Spatial and Temporal Distribution of the Zooplankton Biomass in Sfântu Gheorghe Branch (The Danube Delta, Romania) in Relation to Environmental Factors

Sfântu Gheorghe fluvial branch belongs to the macroregional hydrological system of the Danube Delta. In order to improve the navigation on the river branches, between 1983 and 1989 various technical works have been initiated, which later proved to be one of the most aggressive factors leading to changes over time in the Danube Delta. The influence of anthropogenic impact on the zooplankton biomass distribution patterns in Sfântu Gheorghe was investigated in 2008 - 2010 interval. From this perspective, the aim of this paper was to emphasize the structure and distribution of zooplankton in the new conditions of the river system. Seasonal sampling shows that Copepoda and Cladocera were the dominant groups while the protozoans (Ciliata and Testacea) presented the smallest values of biomass and also emphasized distinct differences among the three sampling periods: summer, spring and autumn.