Project: Developing an ATLSS/ELM Lower Trophic Level Model

Web Sites: ATLSS.ORG

Location: Central Everglades; Palm Beach, Broward and Miami-Dade County

Principal Investigator: Donald L. DeAngelis, Phone: 305-284-1690, e-mail deangelis@umiami.ir.miami.edu

Project Personnel: Quan Dong, Southeast Environmental Research Center, OE 148, University Park, Florida International University, Miami, FL 33199, USA, Phone: 305-348-3044, e-mail: DONGQ@fiu.edu

Other Supporting Organizations: USGS/BRD, NPS

Associated Projects: Component of the ATLSS Program

Overview & Status: This project focuses on the lower trophic levels of food web in the freshwater marshes of the Everglades. The lower trophic levels contain primary producers and primary consumers. They provide both food and physical structures of habitats for the predators. Hydrology, nutrient supply, and other environmental forces drive the food web dynamics through bottom-up processes. The lower trophic levels serve as links of these forces and the upper trophic levels. The responses of lower trophic levels in turn can modify the environmental conditions, for example, the nutrient dynamics. The response may be affected by predation. Thus, the lower trophic levels also may serve as the links of top-down feedback, are important for the integrity and health of ecosystems and can serve as an important performance measure for the Everglades restoration. A suite of models was designed to study the lower trophic levels. A periphyton model was built to examine the interactive relationship between periphyton and phosphorus. A lower-trophic-level model was built to evaluate how hydrology and phosphorus enrichment affect trophic interactions in the food web. The lower trophic levels comprise six functional groups: periphyton, macrophytes, detritus, herbivores, detritivores, and predators.

Needs & Products: The periphyton model is constructed to understand the interactive relationship between periphyton and phosphorus dynamics in the Everglades. The understanding is critical for identification of the phosphorus threshold of ecological imbalance, the design of the periphyton based storm-water treatment areas, the design of dosing studies, and the design of phosphorus reduction plan. The lower-trophic-level model is designed to link hydrological conditions and nutrient supply to the upper trophic levels. Many species at the upper trophic levels are on the list of the Multi-Species Recovery Plan or are key indicators of ecosystem health. The lower-trophic-level model synthesized information and describes dynamics of the trophic interactions. The model output suggested: multiple asymptotic states exist, the system may be only hysterically reversible, the detritivorous energy shunt may serve as an important mechanism to maintain the observed trophic cascade, omnivory is common, phosphorus enrichment may lead to changes in the trophic structure of food web.

Application to Everglades Restoration: The ATLSS integrated suite of models has been used extensively in Everglades Restoration planning. Results have been used in the evaluation of the results of the restudy, ModWaters and C-111 hydrology scenarios on key biota. The suite of ATLSS models can be used parallel with monitoring and adaptive management during and after implementation of a restoration plan.