Long-term effects of fungicides on leaf-associated microorganisms and shredder populations-an artificial stream study.
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 20 μg/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 (≤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 (≤18%), which triggered reductions in final population biomass (18%) and in the number of precopula pairs (≤22%) but could not fully explain the decreased leaf consumption (19%), lipid content (≤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. © 2017 SETAC.
Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany.
Jochen P
JP
Zubrod
Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany.
Dominic
D
Englert
Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany.
Jakob
J
Wolfram
Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany.|nEcoTox, Schifferstadt, Germany.
Ricki R
RR
Rosenfeldt
Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Alexander
A
Feckler
Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany.
Rebecca
R
Bundschuh
Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany.|nEcoTox, Schifferstadt, Germany.
Frank
F
Seitz
Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany.
Marco
M
Konschak
Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany.
Patrick
P
Baudy
Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany.
Simon
S
Lüderwald
Cologne Biocenter, University of Cologne, Cologne, Germany.
Patrick
P
Fink
Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany.
Andreas
A
Lorke
Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany.
Ralf
R
Schulz
Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Mirco
M
Bundschuh
D033304:Amphipoda / Q000187:drug effects*; D000818:Animals; D018533:Biomass; D017753:Ecosystem; D020387:Food Chain; D005658:Fungi / Q000187:drug effects; D005659:Fungicides, Industrial / Q000633:toxicity*; D064307:Microbiota / Q000187:drug effects; D008962:Models, Theoretical; D018515:Plant Leaves / Q000187:drug effects / Q000382:microbiology*; D045483:Rivers; D013995:Time; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D005659:Fungicides, Industrial; D014874:Water Pollutants, Chemical
Aquatic hyphomycetes; Chronic exposure; Gammarus fossarum; Leaf litter breakdown; Population development