The Effects of Short-Term Exposure to an Endocrine Disrupter on Behavioral Consistency in Male Juvenile and Adult Siamese Fighting Fish

Abstract

17α-Ethinyloestradiol (EE2) is known to impact courtship and aggression but how exposure affects the consistency with which individuals express these behaviors over time is not commonly addressed. In addition, how juvenile and adult male fish differ in levels of behavioral consistency, both before and after EE2 exposure, is unknown. To examine these questions, juvenile and adult male Siamese fighting fish were presented with a dummy male and dummy female simultaneously both before and after acute exposure to a nominal (15 ng/L) dose of EE2. Multiple trials were conducted to measure how consistent individual differences are affected by age and EE2 exposure. Both female- and male-directed behaviors decreased after short-term exposure to EE2. Juvenile and adult fish differed in the number of female-directed tail beats and bites they performed, with adult fish performing more tail beats and juvenile fish performing more bites. EE2 exposure had a greater effect on consistent individual differences in female-directed than in male-directed behaviors, which may be a byproduct of intense artificial selection for aggression in this species. Repeatability values were lower both before and after exposure in juvenile than in adult fish, suggesting that individuals become more consistent with age. This study suggests that male Siamese fighting fish vary in their sensitivity to short-term EE2 exposure and stresses the importance of examining behavior over multiple time points both within and across age classes to gain a more thorough understanding of the effects of endocrine disruptors on behavior.

Timescale effects of 17α-ethinylestradiol on behavioral consistency in male threespine stickleback

“…We believe that this is the first study to assay the effects of EE2 exposure on courtship and aggressive behavior at multiple time points and in different social contexts. This is also one of the first studies to examine whether consistent individual differences in behavior are impacted by EDC exposure, despite the fact that the existence of these consistent differences has become a popular subject of behavioral ecology research (but see Dzieweczynski 2011;Dzieweczynski and Hebert 2013). Overall levels of courtship and aggression were reduced in all social contexts following exposure to EE2.…”

Acute exposure to 17α-ethinylestradiol alters boldness behavioral syndrome in female Siamese fighting fish

“…To create an EE2 stock solution, 17α-ethinylestradiol (98% purity; Sigma Aldrich) was dissolved in ethanol (95%) using the methods outlined in Dzieweczynski and Hebert (2013). To arrive at a final concentration of 10 ng/l, 7 μl of the stock solution was added to 475 ml of water, mixed, and then used to replace the water in the home container of each of the females in the experimental group.…”

“…For example, both acute and chronic exposures to the estrogen mimic 17α-ethinylestradiol (EE2) have been found to interfere with both the overall level and consistency of aggression and courtship in males of this species which may interfere with the ability to obtain mates (Clotfelter and Rodriguez, 2006;Dzieweczynski and Hebert, 2013). Little is known about female Siamese fighting fish behavior beyond a few studies on their shoaling behavior and mate choice (e.g.…”

Court Like You Mean It: Male Siamese Fighting Fish are Less Attentive to Courting Males that Have Been Exposed to an Estrogen Mimic

“…The Siamese fighting fish is a frequent subject of behavioral and ecotoxicological studies (e.g., Clotfelter et al. , ; Dzieweczynski & Hebert ) in part due to its well‐defined aggressive and courtship displays (Simpson ). Exposure to estrogen mimics leads to reduced courtship and aggression (Clotfelter & Rodriguez ; Dzieweczynski et al.…”

“…Unexposed subject males watched three possible video combinations of courting males that differed based on whether they were exposed or unexposed to EE2 and one set of videos in which one exposed and one unexposed male swam separately in empty tanks. The Siamese fighting fish is a frequent subject of behavioral and ecotoxicological studies (e.g., Clotfelter et al , 2010Dzieweczynski & Hebert 2013) in part due to its well-defined aggressive and courtship displays (Simpson 1968). Exposure to estrogen mimics leads to reduced courtship and aggression (Clotfelter & Rodriguez 2006;Dzieweczynski et al 2014a) and decreases exploration and activity levels (Hebert et al 2014) in male Siamese fighting fish.…”