KOSMOS mesocosm experiment Gran Canaria 2019 on testing the effect of nutrient composition (Si:N) during artificial upwelling: phytoplankton microscopy

Abundance and biovolume data of the community of larger phytoplankton from the mesocosm experiment conducted in the Canary Islands in autumn 2019. Depth-integrated (0-2.5m) water samples were taken in 2-days intervals over the course of 33 days and autotrophic taxa assessed to the lowest taxonomic level possible using Utermöhl microscopy. Only taxa larger than approx. >5 µm could be considered with this method. Biovolume was calculated based on geometrical measurements (dominant taxa) or the literature (rare taxa). Carbon biomass estimates were purposefully not provided, as the standard literature conversion factors from biovolume to carbon biomass did not apply to many of our samples, likely due to low carbon density within cells. Predominantly mixotrophic or heterotrophic taxa are not provided in this dataset. The upwelling treatment started on day 6. Methodological details in Goldenberg et al. (doi:10.3389/fmars.2022.1015188).