The Good, the Bad and the Ugly -- Interactions Between Physical, Biogeochemical and Biological Drivers of Nutrient Cycling at Ecohydrological Interfaces

Event Date/Time: 
June 8, 2018 - 2:30pm
Event Location: 
3540 Engineering Building
Speaker: 
Professor Stefan Krause, University of Birmingham, UK
CEE Seminar

Abstract

The dynamic interfaces between streams, lakes and their bed sediments have for a long time been in the research focus of ecohydrologists, aquatic ecologists and biogeochemists. Important knowledge gaps remain as to the actual drivers (physical, biogeochemical and biological) of the often observed hot spots and hot moments of nutrient cycling at these highly reactive systems.

This study presents results from a combination of laboratory manipulations, artificial stream and field experiments and numerical models from reach to river network scales to investigate the interplay of physical, biogeochemical and biological drivers of interface nutrient cycling under the impact of and resilience to global environmental change. Our results indicate that biogeochemical hotspots at sediment-freshwater interfaces were strongly affected by patterns of streambed physical properties and bioavailability of organic carbon. Lab incubation experiments revealed that geology, and in particular organic matter content strongly controlled the magnitude of enhanced streambed greenhouse gas production caused by increasing water temperatures. While these findings help to improve our understanding of physical and biogeochemical controls on nutrient cycling, we only start to understand to what degree biological factors can enhance these processes even further. We found that for instance chironomid or brittle star facilitated bioturbation has the potential to substantially enhance freshwater or marine sediment pore-water flow and respiration.