Biotic water-column characteristics for stations from the North-Western Weddell Sea, Bransfield Strait, and Drake Passage (POLARSTERN cruise PS 81, ANT-XXIX/3, January-March 2013)

Around the Antarctic Peninsula (North-Western Weddell Sea, Bransfield Strait, Drake Passage) water samples for measurements of chlorophyll-a were collected with Niskin bottles mounted on a CTD rosette. At each station samples were taken at two depths, the chlorophyll-a maximum (Cmax, defined as the water depth with maximum fluorescence detected during in-situ profiles) and close to the seafloor (bottom). Water samples were poured over a 100-µm sieve to remove larger particles and filtered over glass fibre filters GF/C at approximately 250 mbar. Colouring of filters determined the amount of sea water used (3–5l). Filters were stored at −80°C. Chloroplastic pigments were extracted with 10ml acetone (90%), determined using a fluorimeter and expressed in µg/l. For details see Hauquier et al. (2015) and Veit-Köhler et al. (2018).