|Feifarek, David - Environmental Protection Agency (EPA)|
|Rearick, Daniel - Trent University|
|Bartell, Steve - Normandale Community College|
|Schoenfuss, Heiko - St Cloud State University|
Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/2/2017
Publication Date: 1/15/2018
Publication URL: http://handle.nal.usda.gov/10113/5801886
Citation: Shappell, N.W., Feifarek, D.J., Rearick, D.C., Bartell, S.E., Schoenfuss, H.L. 2018. Do environmental factors affect male fathead minnow (Pimephales promelas) response to estrone? Part 2. Temperature and food availability. Science of the Total Environment. 610–611:32–43. https://doi.org/10.1016/j.scitotenv.2017.08.021.
DOI: https://doi.org/10.1016/j.scitotenv.2017.08.021 Interpretive Summary: In nature, fish experience continuously changing environmental conditions and feed limitations. How do ambient temperature and food availability alter the response of male fathead minnows to estrogen exposure? Fathead minnows were exposed to estrone, a common environmental estrogen, and then assessed for parameters including body, liver and testis weight, length, hematocrit, blood glucose, the stress hormone cortisol, the egg-yolk protein vitellogenin and sperm maturity. Higher water temperature (26 °C / 79°F, used typically for laboratory experiments versus 18 °C / 64°F) was more detrimental than either estrogen exposure or feed restriction, its effects including altered sperm maturation. Vitellogenin, an indicator of environmental estrogen exposure, was affected by estrone, food availability and temperature. The high estrone treatment resulted in significantly elevated vitellogenin, however lower estrone concentrations (= 14 ng/L) did not. Several parameters differed in control fish between experiments, indicating that fish variability is a factor even with laboratory fish cultures. Take home: while “high” estrone concentrations will cause an increase in vitellogenin concentrations and changes in sperm maturation, high environmental temperature appears to have greater impact on fathead minnows. Future studies should evaluate the environmental applicability of aquatic toxicity tests conducted at temperature well above those in which most fathead minnows reproduce in nature.
Technical Abstract: In nature, fish are subject to constantly changing environmental conditions and limitations on food availability, potentially impacting their response to endocrine disruptors. Outcome discrepancies between field studies and laboratory exposures of endocrine disruptors may be a result of these conditions. This study examined effects of temperature and food availability on estrone (E1) exposure in male fathead minnows. Two experiments utilized three by two by two factorial design, consisting of three E1 concentrations (range 0 – 135 ng/L); two temperatures (18°C and 26°C, the latter being prescribed laboratory temperature), two feeding treatments (full fed vs. 25% of full fed) in a 21 day flow-through exposure system. Morphometric endpoints (including body condition factor, somatic index of gonad (GSI) and liver (HSI), and secondary sex characteristics (SSC)), blood parameters (hematocrit (HCT), blood glucose, cortisol, and vitellogenin (VTG) concentrations), and histopathology of liver and testis were determined on Day 22. High temperature (26°C) impacted the greatest number of parameters. In Exp. 1, three sex-linked parameters (testis weight, GSI and VTG decreased at high temperature, and in Exp. 2, additionally SSC and gonad maturity rating also decreased. At 26°C, in Exp. 1 HSI and HCT decreased, and in Exp. 2 length, body and liver weight, and body condition factor were lower. High E1 concentrations increased VTG, though interactions among E1, temperature and/or food on liver weight, HSI, and HCT were inconsistent between experiments. Food restriction decreased GSI in Exp. 1, and blood glucose and liver weight in Exp. 2. While control values of some parameters differed between experiments, at 26°C several parameters were altered independent of E1 exposure, including three out of four measurements of sperm differentiation. In order to realistically expect concordance between laboratory and field investigations of the biological effects of contaminants of emerging concern, attention should be paid to environmentally-relevant exposure conditions.