Exploration of Neural and Behavioural Responses to Anthropogenic Noise in Three Members of the Centrarchidae Family

Anthropogenic noise has been shown to be a fluctuating stressor found in natural environments, however, when fish physiologically and behaviourally respond to these noise sources is less known. Here, noise effects are closely examined in three species of fish found in the family Centrarchidae: bluegill sunfish (Lepomis macrochirus), rock bass (Ambloplites rupestris), and pumpkinseed sunfish (Lepomis gibbosus). In chapter 2, I quantify physiological and behavioural thresholds, percentage of the otolith surface occupied by the sulcus (S:O area), and hair cell densities. I found variation in physiological thresholds between species and variation when comparing physiological and behavioural thresholds, a significantly large S:O area in rock bass than bluegill and pumpkinseed, and no significant differences in hair cell densities. Knowing when fish can detect noise stressors in their environment is important to understand how they interact with their environment and provides a better understanding of when they are negatively being impacted by noise stressors. Chapter 3 examined how fish respond behaviourally to different sounds when their social context changed. When in a pen with heterospecifics, fish experienced significantly more fin beats and spent less time swimming at the onset of acoustic stimuli but displayed a non-significant difference in how much time they spent at the bottom of the pen. Knowing this information, it is important to consider social context when determining overall stress levels of fish in their natural environments, as it can be an added effect when new stressors become present.