How does predation risk affect aggression in the Lake Tanganyika cichlid, Julidochromis ornatus?

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The Ohio State University

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Biodiversity worldwide is being threatened by human-induced rapid environmental change, including climate change, overexploitation, invasive species, and nutrient pollution. One such threatened ecosystem is Lake Tanganyika (East Africa), which has been experiencing rising water temperature due to climate warming. As to how Lake Tanganyika’s diverse and endemic cichlid (fish) assemblage will cope with increasing water temperature remains largely unknown. I propose to explore how the behavior of a common Lake Tanganyika cichlid, Julidochromis ornatus, varies in the presence and absence of a predator, under baseline (25ºC) and projected future (29ºC) temperatures. My expectation is that, in the absence of predation risk, high temperature will cause individuals to become bolder, more aggressive, and more exploratory relative to baseline conditions, owing to the need to secure more food resources. In the presence of predation risk, I expect these behaviors to be similar to the baseline condition, or perhaps intermediate to the baseline and projected future condition. To test this expectation, I will conduct a controlled laboratory experiment with adult J. ornatus. The experiment will consist of four treatments (2 temperatures [low, high] x 2 predation-risk levels [none, high]), with predation risk being simulated using both chemical and visual predator cues (with no risk of real predation). Each treatment will be replicated (n = 15 individuals), with response variables being quantitative estimates of exploration, boldness, and aggressiveness. I personally will quantify the behavior of fish in the presence of predators, which will be compared to previously measured estimates of behavior made this summer on the same individuals in the absence of predators. All behavioral data will be processed using EthoVision software, with analysis of variance (ANOVA) used to quantify differences among treatments. My research will provide new insights into how climate warming might interact with predation risk to influence fish behavior, which could be important to helping understand the ability of endemic cichlids to cope with continued climate change.



Predation, Temperature, Aggression, Behavior