Preliminary chemical and hydrological observations in the Ionian Sea

The paper contains the results of the investigation on nutrients and hydrological parameters at 11 stations at standard depths covering all the water column in the Ionian Sea in March 1983. The following characteristics can be observed from the vertical distribution of dissolved oxygen during the Spring: from 0 to 75 m the waters are always saturated; a maximum gradient depletion occurs between 75-150 m, where easily oxidizable material is decomposed and respiration processes prevail; the concentration gradient is very small from 150 m to the bottom. The distrubution of nutrients can be considered as a normal pattern for Mediterranean waters. In the euphotic zone, nutrients are practically depleted by the phytoplankton uptake. The oxidation of organic material induces a progressive enrichment of reactive phosphate, nitrate and silica from 100 m to the bottom. A nitrate maximum is observed at the compensation depth for photosynthesis. The N:P and Si:P atomic ratios are characterized by a wide variability with depth at the euphotic zone. On the contrary, from 75 m to about 80 m, the ratios increase and afterwards they tend to constant value of 21 for N:P and 35 for Si:P. Some conclusions are also drawn about the levantine and deep waters filling the Ionian basin.peer-reviewe

Nutrient enrichment and circulation of water masses in the Pagassitikos Gulf (Aegean Sea)

This paper is concerned with the circulation of water masses and enrichment in inorganic nutrients in the Pagassitikos Gulf, an enclosed basin on the western coast of the Aegean Sea, during 1975-1976 and 1982. The distribution of temperature, salinity and density in the water column indicated the following features: low salinity surface water predominantly related to freshwater runoff; a subsurface water mass, apparently formed by the mixing of fresh with open sea waters; a thermocline; and deep bottom water with open sea characteristics. The seasonal variation in the pattern of surface salinity suggested an anticlockwise water circulation throughout the embayment. The distribution pattern of nutrients and nutrient ratios were compared with previous studies of neighbouring areas and other isolated basins

Modern agricultural practices and eutrophication in Pagassitikos Gulf, Greece

It seems possible that changes in drainage basins and the fertilizers used in modern agriculture are the causal factors for the observed eutrophication and algal blooms of Pagassitikos Gulf, Greece.L’eutrophisation et le bloom d’algues qui sont observés dans le golfe de Pagassitikos, en Grèce, ont probablement pour origine les changements du drainage qui sont produits dans les bassins environnants, ainsi que [’utilisation des fertilisants chimiques par l’agriculture moderne.Friligos N., Giourga C., Karydis Michael, Margaris Nikos S. Modern agricultural practices and eutrophication in Pagassitikos Gulf, Greece. In: Ecologia mediterranea, tome 20 n°1-2, 1994. pp. 59-65