Utilisation des signatures en isotopes stables en Mer Noir - nouvelle approche pour la comprehension de l'influence des apports terrestres du Danube sur les ecosystemes marines

Coastal marine zones located in front of large rivers are of major biological interest. In these areas, the origin of the organic matter is complex
and highly variable. The continental inputs, added to the nutrients already present in the marine environment, influence considerably the productivity and
functioning of the ecosystems. Used for the first time in aquatic ecology on the Romanian coast, the proportion of stable isotopes of carbon (13C/12C) and
nitrogen (15N/14N) allowed the identification of the organic material sources (terrestrial and marine) as well as the analysis of the food webs due to the predictable isotopic relation between consumers and their food. Preliminary analyses of stable isotopes of the particulate organic matter POM of the Danube
water as well as marine POM, sediments and marine organisms were made on 186 samples collected at 10 stations in October 2004. The identification of
the isotopic signatures of the main sources of organic material (terrestrial and marine) was achieved along with those of some groups of marine organisms
present in this area (macrophytes, bivalves, polychaetes, amphipods, macrurans, brachyurans and fish). The results obtained in the Black Sea were compared
with those of the Mediterranean Sea seawards the Rhone river and showed that the isotopic signatures of the two river POM were close to each other,
whereas they largely differed in marine phytoplankton and macrophytes.