Restoration Strategies Science Plan
As part of the Restoration Strategies Program, the South Florida Water Management District is implementing the Science Plan for the Everglades Stormwater Treatment Areas (STAs). Initiated in 2013 and updated in 2018, the Science Plan is intended to improve the understanding of mechanisms and factors that affect phosphorus treatment performance, particularly those that are key drivers of performance at low phosphorus concentrations (less than 20 parts per billion, or µg/L). Results from the Science Plan studies will aid the design and operations of water quality projects to achieve the stringent phosphorus criterion established for the Everglades. Data and information gathered from the studies also may be used to develop and refine modeling tools.
The Science Plan was developed by a team of SFWMD scientists, modelers and engineers with input from technical consultants and Restoration Strategies Technical Representatives from the U.S. Environmental Protection Agency, Florida Department of Environmental Protection, U.S. Army Corps of Engineers and U.S. Department of the Interior (Everglades National Park and U.S. Fish and Wildlife Service).
Studies under the Science Plan are conducted by District staff, experts from universities and/or technical contractors. Larger studies have involved all three mechanisms. Four umbrella contracts were developed competitively to provide outside support for the first five-year increment of studies. These arrangements will be re-competed in Fiscal Year 2018-2019 for the next five-year increment.
For more information, contact Tom James, SFWMD Principal Scientist.
Related Content
- Restoration Strategies Science Plan – July 2018 Update [PDF]
- 2018 Five-Year Work Plan [PDF]
- Original Detailed Study Plans (September 2014) [PDF]
- Overview of Projects and Findings – 2018 South Florida Environmental Report, Chapter 5C: Restoration Strategies Science Plan Implementation [PDF]
- Restoration Strategies Science Plan – Related Documents
- Restoration Strategies for Clean Water for the Everglades
- Water Quality Improvement
Plan Studies*
* This list will be updated periodically. The status of studies will change from ongoing to completed once they are finalized.
Ongoing
Quantifying Phosphorus Uptake and Release from Periphyton and Phytoplankton Communities
Description/ObjectiveMicrobial communities of bacteria, algae and fungi, are found attached to plants (periphyton), soils (epiphyton), or in free floating form (phytoplankton). They play an important role in Phosphorus (P) cycling within the Everglades Stormwater Treatment Areas (STAs) through uptake, growth and senescence. The amount of cycling through periphyton can affect P reduction in STAs.
This study quantifies periphyton processes of growth, senescence, and nutrient dynamics within the STAs. This information will indicate the significance of periphyton in P cycling and retention reduction within the STAs. The results may support the management of the STAs especially at the outflow regions where P concentrations are very low.
This study includes two phases:
- Phase I - Literature survey and analysis of periphyton-related research conducted in the STAs.
- Phase II - Benchtop and field study plan development and implementation.
Study Plan Overview
Activities Completed and Current Status
Phase 1 – Literature survey: Studies on similar wetlands were reviewed. Results from published literature showed that periphyton community structure is affected by light intensity, temperature, and nutrient availability. Methods and measurements used to estimate periphyton growth, senescence and nutrient dynamics were summarized. Only a few published rates applicable to subtropical systems were found. Methods to measure periphyton community structure, productivity, decomposition and senescence include pigment analysis (chlorophyll, phycocyanin), biovolume, cell counting, oxygen content, mass, accumulation via sediment traps, carbon isotopes (14C), and genetic techniques, such as amplicon sequencing (metagenetics), metagenomics, metatranscriptomics. Nutrient uptake rates can be measured through dissolved inorganic carbon, periphyton tissue nutrients, enzyme activity, phosphorus isotopes (31P, 32P), nitrogen isotopes (15N), combustion (measures particulate or solid phase nitrogen), Acetylene Reduction Assay, and Membrane-Introduction Mass Spectrometer analysis.
Part 2 of Phase I - Analysis of the unpublished research from STAs and Water Conservation Areas: this is on-going. The information gleaned from Phase I should identify any data gaps and guide additional future research approaches in the next phases.
Phase II: Bench top and field experiments: pending approval.
Reports and Publications
- Laughinghouse, H. D., Berthold, D. E, Barbosa, M., and Lefler, F. W, May 2019, A Review on Tropical and Subtropical Periphyton and Phytoplankton Processes and Methods of Quantification, draft.
