Underway water samples were drawn from the shipboard seawater pumping system, so these are near surface samples. Seawater was pumped in from the surface, through the underway flow through sysem while the ship was moving.
Algal HPLC pigment samples were collected by gentle filtration under low vacuum through GF/F filters and frozen in LN for on-shore analyses. Samples were extracted in 90% acetone and analyzed using a HP 1050 HPLC system equipped with autosampler, photodiode array and fluorescence detectors. The gradient elution program utilized was a slight modification of the Zapata et al. method (2000). Complete details of the HPLC method are described elsewhere (DiTullio and Geesey 2002). Replicate injections of standard pigments (purified from algal cultures in lab) produced a coefficient of variation of 3% with a limit of detection of approximately 1 ng.
References:
DiTullio, G.R., Geesey, M.E., 2002. Photosynthetic pigments in marine algae and bacteria. In: Bitton, G. (Ed.), The Encyclopedia of Environmental Microbiology. John Wiley & Sons, Inc., New York, NY, pp. 2453-2470.
Zapata, M., Rodriguez, F., Garrido, J.L., 2000. Separation of chlorophylls and carotenoids from marine phytoplankton: a new HPLC method using a reversed phase C8 column and pyridine-containing mobile phases. Marine Ecology Progress Series 195 (29-45).