Effects of Turbidity and Visual vs. Chemical Cues on Anti‐Predator Response in the Endangered Fountain Darter (Etheostoma fonticola)

Altered turbidity resulting from anthropogenic stressors is a global problem. Threatened by climate change, pollution, and increased recreational usage, the streams and rivers of central Texas are no exception. The impacts of turbidity include behavioral effects as turbidity degrades visual information, which can impair an animal's ability to accurately detect and respond to a predator. Here, we tested the impact of simulated turbidity on anti‐predator response in the endangered fountain darter, Etheostoma fonticola. We examined the response of E. fonticola to four predator cue treatments (chemical, visual, chemical and visual, and no cues) using a native predator, the green sunfish (Lepomis cyanellus). All cue treatments were tested across two vision levels: clear and impaired, to simulate the visual effects of low turbidity (~30 NTU). Our results indicate that E. fonticola requires a combination of visual and chemical stimuli to respond to a native fish predator. In the absence of one or the other sensory modality, E. fonticola did not show an anti‐predator response. Also, anti‐predator response to a combination of visual and chemical stimuli was only present at the clear vision level. When vision was impaired owing to simulated turbidity, a combination of visual and chemical stimuli did not produce a significant anti‐predator response. These results indicate that blocked or compromised vision hampers anti‐predator response in E. fonticola, which may be of concern regarding the future management of this endangered species.