This data is part of the BMBF project CUSCO (Coastal Upwelling Systems in a Changing Ocean). Here we report oxygen primary production rates 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). Oxygen production as well as respiration rates were measured as described in Ortiz et al. (2022; doi:10.3389/fmars.2021.743105) using the Winkler method. For each mesocosm and sampling day samples for initial oxygen values fixed immediately after subsampling ("Initial"), dark incubations ("Dark") and light incubations ("Light") were measured. All samples were incubated with constant light dark/cycles and temperature was adjusted regularly to mesocosm values. After incubation samples were fixed and titrated by means of an automated, precise titration system with colorimetric end-point detection along with the initials (Dissolved Oxygen Analyzer, SIS Schwentinental, Germany). Community respiration (CR) was calculated as the oxygen consumption during dark incubation per hour. Net community production (NCP) was the oxygen production per hour in the light samples and gross production (GP) the sum of CR and NCP
