The evil within? Systemic fungicide application in trees enhances litter quality for an aquatic decomposer-detritivore system. (October 2018)

• Record Type: Journal Article
• Authors: Newton, Kymberly; Zubrod, Jochen P.; Englert, Dominic; Lüderwald, Simon; Schell, Theresa; Baudy, Patrick; Konschak, Marco; Feckler, Alexander; Schulz, Ralf; Bundschuh, Mirco
• Is Part Of: Environmental pollution. Volume 241(2018)
• Page Start: 549
• Page End: 556
• Publication Date: 2018-10
• Subjects: Aquatic hyphomycetes -- Gammarus fossarum -- Resource quality -- Systemic pesticides; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2018.05.069
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Waterborne exposure towards fungicides is known to trigger negative effects in aquatic leaf-associated microbial decomposers and leaf-shredding macroinvertebrates. We expected similar effects when these organisms use leaf material from terrestrial plants that were treated with systemic fungicides as a food source since the fungicides may remain within the leaves when entering aquatic systems. To test this hypothesis, we treated black alder ( Alnus glutinosa ) trees with a tap water control or a systemic fungicide mixture (azoxystrobin, cyprodinil, quinoxyfen, and tebuconazole) at two worst-case application rates. Leaves of these trees were used in an experiment targeting alterations in two functions provided by leaf-associated microorganisms, namely the decomposition and conditioning of leaf material. The latter was addressed via the food-choice response of the amphipod shredder Gammarus fossarum . During a second experiment, the potential impact of long-term consumption of leaves from trees treated with systemic fungicides on G. fossarum was assessed. Systemic fungicide treatment altered the resource quality of the leaf material resulting in trends of increased fungal spore production and an altered community composition of leaf-associated fungi. These changes in turn caused a significant preference of Gammarus for microbially conditioned leaves that had received the highest fungicide treatment over control leaves. This higher food quality ultimately resulted in a higher gammarid growth (up to 300% increase) during the long-term feeding assay. Although the underlying mechanisms still need to be addressed, the present study demonstrates a positive indirect response in aquatic organisms due to systemic pesticide application in a terrestrial system. As the effects from the introduction of plant material treated with systemic fungicides strongly differ from those mediated via other pathways (e.g., waterborne exposure), our study provides a novel perspective of fungicide-triggered effects in aquatic detritus-based food webs. Graphical abstract: Highlights: Systemic fungicides can positively influence leaf-associated microbial communities. Changes in microbial communities are detected by leaf-shredding amphipods. Long-term consumption of microbially conditioned, fungicide-treated leaves promotes amphipod growth. Abstract : Leaves from trees treated with systemic fungicides cause positive effects in an aquatic decomposer-detritivore system.