Abstract

Freshwater ecosystems are often affected by cocktails of multiple pesticides targeting different organism groups. Prediction and evaluation of the ecosystem-level effects of these mixtures is complicated by the potential not only for interactions among the pesticides themselves, but also for the pesticides to alter biotic interactions across trophic levels. In a stream microcosm experiment, we investigated the effects of two pesticides targeting two organism groups (the insecticide lindane and fungicide azoxystrobin) on the functioning of a model stream detrital food web consisting of a detritivore (Ispoda: Asellus aquaticus) and microbes (an assemblage of fungal hyphomycetes) consuming leaf litter. We assessed how these pesticides interacted with the presence and absence of the detritivore to affect three indicators of ecosystem functioning - leaf decomposition, fungal biomass, fungal sporulation - as well as detritivore mortality. Leaf decomposition rates were more strongly impacted by the fungicide than the insecticide, reflecting especially negative effects on leaf processing by detritivores. This result most like reflects reduced fungal biomass and increased detritivore mortality under the fungicide treatment. Fungal sporulation was elevated by exposure to both the insecticide and fungicide, possibly representing a stress-induced increase in investment in propagule dispersal. Stressor interactions were apparent in the impacts of the combined pesticide treatment on fungal sporulation and detritivore mortality, which were reduced and elevated relative to the single stressor treatments, respectively. These results demonstrate the potential of trophic and multiple stressor interactions to modulate the ecosystem-level impacts of chemicals, highlighting important challenges in predicting, understanding and evaluating the impacts of multiple chemical stressors on more complex food webs in situ. (C) 2017 Elsevier B.V. All rights reserved.

Keywords

Ecosystem processes; Invertebrates; Fungi; Microbes; Multi-stressor interactions; Non-target organisms; Pesticides; PICT

Published in

Aquatic Toxicology
2017, Volume: 186, pages: 215-221
Publisher: ELSEVIER SCIENCE BV

SLU Authors

• Dawoud, Mohab

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    
  • Low Emission Capacity Building Project

• Bundschuh, Mirco

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

• Goedkoop, Willem

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

• Mckie, Brendan

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

Associated SLU-program

SLU Plant Protection Network


Sustainable Development Goals

SDG3 Ensure healthy lives and promote well-being for all at all ages
SDG6 Ensure availability and sustainable management of water and sanitation for all
SDG14 Conserve and sustainably use the oceans, seas and marine resources for sustainable development
SDG15 Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss


UKÄ Subject classification

Environmental Sciences


Publication identifier

DOI: https://doi.org/10.1016/j.aquatox.2017.03.008

Permanent link to this page (URI)

https://res.slu.se/id/publ/83059