Joint Ecosystem Modeling: Alligator Production Probability Model

Science Center Objects

Because the American alligator (Alligator mississippiensis) is a keystone species of the Everglades ecosystem, managers need a way to quantitatively assess the effects of alternative restoration scenarios on alligators.

Alligator - stock image

Alligator - stock image. (Public domain.)

The Science Issue and Relevance: Joint Ecosystem Modeling (JEM), a partnership among federal and state agencies, universities, and other organizations, is a long-term project for developing ecological forecast models for Florida’s Greater Everglades ecosystem. Water managers and other decision-makers use ecological models to understand how competing restoration scenarios may impact species of concern and make more informed restoration decisions. JEM provides ecological model output tailored to management decisions. Because the American alligator (Alligator mississippiensis) is a keystone species of the Everglades ecosystem, managers need a way to quantitatively assess the effects of alternative restoration scenarios on alligators. The Alligator Production Probability Model was developed in collaboration with Everglades National Park, University of Florida, and U.S. Fish and Wildlife Service to examine competing restoration plans on alligator production suitability.

Everglades - stock image

Everglades - stock image. (Public domain.)

Methodology for Addressing the Issue: The Alligator Model provides estimates for habitat quality, breeding, courtship & mating, and nesting success, with a focus on estimating yearly hatchling production. The software provides a graphical user interface (GUI) that makes running the model intuitive and straightforward for managers to use. Model inputs are daily water depth, daily salinity (optional), habitat type, alligator hole locations, tree island zones, tree island heights, and spatiotemporal model parameters (most of which are provided). Outputs include habitat area, percent edge habitat, breeding potential, courtship & mating, nest building, nest flooding, habitat suitability, and important hydrologic variables on an annual time interval. These are provided in NetCDF format. The model is available at jem.gov.

Future Steps: Managers and other decision-makers in the Greater Everglades can use the Alligator Production Probability model to examine how hydrologic conditions of alternative restoration scenarios affect habitat suitability for alligator production. Water managers can use the model to optimize hydrologic conditions, in turn stabilizing and improving alligator populations. The Alligator Production Probability model was designed as a living model so that the code can easily be accessed and changed to incorporate new knowledge in the field, thus making it a robust tool that can continue to be used over time.

1979 FWO hydrology alternative

1979 FWO hydrology alternative. Left to Right and Top to Bottom:Habitat, Breeding, Courtship & Mating, Nest Building, Nest Flooding, Overall Suitability.

Related Project(s): Joint Ecosystem Modeling (JEM), Everglades Forecasting (EVER4CAST)