Theses and Dissertations

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Defense Date

2011

Document Type

Thesis - NSU Access Only

Degree Name

M.S. Coastal Zone Management

Department

Oceanographic Center

First Advisor

Jennifer S. Rehage

Second Advisor

Michael Heithaus

Third Advisor

Amy C. Hirons

Abstract

Novel predator introductions are thought to have a significant impact on the survival and fitness of naïve prey, especially in freshwater systems. The ability of prey to recognize and respond appropriately to these novel threats may depend on the prey’s use of general or specific cues to detect predation threats. We used laboratory behavioral experiments to examine the ability of three native Everglades prey species (Eastern mosquitofish, Gambusia holbrooki, flagfish, Jordanella floridae, and riverine grass shrimp, Palaemonetes paludosus) to respond to the presence and to the sensory cues of a native predator (warmouth, Lepomis gulosus) and those of a recently introduced non-native predator (African jewelfish, Hemichromis letourneuxi). Specifically we examined: (1) the predation threat of the non-native jewelfish (2) the combined mortality affect of the native and non-native predator (3) the ability of the prey to respond the non-native predator and (4) the prey species use of chemical and visual cues to detect predation threats. Despite its novelty, our results indicated that the native warmouth and non-native jewelfish had similar predatory effects, although these effects may be somewhat prey specific. For mosquitofish, the novel predator represented less of a predation risk, while predation rates were similar for flagfish and grass shrimp. All three prey species showed surprisingly strong responses to the non-native jewelfish, which were comparable to the responses exhibited to the native predator. This would suggest that prey are relying on general cues for predator detection. However, during the predator cue experiments two of the naïve prey species, mosquitofish and flagfish, were able to respond to the specific chemical cues of the non-native predator with an equal intensity to that of the native predator. These broad response may indicate that some native Everglades prey have a greater behavioral plasticity or more experience with novel predators that allow them to detect and respond to a novel predation threat.

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