ESTABLISHING THE ECOLOGICAL QUALITY STATUS USING BENTHIC INVERTEBRATES AS BIO-INDICATORS IN MARINE MONITORING Camelia Dumitrache *, Valeria Abaza*, Radu Mihnea* , Lucia Ana Varga**, Luminita Gheorghe***, * National Institute for Marine Research and Development “Grigore Antipa” Constanta ** Ministry of Environmental and Sustainable Development, Bucharest *** Directorate of Waters « Dobrogea Littoral » Constanta Abstract Marine environmental quality is assessed usually by means of different monitoring parameters in water and sediment. The biological criteria are considered important components of water quality because they are direct measures of condition of the biota. New European rules emphasize the importance of biological indicators, in order to establish the ecological quality status of marine environment. Benthic invertebrates are used as bio- indicators of marine monitoring, because these organisms are adapted for life on or in particular bottom types, are more stable than planktonic organisms and respond relatively rapidly to anthropic and natural stress. The present paper analyses the structure and the quantitative development of zoobenthic communities from Romanian shallow waters between 2002 and 2006 when a slight recovery tendency, due to the diminution ecological pressure by eutrophication/pollution has been noted. The main parameters characterizing the structure and the populations in the communities, the specific composition, abundance and weight dominance of species and groups in communities have evinced the tendencies of marine zoobenthic evolution and its present potential productivity. Key words: Black Sea, macrozoobenthos, marine environment, ecological quality status Introduction Macrozoobenthic species have been the focus of monitoring programmes for many reasons: they are sedentary or sessile and integrators of environmental quality. They are relatively easy to collect, to identify and their ecology and habitat requirements are generally well known. They are responsive in a predictive manner to changes in sediment quality and water, and therefore good environmental indicators. Sampling methodology and methodologies of data analysis The results are based on the processing of 120 qualitative and quantitative zoobenthic samples, systematically collected during research cruises, carried out on the monitoring sampling network of the Romanian Black Sea coastal waters (Sulina to Vama Veche), at 5m to 20 m depths between 2002 and 2006. (Fig.1)