Date of Award

5-2018

Culminating Project Type

Thesis

Degree Name

Biological Sciences - Cell and Molecular: M.S.

Department

Biology

College

College of Science and Engineering

First Advisor

Heiko Schoenfuss

Second Advisor

Jessica Ward

Third Advisor

Satomi Kohno

Fourth Advisor

Mark Mechelke

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Keywords and Subject Headings

bluegill sunfish, fathead minnow, toxicology, climate change, predator-prey, estrogen

Abstract

Contaminants of emerging concern (CECs), for example estrone (E1), and their effects to aquatic organisms have been researched consistently, however little is known about how temperature can influence exposure effects of CECs. Chemical exposures and temperature have been shown to independently affect fish and their populations, but little is known about their impact on predator-prey relationships. Previous studies indicate that changes arise through behavioral and physiological changes in either predator or prey. To test the effects of E1 and temperature on predator-prey relationships, adult bluegills and larval fathead minnows were exposed to E1 (125, 625 ng/L) or an ethanol control for 30 days at four temperatures (15°C, 18°C, 21°C, 24°C) to reflect natural variation between seasons.Behavioral experiments were conducted to assess the effects of temperature and estrone exposure on minnows in the larval life stage (i.e., foraging and predator evasion). Significant differences due to water temperature were observed in body length, escape angle, and total escape response of predator evasion responses. On day 30 of exposure, predation trials were performed using one adult sunfish and a group of five control and five exposed (125 or 625ng/L) larvae. Exposed larvae (125ng/L: 49.2%; 625ng/L: 52.9%) displayed a concentration-dependent reduction in survival in comparison to the control minnows (74.2%) following predation from the sunfish predator. Additionally, the prey catching abilities of the sunfish may have been affected, potentially mitigating the predation effects on the minnows. In addition, a series of anatomical and physiological endpoints were explored to assess the independent and interactive effects of estrone exposure and temperature on plasma vitellogenin induction, blood glucose, histology, and morphometric indices on sunfish in the adult life stage. This study provides evidence that minnow populations may suffer due to impaired predator evasion performance and provides information for environmental agencies evaluating ecological effects of exogenous estrogens and climate change.

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