PT - JOURNAL ARTICLE AU - Domenico Savio AU - Lucas Sinclair AU - Umer Z. Ijaz AU - Philipp Stadler AU - Alfred P. Blaschke AU - Georg H. Reischer AU - Guenter Blöschl AU - Robert L. Mach AU - Alexander K.T. Kirschner AU - Andreas H. Farnleitner AU - Alexander Eiler TI - Bacterial diversity along a 2600 km river continuum AID - 10.1101/010041 DP - 2014 Jan 01 TA - bioRxiv PG - 010041 4099 - http://biorxiv.org/content/early/2014/12/22/010041.short 4100 - http://biorxiv.org/content/early/2014/12/22/010041.full AB - The bacterioplankton diversity in large rivers has thus far been undersampled, despite the importance of streams and rivers as components of continental landscapes. Here, we present a comprehensive dataset detailing the bacterioplankton diversity along the midstream of the Danube River and its tributaries. Using 16S rRNA-gene amplicon sequencing, our analysis revealed that bacterial richness and evenness gradually declined downriver in both the free-living and particle-associated bacterial communities. These shifts were also supported by beta diversity analysis, where the effects of tributaries were negligible in regards to the overall variation. In addition, the river was largely dominated by bacteria that are commonly observed in freshwaters. Dominated by the acI lineage, the freshwater SAR11 (LD12) and the Polynucleobacter group, typical freshwater taxa increased in proportion downriver and were accompanied by a decrease in soil and groundwater bacteria. Based on the River Continuum Concept, we explain these taxonomic patterns and the accompanying changes in alpha and beta diversity by the physical structure and chemical conditions coupled with the hydrologic cycle along the length of the river.