise could not be deployed. A major drawback to the scientific program was our inability to deploy the 720 m profiling mooring because of the emergency transit to French‐Guayana. At specific sites around the hydrothermal field we deployed 4 seismometers to monitor local seismicity. These seismoneters will be collected on a later cruise of the SPP1144. Additionally, an ocean bottom tiltmeter (OBT) and an ocean bottom accelerometer (OBA) were deployed at Logatchev itself and will allow the correlation of regional and local seismicity to seafloor movements at the black smoker vents. Two high‐ temperature monitoring recorders are now deployed at two different vent sites and will monitor changes at two different sampling rates (1s for 1 month and 15s for a longer period), it will now be possible to relate changes in hydrothermal activity and vent exit temperature to tectonic processes. The hydrothermal plume as well as low‐ and high‐ temperature hydrothermal fluids have been sampled successfully, as have been the vertical temperature gradients in low‐temperature diffuse discharge areas. Temperature measurements at individual sites show a pronounced increase in vent fluid page ‐ 3 ‐ Cruise Report HYDROMAR V (04.12.07 – 02.01.08) l’Atalante temperatures (353°C to 375°C) when compared to earlier years and even to the last SPP1144 cruise that took place in January 2007. We have to wait for the on‐shore geochemical analyses of the vent fluids in order to see if there are major chemical changes of the vent fluids associated with this increase. On‐board analyses of the Cl‐ concentration (Clmin=540mM Cl) reveal no changes to previous measurements indicating that no significant change in the chlorinity has taken place. Another major focus was the sampling of the vent biota, which, due to the limited time on site, recovered less material than originally anticipated. Preliminary data suggest that two different populations are present at the two major working sites Irina 2 and Quest. The gills, foot and gonads of most of the specimens collected vary distinclty between the two sites. Plume surveys were repeatedly performed at the same sites to investigate plume behavior over time and with changing tides. One of the major outcomes of this study was the variability of the plume height above ground. Within 8 hours the plume maximum was recorded at water depths of 2700m and 3000m respectively, a difference of 300 m. This indicates the strong influence of bottom currents and tides on the plume dispersal at Logatchev. During this cruise we deploy an ADCP on a tripod in the immediate vicinity of a black smoker site, measuring local bottom currents and recording plume behavior for 7 days. Preliminary analyses of this unique data set show the strong tidal variations of the bottom currents affecting plume dispersal. page ‐ 4 ‐ Cruise Report HYDROMAR V (04.12.07 – 02.01.08) l’Atalante 1.1 Participants Atalante cruise Hydromar V 1. Dr. Sven Petersen Chief Scientist IFM‐GEOMAR 2. Nico Augustin Geology IFM‐GEOMAR 3. Uwe Koy Physic. Oceanography IFM‐GEOMAR 4. Martin Vogt Physic. Oceanography IFM‐GEOMAR 5. Claudia Denker Physic. Oceanography IFM‐GEOMAR 6. Dr. Robin Keir Gas chemistry IFM‐GEOMAR 7. Peggy Wefers Gas chemistry IFM‐GEOMAR 8. Kerstin Claudia Buller Gas chemistry IFM‐GEOMAR