title: Changes in reproductive biomarkers in an endangered fish species (bonytail chub, Gila elegans) exposed to low levels of organic wastewater compounds in a controlled experiment.
abstract: In arid regions of the southwestern United States, municipal wastewater treatment plants commonly discharge treated effluent directly into streams that would otherwise be dry most of the year. A better understanding is needed of how effluent-dependent waters (EDWs) differ from more natural aquatic ecosystems and the ecological effect of low levels of environmentally persistent organic wastewater compounds (OWCs) with distance from the pollutant source. In a controlled experiment, we found 26 compounds common to municipal effluent in treatment raceways all at concentrations <1.0 microg/L. Male bonytail chub (Gila elegans) in tanks containing municipal effluent had significantly lower levels of 11-ketotestosterone (p=0.021) yet higher levels of 17beta-estradiol (p=0.002) and vitellogenin (p=0.036) compared to control male fish. Female bonytail chub in treatment tanks had significantly lower concentrations of 17beta-estradiol than control females (p=0.001). The normally inverse relationship between primary male and female sex hormones, expected in un-impaired fish, was greatly decreased in treatment (r=0.00) versus control (r=-0.66) female fish. We found a similar, but not as significant, trend between treatment (r=-0.45) and control (r=-0.82) male fish. Measures of fish condition showed no significant differences between male or female fish housed in effluent or clean water. Inter-sex condition did not occur and testicular and ovarian cells appeared normal for the respective developmental stage and we observed no morphological alteration in fish. The population-level impacts of these findings are uncertain. Studies examining the long-term, generational and behavioral effects to aquatic organisms chronically exposed to low levels of OWC mixtures are needed.
authors.affiliation: University of Arizona, Environmental Research Laboratory, 2601 E. Airport Drive Tucson, AZ 85706, USA. dwalker@ag.arizona.edu
authors.forename: David B
authors.initials: DB
authors.lastname: Walker
authors.forename: Nicholas V
authors.initials: NV
authors.lastname: Paretti
authors.forename: Gail
authors.initials: G
authors.lastname: Cordy
authors.forename: Timothy S
authors.initials: TS
authors.lastname: Gross
authors.forename: Steven D
authors.initials: SD
authors.lastname: Zaugg
authors.forename: Edward T
authors.initials: ET
authors.lastname: Furlong
authors.forename: Dana W
authors.initials: DW
authors.lastname: Kolpin
authors.forename: William J
authors.initials: WJ
authors.lastname: Matter
authors.forename: Jessica
authors.initials: J
authors.lastname: Gwinn
authors.forename: Dennis
authors.initials: D
authors.lastname: McIntosh
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D003530:Cyprinidae / Q000502:physiology*; D004958:Estradiol / Q000032:analysis / Q000378:metabolism; D005260:Female; D007220:Industrial Waste / Q000009:adverse effects*; D007664:Ketosteroids / Q000032:analysis / Q000378:metabolism; D008297:Male; D010053:Ovary / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D012098:Reproduction / Q000187:drug effects* / Q000502:physiology*; D018570:Risk Assessment; D013737:Testis / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D014819:Vitellogenins / Q000032:analysis / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D015415:Biomarkers; D007220:Industrial Waste; D007664:Ketosteroids; D014819:Vitellogenins; D014874:Water Pollutants, Chemical; D004958:Estradiol