Nutrient samples were frozen at -20˚C and transported to the home laboratory where they were measured using a QuAAtro gas segmented continuous flow analyzer (AutoAnalyzer) from SEAL Analytical. Particulate organic matter (POM) distribution in the water column was determined after filtration onto pre combusted, acid-washed GF/F filters (Franz et al., 2012a). For particulate organic carbon (POC) and particulate nitrogen (PN), filters were exposed to fuming hydrochloric acid for 12 h to remove carbonate and subsequently dried (60 °C, 12 h). Analyses were carried out with a Euro EA elemental analyser calibrated with an acetanilide standard. Particulate organic phosphorus (POP) collected on GF/F filters was determined colorimetrically as ortho-phosphate after potassium peroxydisulphate digestion following the method of Hansen and Koroleff (1999).

Winkler data are not finally cross checked