Biotic Typology of the Danube River Based on Distribution of Mollusc Fauna as Revealed by the Second Joint Danube Survey (2007)

Abstract

The aim of this study is to present the distribution of aquatic molluscs along a 2600 km long stretch of the Danube River based on information obtained during the Second Joint Danube Survey (JDS2) in 2007. The collected data are used to validate the abiotic typology of the Danube River and to determine the extent of variations in mollusc richness and composition that can be explained by the basic habitat characteristics of the sites. The examination of the distribution of mollusc fauna reveals differences between the three main sectors of the river, the Upper, Middle and Lower Danube. The Iron Gate Section was identified as the boundary between the Middle and Lower, Danube. A total of 42 aquatic mollusc species-group taxa of 14 families are detected within the study area. The Middle and Upper sectors are characterised by higher species richness and diversity as compared to the Lower Danube.