Mathematical modelling is a useful tool to investigate potential ecological responses to variations in hydrodynamic and nutrient inputs in managed aquatic landscapes. The objective of this study was to develop a periphyton growth model and use it to identify critical factors in ecosystem phosphorus dynamics in pristine freshwater wetlands of Everglades National Park (ENP). We simulated changes in periphyton biomass under increased total phosphorus (TP) input for comparison to an ongoing manipulative field experiment. The field experiment analyzes the responses of periphyton, macrophytes, soils, and fauna to increased TP concentrations in replicated flow-through flume channels built within ENP. Both field and model experiments introduce TP enrichments of 5, 15, and 30 μg l-1 above ambient concentrations (typically 5-10 μg l-1). The model domain was an individual flume channel (3 m wide x 85 m long) with incident light, water temperature, and volume flux at the head as forcing functions. Base case model periphyton biomass increased with incoming TP during the wet season (June-November) and reached a maximum of 70 g C m-2 in late August. There was strong evidence of P-limited primary production as water column TP accounted for 95.5% of the variability in average daily carbon biomass. In addition to positive responses in biomass, water column TP and net production also increased under increased TP input. TP enrichment led to lower recycling within and increased export from the model flume channel. Although our simplified model was not structured to simulate shifts in periphyton composition frequently observed as a consequence of P enrichment, the processes and ramifications of community structure are complicated and are not well understood. We suggest a two or more component formulation that can account for a continuum of oligotrophic to eutrophic conditions in order to model periphyton biogeochemical relationships in the Everglades. Refined versions of this model will be used to better simulate observed changes during the course of the field experiment in order to generate new hypotheses for further investigations. (C) 2000 Elsevier Science B.V.
ASJC Scopus subject areas
- Ecological Modeling