Approximately rectangular in shape, the Gulf of Trieste (Fig. 1) is the northernmost gulf of the enclosed Adriatic Sea, with an average depth of ,20 m, a surface area of 600 km2 and a volume of 9.5 km3. Freshwater inputs are larger along the northern than the southern coast, approx. annual rate of flow of 90– 130 m3/s, and peaks of over 1000 m3/s, when compared with 5–10 m3/s and peaks up to 100 m3/s (Mozeticˇ et al., 1998), respectively. The structure of the water column and water movements vary greatly with dominant seasonal influences.