This dataset includes measured and calculated data over the epi-mesopelagic layer (0-800 m depth) of 28 stations with 14 of them inside or in the vicinity of a cyclonic eddy that formed off Mauritania along the 900 km zonal corridor between Mauritania and the Cabo Verde islands in the eastern Tropical North Atlantic during the M156 cruise on the RV Meteor from July 3rd to August 1st 2019. Particulate organic carbon and nitrogen were analyzed according to Sharp (1974; https://doi.org/10.1371/journal.pone.0131538). Transparent exopolymer particles (TEP) and Coomassie blue stainable particle (CSP) were measured by the microscopic method after Engel et al. (2009; Determination of Marine Gel Particles , Practical guidelines for the analysis of seawater. / ed. by Oliver Wurl Boca Raton [u.a.] ; CRC Press, ISBN: 978-1-420-07306-5 ). spectral slope of the particle size distribution were calculated after Mari, X. and Kiørboe, T. (1996). Abundance, size distribution and bacterial coloniza− tion of transparent exopolymeric particles (TEP) during spring in the kattegat. J. Plankton Res., 18(6):969–986.