Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Alkor	AL595	31.05.2023 - 20.06.2023		North Sea Iceland Sea North Atlantic Ocean

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Holz Sebastian	Helmholtz Centre for Ocean Research Kiel (Eastshore campus) (GEOMAR)	Kiel	Kiel

Ziel der Reise / Objectives of Cruise:

In order to better understand the geological framework of the working area and to facilitate the interpretation of the previously acquired geophysical and geological data, we proposed to perform AUV tests in a working area. While our first results of electromagnetic methods in combination with heat flow measurements, gravity coring and fluid sampling from previous cruises hinted towards a potential massive mineralization within the seafloor to the West of the active GVF, the interpretation was limited by the rather low-resolution of the currently available bathymetry (10m lateral resolution) and the lack of visual coverage. Consequently, the testing of AUVs at greater water depths was also aiming to yield scientifically meaningful data valuable for the interpretation of our previous experiments by allowing for an improved structural interpretation (high-resolution bathymetry, photogrammetry). Additionally, a high-resolution bathymetry would also be essential for planning of target-oriented drilling in the scope of a potential future MeBo drilling proposal. Generally, complex measurement platforms like GEOMAR's recently acquired Hover-AUVs Anton & Luise require substantial testing in suitable working areas in order to be successfully integrated into an institute's infrastructure. Therefore, AUV testing and measurements focused on the following goals: - operation of AUVs close to the maximum operational depths of 500m, - operation of AUVs in stationary LBL network, - acquisition of high-resolution bathymetry (~50cm lateral resolution or better on an area of approximately 2km²), - acquisition of additional data with external sensors (e.g. photogrammetry, magnetics) and other available sensors. The acquisition of magnetic data was considered as a low priority task and - in the end - was not carried out because AUV Luise was not operational during the last days of the cruise. We also aim to broaden the scope of investigations to include methods, which have previously not been performed in the working area or have never been published. With its extensive subsurface boiling system emitting gas-charged bubbles and fluid-sediment interactions with methane and higher hydrocarbon enrichments, the vent field marks an ideal site for studying microbial life, its adaptations and development. To our knowledge, the last and only microbial study at the GVF was carried out more than 20 years ago (cruises POS253 & POS291) and results have only been published as part of a PhD thesis. Therefore, the substantial methodological and scientific advances of life sciences in the past decades have not been applied to microbial communities at the GVF. The proposed microbial studies aim to perform a baseline study on microbial activity in the shallow sediments (<3m) to be sampled with MUC, GC and BIGO lander. More specifically, microbes from the three domains of life - eukaryotes, bacteria and archaea - will be sampled. Coordinated sampling of these communities is still rare, and we are yet to understand the full biogeochemical processing and microbial exchanges, as well as gaining new insights into evolution in deep time. For this, integrated studies are essential. To this end, we will perform DNA and - if sufficient biomass is available - RNA extraction and illumina sequencing of 16S RNA gene (bacteria and archaea) and 18S rRNA (eukaryotes) amplicon sequencing for analyses of the microbial community. Omic tools can be applied to these samples within other research projects. Enrichment cultures will be set up targeting chemosynthetic microorganisms and heterotrophs producing natural products. This study will provide a good frame work for later in depth and extensive analyses of bio-geo-coupling processes based on in-situ experiments. Results will contribute to the Helmholtz InnoPool project "High CO2 - metabolic responses and bioeconomic opportunities".

Messungen / Measurements