Abstract
Progestins are utilized as a component of human contraceptives, and enter the environment via wastewater treatment plant effluent. Certain progestins activate fish androgen receptors and cause decreases in fecundity and masculinization of females. In this study, a nest acquisition assay and computer assisted sperm analysis (CASA) was used to examine the effects of levonorgestrel (LNG) on male fathead minnow (Pimephales promelas) reproductive fitness. Males were exposed to 0, 10, or 100ng/L LNG for 14d. Combinations of a control male and a male from one of the treatments were placed into a competitive nesting assay, and time each male spent holding the nest and time spent exhibiting aggressive behaviors were analyzed at 48hrs post-exposure. Semen samples were analyzed for total motility, straight-line velocity, curvilinear velocity, average path velocity, linearity, beat cross frequency, and wobble at 0, 30, 60, 90, and 120sec post-activation. Males exposed to either concentration of LNG exhibited increased nest acquisition success and lower levels of aggression compared to control-control pairings, as well as decreases in multiple sperm motion characteristics. Results from our study suggest that further research is required to ascertain the effects of LNG on male gamete quality and reproductive behaviors. This article is protected by copyright. All rights reserved
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