Do toxicants INterfere with ecosystem FUnctioning in SEDiments? (INFUSED)

• Applicant: Professor Dr. Mirco Bundschuh
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management ; Microbial Ecology and Applied Microbiology
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 553375977

Energy budgets of headwater stream ecosystems in forested catchments rely strongly on the inputs of allochthonous organic material such as leaf litter. The overwhelming share of this organic material (approx. 90%) becomes buried and accumulates in the hyporheic zone. Understanding the processes (mediated by both microorganisms or macroinvertebrates) that make the energy bound in this material available for the wider food web against the background of the ever-increasing pressure induced by chemical contamination is fundamental in a changing world. This aspect is of particular relevance as recent evidence indicates that the impact of chemicals in the benthic cannot be transferred to the hyporheic zone. This discrepancy is likely related to the distinct differences in the environmental conditions shaping for example the microbial community composition and activity in the benthic relative to the hyporheic zone through environmental filtering. In the hyporheic zone, downwelling surface water and upwelling groundwater create habitats of variable environmental conditions complicating a generalization of observation. INFUSED aims at addressing these significant challenges foresting our understanding how chemicals affect organic matter processing moving beyond the focus on benthic systems using a set of experimental approaches. Thereby INFUSED addresses the impact of fungicides and antibiotics on organic matter decomposition in the up- and downwelling hyporheic zones. These observations will be contrasted to the effects observed in the benthic zone, which also serves as reference point. Indirect effects of these antimicrobial chemicals on detritivores will be targeted through food selection followed by long-term feeding assay. A follow-up experiment focuses on chemical stressors that may affect the activity of detritivores hypothesizing that their sediment digging activity is negatively affected with repercussions on their ability to reach and consequently consume buried organic material. Building on these insights, INFUSED will assess the propagation of direct and indirect effects through a near-natural food web. Stable isotope labeling will support the quantification of the relative importance of hyporheic organic matter for a complex food webs. All in all, INFUSED will boost our understanding of potential implications of chemicals in organic matter processing within the hyporheic zone. Thereby, it is hypothesized that fungicides and antibiotics directly interfere with both microbial ecosystem functions that is organic matter processing and the provisioning of high-quality food for detritivores. In contrast, chemicals (e.g., insecticides) affecting detritivores will impact organic matter processing top down. The combined impact of fungicides/antibiotics on the one and insecticides on the other hand can unpredictably shape the wider aquatic food web.

• DFG Programme: Research Grants
• International Connection: Romania
• Cooperation Partner: Dr. Octavian Pacioglu