210Po/210Pb dynamics in relation to zooplankton biomass and trophic conditions during an annual cycle in northwestern Mediterranean coastal waters

► This a one year sampling of zooplankton and water at 3 different depths to study 210Po and 210Pb in them. ► A zooplankton bloom was present in May after an extended period of a higher primary productivity proxy. ► An inverse trend was found for 210Po in zooplankton and water or the dissolved phase. ► Maximum zooplankton biomass showed minimum 210Po in zooplankton and a maximum in the dissolved phase. ► A dilution phenomenon is present in zooplankton and water, depending zooplankton or particle concentration.