Abstract

Animals involved in leaf litter breakdown (i.e., shredders) play a central role in detritus-based stream food webs, while their fitness and functioning can be impaired by anthropogenic stressors. Particularly fungicides can affect shredders via both waterborne exposure and their diet, namely due to co-ingestion of adsorbed fungicides and shifts in the leaf-associated fungal community, on which shredders' nutrition heavily relies. To understand the relevance of these effect pathways, we used a full 2 x 2-factorial test design: the leaf material serving as food was microbially colonized for 12 days either in a fungicide-free control or exposed to a mixture of five current-use fungicides (sum concentration of 62.5 mu g/L). Similarly, the amphipod shredder Gammarus fossarum was subjected to the same treatments but for 24 days. Waterborne exposure reduced leaf consumption by 20%, which did not fully explain the reduction in feces production (similar to 30%), indicating an enhanced utilization of food to compensate for detoxification mechanisms. This may also explain the reduced feces production (similar to 10%) of gammarids feeding on fungicide-exposed leaves. The reduction may, however, also be caused by a decreased nutritious quality of the leaves indicated by a reduced species richness (similar to 40%) of leaf-associated fungi. However, compensation for these effects by Gammarus was seemingly incomplete, since both waterborne exposure and the consumption of the fungicide-affected diet drastically reduced gammarid growth (similar to 110% and similar to 40%, respectively). Our results thus indicate that fungicide mixtures have the potential for detrimental implications in aquatic ecosystem functioning by affecting shredders via both effect pathways. (C) 2015 Elsevier B.V. All rights reserved.

Keywords

Agriculture; Aquatic hyphomycetes; Dietary exposure; Environmental risk assessment; Fungicide mixture; Leaf litter breakdown

Published in

Aquatic Toxicology
2015, Volume: 169, pages: 105-112
Publisher: ELSEVIER SCIENCE BV

SLU Authors

• Bundschuh, Mirco

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

Associated SLU-program

SLU Plant Protection Network


Sustainable Development Goals

SDG6 Ensure availability and sustainable management of water and sanitation for all


UKÄ Subject classification

Other Biological Topics


Publication identifier

DOI: https://doi.org/10.1016/j.aquatox.2015.10.008

Permanent link to this page (URI)

https://res.slu.se/id/publ/69541