Neonicotinoids influence on trophic relations and ecosystem functioning in freshwater ecosystems (NITRO)

• Applicants: Professor Dr. Ralf Schulz; Professor Dr. Ralf B. Schäfer
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: from 2014 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 263794276

The decline of biodiversity may result in losses of crucial ecosystem functions such as leaf breakdown. To which extent toxicants influence the relationship between diversity and ecosystem functioning in freshwater ecosystems is largely unknown. Neonicotinoids represent a relatively new group of systemic insecticides that are taken up in plants. Plant material may enter streams and may adversely affect the breakdown by insect detritivores. In this project we will elucidate the effects of neonicotinoids on the relationship between resource diversity and leaf breakdown as well as investigate cumulative effects and effect propagation in a tri-trophic system. In the first part of the project, the potential cumulative sublethal effects of repeated exposures to the neonicotinoid insecticide imidacloprid on six detritivores will be studied in microcosms with natural stream water. Subsequently, the toxicodynamics will be scrutinised for two species to gather a mechanistic understanding of physiological processes. In the second part the effects of imidacloprid originating from leaf litter and resource diversity on the leaf breakdown rate will be investigated. This experiment will be conducted in field enclosures in three pristine stream sites. In the last part of the project, we will investigate whether neonicotinoids originating from leaf litter can have effects in the food chain. This will be examined in field and laboratory experiments where predators will prey on detritivores that ingested contaminated leaves. In addition, collector species will be fed with fine particulate organic matter excreted by detritivores feeding on imidacloprid-contaminated leaves. Overall this research project will add considerably to the mechanistic understanding of the effects of systemic insecticides on detritivore populations, trophic relations and the relationship between resource diversity and an ecosystem function.

• DFG Programme: Research Grants
• International Connection: Denmark, Sweden, United Kingdom
• Participating Persons: Dr. Roman Ashauer; Professor Dr. Mirco Bundschuh; Professor Dr. Martin Entling; Dr. Gunnar Fent; Professor Brendan McKie, Ph.D.; Professor Dr. Christian Ritz