We are investigating how variability in regional climate, freshwater inputs, disturbance, and perturbations affect the coastal Everglades ecosystem. Our long term research program will focus on testing the following central idea and hypotheses: Regional processes mediated by water flow control population and ecosystem level dynamics at any location within the coastal Everglades landscape. This phenomenon is best exemplified in the dynamics of an estuarine oligohaline zone where fresh water draining phosphorus-limited Everglades marshes mixes with water from the more nitrogen-limited coastal ocean. Hypothesis 1: In nutrient-poor coastal systems, long-term changes in the quantity or quality of organic matter inputs will exert strong and direct controls on estuarine productivity, because inorganic nutrients are at such low levels. Hypothesis 2: Interannual and long-term changes in freshwater flow controls the magnitude of nutrients and organic matter inputs to the estuarine zone, while ecological processes in the freshwater marsh and coastal ocean control the quality and characteristics of those inputs. Hypothesis 3: Long-term changes in freshwater flow (primarily manifest through management and Everglades restoration) will interact with long-term changes in the climatic and disturbance (sea level rise, hurricanes, fires) regimes to modify ecological pattern and process across coastal landscapes. We will be testing our hypotheses along freshwater to marine gradients in two Everglades drainage basins (Shark River Slough and Taylor Slough). We have observed a clear productivity peak in the low salinity zone of Shark River Slough (SRS) but not Taylor Slough (TS). This peak appears to be the result of low P, high N freshwater meeting higher P, lower N marine water. We will quantify nutrient regeneration from dissolved organic matter (DOM), and expect this to be a major contribution to this oligohaline productivity peak. We will also examine how this stimulus of the microbial loop affects consumer dynamics. This LTER will thus focus on how changes in freshwater flow and climatic variability control the relative roles that nutrients and organic matter play in regulating estuarine and coastal productivity.