Phosphorus biogeochemistry and the impact of phosphorus enrichment: Why isthe everglades so unique?

The Florida Everglades is extremely oligotrophic and sensitive to small inc reases in phosphorus (P) concentrations. P enrichment is one of the dominan t anthropogenic impacts on the ecosystem and is therefore a main focus of r estoration efforts. In this review, we synthesize research on P biogeochemi stry and the impact of P enrichment on ecosystem structure and function in the Florida Everglades. There are clear patterns of increased P concentrati ons and altered structure and processes along nutrient-enrichment gradients in the water, periphyton, soils, macrophytes, and consumers. Periphyton, a n assemblage of algae, bacteria, and associated microfauna, is abundant and has a large influence on phosphorus cycling in the Everglades. The oligotr ophic Everglades is P-starved, has lower P concentrations and higher nitrog en-phosphorus (N:P) ratios, and has oxidized to only slightly reduced soil profiles compared to other freshwater wetland ecosystems. Possible general causes and indications of P limitation in the Everglades and other wetlands include geology, hydrology, and dominance of oxidative microbial nutrient cycling. The Everglades may be unique with respect to P biogeochemistry bec ause of the multiple causes of P limitation and the resulting high degree o f limitation.