The Mar Piccolo of Taranto is located North of the town of Taranto (Fig. 1) and has a surface area of 20.72 km2. It is an inner, semi-enclosed basin with lagoon features divided by two rocky promontories into two inlets, called First Inlet (Primo Seno) and Second Inlet (Secondo Seno) which have a maximum depth of 13 and 8 m, respectively. The Mar Piccolo is connected with the Mar Grande through two channels, the Navigabile channel and the Porta Napoli channel, of which only the former is important for the water exchange in the basin. Tidal range does not exceed 30-40 cm. The presence of both 34 submarine freshwater springs (locally called "Citri") and the outfalls of small tributary rivers influence the salinity (Pastore, 1993). The scarce hydrodynamism and the reduced water exchange with the nearby Mar Grande determine, mainly in summer, a high water stratification.