ATLSS: Across Trophic Level System Simulation for the Freshwater Wetlands of the Everglades and Big Cypress Swamp


The Everglades and Big Cypress Swamp of South Florida are characterized by complex patterns of spatial heterogeneity and temporal variability, with water flow being the major factor controlling the trophic dynamics of the system. A key objective of modeling studies for these systems is to compare the future effects of alternative hydrologic scenarios on the biotic components of the systems. Due to the varying scales at which trophic interactions occur, and the importance of population structure and individual behavior for population prediction in higher trophic level organisms, use of a single modeling approach is not appropriate. We are developing a set of models designed to integrate three approaches for different trophic levels of the system: (1) process models for lower trophic levels (including benthic insects, periphyton and zooplankton), (2) structured population models for five functional groups of fish and macroinvertebrates, and (3) individual-based models for large consumers (wood storks, great blue herons, white ibis, American alligators, white-tailed deer, and Florida panther). These are integrated across the freshwater landscape of the Everglades and Big Cypress Swamp and coupled to GIS maps for cover type. Spatial scales of resolution for the models are as small as 100 m, with the capability to vary this based upon the scale of available input data. The system is then coupled to a hydrology model, and used to assess the effects of alternative proposed restoration scenarios on trophic structure.

Future plans for this project include: (1) continuing development of new models for particular trophics components not currently included (e.g. nutrient fluxes, bacteria/fungi, Apple Snail, Snail Kite, feral hog); (2) development of a fine-scaled landscape vegetation model that includes successional changes across the landscape, and simulates vegetation responses to major disturbances (fires, freezes, and hurricanes); (3) continued integration of all ATLSS model components to allow a unified approach to questions which cross trophic levels, and allow complete analysis of alternative flow scenarios without requiring very different model runs; and (4) aiding the development of modeling systems based upon the ATLSS approach for the remaining major areas of environmental concern within the region (e.g. the Kissimmee River basin, Lake Okeechobee, Florida Bay, Florida reef tract) and integrating these models at their boundaries.

The overall ATLSS project is coordinated by Donald DeAngelis of the Biological Resources Division, U.S. Geological Survey (BRD). The model components being constructed at the Institute for Environmental Modeling of the University of Tennessee at Knoxville (UTK) are coordinated by Louis Gross (Professor of Ecology and Mathematics, UTK) and Michael Huston (Oak Ridge National Laboratory/UTK Collaborating Scientist and Professor of Ecology, UTK), with code development and production carried out by Ethel Jane Comiskey, Mark Palmer, Michael Peek, and Scott Sylvester. Particular models have been developed by with the assistance of several UTK graduate students including Holly Gaff, Phil Nott, Rene' Salinas and Maurice Shorrosh. Other key personnel involved in the modeling components of the project include: D. Martin Fleming (Scientist, NBS), Paul Fishwick (University of Florida), William Loftus (Scientist, NBS), Robert Ulanowicz (Professor, Chesapeake Biological Laboratory, University of Maryland); and Wilfried Wolff (Scientist, Forschungszentrum Julich, Germany). Financial support for the project is provided by several agencies, all coordinated through the BRD.