ADRIATIC SEA HYDROGRAPHY

This paper is intended as a short summary of 20 years of research on t he Adriatic Sea carried out by the Oceanography Department of IRPeM-CN R. The objective is to give a general overview of the sea and describe the environment in which anchovies live. The Adriatic Sea is a narrow basin elongated from north-west to south-east for about 800 km with a maximum width of 200 km at Bari and a minimum width of 100 km in fron t of Rimini. It communicates with the Ionian Sea through the Otranto S traits (74 km wide and 800 m sill depth). It is the most continental s ub-basin of the Mediterranean, defined between two mountain chains: th e Apennins to the west side and the Dinaric Alp and Balkans to the eas t. The Adriatic can be divided into three distinct sub-basins: Norther n, Middle and Southern. Due to the geographical position, its orograph y and bathymetry, the Adriatic Sea hydrography Is strongly influenced by meteorological conditions, particularly in the north. Climatologica lly, temper ature variations greater than 20 degrees C are observed be tween winter and summer, and about 8 degrees C from north to south in winter, as well as a salinity gradient of about 3 psu (practical salin ity unit) between the western coastal water and the offshore water. In terannual variability has been evident from the first systematic ocean ographic observations of this sea and is remarkable. There are three p rincipal water masses in the Adriatic Sea: the Adriatic Surface Water (AdSW), the Levantine Intermediate Water (LIW) and the Adriatic Deep W ater (AdDW) (every sub-basin has its own characteristic deep water). T he general circulation is cyclonic with a now towards the northwest al ong the eastern side and a return flow towards the southeast along the western side. The circulation in the three sub-basins is often domina ted by their own cyclonic gyres that vary in intensity according to th e season. The sub-gyre of the southern Adriatic tends to persist throu ghout the year. The sub-eyre of the middle Adriatic is more pronounced in summer and autumn, while in the north, a cyclonic gyre is evident, in front of the Po river mouth, only in autumn.