INVESTIGATING THE MANAGEMENT POTENTIAL OF A SEAGRASS MODEL THROUGH SENSITIVITY ANALYSIS AND EXPERIMENTS

Loss of seagrass-dominated ecosystems worldwide has been attributed to anthropogenic modifications of watersheds; in response, proper manage ment of these systems has become a priority. In this paper, sensitivit y analysis and comparison of model predictions to field observations i dentified conditions under which a subtropical to tropical seagrass ec osystem model would be a useful management tool. Sensitivity analysis indicated that under low-nutrient conditions, physical factors such as temperature, light, and salinity controlled model predictions of seag rass and epiphyte biomass, but that when nutrients were abundant (5 mu mol/L sediment pore water P; 10 mu mol/L water column P) control shif ted to biological interactions. This analysis suggests that important areas for future research include formulations for biomass-dependent p roductivity (e.g., competition for nutrients or light) and the effects of altered nutrients on epiphyte productivity and shading. Model pred ictions matched the seasonal abundance of seagrasses measured in three distinct seagrass communities in Biscayne Bay, Florida, suggesting th at in its present form the model could be useful to managers to run '' what-if'' scenarios in order to make Long-term decisions about upstrea m water management practices, including allowable nutrients and freshw ater diversion. These management decisions are currently being conside red without the benefit of a model.