During the RV Polarstern cruise ARK-XXVII/3 to the Arctic Ocean in summer 2012, when sea ice declined to a record minimum bottom, sediments were collected with a TV-guided multicorer at stations in the Nansen and Amundsen basin. Chlorophyll a and phaeopigments were extracted from sediments with acetone using three replicates per station. The concentrations in the acidified supernatants were measured with a Turner Trilogy fluorometer (Boetius and Damm, 1998). The sum of chlorophyll a and phaeopigments is expressed as chloroplast pigment equivalents (CPE) (Thiel, 1982).
This is a contribution to the European Research Council Advanced Investigator Grant 294757 to Antje Boetius.