Does the Current Fungicide Risk Assessment Provide Sufficient Protection for Key Drivers in Aquatic Ecosystem Functioning?

Abstract

The level of protection provided by the present environmental risk assessment (ERA) of fungicides in the European Union for fungi is unknown. Therefore, we assessed the structural and functional implications of five fungicides with different modes of action (azoxystrobin, carbendazim, cyprodinil, quinoxyfen, and tebuconazole) individually and in mixture on communities of aquatic hyphomycetes. This is a polyphyletic group of fungi containing key drivers in the breakdown of leaf litter, governing both microbial leaf decomposition and the palatability of leaves for leaf-shredding macroinvertebrates. All fungicides impaired leaf palatability to the leaf-shredder Gammarus fossarum and caused structural changes in fungal communities. In addition, all compounds except for quinoxyfen altered microbial leaf decomposition. Our results suggest that the European Union's first-tier ERA provides sufficient protection for the tested fungicides, with the exception of tebuconazole and the mixture, while higher-tier ERA does not provide an adequate level of protection for fungicides in general. Therefore, our results show the need to incorporate aquatic fungi as well as their functions into ERA testing schemes to safeguard the integrity of aquatic ecosystems.

The relative importance of diet-related and waterborne effects of copper for a leaf-shredding invertebrate

“…This seems worrying given that detritus can be a significant sink for metals and organic contaminants (e.g., Bundschuh et al, 2013;Sridhar et al, 2001;Zubrod et al, 2015a). To safeguard the integrity of aquatic ecosystems, it thus seems necessary that prospective risk assessments cover all significant exposure routes including dietary uptake.…”

Pesticide impact on aquatic invertebrates identified with Chemcatcher® passive samplers and the SPEARpesticides index

“…In fact, the 'leaf conditioning' by bacteria and fungi is an indispensable prerequisite for the feeding activity of shredding invertebrates (Bärlocher and Kendrick, 1975;Cummins et al, 1973), with the fungal community composition determining the leaf palatability Suberkropp, 1984, 1989;Suberkropp et al, 1983;Gulis and Suberkropp, 2003). Hence, fungicides acting on the microbial decomposers indirectly affect the habitat or food choices of shredding invertebrates Flores et al, 2014;Rasmussen et al, 2012aRasmussen et al, , 2012bZubrod et al, 2011Zubrod et al, , 2015, and the reduction of shredders has been linked to a slow-down of leaf decomposition processes (e.g., Flores et al, 2014;Rasmussen et al, 2008;Wallace et al, 1982). In the present study, shredders were found at sites with and without Carbofuran impact, at mean proportions of 19% (total of taxa) and 21% (total of SPEAR).…”

Quantitative real-time PCR as a promising tool for the detection and quantification of leaf-associated fungal species – A proof-of-concept using Alatospora pulchella

“…As shown, for instance, by Arsuffi and Suberkropp [23], shredders distinguish between fungal species on leaf litter, potentially triggered by the production of feeding stimulants or distasteful compounds. This concept was recently applied to explain fungicide-induced shifts in microorganism-mediated leaf palatability for Gammarus fossarum [3, 24], a key shredder in low-order streams of Europe [45]. The study of Zubrod et al [3], however, was based on spore counts, which does not necessarily correlate with the biomass of the respective aquatic hyphomycete species [10].…”

“…This concept was recently applied to explain fungicide-induced shifts in microorganism-mediated leaf palatability for Gammarus fossarum [3, 24], a key shredder in low-order streams of Europe [45]. The study of Zubrod et al [3], however, was based on spore counts, which does not necessarily correlate with the biomass of the respective aquatic hyphomycete species [10]. Applying qPCR could result in deeper insights into shredder food preferences by estimates of single-species biomasses linked to prior knowledge of preferred species.…”

“…Contaminants like fungicides and pharmaceuticals potentially threaten the functioning of this group, suggesting that aquatic hyphomycetes may be suitable bioindicators to assess anthropogenic stress [3–5]. To better understand the contribution of individual aquatic hyphomycete species to leaf litter decomposition and to estimate the impact of anthropogenic stress, knowledge of fungal community composition and of performances (e.g., biomass production) by individual species is essential, given the substantial interspecific variability among aquatic hyphomycetes [6].…”