Harris, Cassandra2020-01-162020-01-162019http://udspace.udel.edu/handle/19716/24943Chemosensory predator recognition is a vital component for the survival for coral reef fishes. However, rather than detecting species-specific predator cues, the use of diet generalization allows prey to respond to any potential predator. Behavioral studies have demonstrated that diet influences the perception of fish, with naturally herbivorous fish perceived as predators when fed a piscivorous diet. Host diet highly influences the community composition of the gut microbiome, so it may be possible that the gut microbiome is generating the chemical cues stimulating predator avoidance behavior. In this study, the diet of herbivorous or invertivorous coral reef fishes were manipulated to that of a piscivore, with natural piscivores used as a control. In between each trial, the fish were starved to clear their gut contents. As diets shifted, the behavioral response of prey anemonefish were examined and fecal matter was collected. When fed a natural diet, anemonefish showed indifference to the chemosensory cues of the herbivore and invertivore, but demonstrated avoidance behavior towards cues from all species fed a piscivorous diet. Fecal matter bacterial 16S rRNA genes were sequenced to identify changes in gut microbiome community as the diet changed. These results were not reliable due to the impact of starvation, so trials were repeated without starvation. Fish were fed for a minimum of 4 weeks with the exclusion of a starvation period when diets were transitioned prior to data collection. Our results revealed that as Yellow Tangs and Triggerfish were transitioned to a piscivorous diet, there was a significant increase in the abundance of Rhodobacterales. Trimethylamine (TMA) dehydrogenase was found in the gut microbiome of the 3 piscivorous diets from Yellow Tangs, Triggerfish, and Hawkfish. These enzymes are found in the genera Ruegeria and Leisingera that belong to Rhodobacterales. The data suggests that Rhodobacterales could be the bacteria that contributes to the changes in chemical cues when switched to a piscivorous diet. The oxidized version of TMA, TMAO, is known as a biomarker for seafood consumption in higher animals, and may possibly contribute to the chemical cue for fish that alerts prey of nearby predators, but much more research has to be done to validate this theory.Thesis11361535702019-08-07en