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Anti-Predator Responses of Fathead Minnows to Alarm Substance Pheromone

Anti-Predator Responses of Fathead Minnows to Alarm Substance Pheromone Sarah Thomson & John D. Krenz Department of Biological Sciences, Minnesota State University, Mankato. Introduction

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Anti-Predator Responses of Fathead Minnows to Alarm Substance Pheromone

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  1. Anti-Predator Responses of Fathead Minnows to Alarm Substance Pheromone Sarah Thomson & John D. KrenzDepartment of Biological Sciences, Minnesota State University, Mankato Introduction All Ostariophysan fishes, which account for 72% of all freshwater fishes, possess specialized epidermal cells that release a pheromone only when damaged by a predator (Ferrari et al. 2010). Fathead minnows (Pimephales promelas) rely on this alarm substance (AS) as a signal of imminent predation risk. Predator-naïve minnows must become conditioned to AS, by pairing its detection with a direct predator cue, such as the sight, sound, or motion of a nearby fish (Ferrari 2006). After conditioning, minnows will respond to AS alone by shoaling, hiding behind shelter, dashing, freezing (Carreau-Green et al. 2008), and diving towards the substrate (Wisenden et al. 2001). I conditioned fathead minnows in the lab to AS, and then tested their response to AS alone. I compared the anti-predator behaviors of these minnows to an unconditioned control group of minnows, as well as each minnows response to the introduction of water (another control). The results of this study are relevant since there is a lack of studies focusing on individual behavior in fathead minnows conditioned to this substance. • Results and Discussion • Conditioned minnows expressed more anti-predatory responses when exposed to the alarm pheromone compared to the control (Figure 2), but this difference was not statistically significant. • Unconditioned minnows responded with anti-predator behavior fewer times when exposed to the alarm substance compared to exposure to water (Figure 3), but this difference was also not statistically significant. • The lack of a statistically significant difference could have been caused by fathead minnow’s increased sensitivity to the alarm substance during the breeding season (Polluck et al. 2006), which is not the time frame of this study. • This study suggests fathead minnows decrease their anti-predatory behavior when they are not in a shoal. Conditioned Unconditioned Water Alarm Alarm Water Figure 1: Methodology for the group conditioning process transitioning to the individual analysis. fathead minnow Figure 2: Behavior displayed by individual conditioned fathead minnows. The difference in behavior is not statistically significant. Figure 4: Anti-predatory behavior displayed in the conditioned and unconditioned fish. The difference is not statistically significant. Literature cited Carreau-Green, N.D., Mirza, R.S., Martinez, M.L, and Pyle, G.G. 2008. The Ontogeny Chemically Mediated Antipredator Responses of Fathead Minnow Pimephales promelas. Journal of Fish Biology 73:2390-2401. Ferrari, Maud C.O., Messier, Francois, and Chivers, Douglas P. 2006. The Nose Knows: Minnows Determine Predator Proximity and Density Through Detection of Predator Odours. Animal Behaviour 72:927-932. Ferrari, Maud C.O., Wisenden, Brian D., and Chivers, Douglas P. 2010. Chemical Ecology of Predator-Prey Interactions in Aquatic Ecosystems: a Review and Prospectus. Canadian Journal of Zoology 88:698-724. Pollock, M.S., Pollock, R.J., and Chivers, D.P. 2006. Effect of Body Size, Body Condition, and Breeding State on Responses to Alarm Cues by Fathead Minnows. Canadian Journal of Zoology 84:1351-1357. Wisenden, Brian D., and Harter, Katherine R. 2001. Motion, Not Shape, Facilitates Association of Predation Risks with Novel Objects by Fathead Minnows (Pimephales promelas). Ethology 107:357-364. Acknowledgments We thank the Department of Biological Sciences for equipment and laboratory space. We also thank the Undergraduate Research Center for aiding in presenting our study. Methods Thirty predator-naïve fathead minnows were divided into two identical 38-L aquaria. One group was conditioned to AS plus simulated fish motion daily for 1 wk. The other group experienced motion with the addition of distilled water (control; Figure 1). After conditioning, I exposed each individual to AS and water, and recorded their behavior following each exposure. Figure 3: Behavior displayed by individual unconditioned fathead minnows. The difference in behavior is not statistically significant. Presenter Information: Sarah Thomson– Minnesota State University, Mankato – Sarah.Thomson@mnsu.edu

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