This data is part of the BMBF project CUSCO (Coastal Upwelling Systems in a Changing Ocean). Here we report the dissolved organic carbon and total dissolved nitrogen concentrations during a 35-day experiment, where we enclosed natural plankton communities in in-situ mesocosms off Peru. The experiment investigated the interactive effects of light and upwelling on the Humboldt upwelling ecosystem by mimicking a gradient of upwelling intensities (0%, 15%, 30%, 45% and 60%) under summer-time high light and winter-time low light. Integrated seawater samples from a depth between 0 and 10m were collected using a 5L Integrating Water sampler (IWS; Hydro-Bios, Kiel). Sub-samples (60 mL) were syringe filtered through two pre-combusted glass fiber filters (5 h, 450 °C). To reduce clogging, one 3.1 µm GMF filter was placed on top of a 0.7 µm GFF filter. The filtrate was acidified to pH 2 with 25% HCl before storing at -20°C until analysis. The DOC and TDN concentrations were measured using a TOC-VCPH analyser (Shimadzu). Instrument accuracy was evaluated by comparison against a deep Atlantic seawater reference (Consensus Reference Material project: D. Hansell, University of Miami, USA).

Mesocosm 10 describes the control sample from the Pacific