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Meteor-Blog 8. August 2008: Premiere for Eddy: in situ measurements at REGAB

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in situ measurements of chemical fluxes or biorespiration are one major research focus during GUINECO cruise onboard Meteor. Head scientist Prof. Antje Boetius today describes the first deep sea deployment of the EDDY System. EDDY determines via oxygen respiration rates the activity of the local different microbial and faunal communities are.

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Does the biodiversity of deep-sea organisms play a role for the climate on Planet Earth? Questions all about marine research will be answered directly aboard of the German research vessel Meteor by cruise leader Prof. Antje Boetius and her crew. In cooperation with the geoportal from 17.08.08 to 24.08.08 they contribute a Science-Blog of METEOR expedition M76/3 GUINECO – MARUM research of fluid and gas seeps on the Westafrican continental margin. Technical highlight of the cruise is the remote-controlled under water robot QUEST4000 by MARUM that will be deployed for taking fauna and sediments samples and conduction of in situ experiments. Go on a dive down to places no other human being has ever seen before: explore the fascinating deep-sea fauna and watch the scientists’ work at gas and fluid seeps deep down on the ocean bottom.

Expedition M76/3b is a collaboration of MARUM – Center for Marine Environmental Sciences at Bremen University and its associated institutes MPI and AWI as well as the French research institute IFREMER and the University of Paris.

More Informationen of the Meteor-Blog, an overview of all contributions to the blog and expedition M76/3B:

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8. August 2008 (Author: Antje Boetius)

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Premiere for Eddy: in situ measurements at REGAB

Antje Boetius: Mit PC auf DeckThe author Antje Boetius has introduced herself in the BLOG of 25 July.

8. August: shiptrackAfter several delays due to necessary repairs on the ROV we have deployed the lift with lots of instruments: the microprofiler measuring sulfide and oxygen fluxes as well as pH and temperature with microsensors (see BLOG of 26 July for further explanation), and the Eddy system for integrated benthic community respiration. This system is composed of an instrument measuring the bottom current velocity and an oxygen sensor measuring even tiny variations in oxygen concentrations. From these measures, the total benthic community respiration can be calculated, integrated over 10-100 square meters of ocean floor. Benthic community respiration is an important measure for the activity of a benthic community, and can be converted to CO2 fluxes. We will try here for the first time if this measure is useful in deep-sea habitats, and we try to calibrate it with parallel benthic chamber incubations, a classical method for measuring benthic respiration.

8. August: Bild 1

Picture 1: Taking INSINK close to a mussel bed. Gas release was observed during sampling.

Today’s dive also provided us with the first in situ measures of microbial activity at the REGAB seafloor. We used the in situ incubation system INSINK to assess microbial respiration of sulfate in the highly gassy sediments associated with mussel beds (Figure 1). Especially with gassy sediments, measurements on board are problematic because the gas expands dramatically upon pressure release during core recovery.

8. August: Bild 2Picture 2: Eddy measurement on the mussel bed associated with outcropping hydrate in the central pockmark (target 18)

Also we deployed the Eddy system on three different locations to measure integrated benthic oxygen consumption: 1) on the central pockmark site comprising hilly carbonate layers overgrown by mussels associated with outcropping hydrates and surrounded by tubeworm bushes (Figure 2),8. August: Bild 3 2) in the south of the carbonate platform facing a flat sedimentary area with patches of vesicomyid bivalves (Figure 3), and 3) in the same area but facing mussel beds on highly gassy sediments. In addition, we deployed the microprofiler close to and away from a larger patch of vesicomyid clams.

8. August: Bild 4Picture 3: Eddy measurement on the vesicomyid field

Picture 4: Taking push cores half a meter away from the mussel bed (marker 6).

It was possible to collect two sets of push cores, one ca. half a meter away from the mussel bed (Figure 4), and a second one on the vesicomyids, including the recovery of those cores we had left over from dive 221 because of an arm failure. Tonight the navigation worked really well and we were surprised how simple it was to find back the left over cores. Also, we sampled the mussels growing on the gassy seabed with a net for further analyses of the symbiotic mussels of REGAB (also see BLOG of 04 August).

8. August: Bild 5Picture 5: Closing the lift equipped with the micro- and xy-profiler as well as with the RCM

The third new instrument to be deployed, the xy-profiler measuring multiple microsensor profiles could not be started, and hence was collected early back into the lift (Picture 5). So far, this was our longest dive during this expedition and it was great to complete so many different tasks during one deployment. The problem with the oil leaks seems to have improved considerably, so we hope for a bit more luck for the remaining 10 days.

With many greetings

Antje Boetius