Litter breakdown for ecosystem integrity assessment also applies to streams affected by pesticides
- 357 Downloads
While the impact of various anthropogenic alterations, e.g. nutrient enrichment, has been documented on leaf litter breakdown—a key process for stream ecosystems—, our objective was to assess the response of this process to pesticides in agricultural streams. We hypothesized the impairment to be correlated with the pesticides contamination gradient, and the invertebrate decomposers to be more affected than microbial ones. Alder total breakdown rate was found to strongly decrease along the pesticide concentration in 12 French streams, only due to invertebrate-driven breakdown (as determined in coarse-mesh bags) since microbial-driven breakdown (fine-mesh bags) remained unchanged. Coherently, litter-associated shredder taxa richness and abundance together with SPEARpesticide (a specific indicator based on invertebrate traits) were greatly reduced, whereas pesticide toxicity did not affect litter-associated fungal biomass and taxa richness. Consequently, the presence of pesticides compromised leaf breakdown, as microbial decomposers did not compensate for the invertebrate decomposers decline. This occurred while pesticides concentrations even in the most contaminated stream were under the European Union’s Uniform Principles thresholds for targeted species. Our study showed that litter breakdown, particularly the ratio of total to microbial-driven breakdown rate, is a pertinent proxy to assess the functional integrity of pesticide-contaminated streams.
KeywordsDecomposition rate Fungi Shredders SPEARpesticide Toxic units
We thank two anonymous reviewers for their helpful comments. We are very grateful to Didier Lambrigot and Robert Fernandez for ergosterol determination and field assistance and to Margaux Saüt and coworkers from the Adour-Garonne Water Agency for providing water chemistry data. This work was financially supported by the CIFRE PhD Plan of the French Association for Research and Technology, the Adour-Garonne Water Agency, Asconit Consultants and the Centre National de la Recherche Scientifique (CNRS).
- Chauvet, E., 1990. Hyphomycètes aquatiques du sud-ouest de la France. Gaussenia 6: 3–31.Google Scholar
- Cheng, Z. L., P. Andre & C. Chiang, 1997. Hyphomycetes and macroinvertebrates colonizing leaf litter in two Belgian streams with contrasting water quality. Limnetica 13: 57–63.Google Scholar
- ECOTOX Database. US Environmental Protection Agency [available on internet at http://cfpub.epa.gov/ecotox/ecotox_home.cfm].
- EEC, 1991. Council Directive of 15 July 1991 Concerning the Placing of Plant Protection Products on the Market (91/414/EEC).Google Scholar
- Flores, L., Z. Banjac, M. Farré, A. Larrañaga, E. Mas-Martí, I. Muñoz, D. Barceló & A. Elosegi, 2014. Effects of a fungicide (imazalil) and an insecticide (diazinon) on stream fungi and invertebrates associated with litter breakdown. Science of the Total Environment 476–477: 532–541.CrossRefPubMedGoogle Scholar
- Gessner, M. O., F. Bärlocher & E. Chauvet, 2003. Qualitative and quantitative analysis of aquatic hyphomycetes in streams. In Tsui, C. K. M. & K. D. Hyde (eds), Freshwater Mycology. Fungal Diversity Press, Hong Kong: 127–157.Google Scholar
- Piscart, C., S. Navel, C. Maazouzi, B. Montuelle, J. Cornut, F. Mermillod-Blondin, M. Creuze des Chatelliers, L. Simon & P. Marmonier, 2011. Leaf litter recycling in benthic and hyporheic layers in agricultural streams with different types of land use. Science of the Total Environment 409: 4373–4380.CrossRefPubMedGoogle Scholar