L-8 FEB Study
Description/Objective
The L-8 Flow Equalization Basin (FEB), is a 950-acre basin that can store nearly 45,000 ac-ft of water. The primary purposes of the L-8 FEB are to reduce peak stormwater flows, temporarily store stormwater runoff and improve water delivery to Stormwater Treatment Areas (STAs) STA-1E and STA-1W. This improved water delivery should enhance STA performance to achieve state water quality standards in the Everglades.
In water year 2018 (WY2018: May 2017 to April 2018) the flow weighted mean concentration (FWMC) of total phosphorus (TP) in outflow from the L-8 FEB was higher than inflow WY2018. Potential sources of the increase TP in outflow include groundwater, levee sediment erosion, benthic sediment resuspension, and phosphorus release from aquatic plants and animals. The objective of this study is to determine the potential sources of this excess TP and to provide operational guidance to limit the occurrence of higher TP outflow than inflow.
The study includes three phases:
- Phase I - evaluate vertical and horizontal water column phosphorus concentrations to determine if increased TP is related to water levels and/or groundwater interactions.
- Phase II - investigate the potential of levee sediment erosion and benthic sediment resuspension on TP concentration increases.
- Phase III – (if needed) investigate biological sources of P
A detailed study plan can be found here;
Activities Completed and Current Status
Phase I sampling of groundwater and waters within the L-8 FEB found much lower TP concentrations in groundwater samples than surface water samples [1]. This result indicates that groundwater does not contribute to the intermittent high TP concentrations at the outflow site. Particulate P (PP) constitutes the majority fraction of TP in the surface water suggesting that resuspension, or introduction of sediments may be the source of PP in the FEB surface water, which in turn could contribute to the occasionally observed high TP concentrations at the outflow site.
Phase II sampling activities are being planned to investigate levee sediment erosion or benthic sediment resuspension as potential sources of TP in the water column.
Reports and Publications
- DB Environmental, 2019, L-8 FEB Surface Water and Groundwater Quality Monitoring, Deliverable #A3.5 Sampling Report. Prepared in fulfilment of Contract 4600003883 on Inter-Agency Agreement to Conduct Scientific Studies Relevant to the Stormwater Treatment Areas. South Florida Water Management District, West Palm Beach, FL.
Evaluation of Inundation Depth and Duration for Cattail Sustainability
Description/Objective
Cattail (Typha domingensis) communities are an important component of Stormwater Treatment Areas (STAs). They remove particulate phosphorus (PP) by reducing water turbulence allowing the particles to settle. PP in moving water also may be removed by hitting and sticking to plant leaves. Soluble P is removed by algae attached to Cattail leaves. The particulate and algae P eventually settle into the soils, where it is either buried, or degraded into soluble forms. The soluble P may be taken up by cattail roots and stored in roots, rhizomes, shoots or leaves of the plant.
Rows of cattail planted at intervals throughout STAs support other aquatic vegetation by reducing water flow in the STA and blocking the effects of winds from major storm events.
Cattails are hardy plants, but they can die off if water levels are too deep for too long a period. Phase I of this study evaluates cattail in the field through seasonal monitoring of water depths, cattail density, leaf elongation, photosynthesis, and plant biomass in a number of locations in STA-3/4 with varying water depths. Declines in any of these measures are an indicator of poorer Cattail health. Phase II of this study evaluates the effects of water depth on cattail health in more controlled environments: half-acre test cells in which water depths are maintained at constant water levels between 1.3 and 4.1 feet. The results of this study will support operation of STAs by defining optimal water depths and the length of time suboptimal (deep) water depths can be maintained to support cattail communities in the STAs.
A detailed study plan can be found here:
Activities Completed, Results and Current Status
Phase I field monitoring occurred from Water Year (WY – April to May) 2016 to WY2018. Cattail densities during the wet seasons were lower in the deeper inflow region of STA-3/4 Cell 2A than in the shallower outflow region. Cattail densities declined in the inflow region due to water depths >91 cm for long periods of time in the 2016 and 2017 wet seasons. Leaf elongation rates were consistently higher in the inflow region. Photosynthetic rates and total live biomass were not different between the inflow and outflow regions. Throughout the STA cell, cattail biomass declined over time. The belowground biomass:leaf ratio declined over time in the inflow region.
