Assessing combined impacts of agrochemicals: Aquatic macroinvertebrate population responses in outdoor mesocosms

Title
Assessing combined impacts of agrochemicals: Aquatic macroinvertebrate population responses in outdoor mesocosms
Publication Type
Journal Article
Year of Publication
2018
Authors

Barmentlo SH, Schrama M, Hunting ER, Heutink R, van Bodegom PM, de Snoo GR, Vijver MG

Journal
Science of The Total Environment
Volume
631-632
Pagination
341-347
ISBN Number
Keywords

Agrochemicals
Mixtures
Outdoor testing
Aquatic invertebrates
Mesocosm

Abstract

Agricultural ditches host a diverse community of species. These species often are unwarrantedly exposed to fertilizers and a wide-array of pesticides (hereafter: agrochemicals). Standardized ecotoxicological research provides valuable information to predict whether these pesticides possibly pose a threat to the organisms living within these ditches, in particular macro-invertebrates. However, knowledge on how mixtures of these agrochemicals affect macro-invertebrates under realistic abiotic conditions and with population and community complexity is mostly lacking. Therefore we examined here, using a full factorial design, the population responses of macroinvertebrate species assemblages exposed to environmentally relevant concentrations of three commonly used agrochemicals (for 35┬ádays) in an outdoor experiment. The agrochemicals selected were an insecticide (imidacloprid), herbicide (terbuthylazine) and nutrients (NPK), all having a widespread usage and often detected together in watersheds. Effects on species abundance and body length caused by binary mixture combinations could be described from single substance exposure. However, when agrochemicals were applied as tertiary mixtures, as they are commonly found in agricultural waters, species’ abundance often deviated from expectations made based on the three single treatments. This indicates that pesticide-mixture induced toxicity to population relevant endpoints are difficult to extrapolate to field conditions. As in agricultural ditches often a multitude (approx. up to 7) of agrochemicals residues are detected, we call other scientist to verify the ecological complexity of non-additive induced shifts in natural aquatic invertebrate populations and aquatic species assemblages.

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