Long-term phytoplankton monitoring is key to understanding marine systems. This study presents a decade of observations along a coastal-offshore transect in the Strait of Dover using automated in vivo methods. Since 2012, phytoplankton groups have been analyzed via multi-spectral fluorometry and flow cytometry, alongside biogeochemical and hydrological measurements. This dataset offers valuable insights into phytoplankton dynamics and environmental drivers in a temperate coastal system.