Phase II water depth experiments are being conducted in the STA-1W Northern Test Cells (see photo above). Phase I results were used to develop the experimental design of this test cell experiment, which includes treatment water depths of: 1) 40 cm (Control), 2) 61 cm, 3) 84 cm, 4) 104 cm, and 5) 124 cm. Each treatment is replicated in 3 treatment cells. Test cells were refurbished in 2016 to improve soil and water control. Seedling cattails were planted, and cattail seeds were scattered in the test cells from May to June 2018. Cattail plants grew in and were fully mature in spring of 2019. Experiments began on July 1st, 2019. This study is in the monitoring phase and will be completed by June 2020. This study will determine more precisely the water depth and duration Cattail can tolerate without a decline in health.
Figure 1. STA-3/4 Cell 2A survey plot (red) and water level logger (blue) locations.

Reports and Publications
- Diaz, O., Appendix 5C-5: Evaluation of Inundation Depth and Duration Threshold for Cattail Sustainability., in South Florida Environmental Report – Volume I. 2018: South Florida Water Management District, West Palm Beach, FL.
- Diaz, O. and K. Vaughan., Appendix 5C-2. Evaluation of Inundation Depth and Duration Threshold for Cattail Sustainability: In-Situ Study., in 2019 South Florida Environmental Report – Volume I. 2019: South Florida Water Management District, West Palm Beach, FL.
Use of Soil Amendments or Soil Management to Control Phosphorus Flux
Description/Objective Stormwater Treatment Areas (STAs) remove phosphorus (P) from agricultural runoff before discharging into the Everglades and have been constructed to a large extent on agricultural lands. Once the STAs are initially flooded, P in the soils can be released (flux) into the water column. This study screens methods that reduce P flux from the soil by application of amendments and/or soil management techniques. Screened methods may be useful in appropriate locations within STAs to support lower outflow P concentrations.
This study includes three phases:
- Phase I – Review existing information.
- Phase II – Small-scale experiments to screen amendments or soil management techniques identified in Phase I
- Phase III – Field trials of the most promising technologies identified in Phases I and II.
Activities Completed and Current Status
Phase I: Completed. Technologies to reduce soil-P flux in wetlands or lakes were reviewed from the literature and past SFWMD projects. The technologies were evaluated for their potential to scale up to field trials in the STAs.
Phase II was cancelled Due to uncertainties of long-term treatment effectiveness of soil amendments, potential effects to STA operations, high costs to implement at full-scale and potential effects to downstream.
Phase III is ongoing to evaluate the efficacy of soil management, specifically soil inversion, in STA-1 West (STA-1W) expansion area.
Results
A comprehensive review of available technologies and amendments indicated that many could lower P flux from soils. Due to uncertainties of long-term treatment effectiveness of soil amendments, potential effects to STA operations, high costs to implement at full-scale and potential effects to downstream Everglades flora and fauna; no further evaluation was considered, with one exception: soil inversion (i.e., soil management with no amendments).
Soils in STA-1 West Cell 7 expansion were inverted as a remedial action to bury high copper concentrations that resulted from past agricultural practices in the past decades. Soils in Cell 8 were not inverted and are considered a control. Prior to flooding the cell, soils were collected and incubated to determine the amount of soluble P release. Release from inverted soils was less than non-inverted soils. The cells have since been flooded but are not operational. Surface soil P content is more variable in Cell 7 than in Cell 8, but not significantly different. Water-column P concentrations within both cells varied spatially.
Reports and Publications
- Chimney, M., 2015, Phase I Summary Report for the Use of Soil Amendments/Management to Control P Flux Study. Technical Publication WR-2015-006. South Florida Water Management District, West Palm Beach, FL.
- Josan, M., B. Taylor, and K. Grace, 2019, Appendix 5C-3: Use of Soil Inversion to Control Phosphorus Flux. In: 2019 South Florida Environmental Report – Volume I. South Florida Water Management District, West Palm Beach, FL.
Stormwater Treatment Area Water and Phosphorus Budget Improvements
Description/Objective
Water and phosphorus (P) budgets are important tools that can be used to understand the treatment performance of Stormwater Treatment Areas (STAs). Accurate water budgets are critical to develop accurate P budgets. The objective of this study is to improve the annual water and P budgets for selected Stormwater Treatment Area (STA) treatment cells or flow-ways.