- Rasmussen, J. J., R. J. Monberg, A. Baattrup-Pedersen, N. Cedergreen, P. Wiberg-Larsen, B. Strobel & B. Kronvang, 2012c. Effects of a triazole fungicide and a pyrethroid insecticide on the decomposition of leaves in the presence or absence of macroinvertebrate shredders. Aquatic Toxicology 118–119: 54–61.CrossRefPubMedGoogle Scholar
- Reyjol, Y., C. Argillier, W. Bonne, A. Borja, A. D. Buijse, A. C. Cardoso, M. Daufresne, M. Kernan, M. T. Ferreira, S. Poikane, N. Prat, A.-L. Solheim, S. Stroffek, P. Usseglio-Polatera, B. Villeneuve & W. van de Bund, 2014. Assessing the ecological status in the context of the European Water Framework Directive: where do we go now? Science of the Total Environment 497–498: 332–344.CrossRefPubMedGoogle Scholar
- Schäfer, R. B., M. Bundschuh, D. A. Rouch, E. Szöcs, P. C. Von der Ohe, V. Pettigrove, R. Schulz, D. Nugegoda & B. J. Kefford, 2012a. Effects of pesticide toxicity, salinity and other environmental variables on selected ecosystem functions in streams and the relevance for ecosystem services. Science of the Total Environment 415: 69–78.CrossRefPubMedGoogle Scholar
- Tachet, H., P. Richoux, M. Bournaud & P. Usseglio-Polatera, 2010. Invertébrés d’eau douce: systématique, biologie, écologie. CNRS Editions, Paris. 600 pp.Google Scholar
- Thompson, M. S. A., C. Bankier, T. Bell, A. J. Dumbrell, C. Gray, M. E. Ledger, K. Lehmann, B. A. McKew, C. D. Sayer, F. Shelley, M. Trimmer, S. L. Warren & G. Woodward, 2015. Gene-to-ecosystem impacts of a catastrophic pesticide spill: testing a multilevel bioassessment approach in a river ecosystem. Freshwater Biology. doi: 10.1111/fwb.12676.Google Scholar
- Tsui, C. K. M., K. D. Hyde & I. J. Hodgkiss, 2001. Effects of glyphosate on lignicolous freshwater fungi of Hong Kong. Sydowia 200: 167–174.Google Scholar
- University of Hertfordshire, 2013. The Pesticide Properties Database (PPDB). Agriculture and Environment Research Unit (AERU), University of Hertfordshire: 2006–2013.Google Scholar
- Von der Ohe, P. C., E. De Deckere, A. Prüss, I. Muñoz, G. Wolfram, M. Villagrasa, A. Ginebreda, M. Hein & W. Brack, 2009. Toward an integrated assessment of the ecological and chemical status of European river basins. Integrated Environmental Assessment and Management 5: 50–61.CrossRefPubMedGoogle Scholar
- Wasson, J.-G., A. Chandesris, H. Pella & L. Blanc, 2002. Les hydro-écorégions de France métropolitaine approche régionale de la typologie des eaux courantes et éléments pour la définition des peuplements de référence d’invertébrés. Cemagref report, 190 pp.Google Scholar
- Woodward, G., M. O. Gessner, P. S. Giller, V. Gulis, S. Hladyz, A. Lecerf, B. Malmqvist, B. G. McKie, S. D. Tiegs, H. Cariss, M. Dobson, A. Elosegi, V. Ferreira, M. A. S. Graça, T. Fleituch, J. O. Lacoursière, M. Nistorescu, J. Pozo, G. Risnoveanu, M. Schindler, A. Vadineanu, L. B.-M. Vought & E. Chauvet, 2012. Continental-scale effects of nutrient pollution on stream ecosystem functioning. Science 336: 1438–1440.CrossRefPubMedGoogle Scholar
- Zubrod, J. P., D. Englert, A. Feckler, N. Koksharova, M. Konschak, R. Bundschuh, N. Schnetzer, K. Englert, R. Schulz & M. Bundschuh, 2015. Does the current fungicide risk assessment provide sufficient protection for key drivers in aquatic ecosystem functioning? Environmental Science and Technology 49: 1173–1181.CrossRefPubMedGoogle Scholar