Repository to house scripts for White et al. 2025 publication in Marine and Coastal Fisheries
Linking hydrology, temperature, and energetics: global change implications for the foraging ecology of a generalist predator
Authors Mack White1*, W. Ryan James1,2,3, Justin S. Lesser1,2, Ryan J. Rezek4, Jonathan R. Rodemann1,2, Ross E. Boucek5, Rolando O. Santos2,3, Jennifer S. Rehage1,2
Affiliations 1Florida International University, Earth and Environment Department, Miami, Florida, 33199 2Florida International University, Institute of Environment, Miami, Florida, 33199 3Florida International University, Biological Sciences Department, Miami, Florida, 33181 4Coastal Carolina University, Department of Marine Science, Conway, South Carolina, 29528 5Bonefish and Tarpon Trust, Miami, Florida, 33133
Correspondence Mack White Email: mackwhiteecology@gmail.com{.email}
Structured Abstract Objective: The objectives of this study were 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 function of body size and temperature. Lastly, we use predation simulations to test how changes in prey quality, together with snook energy requirements, interact to shape prey demand.
Methods: This study utilized long-term empirical diet information for snook 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 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 energy available in fish and invertebrate prey collected from the system. Lastly, we conducted predation simulations to highlight the effects of variable diet scenarios on snook foraging behaviors required to meet their total daily energetic requirements at various temperatures and body sizes.
Results: Snook were observed consuming less fish, coupled with an increased likelihood of empty stomachs, at higher temperatures. Snook reliance on invertebrate taxa increased at high marsh stages. In addition to marsh stage, smaller-bodied individuals were more likely to consumer invertebrates. Predation simulations revealed that snook consuming invertebrate-dominated diets required greater prey biomass, as well as an increased number of individual prey items, to meet their daily energetic requirements when compared to diets containing fish. However, if snook maintained even a small proportion of fish in their diet, it greatly 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. Empirical data revealed a decrease in the probability of high-quality fish prey in the diets of snook, however. Further, empirical diet data showed 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 as a result 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.
Lay Summary Warming temperatures and hydrologic variability associated with global change are disrupting trophic interactions with ecosystem-level implications. Our findings identify the effects of environmental conditions on the prey use of a generalist predator, snook, and its energetic implications as a result of differences in prey quality and shifting predator energy requirements associated with warming temperatures. Our study highlights the importance of understanding shifts in prey assemblages associated with hydroclimatic drivers through the lens of predator energetic needs. Keywords predator-prey; foraging ecology, snook, climate change, animal energetics Acknowledgements We thank our collaborators at Everglades National Park and Florida International University for their ongoing support of our research. We acknowledge our funders at the U.S. Army Corps of Engineers under Cooperative Agreement #W912HZ-12-2-0015 and the National Science Foundation through the Florida Coastal Everglades Long-term Ecological Research program under DEB-1237517 and DEB-1832229. We thank all previous graduate students and technicians for their hard work in collecting and maintaining the long-term datasets used here. This is contribution #XXXX from the Institute of Environment at Florida International University.