The study includes two phases:
- Phase I – Evaluate the annual water budgets for STA-3/4 Cells 3A/3B; used as a test case. Evaluate sources of error and improve the annual water budgets.
- Phase II – Improve period of record (POR) flow data and water and P budgets for all cells of STA-3/4 [2] and STA-2 Flow-ways 1-3 [3].
Activities Completed and Current Status
Phase I evaluation was completed in 2014. Phase II is ongoing.
Period of record flow data for all cells of STA-3/4 and STA-2 Flow-ways 1 to 3 have been improved. Work to improve the SFWMD's Water Budget Tool was completed. Improved POR water and P budgets for STA-2 Flow-ways 1 to 3 were completed in 2017 [3] and all cells of STA-3/4 were completed in 2018.
Results
For STA-3/4 Cells 3A/3B, small differences in water levels across large culverts at mid-levees were the main source of error in annual cell-by-cell water budgets. The budgets were greatly improved by updating flows between the upper and lower portions of the flow-way. Annual errors for the water budgets were reduced to 8% or less. Rainfall, evapotranspiration, change in storage and seepage were minor contributors to these cells' annual water budgets and the current methods for estimating these components were found to be acceptable for Phase II.
Annual water and P budgets were developed for STA-2 Flow-ways 1 to 3 for Water Year 2002 (WY2002) to WY2016, and for STA-3/4 Cells 1A, 1B, 2A, 2B for WY2006 to WY2017 and for STA-3/4 Cells 3A and 3B for WY2009 to WY2017 [4]. Improved POR flow and stage data for STA-2 and STA-3/4 inflow and outflow structures were used in the analyses. Rainfall, evapotranspiration, and seepage estimates were included. A new calibrated seepage coefficient (1.1 cfs/ft/mi) was used for the water budgets. These efforts resulted in more reliable water and P budgets and other performance estimates including annual and long-term average annual hydraulic retention times, hydraulic loading rates, P loading rates, and P reduction efficiency.
Reports and Publications
- Polatel, C., et al., 2014, Stormwater Treatment Area Water and Phosphorus Budget Improvements – Phase I: STA-3/4 Flow-ways 3A and 3B Water Budgets. Technical Publication WR-2014-004. . South Florida Water Management District, West Palm Beach, FL.
- Zhao, H. and T. Piccone, 2019, Appendix 5C-5 Summary Report for Water and Total Phosphorus Budget and Performance Analysis for Stormwater Treatment Area 3/4. In: 2019 South Florida Environmental Report – Volume I. South Florida Water Management District, West Palm Beach, FL.
- Zhao, H. and T. Piccone, 2018, Appendix 5C-6 Summary Report for Stormwater Treatment Area 2 Flow-ways 1, 2, and 3 Water and Total Phosphorus Budget Analyses. In: 2018 South Florida Environmental Report – Volume I. South Florida Water Management District, West Palm Beach, FL.
- Zhao, H. and T. Piccone, Large Scale Constructed Wetlands for Phosphorus Removal, An Effective Nonpoint Source Pollution Treatment Technology. 145:. Ecological Engineering, 145.
Improving Resilience of Submerged Aquatic Vegetation in the Stormwater Treatement Areas
Description/Objective
To understand how Phosphorus (P) is processed and removed within well performing Stormwater Treatment Areas (STAs), this multi-component study was undertaken. This study evaluates the mechanisms and factors that affect P reduction from the water column particularly in the outflow regions of the STAs. The components include assessments of flow-way (FW) water quality, internal phosphorus loads, soil, microbial enzymes, vegetation, particulate transport and settling, fauna, and organic P speciation. In addition, a data synthesis and integration component was used to evaluate the collected data that explain factors and processes influencing STA performance and will serve as the basis to develop or improve management options to reduce total P (TP) discharge concentrations from the STAs.
