On the MOSES cruise Sternfahrt_1 water samples were taken on 8 stations. Samples were exchanged between the institutes Alfred-Wegener-Institut Zentrum für Polar- und Meeresforschung (AWI), Helmholtz Centre for Ocean Research Kiel (Geomar) and Helmholtz-Zentrum Geesthacht Centre for Materials and Coastal Research (HZG) for later comparison of the nutrient data.

Preparation and analysis of nutrient samples: For this comparison of nutrient data, three aliquots of one water sample were processed as indicated below, resulting in one set of samples for the Alfred-Wegener-Institut Zentrum für Polar- und Meeresforschung (AWI), one for Helmholtz Centre for Ocean Research Kiel (Geomar) and one for Helmholtz-Zentrum Geesthacht Centre for Materials and Coastal Research (HZG). Each set of samples was than analyzed in the respective laboratories. 1) AWI (I. Bussmann, I. Stimac) Water samples were drawn from a Niskin bottle into 0.5 L Nalgene bottles which had been rinsed with sample water. From these bottles water was filtered directly into 15 ml Falcon tubes and frozen at -20°C. Filters were syringe filters, SFCA, 0.2µm, 25 mm, Fisher Scientific. Samples were analyzed with a QuAAtro autoanlyzer according the manufacturer's instruction: for nitrite with the method No. Q-070-05 Rev. 4, for nitrate and nitrite with Method No. Q-068-05 Rev. 6, phosphate with the method No. Q-064-05 Rev. 4, ammonia with the method no. Q-080-06 Rev. 2, and silicate with the method No. Q-066-05 Rev. 3. 2) Geomar (M. Nehir) Water samples for inorganic nutrients (nitrate/nitrite, phosphate, and silicate) were taken from ta Niskin bottle. During sampling, latex gloves were worn to avoid contamination. A pre-rinsed Pall AcroPak 1000 Supor Membrane 0.8/0.2 μm filter (with prefilter) was used to transfer samples into acid washed (10% HCl) 50 ml polypropylene conical centrifuge tubes from Jet Biofil. Samples were kept frozen (-20 °C) until the laboratory analysis, then analyzed at GEOMAR using a SEAL QuAAtro AutoAnalyzer (SEAL Analytical) that is based on the colorimetric methods. 3) HZG (G.Flöser, H. Rust) Samples were filtered with syringe and filters (Spartan 30/0.2 RC 0.2 µm. Whatman) into 50 or 100ml PE bottles. The samples were frozen at -20°C and stored frozen until analysis. Samples were analyzed with an Autoanalyzer (Seal X-Y-2 Sampler AA3, Seal Analytics) according to the manufacturer's instructions: for nitrite with method G-062-92 Rev 2, for ammonium with method G-171-96 Rev 14, for phosphate with method G-170-96 Rev 1 and silicate with method G-177-96 Rev 8.