Abstract

Antibiotics may constitute a risk for aquatic detritivorous macroinvertebrates (i.e., shredders) via waterborne and dietary antibiotic exposure. In addition, antibiotics can alter the food quality for shredders mediated by shifts in leaf-associated decomposer (i.e., aquatic fungi and bacteria) communities. However, little is known about the relative importance of the waterborne and dietary effect pathway. Therefore, we followed a tiered testing approach aimed at assessing the relative importance of these effect pathways. We employed the antibiotic ciprofloxacin (CIP) and the shredder Gammarus fossarum as model stressor and test species, respectively. In a first step, we assessed the short-term waterborne toxicity of CIP using survival and leaf consumption of G. fossarum as response variables. Alterations in the leaf-associated decomposer community, which may be reflected by their palatability, were assessed using food choice assays. Finally, we conducted a 2 x 2-factorial experiment over 24 days assessing the pathways individually and combined using energy processing (i.e., leaf consumption and feces production), growth and energy storage (i.e., neutral lipid fatty acids) as variables. Short term waterborne exposure indicated low toxicity with LC50 and EC50 values of 13.6 and 6.4 mg CIP/L, respectively. At the same time, shredders did not prefer any leaf material during the food choice assay. However, the fungal community was significantly affected in the highest CIP-treatments (0.5 and 2.5 mg/L) suggesting an altered food quality for shredders. This assumption is supported by the results of the long-term assay. At 0.5 mg CIP/L, gammarids' leaf consumption, growth and energy storage were increased when subjected via the dietary pathway, which was linked to changes in the leaf-associated microbial community. Our data highlight the importance of dietary effect pathways for effects on shredders, potentially impacting energy dynamics in detritus-based stream ecosystems.

Keywords

Aquatic fungi; Fatty acids; Fluoroquinolone; Food quality; Leaf litter breakdown

Published in

Aquatic Toxicology
2020, Volume: 222, article number: 105461
Publisher: ELSEVIER

SLU Authors

• Bundschuh, Mirco

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

Sustainable Development Goals

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

Fish and Aquacultural Science


Publication identifier

DOI: https://doi.org/10.1016/j.aquatox.2020.105461

Permanent link to this page (URI)

https://res.slu.se/id/publ/105609