A detailed study plan can be found here:
Activities Completed, Results and Current Status
The overall study began in 2013 and all nine sub-study components have been completed:
- Flow-way Water Quality Assessment: P cycling in three well-performing STA FWs was evaluated under different flow conditions: high, moderate, low and no flow. TP concentrations were high at the inflow region--consisting primarily of inorganic phosphate--and low at the outflow region--consisting primarily of particulate P (PP) and dissolved organic P (DOP). These results were consistent for all flow conditions in all FWs. More P was removed from the water column of emergent aquatic vegetation (EAV) regions than submerged aquatic vegetation (SAV) regions. In SAV regions, TP increased under no flow condition--primarily as particulate P (PP)--which could be from internal loads caused by periphyton sloughing, litter fragmentation, resuspension via entrainment or bioturbation. P concentrations were slightly higher in SAV systems than in EAV systems under no flow condition.
- Flux Measurements: P concentrations in field chambers also increased during no flow periods, which indicate internal P loading from vegetation mining of soils and turnover. This increasing P trend, evaluated with a computer model, indicated that internal loading was a significant contributor to the P cycle. Internal loading was highest at inflow regions and lowest in outflow regions of the FWs.
- Soil P Characterization: P concentrations in floc and recently accreted soils (RAS) declined from higher values at the inflow regions to low values at the outflow regions. Phosphorus in floc and RAS was higher and more spatially extensive in EAV than SAV areas of the STAs. The decreasing trend of P from inflow to outflow resulted in increasing trend of N:P ratio from inflow to outflow. P was primarily in an organic form in EAV and inorganic mineral form in SAV areas. P accretion rate was higher in SAV than in EAV due to accumulation of material high in inorganic matter.
P sorption and desorption were influenced by vegetation type, depth in the profile and distance from the inflow. The floc and RAS were more reactive than underlying soils. SAV-dominated sites generally exhibited a greater potential to retain P at lower surface water P concentrations. EAV-dominated sites exhibited reduced potential to retain P at low surface water P concentrations. No trend was found for P sorption or desorption from the inflow to the outflow regions. P desorption tended to be higher under EAV than SAV-dominated sites. P sorption was strongly related to extractable and total Fe and Al for EAV-dominated FWs, and Ca and Mg in SAV-dominated FWs.
- Microbial Enzymatic Patterns: Within the STA flowways, the microbial communities play an important role in nutrient cycling, especially when nutrient limiting conditions exist. Required nutrients (i.e., C, N, or P) can be released from the dissolved organic compounds by enzymes produced by the microbes. To understand the impact of flow conditions on the microbial communities, enzyme activity in the surface water, floc, litter, and periphyton was measured along the flowways from inflow to outflow and within the major plant communities (EAV and SAV).
The level of enzyme activity was affected by flow conditions among each component and differing responses were observed along the flowways and within the vegetation communities. The level of enzyme activity was highest in the periphyton and lowest in the surface water. During flow conditions, often the level of enzyme activity in the surface water was below detection. In the floc, flow resulted in more N-limited conditions in the EAV areas and more P-limited conditions in the SAV areas. In the periphyton, C-limited conditions increased during flow in the EAV areas, but an opposite effect was observed in the SAV areas. In both plant communities, N-limiting conditions in the periphyton was greatest during no flow periods. In both the floc and periphyton, greatest P-limiting conditions were observed at the outflow locations. These variable responses indicate that flow conditions have a complex effect on the microbial responses within each component and that nutrient limiting conditions change along the flowways and within the major components.
- Vegetation Assessments: Satellite images of STA areas in wet and dry seasons detected differences in SAV and EAV spectral signatures. SAV areas dominated by a single species, specifically Chara, could be accurately identified. Mixed SAV species beds were more difficult to distinguish. When cross-validated with ground observations, the spectral analysis correctly classified 96% of reference samples.
EAV in STA-2 had higher concentrations of P, N and C in plant material compared to SAV. Of the SAV species, Chara had the highest nutrient storages of all species. EAV biomass and performance were consistent throughout the study in FW 1 while FW 3 experienced a decline in performance following the significant loss of SAV.
- Particulate Transport and Settling: Water velocities in the STAs are affected by gate operations, wind, and distance to remnant agricultural canals and ditches, with highest velocities near inflow and outflow structures and remnant canals/ditches. Inflow regions had the highest observed sediment settling/resuspension and net accumulation rates. Measured net P accumulation rates into floc were similar in magnitude to net P storage estimated from mass balance for STA-2 FW 3. STA-3/4 Cell 3B had lower storage rates, which is attributed to lower accumulation, higher erosion, and/or more spatial variability at the inflow region of this cell.
