This IGA-HP Gravelines dataset includes long-term time series on marine phytoplankton, zooplankton, and hydrological data from 1978 onward at the coastal station named “canal d’Amenée” (in French) near the Gravelines Nuclear Power Plant located in the southern bight of the North Sea, near the Dover Strait (eastern English Channel). Phytoplankton data essentially cover microscopic taxonomic identifications and counts (cells.l-1), and pigment concentrations (Chlorophyll-a and pheopigment) (µg.l-1). Zooplankton data cover binocular microscope taxonomic identifications and counts (nb.m-3). Hydrological data include temperature (°C), salinity (PSU), turbidity (NTU), dissolved oxygen concentration (mg.l-1), and dissolved inorganic nutrient concentrations (ammonium, nitrite + nitrate, phosphate, silicate) (µmol.l-1).