FS Meteor M137
Cruise summary report
| Cruise Info. | |
| Ship name (ship code) | FS Meteor (06M3) |
| Cruise identifier | M137 |
| Cruise period | 2017-05-06 — 2017-05-29 |
| Status | Completed |
| Port of departure | Callao, Peru |
| Port of return | Callao, Peru |
| Purpose | Research |
| Objectives | Collaborative Research Centre 754 "Climate - Biogeochemistry Interactions in the Tropical Ocean"
Objectives a. To experimentally elucidate the magnitude and pathways of benthic nutrient fluxes (N, P, Fe, other trace metals) in response to the sustained availability of bottom water NO3- and O2. The results will be linked to time series of O2, NO3-, and NO2- in order to allow for a better up-scaling and predictive capability of the benthic-pelagic coupling in the Peruvian OMZ at seasonal and inter-annual time scales. b. To what extent are benthic N, P and S fluxes coupled and controlled by filamentous sulfide oxidizing bacteria Beggiatoa and Thioploca as well as by denitrifying foraminifera? This involves the determination of the turnover of the internal NO3-/NO2- pools in foraminifera and filamentous sulfur bacteria in response to changing bottom water levels of electron acceptors. It will be determined to what extent foraminifera and sulfur bacteria compete for NO3- and NO2- resulting into the prevalence of fixed N loss versus recycling. It further encompasses genetic studies of foraminifera as well as studies about the phosphate pools in both groups. c. Another important goal of the ex situ and in situ experiment series was to determine the timing and magnitude of sulfidic events after stepwise depletion of O2, NO3- and NO2- in the bottom water. These studies encompass the determination of the capacity of bacteria and foraminifera to survive conditions of bottom water depleted in O2, NO3- and NO2-. d. To quantify benthic and pelagic cycling of nutrients and trace metals in the OMZ by budgeting physical fluxes of solutes including turbulent-, lateral-diffusive- and advective fluxes in the water column combined with benthic flux measurements during austral winter. The measurement program focused on quantifying diapycnal solute fluxes due to turbulent mixing in the water column and particularly in the bottom boundary layer. The findings will be compared to the results from the M92 cruise in austral summer to assess the impact of seasonal changes in stratification on the generation of non-linear internal waves. Observations of the large-scale boundary circulation and water column nutrient and trace metal distributions will allow the quantification of advective nutrient and trace metal fluxes. e. The water-column measurement program additionally focused on lateral-diffusive fluxes of nutrients and trace metals by mesoscale eddies and their role in the nutrient budget. Eddies may transport nutrients, trace metals as well as significant amounts of particulate organic matter offshore. |
| Chief scientist | Stefan Sommer (GEOMAR Helmholtz Centre for Ocean Research, Kiel (West Shore Campus)) |
| Project | GEOTRACES -Trace elements and their isotopes in the water column |
| Cruise report |  (0.44 MB) |
| Ocean/sea areas | |
| General | South East Pacific Ocean (limit 140W) |
| Specific | Peruvian oxygen minimum zone |
| Track charts | (0.27 MB) |
