Ecological study of gas fields in the northern Adriatic. 7. Thermohaline and optical properties

Abstract

       The seasonal variability of the northern Adriatic is examined using in-situ temperature, salinity, density, transparency, color and turbidity data. The in-situ data consist of regional his­torical data and ships from the period 1911-1986 and platforms data collected in the IVANA and IKA gas fields during 1978-1986.

       The main characteristic of this area was the vertical homogeneity in winter and a very sta­ble stratification in summer. In the IVANA field, vertical mixing was more intensive than in IKA field. Salinity range was much higher in IVANA, due to a stronger influence of the fresh-water inflows brought by the Po river. In the surface layer two minima and two maxima of salinity occur in a year.

       Density follows the variations in temperature and salinity but sometimes was rather due to temperature variations.

      Transparency, turbidity and color of the sea were under the influence of the river inflows from the western coast (particularly the IVANA field), and also under the influences from the Istra coast. Considerable seasonal variations of optical properties were caused by biological phyto­plankton cycles, river inflows and seasonal dynamics.