title: Assessing relationships between chemical exposure, parasite infection, fish health, and fish ecological status: a case study using chub (Leuciscus cephalus) in the Bílina River, Czech Republic.
abstract: Multiple stressor scenarios, as they are relevant in many watersheds, call for approaches extending beyond conventional chemical-focused approaches. The present study, investigated the fish population, represented by chub (Leuciscus cephalus), in the Bílina River (Czech Republic), which is impacted by various pollution sources and might pose a risk on the fish population. To confirm or reject this hypothesis it was examined whether there exists an association between abundance of chub and exposure to toxic chemicals as well as natural stressors, represented by parasites, and whether health-related suborganismal traits, namely, organ indices, tissue histopathology, and immune parameters, would help in revealing relationships between stressor impact and population status. Toxic pressure was assessed by the toxic unit approach, which gives an integrative estimate of toxic effect concentrations and by measuring the biomarkers cytochrome P4501A and vitellogenin, which indicate exposure to bioavailable arylhydrocarbon- or estrogen receptor ligands. Parasite pressure was estimated by determining abundance and species composition of ecto- and endoparasites of chub. Chub abundance was high upstream in the Bílina, low to zero in the middle stretches, and increased again downstream. Toxic pressure increased in the downstream direction, while parasite intensity decreased in this direction. Health status of chub did not differ clearly between up-, middle-, and downstream sites. Thus, it appears that neither toxic pressure nor parasite pressure nor their combination translates into a change of chub health status. By using varied assessment tools, this study provides evidence against a presumed causative role of toxicants impairing the fish ecological status of the Bílina River.
authors.affiliation: Centre for Fish and Wildlife Health, Vetsuisse Faculty, University of Berne, P.O. Box 8466, 3001 Bern, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Wenger
authors.affiliation: Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Květná 8, 60365 Brno, Czech Republic.|Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, 61137 Brno, Czech Republic.
authors.forename: Markéta
authors.initials: M
authors.lastname: Ondračková
authors.affiliation: Department of Chemistry and Toxicology, Veterinary Research Institute, Hudcova 70, 62100 Brno, Czech Republic.
authors.forename: Miroslav
authors.initials: M
authors.lastname: Machala
authors.affiliation: Department of Chemistry and Toxicology, Veterinary Research Institute, Hudcova 70, 62100 Brno, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Neča
authors.affiliation: Institute of Experimental Biology, Faculty of Science, Masaryk University, Kotlářská 2, 61137 Brno, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Hyršl
authors.affiliation: Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, 61137 Brno, Czech Republic.
authors.forename: Andrea
authors.initials: A
authors.lastname: Šimková
authors.affiliation: Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Květná 8, 60365 Brno, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Jurajda
authors.affiliation: Umweltforschungszentrum (UFZ), Department of Effect-Directed Analysis; Helmholtz-Centre for Environmental Research-UFZ, Leipzig, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: von der Ohe
authors.affiliation: Centre for Fish and Wildlife Health, Vetsuisse Faculty, University of Berne, P.O. Box 8466, 3001 Bern, Switzerland.
authors.forename: Helmut
authors.initials: H
authors.lastname: Segner
mesh_terms: D000818:Animals; D015415:Biomarkers; D003530:Cyprinidae / Q000378:metabolism* / Q000469:parasitology*; D004463:Ecology; D006304:Health Status; D025341:Principal Component Analysis; D012333:RNA, Messenger / Q000032:analysis; D018570:Risk Assessment; D045483:Rivers / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D015415:Biomarkers; D012333:RNA, Messenger; D014874:Water Pollutants, Chemical
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