TY - JOUR T1 - Bacterial diversity along a 2 600 km river continuum JF - bioRxiv DO - 10.1101/010041 SP - 010041 AU - Savio Domenico AU - Sinclair Lucas AU - Umer Z. Ijaz AU - Alfred P. Blaschke AU - Georg H. Reischer AU - Blöschl Guenter AU - Robert L. Mach AU - Alexander K.T. Kirschner AU - Andreas H. Farnleitner AU - Eiler Alexander Y1 - 2014/01/01 UR - http://biorxiv.org/content/early/2014/10/07/010041.abstract N2 - Understanding the biogeochemistry of large rivers is of high relevance as they play a major role in the global carbon cycle and provide diverse ecosystem services. Since these ecosystem functions are mainly mediated by bacteria, knowledge about their diversity represents a centrepiece in determining the role of rivers in the landscape. Here, we present a comprehensive dataset on the bacterioplankton diversity along a 2 600 km midstream transect of the second largest river in Europe, the Danube River, and its tributaries using an Illumina®-based sequencing approach (16S rRNA-gene amplicon sequencing). Our analysis revealed a clear gradual development of the riverine bacterioplankton community in both the 0.2-3.0 μm and the > 3.0 μm size fractions along the entire river. We found that bacterial richness and evenness gradually decreased downwards the river. This trend of a gradual development of the bacterioplankton community along the river was additionally underpinned by beta diversity analysis where effects of tributaries were negligible in regards to the overall trends. In addition, we found very few taxa typical for lotic systems and that the relative contribution of so-called typical freshwater bacteria often observed in lakes was increasing towards the river mouth. This supports the hypothesis of a succession from soil and groundwater bacteria towards lake bacteria in lotic systems. Putting our findings into a broad ecological context, we suggest that patterns of bacterioplankton diversity in large rivers follow predictions of the River Continuum Concept published in 1980, with a modification for planktonic microorganisms. ER -