Environmental Toxicology and Chemistry, August 2017, Vol.36(8), pp.2178-2189
Byline: Jochen P. Zubrod, Dominic Englert, Jakob Wolfram, Ricki R. Rosenfeldt, Alexander Feckler, Rebecca Bundschuh, Frank Seitz, Marco Konschak, Patrick Baudy, Simon Luderwald, Patrick Fink, Andreas Lorke, Ralf Schulz, Mirco Bundschuh Abstract Leaf litter is a major source of carbon and energy for stream food webs, while both leaf-decomposing microorganisms and macroinvertebrate leaf shredders can be affected by fungicides. Despite the potential for season-long fungicide exposure for these organisms, however, such chronic exposures have not yet been considered. Using an artificial stream facility, effects of a chronic (lasting up to 8 wk) exposure to a mixture of 5 fungicides (sum concentration 20I1/4g/L) on leaf-associated microorganisms and the key leaf shredder Gammarus fossarum were therefore assessed. While bacterial density and microorganism-mediated leaf decomposition remained unaltered, fungicide exposure reduced fungal biomass ([less than or equal to]71%) on leaves from day 28 onward. Gammarids responded to the combined stress from consumption of fungicide-affected leaves and waterborne exposure with a reduced abundance ([less than or equal to]18%), which triggered reductions in final population biomass (18%) and in the number of precopula pairs ([less than or equal to]22%) but could not fully explain the decreased leaf consumption (19%), lipid content ([less than or equal to]43%; going along with an altered composition of fatty acids), and juvenile production (35%). In contrast, fine particulate organic matter production and stream respiration were unaffected. Our results imply that long-term exposure of leaf-associated fungi and shredders toward fungicides may result in detrimental implications in stream food webs and impairments of detrital material fluxes. These findings render it important to understand decomposer communities' long-term adaptational capabilities to ensure that functional integrity is safeguarded. Environ Toxicol Chem 2017;36:2178-2189. [c] 2017 SETAC Supporting information: Additional Supporting Information may be found in the online version of this article This article includes online-only Supplemental Data. CAPTION(S): Supporting Data.
Aquatic Hyphomycetes ; Chronic Exposure ; Gammarus Fossarum ; Leaf Litter Breakdown ; Population Development