Document Type

Article

Publication Date

9-1-2025

Abstract

Objective: The objective of this study was to quantify the effects of temperature, hydrology, and body size on the diet and energy requirements of a generalist predator, Common Snook Centropomus undecimalis (hereafter, “snook”), to gain a better understanding of predator–prey dynamics in the wake of global change. We first ask how temperature, hydrology, and body size influence the occurrence of fish, invertebrates, and empty stomachs in the diet of snook. Next, we model the energetic requirements of snook as a function of body size and temperature. Last, we use predation simulations to test how changes in prey quality, together with snook energy requirements, interact to shape prey demand. Methods: This study used long-term empirical diet information for snook that were collected from the Shark River, Everglades National Park, alongside models of consumer energetic needs and predation simulations. We used a set of generalized linear models to determine the relationships between snook diet and a suite of predictor variables representing hydrology, temperature, and body size. Models of consumer energetic requirements were used to better understand the total daily caloric needs of snook across a range of temperature and body sizes relative to the available energy in the fish and invertebrate prey that were collected from the system. Last, we conducted predation simulations to highlight the effects of variable diet scenarios on the foraging behaviors that are required to meet the total daily energetic requirements of snook at various temperatures and body sizes. Results: Snook were observed consuming less fish, coupled with an increased likelihood of empty stomachs, at higher temperatures. Reliance on invertebrate taxa increased at high marsh stages. In addition to marsh stage, smaller-bodied individuals were more likely to consume invertebrates. The predation simulations revealed that snook that consumed invertebrate-dominated diets required greater prey biomass as well as an increased number of individual prey items to meet their daily energetic requirements relative to fish that consumed diets that contain fish. However, if snook maintained even a small proportion of fish in their diet, it substantially reduced the number and biomass of prey needed to meet their energetic requirements. Conclusions: Our predation simulations indicated that snook should select for high-quality fish prey as temperatures warm. However, the empirical data revealed a decrease in the probability of high-quality fish prey in the diets of snook. Furthermore, the empirical diet data showed that low-quality invertebrate prey were more likely to be seen in the diets of snook at high water levels. As temperatures increase and hydrology becomes increasingly variable because of global change, snook will likely need to consume larger quantities of lower quality prey (i.e., compensatory foraging) or disperse to forage in more optimal habitats. These results highlight the dynamic interplay between environmental conditions and consumer energetic needs for shaping the foraging ecology of a generalist predator.

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Oxford University Press originally published this article.

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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