Aquatic Productivity in a Subtropical Marsh Along a Soil Nutrient Gradient – an Assessment of the Everglades Stormwater Treatment Areas.

Aquatic productivity, including gross primary productivity (GPP), respiration (R) and net aquatic productivity (NAP), provide a useful composite indicator of ecosystem function in wetlands. Productivity is limited by light, nutrient availability and hydrologic dynamics in wetlands systems. More specifically, hydrologic timing has been demonstrated to either affect aquatic productivity directly or indirectly by influencing other ecosystem processes (e.g. nutrient uptake, photosynthesis, respiration and reproduction rates of aquatic producers and consumers, etc.). This study explores wetland aquatic productivity and water quality relative to vegetative communities and Everglades stormwater treatment area function in relation to changes in water management.

High-frequency measurements of dissolved oxygen, temperature, pH and specific conductance were taken using in-situ probes in select treatment wetlands of the Everglades basin. This information was used in combination with ambient weather data to assess GPP, R and NAP in Stormwater Treatment Area (STA) 2 Cell 1 (emergent aquatic vegetation) and Cell 3 (submerged aquatic vegetation). Water samples collected during sonde deployment were used for determination of total phosphorus, soluble reaction phosphorous, total nitrogen, nitrate-nitrite, dissolved organic carbon, calcium and other ions in the surface water. Soils collected were used to assess nutrient storage and to identity factors regulating aquatic productivity in the two distinct wetland vegetation communities during various flow scenarios. Changes in flow regime, differences in vegetation communities, nutrient availability, and water quality significantly influenced aquatic productivity along the flow path with these wetlands.

This information is valuable with respect to STA treatment efficiency and provides a crucial understanding in meeting the expected outflow water quality goals of the STAs because aquatic productivity plays a key role in P uptake and removal by primary producers.