1. Biologische Anstalt Helgoland Alfred-Wegener-Institut The Helgoland biological-oceanographical time-series Helgoland Reede Station (54 o 11.3’N, 7 o 54.0’E) water depth 6 - 8.5 m (tidal) Helgoland Transects (Central German Bight) Renate Scharek, Silvia Janisch, Peter Mangelsdorf, Christian Schütt, Hilke Döpke, Karl-Walter Klings, Gunnar Gerdts, Antje Wichels, Gerrit Sahling

2. Location of Helgoland and “Helgoland Reede“ sampling site in the German Bight of the North Sea

3. Aerial view

4. Compilation

5. The three Helgoland Phytoplankton Transects consist of six stations each River Elbe River Eider

6. Vessells serving the “Helgoland Reede” and the “Helgoland transects” time-series “Aade““Uthörn”

7. Annual medians of concentrations of phosphate, nitrate and phytoplankton carbon on “Helgoland Reede“ from 1962 till 1994

8. Monthly medians of salinity, concentrations of silicate, phosphate and nitrate on “Helgoland Reede“ from 1995 till 1999

9. Monthly medians of phytoplankton carbon, devided into diatom carbon and flagellate carbon (below) on “Helgoland Reede“ from 1995 till 1998

10. On “Helgoland Reede” a clear seasonality can be observed in temperature, salinity, nutrient concentrations, phytoplankton stocks and species composition. However, also in apparent bacterial diversity, as investigated by Denaturing-Gradient-Gel- Electrophoresis patterns (DGGE), seasonally dependent diversity of planktonic marine bacteria can be detected (Schütt et al. unpublished).