Bodur, Yasemin

Janssen, Felix

Molari, Massimiliano

Otte, Julia M.

Volz, Jessica

Wenzhöfer, Frank

Yapan, Batuhan C.

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 Background & Summary  Manganese (Mn) nodules contain Ni, Co, Cu, Mn, Fe, and rare earth elements.   The environmental impacts of large-scale deep-sea nodule mining are currently unknown.   In Feb.-May 2019 (RV SONNE cruise SO268, Mining Impact II) the Belgian & German licence area in the Clarion-Clipperton Zone (CCZ; Eastern Pacific) were studied to obtain baseline characteristics of the > 4000 m deep habitat.  Research aspects: i) characterization of the distinct present & active microbial and viral communities of bottom water (> 4000 m deep), (< 5 m deep) seafloor sediment, and Mn nodules, ii) diversity and distribution of potential deep-sea cable bacteria and metal-cycling microorganisms, iii) enrichment of Mn-/Fe-cycling bacteria, iv) investigation of deep-sea microbial metabolisms by metagenomic/-transcriptomic, v) quantification of microbial extracellular enzyme activity & cell number, and vi) analysis of (bio-/)geochemistry  In summary, the potential consequences associated with removal of Mn nodules and resuspension of sediments during mining could help to evaluate the environmental risks.  To quantify microbial & viral community composition by Illumina 16S rRNA sequencing (RNA & DNA based) from ≤ 100 Mn nodules and eight 5 m long gravity cores from the CCZ.  To follow the distribution, quantify the abundance, detect the diversity and activity of relevant metal-cycling microorganisms, and as well of potential deep seafloor cable bacteria.  To enrich potential Mn- and Fe-cycling microorganisms from “live” sediment & “live” Mn nodules under (an)oxic conditions.  To evaluate microbial activity by extracellular enzyme activity.  To investigate microbial metabolism of potential Mn- and Fe-cycling microbes by metagenomics /metatranscriptomics.  To compare metal-cycler of different locations (a) Mn nodule areas (CCZ/DISCOL), (b) massive sulfide deposit (Indian Ocean). Main Goals Microbial and viral communities of the deep seafloor sediment and manganese nodules from the CCZ, Pacific   J. M. OTTE1,2,3, M. MOLARI1,3, B. C. YAPAN1,3, J. B. VOLZ2, Y. BODUR1,3, F. JANSSEN1,2,3, F. WENZHÖFER1,2,3  1HGF MPG Group on Deep Sea Ecology and Technology; 2 Alfred-Wegener-Institute Helmholtz Centre for Polar  and Marine Research, Germany; 3 Max-Planck-Institute for Marine Microbiology, Germany  Thanks to HGF Group Bremen and Bremerhaven; Crew and Scientists of SO268; Special thanks to Jakob Barz (help in the lab) and Dr. Katja Laufer, Geomar (ideas & discussions) Deployments during SO268 German Claim (BGR) Belgium Claim (GSR) Manganese (Mn) Nodules                                    Gravity Core Sediment    5 m long gravity cores (GC) from eight different locations of the CCZ  Differences in O2 penetration depth (around 2-3.5 m; oxic and suboxic layers)   8 to 27 samples per GC core, taken at 0-5 m depth; stored at -20°C and -80°C  Preliminary enzyme activity results of an oxic GC (GSR) from a carst region: Aminopeptidase activity until 40 ± 5 cm depth→ detectable active Corg degradation    ≤ 100 Mn nodules from BGR & GSR and different depth (~0.5 cm)  Differences in volume (17 - 640 cm3), weight (30 - 960 g), shape (round or elliptical), porosity, attached fauna  Subsamples from on top of the nodule surface (a), bottom side (b), inside of the nodule core (c), 3 samples per nodule for DNA & RNA extraction; enzyme activity tests; cell counts Surface Bottom Sediment Field Sites – Clarion-Clipperton Fracture Zone (Eastern Pacific Ocean) After Volz et al., submitted Volz et al., 2018    Suboxic >0.5m, Mn2+ peak  POC flux: 2 mg m-2 d-1  NO3- reduction     Oxic, no Mn2+   POC flux: 1.5 mg m-2 d-1  Constant NO3- Preliminary Results – Microbial Activity of Manganese Nodules    High unexpected activity in & on Mn nodules!  β-Glucosidase: degradation of oligosaccharides  Chitobiase: degradation of chitin   Micro-habitat of Mn nodules may be a potential major location of microbial Corg degradation   Implication: what happens after mining operations when Mn nodules are removed?   Open question: who are the active players which are responsible for Corg degradation in &on nodules?     Activity: surface layer > bottom layer   Highest activity on nodule surface of BGR Ref.:  > 1.6 µM/h; nodule core: 0.3 µM/h    Activity: deep-sea sediment > Mn nodule 2.0 Extracellular enzyme activity (µM/h) 1.5 1.0 0.5 Layers Surface Bottom Core Sediment Bottom water Chitin (polymer of β-(1-4)-linked N-acetyl-β-glucosamine) Cellulose (polymer of β-(1-4)-linked glucosyl residues)   e.g. β-Glucosidase and Chitobiase Mn nodule surface Mn nodule core Mn nodule bottom * Not scaled* Sponge Ophiuroid Sampling locations of cruises SO239 & SO268 *ROV 6000, Geomar, Kiel is not shown* Working on board during SO268 Microbe BGR Ref. BGR Trial GSR Ref. GSR Trial 

Microbial and viral communities of the deep seafloor sediment and manganese nodules from the CCZ, Pacific

https://epic.awi.de/id/eprint/50273/1/Poster.pdf

Microbial and viral communities of the deep seafloor sediment and manganese nodules from the CCZ, Pacific

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