Analysis of particulate organic carbon, nitrogen and phosphorus in Antarctic phytoplankton in response to temperature and nitrogen:phosphorus supply interactions

Data were obtained from a laboratory growth experiment conducted from April to May 2021 at the Institute for Chemistry and Biology of the Marine Environment (University of Oldenburg). Three Antarctic phytoplankton species (Chaetoceros simplex, Phaeocystis antarctica (single cell culture) and Geminigera cryophila) were grown in monocultures and a mixture of all three species. We used a factorial design including four different N/P treatments (control plus three different N/P levels) and 10 different temperatures (-2, -1, 0, 1, 2, 3, 4, 6, 8 and 10°C). The detailed experimental setup is explained in doi:10.1594/PANGAEA.971329. In order to determine the effect of temperature and nutrient interactions on the stoichiometry of the Antarctic phytoplankton species used in the experiment, 2 x 50 ml from each culture were sampled at the end of the experiment and filtered onto acid washed and pre-combusted glass-fibre filters (GF/C, Whatman, UK). One filter was used for particulate organic carbon (C) and nitrogen (N), the second filter for particulate organic phosphorus (P). After sampling, all filters were stored at -20 °C. Prior to the measurements, the CN filters were dried at 60 °C for seven days, placed in tin capsules, and measured using an HCN elemental analyser (Flash EA 1112; Thermo Scientific, Walthmann, MA, USA). After the P filters were combusted at 450 °C for 4.5 hours, particulate organic phosphorus (POP) was measured photometrically by a molybdate reaction after heat digestion at 90 °C with potassium peroxydisulfate (K₂S₂O₈) solution (Wetzel and Likens, 2000).