Анотация: The present book is aimed at summarizing the most of the studies have been carried out during the last two decades on the ecosystems of the lake Srebarna the most prominent Bulgarian Nature Reserve on the Lower Danube bank. The studies have been performed mostly by scientists and researchers of the newly established Institute of Biodiversity and Ecosystem Research, with close collaboration with colleagues from the Biological Faculty of the Sofia University and other institutes of the Bulgarian Academy of Sciences and/or high schools/universities of that country.