Marine Science Faculty Publications


Experimental Test of Preference by a Generalist Piscivore on Morphologically- and Behaviorally- Different Prey

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Generalist predators can have wide diet breadths that are influenced by the relative abundance of different prey available to them, making it difficult to determine prey preference from field observations. To ascertain preference, controlled experimentation is required that accounts for prey-specific variation in the time it takes to search, capture, and consume the prey; all of which can be affected by its morphology and behavior. Based on previous stomach content studies, Pinfish, Lagodon rhomboides and Clown Gobies, Microgobius gulosus, comprise a substantial proportion of the diet of Spotted Seatrout, Cynoscion nebulosus, despite strong differences in the morphology and behavior of these prey. Pinfish are demersal, deep-bodied fish that form loose aggregations with strong dorsal- and anal-fin spines that shoal in large aggregations, whereas Clown Gobies are benthic, shallow-bodied fish with weaker fin spines and are solitary but evenly distributed over the substrate. We conducted controlled, laboratory feeding experiments to test prey preference by Spotted Seatrout for these two common prey. Spotted Seatrout did not exhibit a feeding preference for either Pinfish or Clown Gobies, despite the strong differences in morphology and behavior. However, we observed higher consumption rates of the Clown Goby, but not the Pinfish, during 24-hour trials compared to those lasting 48 hours. This suggests that the densities of a solitary prey, but not a shoaling one, may have influenced search times by the generalist predator. Our experiments highlight the complexities of feeding behaviors by a generalist predator in highly dynamic ecosystems.

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Journal of Experimental Marine Biology and Ecology, v. 460, p. 193-196