Metabarcoding analysis of a 48 sample time series from Jan 2011 to Dec 2013 targeting 18S V4 rRNA of Eukaryotic plankton from the Long-Term Ecological Research site MareChiara (LTER-MC) in the Gulf of Naples, Mediterranean Sea. For DNA extraction, about 3 liters of surface sea-water sample (0.5 m) was filtered under mild pressure on each of two cellulose ester filters (47 mm diameter, 1.2 µm pore-size, EMD Millipore, USA). Filters were stored at -80°C. Nextera dual index approach and 2 × 250 bp were applied for V4 region sequencing on a MiSeq platform.