Abstract

Fungicides pose a risk for crustacean leaf shredders serving as key-stone species for leaf litter breakdown in detritus-based stream ecosystems. However, little is known about the impact of strobilurin fungicides on shredders, even though they are presumed to be the most hazardous fungicide class for aquafauna. Therefore, we assessed the impact of the strobilurin azoxystrobin (AZO) on the survival, energy processing (leaf consumption and feces production), somatic growth (growth rate and molting activity), and energy reserves (neutral lipid fatty and amino acids) of the amphipod crustacean Gammarus fossarum via waterborne exposure and food quality mediated (through the impact of leaf colonizing aquatic microorganisms) and thus indirect effects using 2 x 2-factorial experiments over 24 days. In a first bioassay with 30 mu g AZO/L, waterborne exposure substantially reduced survival, energy processing and affected molting activity of gammarids, while no effects were observed via the dietary pathway. Furthermore, a negative growth rate (indicating a body mass loss in gammarids) was induced by waterborne exposure, which cannot be explained by a loss in neutral lipid fatty and amino acids. These energy reserves were increased indicating a disruption of the energy metabolism in G. fossarum caused by AZO. Contrary to the first bioassay, no waterborne AZO effects were observed during a second experiment with 15 mu g AZO/L. However, an altered energy processing was determined in gammarids fed with leaves microbially colonized in the presence of AZO, which was probably caused by fungicide-induced effects on the microbial decomposition efficiency ultimately resulting in a lower food quality. The results of the present study show that diet-related strobilurin effects can occur at concentrations below those inducing waterborne toxicity. However, the latter seems to be more relevant at higher fungicide concentrations.

Keywords

Amino acids; Fatty acids; Food quality; Leaf litter breakdown; Metabolic disruptor; Microbial decomposers

Published in

Ecotoxicology and Environmental Safety
2021, Volume: 209, article number: 111848
Publisher: ACADEMIC PRESS INC ELSEVIER SCIENCE

SLU Authors

• Bundschuh, Mirco

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    
  • University of Koblenz-Landau

UKÄ Subject classification

Environmental Sciences


Publication identifier

DOI: https://doi.org/10.1016/j.ecoenv.2020.111848

Permanent link to this page (URI)

https://res.slu.se/id/publ/111128