Structural changes of biological compartments in Danube Delta systems due to persistent organic pollutants and toxic metals

The main objective of this paper is to highlight the dynamics of biotic community in terms of spatial and temporal relationship. The biotic community dynamics in St. Gheorghe Branch were discussed based on existing data and the results of our own research during 2003–2009. Surface water and sediment samples
have been collected monthly from two control sections, Murighiol and Uzlina. The analyzed parameters were according to the Norm concerning the reference objectives for the surface water quality classification (Romanian Order MEWM no. 161/2006) and also, to the EU Water Framework Directive 2000/60/EC which established a framework for community action in the field of water policy. The variation of parameters during the investigated period along St. Gheorghe Branch was strongly influenced by the climatic conditions (drought, flood). Further studies need to be carried out in this area in order to accomplish a sustainable management and to evaluate the occurrence of persistent organic pollutants and toxic metals in tissues,
and to assess the risk of these contaminants on the ecosystem and human health.