Suspended matter fatty acid composition, nitrogen stable isotope ratios and diatom dominance of the phytoplankton community during the mesocosm experiment in the Canary Islands in autumn 2018. Depth-integrated (0-14 m) water samples were filtered (>0.7µm). Chlorophyll a is based on HPLC. Particulate organic matter C, N and δ15N were measured with an element analyser and mass spectrometer. Diatom biovolume was measured by flow imaging analysis. Fatty acids (FA) composition of particulate matter was determined by gas chromatography. The upwelling treatment started on day 4. Methodological details in Ortiz et al. (2022) (doi:10.3389/fmars.2021.7431059), Baumann et al. (2021) (doi:10.3389/fmars.2021.742142) and Goldenberg et al. (under review).