| Summary: | Progress Code: completed Statement: These data are considered to be of high quality. Purpose This is an antFOCE dataset, collected in order to determine community composition from a pigment perspective. General description: The associated file contains sediment pigment data from the antFOCE project 4127. Units: all pigment data in ug/g, 0 = below detection limit of HPLC. Sample collection details: At the start and end of the antFOCE experiment, four sediment core samples were taken from inside and outside each chamber or open plot by divers. The top 1 cm of the cores was then removed and placed in the dark, first at -20ºC for 2 hours, then at -80ºC until analysis at the Australian Antarctic division. Pigment analysis Frozen samples were transported under liquid N2 to a freeze drier (Dynavac, model FD-5), in pre-chilled flasks with a small amount of liquid N2 added. Custom made plumbing fitted to the freeze drier enabled samples to be purged with N2 to prevent photo-oxidation up until solvent extraction. Prior to pigment extraction five 2 g stainless steel ball bearings were added to homogenise the freeze dried sediment. The samples were bead beaten for 1 minute (Biospec products). Subsamples (~0.05 g) were immediately transferred to cryotubes with 700 µl of dimethylformamide (DMF) for two hours. Samples were kept at -80ºC and under a safe light (IFORD 902) at all times. All pigment concentrations are standardised to sediment weight. Pigments were extracted with dimethylformamide (DMF 700 µl) over a two hour period at -20ºC. Zirconia beads, and 100 µl of Apo 8 and an internal standard were added to each sub-sample. After a two hour extraction, sub-samples were bead beaten for 20 seconds and then placed in a centrifuge with filter cartridge inserts for 14 minutes at 2500 rpm at -9ºC to separate the solvent from the sediment. The supernatant was transferred into to a vial and placed in a precooled rpHPLC autosampler. The rpHPLC system used is described in Hodgson et al. (1997). Pigment detection was at 435, ...
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