@masterthesis{Krueger2015, type = {Bachelor Thesis}, author = {Kr{\"u}ger, Simone}, title = {The impact of discharge regulation on microbial sediment respiration at a land-water-interface of the river Spree}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-40496}, school = {BTU Cottbus - Senftenberg}, year = {2015}, abstract = {Flooding of dry sediments is known to trigger pulses of microbial respiration at land-water-interfaces. The regulation of discharge variability is therefore proposed to affect the respiration balance of these sites. In this study, I assessed the impact of discharge regulation on microbial respiration associated to surface sediments at a land-water-interface of the river Spree. I developed a theoretical model, based on empirical respiration data, to estimate the two-month total respiration at the study site for three discharge scenarios. The real scenario represented the actual discharge at the study site, which was regulated by the Spremberg reservoir dam. In the unregulated scenario, the regulating effect by the dam was excluded. In the extremely regulated scenario, a hypothetical constant discharge was modeled. For each scenario, the daily discharge, the corresponding flooded areas, the extent of dry or rewetted areas, and the durations of flooding or rewetting by rain at the study site were determined. Microbial respiration rates associated to surface sediments were measured with a respirometer under flooded, dry, and rewetted conditions. The model applied these rates to the respective flooded, dry or rewetted areas of the study site, to calculate the daily areal respiration. In all sediments from the land-water-interface, a distinctive respiration pulse was measured on the first day of flooding, and higher respiration rates under flooded than under dry conditions. The discharge of the unregulated scenario was characterized by a higher variability and larger flow volume than the regulated real scenario. Due to the higher total discharge, larger areas were flooded in the unregulated scenario, the total respiration from sediments under long-term flooded conditions was therefore higher. Moreover, the daily extent of flooded areas fluctuated more strongly, hence more short-term respiration pulses upon flooding were triggered than in the real regulated scenario. The calculated total two-month respiration of the unregulated scenario exceeded that of the regulated real scenario by almost 14 \%. These results suggest that discharge regulation can have a considerable negative impact on sediment-associated microbial respiration at land-water-interfaces.}, subject = {Respiration; Land-water-interface; Spree; Atmung; Bodenatmung; Flussufer}, language = {en} }