Effects of leaf litter extracts from four tree species on aquatic invertebrates: an ecotoxicological risk assessment approach

35 páginas, 2 figuras, 4 tablas. --This is a post-peer-review, pre-copyedit version of an article published in Aquatic Ecology. The final authenticated version is available online at: http://dx.doi.org/10.1007/s10452-020-09800-xUpper reaches of temperate streams and oligotrophic lakes depend trophically on the organic matter coming from the surrounding watershed. These aquatic ecosystems accumulate particulate and dissolved organic matter, and chemical compounds liberated from decomposing leaves or from the leachates of leaf litter. These materials supply a wide range of chemical compounds, which may serve as food, but also cause ecotoxicological effects on aquatic organisms. However, this ecotoxicological risk has been amply ignored, especially for freshwater invertebrates. The aims of our study are: (1) to assess the direct toxicity of aqueous extracts of leaf litter from two native (Populus alba, Fraxinus angustifolia) and two tree species exotic to Europe (Robinia pseudoacacia, Ailanthus altissima) on a pelagic and a benthic species of model aquatic invertebrates: Daphnia magna (Cladocera) and Potamopyrgus antipodarum (Mollusca) and (2) to estimate the ecotoxicological risk of the leaf litter extracts to lacustrine ecosystems using different simulated scenarios of shallow lakes. For both invertebrate species, we assessed the effective concentration of leaf extract causing an effect on 50% of the population (EC50) by means of laboratory bioassays. Our results show that the extracts of leaf litter from all the tested trees have a potential ecotoxicological risk in some scenarios, which is independent from the geographic origin of the tree speciesFunds for this research came from the University of Alcalá (research projects CCG2013/EXP-054, CCG2016/EXP-054 and CCG2018/EXP-074), and the projects CGL2011-16388/BOS, CGL2015-65346R and EXARBIN RTI2018-093504-B-I00 (MCIU/AEI/FEDER, UE) of the Ministerio de Economía y Competitividad of Spain, and POII10-0179-4700 of the Junta de Comunidades de Castilla La Mancha and FONDECYT/CONICYT No. 3180289 (Chile)Peer reviewe