Spatio-temporal evolution of the biotic components in the aquatic ecosystems from Danube Delta biosphere

Abstract

The paper presents data from the comparative biological analysis of the aquatic ecosystems of the Danube delta in two sampling sites: Uzlina and Murighiol for the sampling period (April 2005-October 2006). The results on the biotic communities determined from Uzlina and Murighiol locations demonstrated the following aspects: in the Murighiol and Uzlina control sections from the point of view of phytoplankton, zooplankton and benthic macroinvertebrates components, in the period 2004-2006, similarly to the year 2003, the Danube water is an eutrophic system equilibrated for class second according to the Norm concerning the reference objectives for the surface water quality classification (Order No 161/2006); the phytoplankton and zooplankton biocenosis represents the trophic basis necessary for ichthiofauna development in the aquatic ecosystems in the control sections: Murighiol and Uzlina; in the Murighiol control section, the phytoplankton is better represented than in the Uzlina control section for numerical density and remanent biomass; dominant species from phytoplankton and zooplankton – for numerical density and remanent biomass – are oligo-betamesosaprobic species. The researches will be continued in order to assess the seasonal variations, the final results will estimate the value of the trophic basis in the two control sections in the framework of the Danube delta biosphere, because the main actions that must be achieved in this areas in order to accomplish a sustainable management are represented by: the reduction of the nutrient charge in the Danube, especially the Danube delta inputs, controlling the punctiform and diffuse pollution sources; the prevention of a wetlands’ loss through the pressure reduction on them; the restoration of wetlands, being the only way to prove the capacity to support and productivity of the entire Danubian system.