SFB 1439:  Multilevel response to stresser increase and release in stream ecosystems

• Subject Area: Geosciences ; Biology ; Medicine
• Term: since 2021
• Website: Homepage
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 426547801

RESIST aims to understand and explain the mechanisms underlying the degradation of and recovery from multiple stressors in stream ecosystems. We propose and will test a novel theoretical frame-work developed by the applicants to disentangle various mechanisms causing stressor interactions during phases of ecosystem degradation and recovery: the ‘Asymmetric Response Concept’ (ARC). Within the ARC, we propose that degradation and recovery are governed by four main processes: (1) interactions of stressors affecting environmental variables; (2) interactions of stressors or envi-ronmental variables affecting organisms at the individual and population level; (3) biotic interactions translating multiple stressor effects on organisms to the community level; and (4) dispersal pro-cesses attenuating effects of single or multiple stressors and guiding recovery processes. As the central tenet of the ARC, the significance of these four processes differs fundamentally between phases of degradation and recovery. Based on the ARC, we will test three main hypotheses ad-dressing the role of these four processes during phases of degradation and recovery, the response of different organism groups to these processes, and the rates of recovery that may differ be-tween community composition and ecosystem functioning. We will implement concerted experimental approaches that are designed to effectively combine experiments, field studies and modelling. This will allow us to disentangle intricacies of response for a wide array of organisms, ranging from bacteria to fish, and for four ecosystem functions. We will focus on three prominent and globally relevant stressors: temperature increase, salinization, and hydromorphological alterations. We will study their individual and combined effects on processes governing degradation and recovery in two mesocosm experiments (the indoor AquaFlow and the outdoor ExStream system) and in two field studies in the Emscher/Boye and Kinzig catchments incorporating both degraded and restored stream ecosystems. The experimental results on mech-anisms will be complemented by, and fed into models to understand, explain, synthesise and pre-dict responses of stream biodiversity and ecosystem functioning to the factors that govern degra-dation and recovery.

• DFG Programme: Collaborative Research Centres

Current projects

• A01 - Direct and indirect effects of multiple stressors in freshwater ecosystems on microbial parasites and scavengers (Project Head Probst, Alexander )
• A02 - Effect of multiple stressors on the microbial ecosystem functions DOC degradation and biomass recycling in water and sediment (Project Heads Brauer, Verena ;  Meckenstock, Rainer Udo )
• A03 - Functional and compositional responses of stream microphytobenthic communities to multiple stressor increase and decrease (Project Head Beszteri, Bánk )
• A04 - The roles of bacteria and fungi for CPOM degradation during stressor increase and release: A metatranscriptomic approach (Project Head Beisser, Daniela )
• A05 - Impairment and recovery of stream ecosystems experiencing multiple stressors: Responses of leaf-associated fungi, microbial activities and litter decomposition (Project Head Gessner, Mark )
• A06 - Stressor modulated community responses and functional redundancy of microbial predator-prey interactions (Project Head Boenigk, Jens )
• A07 - Degradation and recovery of protistan parasite communities under multiple stressors (Project Heads Beisser, Daniela ;  Boenigk, Jens ;  Dunthorn, Ph.D., Micah ;  Sures, Bernd )
• A08 - Individual and combined stressor effects on freshwater invertebrate communities and an associ-ated ecosystem function: an ExStream mesocosm study (Project Head Leese, Florian )
• A09 - Responses of metazoan parasite communities to stressor increase and release (Project Head Sures, Bernd )
• A10 - The scent of danger - predator-mediated shifts in benthic invertebrate community composition and genotypic diversity in multiply-stressed riverine ecosystems (Project Head Tollrian, Ralph )
• A11 - Multiple stressor effects on sculpins (Cottus sp.) and related top-down effects on riverine food-webs (Project Head Lampert, Kathrin )
• A12 - Effects of multiple stressors on food web architecture and processes (Project Head Weitere, Markus )
• A13 - Diet-consumer interactions under variable stressor conditions as revealed by stable isotope stud-ies of individual amino acids (Project Heads Jochmann, Maik ;  Schmidt, Torsten )
• A14 - Spatio-temporal dynamics of environmental variables, stressors and their interactions on the in-stream- and catchment scale (Project Head Fohrer, Nicola )
• A15 - Enhancing the predictive ability of species distribution models: stressor interactions, life cycle, and depicting degradation and recovery (Project Head Jähnig, Sonja )
• A16 - Biotic and abiotic drivers of macroinvertebrate dispersal (Project Head Feld, Christian K. )
• A17 - Temporal and spatial effects of stressors, biotic interaction and dispersal on riverine benthic in-vertebrate community variability (Project Heads Haase, Peter Martin ;  Hering, Daniel )
• A18 - Delineating multiple stressor-response relationships at the individual level: A mechanistic model-ling approach (Project Head Le, Ph.D., Thi Thu Yen )
• A19 - Testing the Asymmetric Response Concept in disturbed and recovering stream ecosystems: inte-grating the contributions of multi-stressor tolerance, dispersal and biotic interactions to (a)symmetry of response (Project Head Vos, Matthijs )
• A20 - The role of individual tolerance for community assembly during degradation and recovery (Project Head Schäfer, Ralf B. )
• MGK - Integrated Research Training Group of RESIST (Project Heads Brauer, Verena ;  Sures, Bernd )
• Z01 - Central administration of the CRC 1439 (Project Head Sures, Bernd )
• Z02 - Maintenance of experimental systems, central field work and central sample analysis (Project Heads Boenigk, Jens ;  Fohrer, Nicola ;  Hering, Daniel ;  Leese, Florian )
• Z03 - Central scientific project: RESIST synthesis (Project Heads Hering, Daniel ;  Jähnig, Sonja ;  Schäfer, Ralf B. )
• ZINF - Data management and integration (Project Heads Beisser, Daniela ;  Probst, Alexander )

• Applicant Institution: Universität Duisburg-Essen
• Participating University: Christian-Albrechts-Universität zu Kiel; Ruhr-Universität Bochum; Universität Koblenz; Universität zu Köln
• Participating Institution: Helmholtz-Zentrum für Umweltforschung (UFZ); Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB); im Forschungsverbund Berlin e.V.
• Spokesperson: Professor Dr. Bernd Sures