Skip to main content
U.S. flag

An official website of the United States government

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

January 1, 2009

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 μg/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 17β-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 17β-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.

Publication Year 2009
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
DOI 10.1016/j.aquatox.2009.08.008
Authors David B. Walker, Nicholas V. Paretti, Gail Cordy, Timothy S. Gross, Steven D. Zaugg, Edward T. Furlong, Dana W. Kolpin, William J. Matter, Jessica Gwinn, Dennis McIntosh
Publication Type Article
Publication Subtype Journal Article
Series Title Aquatic Toxicology
Index ID 70044164
Record Source USGS Publications Warehouse
USGS Organization Arizona Water Science Center; Toxic Substances Hydrology Program