@phdthesis{Oprei2025, author = {Oprei, Anna}, title = {Auswirkungen der h{\"a}ufigen Sedimentumlagerung auf Struktur und Funktion sedimentgebundener mikrobieller Gemeinschaften in Tieflandb{\"a}chen}, doi = {10.26127/BTUOpen-7124}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-71242}, school = {BTU Cottbus - Senftenberg}, year = {2025}, abstract = {Sandy sediments are transported at low flow in so called migrating ripples. Migrating ripples are triangular bedforms with a flat upstream (stoss) and a steep downstream face (lee). Sediment grains are eroded on the stoss side of the ripple and deposited on the lee side of the ripple. They are buried under subsequently falling grains and rest until the next erosion cycle begins. During ripple migration, biofilms associated to sediment grains undergo frequent moving-resting cycles, and are exposed to abrasion and scour as a result of colliding grains during the moving phase, and to light limitation during the resting phase. These specific environmental conditions suggest that high frequent sediment shifting in migrating ripples affects the function and structure of benthic communities with profound consequences on ecological dynamics and biogeochemical processes. This thesis aimed to 1) shed light on the understudied effects of high frequent sediment shifting in migrating ripples on benthic microbial communities, and 2) unravel how legacy effects interact with the response of microbial communities towards high frequent sediment shifting in the context of sediment disturbance. To tackle the first research question, I characterized the specific microenvironment in migrating ripples compared to patches of stationary sediment in a field study. The results showed that migrating ripples created streambed heterogeneity by modulating the abundance, diversity, and structure of the microbial community. In a series of two microcosm experiments, it became evident that light oscillation played the pivotal role during high frequent sediment shifting. To answer the second research question, I studied how the microbial community of incoming sediment from bank erosion reacts to ripple migration after transitioning to the aquatic habitat. The results showed that although the terrestrial-aquatic transition had stronger impacts on the microbial community than subsequent sediment transport in migrating ripples, microbial colonization was decelerated under high frequent sediment shifting. A manipulative field study served to investigate the long-term effects of migrating ripples on microbial communities after transitioning to stationary conditions. Whereas heterotrophic activity was restored within a few days, primary productivity was hampered for several months. Conclusively, the findings of this thesis confirm that high frequent sediment shifting at low-flow conditions shapes local and regional biodiversity, meta-community dynamics, and the flow of matter through the benthic food web. I suggest that the current concept of sediment disturbance focusing on catastrophic flood events should be expanded towards sediment transport along a dynamic range of moving-resting frequencies across different spatiotemporal scales.}, subject = {Sediment transport; Migrating bedforms; Microbial metabolism; Ripples; Sedimenttransport; Wandernde Sandrippel; Mikrobieller Stoffwechsel; Biofilm; Stress; Microbial communities; Geomikrobiologie; Mikrobenthos; Mikrobioz{\"o}nose; Sedimenttransport; Sandrippel}, language = {en} }