Tests of the sediments from SAV areas at relatively low and stable water velocities (< 0.5 cm/s) indicate that water column particulates originate from sloughed SAV biomass rather than sediments and are caused by wave related stress rather than flow driven stress. PP resuspension and settling measurements in SAV areas are approximately 10 times higher than total P loading and accumulation rates derived from mass balance. Therefore, the potential for large swings in P storage or loss may be expected depending on the factors that drive these fluxes.
- Fauna Study: STA fish nutrient content and nutrient ratios were similar to values reported for enriched areas of Water Conservation Area 2A. Fish tissues contained an estimated 1 metric ton of TP and 3.7 metric tons of TN in STA-2 Cells 3, 4, 5, and 6. Because of the substantial fish population, further analyses on the contribution of fauna to the water column P in the outflow regions of STAs is being investigated as a separate study.
- Organic P Speciation: Biomarkers (lignin phenols, amino acids, and pigments) estimated the quality of organic matter (OM) found in the treatment wetland STA-3/4 and a reference wetland WCA-2A. Linkages between C and P cycling were assessed within these two systems using these biomarkers. More vascular plant-based OM was found in EAV areas, and more algal-based OM was found in SAV areas. OM was fresher and more degradable in treatment SAV sites than reference wetland sites. Other than dense cattail areas, water column particulate OM in SAV areas was primarily from microbial sources. Amino acid degradation indices and organic P were positively correlated with bacterial amino acid biomarkers, suggesting microbial abundance was associated with “fresher” OM. This multi-biomarker approach may evaluate the relative “freshness” of OM pools, identify sources of OM, and provide relative measures of water column processes in P cycling in STAs.
- Data Synthesis and Integration: This effort focused on two major approaches. One using a numerical version of a conceptual model that incorporated a number of different (yet connected) data sets. This “bottom up approach” model identifies specific fluxes and transformations among major P reservoirs within the STAs. When integrated with existing data, key processes (settling, resuspension, etc.) were captured well with a better model-data match for EAV than for SAV. The “top down approach” model focused on two major controlling variables, internal load and flow. This model evaluated transect data and the effects of varying flows on outflow P concentrations. Model results suggest that internal loading and flow affected outflow P concentration dynamics.
Reports and Publications
- Villapando, R. and J. King, 2019, Appendix 5C-3: Evaluation of Phosphorus Forms. Flux, and Transformation Processes in the Stormwater Treatment Areas in Volume I 2019 South Florida Environmental Report.
- DBE, 2018 Field and Supplemental Laboratory Support for Evaluating Phosphorus Sources, Flux, and Transformation Processes in the Stormwater Treatment Areas – Annual Report. Prepared by DB Environmental, Inc. under Agreement 4600003029-WO01 for South Florida Water Management District, West Palm Beach, FL.
- DBE, 2019, Field and Supplemental Laboratory Support for Evaluating Phosphorus Sources, Flux, and Transformation Processes in the Stormwater Treatment Areas – Annual Report. Prepared by DB Environmental, Inc. under Agreement 4600003029-WO01 for South Florida Water Management District, West Palm Beach, FL.
- Jerauld, M., et al., 2019, Measurement of internal phosphorus loading rate (iPLR) in a low-P stormwater treatment wetland. Prepared in fulfillment of 4600003029‐WO01 on Technical Environmental Services in Support of the Restoration Strategies (RS) Science Plan.
- King, J., and R. Villapando, 2018, Appendix 5C-3: Evaluation of Phosphorus Forms. Flux, and Transformation Processes in the Stormwater Treatment Areas in Volume I 2018 South Florida Environmental Report.
- King, J. and R. Villapando, 2020, Chapter 5C: Evaluation of Phosphorus Forms. Flux, and Transformation Processes in the Stormwater Treatment Areas in Volume I 2020 South Florida Environmental Report.
- DBE, 2017, Field and Supplemental Laboratory Support for Evaluating Phosphorus Sources, Flux, and Transformation Processes in the Stormwater Treatment Areas – Annual Report. Prepared by DB Environmental, Inc. under Agreement 4600003029-WO01 for South Florida Water Management District, West Palm Beach, FL.
