Do environmental factors affect male fathead minnow (Pimephales promelas) response to estrone? Part 1. Dissolved oxygen and sodium chloride

Authors: FEIFAREK, DAVID - St Cloud State University; Shappell, Nancy; SCHOENFUSS, HEIKO - St Cloud State University

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2017
Publication Date: 1/1/2018
Publication URL: https://handle.nal.usda.gov/10113/5801885
Citation: Feifarek, D.J., Shappell, N.W., Schoenfuss, H.L. 2018. Do environmental factors affect male fathead minnow (Pimephales promelas) response to estrone? Part 1. Dissolved oxygen and sodium chloride. Science of the Total Environment. 610-611:1262-1270. http://dx.doi.org/10.1016/j.scitotenv.2017.07.251.

Interpretive Summary: Laboratory studies designed to investigate the effects of environmental levels of estrogens on minnows are sometimes not very consistent with observations from field studies. One reason for incongruent results could be the fact that stressors that affect fish in natural waterways (high water salt content or low oxygen levels) are seldom replicated in laboratory studies. In this study we investigated the effects of estrogens and a range of salt concentrations on a variety of toxicological endpoints in fathead minnows. None of the variables measured in fish were reproducibly affected in waters amended with salt. However when we studied the effects of estrogens in waters containing low levels of dissolved oxygen, a variable strongly associated with estrogen exposure (vitellogenin production) was consistently increased in minnows. Our results indicate that environmental factors can alter the response of fathead minnows to estrogens and indicate the need for a wide range of environmental conditions to be tested in the laboratory.

Technical Abstract: Laboratory exposures indicate that estrogens and their mimics can cause endocrine disruption in male fishes. Studies of resident fish populations in estrogen-polluted waters support these findings, yet biomarker expression associated with exposure to estrogenic endocrine disruptors often differs dramatically between field and laboratory studies. The dynamic nature of aquatic ecosystems may be a contributing factor, as changes in environmental parameters can trigger physiological and anatomical changes in fish potentially altering the uptake and effects of estrogenic chemicals. To explore the role of environmental variables on biomarker expression in response to estrogenic exposure, adult male fathead minnows (Pimephales promelas) were exposed to estrone under varied environmental conditions (differing dissolved oxygen and chloride concentrations) in a laboratory flow-through system. Morphological and hematological parameters were assessed. At the concentrations tested, no main effect differences (P< 0.05) were found associated with dissolved oxygen (DO) or chloride treatments, excepting a decrease in secondary sex characteristic score (SCC) with low DO in one experiment. An interaction between DO or chloride and E1 was present in the case of blood glucose in one experiment. While vitellogenin concentrations were elevated with exposure to estrone (29 to 390 ng/L), the effect on other indices were variable. For SSC, blood glucose, hematocrit, and hepatic and gonado-somatic index – 1 of 4 experiments were affected by estrone exposure, while estrone treatment decreased body condition factor in 3 of 4 experiments. These results indicate the variable response to estrone, even within the confines of controlled laboratory conditions.