- University of Florida, 2019 Evaluation of Soil Biogeochemical Properties Influencing Phosphorus Flux in the Everglades Stormwater Treatment Areas (STAs) Final Report. Submitted to South Florida Water Management District, West Palm Beach, FL.
- Gann, D., M. Bernardo, and J. Richards, 2019, Detection and Differentiation of Submerged Aquatic and Emergent/Floating Marsh Vegetation using Remote Sensing Methods -- Spectral Separability from WorldView Data (Pilot Study). Report Submitted to the South Flrodia Water Management District, West Palm Beach, FL.
- Florida International University, 2019, Settling and Entrainment Properties of STA Particulates Draft Final Report. Prepared under Agreement No. 4600003032-WO02-9500006758 for South Florida Water Management District,. West Palm Beach, FL.
- Evans, N., et al., 2019, Appendix 5C-4: Effects of Abundant Faunal Species on Phosphorus Cycling in the Stormwater Treatment Area in Volume I 2019 South Florida Environmental Report.
- Morrison, E., et al., Multiple biomarkers highlight the importance of water column processes in treatment wetland organic matter cycling. J Water Research., 168: p. 115-153.
- Juston, J. and B. Kadlec., Data-driven modeling of phosphorus (P) dynamics in low-P stormwater wetlands. Environmental Modelling & Software 118: p.:226-240.
Evaluation of Factors Contributing to the Formation of Floating Tussocks in the Stormwater Treatment Areas
Description/Objective
Floating tussocks (wetlands) in Stormwater Treatment Areas (STAs) can uproot Emergent Aquatic Vegetation (EAV), shade out submerged aquatic vegetation (SAV), increase turbidity, block gates and other water control structures, and create short circuits. All these actions can reduce STA performance. This study evaluates factors that cause the formation of floating wetland areas in STAs, methods to determine current coverage of these floating areas, and an assessment of strategies to reduce their occurrence.
The study includes two phases
- Phase 1 includes 4 tasks:
- A literature review of floating wetland types, buoyancy mechanisms, formation, and controls.
- A nomenclature of floating wetlands based on soils, plant communities, size, and location.
- Classification maps of floating wetland communities in STA 1W Cell 2A and STA 2 Cell 7 using unmanned aerial systems (UAS).
- Thermographic imagery to detect floating vs. emergent vegetation.
- Phase II will build on the findings from Phase I to determine potential causes and methods to reduce the occurrence of floating wetland formation.
- Evaluate relationships between occurrence and distribution of floating wetlands and potential environmental and management factors that are likely to trigger floating wetland formation
- Refine UAS methodology and workflow, then apply to all STA emergent aquatic vegetation (EAV) cells, and
- Develop a Typha Wetland Buoyancy Model to develop a metric of soil cohesion that can be used to quantify the soils “holding capacity”.
Activities Completed and Current Status
- Phase I is complete.
- Phase II is ongoing.
Results
UAS identified floating wetlands that otherwise would not be apparent in satellite imagery. Floating wetlands were identified based on observed flattened vegetation, presence of fern seedlings, and nearby open seams. Thermographic imagery was difficult to interpret. However, midday imagery was most useful and could complement the other spectral interpretation. A nomenclature of floating wetlands (tussocks, mats, islands, and complexes) was developed from the literature review. A buoyancy model based on this literature review will be developed in Phase II.
Investigation of the Effects of Abundant Faunal Species on Phosphorus Cycling in the Everglades Stormwater Treatment Areas
Description/Objective
Aquatic fauna, fish and large invertebrates such as crayfish, may significantly affect phosphorus (P) cycling within Stormwater Treatment Areas (STAs). This study evaluates the potential of aquatic fauna to affect P reduction in STA surface waters. The study should provide management recommendations for aquatic fauna to improve STA treatment performance.
The study includes five tasks:
- Task I – (Ongoing through May 2021): Estimate biomass of fish and aquatic invertebrates (STA-2) and aquatic faunal community composition (STAs 1E, 1W and 3/4); analyze P and nitrogen (N) storage in tissues of individuals of abundant fishes (STA-2).
- Task II – (Ongoing through May 2020): Estimate P excretion rates of selected abundant fishes to estimate contribution to STA P budgets. Evaluate benthic (sediment foraging) fish species to determine their contribution to water column nutrients through bioturbation (i.e. activities that resuspend soils, including particle disturbance, ingestion and defecation).
- Task III – (Ongoing through October 2021): Use biomass and excretion estimates to calculate areal (per ha) P excretion by the entire aquatic faunal population in STA-2 (i.e. rates of P released to the water column via excretion, μg P/ha/ h).
- Task IV – (to begin in 2020): Calibrate electrofishing by comparing biomass of non-native fish collected by electrofishing to known numbers of these fish stocked in enclosed test cells.
- Task V – (to begin in 2020) Estimate the effect of herbivory on SAV production
Activities Completed and Current Status
The STAs support a high biomass of aquatic fishes and macroinvertebrates. By comparison, the biomass per unit area was approximately 2-15 times more than in other Everglades regions.
Ten of the most abundant fish species stored one metric ton of P and 3.7 metric tons of N within their body tissues, and excreted >0.626 kg of P per hour and >3.897 kg of N per hour. These calculations demonstrate that storage and excretion by fishes are important processes of P and N cycles within STA habitats. Future research will focus on refining the current estimates and incorporating the effects of fish into nutrient budgets for the STAs.
Reports and Publications
- Evans, N., J. Trexler, and M. Cook, 2018, The Effects of Faunal Communities on Water Quality in the Everglades Stormwater Treatment Areas. In: . 2018 South Florida Environmental Report – Volume I, , in Appendix 5C-3: Evaluation of Phosphorus Sources, Forms, Flux, and Transformation Processes in the Stormwater Treatment Areas,, O. Villapando and J. King, Editors.: South Florida Water Management District, West Palm Beach, FL.
- Evans, N., et al., 2019, Appendix 5C-4: Effects of Abundant Faunal Species on Phosphorus Cycling in the Stormwater Treatment Areas. In 2019 South Florida Environmental Report – Volume I, . South Florida Water Management District, West Palm Beach, FL.
- Evans, N., et al., 2020, Appendix 5C-1: Estimating Phosphorus and Nitrogen Excretion in Fishes in the Everglades Stormwater Treatment Areas In 2020 South Florida Environmental Report – Volume I, . South Florida Water Management District, West Palm Beach, FL.
Completed
Evaluate Phosphorus Sources, Forms, Flux and Transformation Processes in the Everglades Stormwater Treatment Areas
Description/ObjectiveEvaluate factors that affect phosphorus (P) treatment performance of the Stormwater Treatment Areas (STAs), particularly those that are key drivers at the lower reaches of the treatment flow-ways (FWs). This study will provide critical information to explain factors and processes that influence STA performance and will serve as basis to develop or improve management options to reduce total P (TP) discharge concentrations from the STAs.
There are multiple components (sub-studies) to this study, including:
- Data Mining
- Flow-way Water Quality Assessment
- Microbial Enzyme Activity
- Vegetation Assessments
- Organic P Speciation
- Soil Characterization
- Particulate Dynamics
- Phosphorus Flux Dynamics
- Role of Fauna
Activities Completed and Current Status
Data mining was completed in 2017. Flow event and sub-study data collections will continue through 2019. The individual sub-studies are in different stages of implementation. Transects samples, microbial samples, porewater samples and flux measurements were taken for six separate flow events. Particulate samples were collected using traps in STA-2 FW 3 and STA-3/4 Western FW; these samples are being analyzed for nutrient content. Erosion, velocity and meteorological measurements have provided important information of the effects of flow on particulate transport. Soil and vegetation biomass were sampled in all study flow-ways. Vegetation coverage surveys, biomass measurements and fauna surveys in both emergent aquatic vegetation (EAV) and submerged aquatic vegetation (SAV) cells are continuing according to the study plan.
Results*
* (For detailed information on each sub-study, please see Reports and Publications.)
- Data Mining: This sub-task showed the importance of nitrogen (N) and phosphorus coupling on STA P reduction. The analysis revealed a zonal pattern of components along the flow-way (soil, vegetation and surface water characteristics) and the significance of labile soil P as a consistent and sensitive indicator of P flux.
- Flow-way Water Quality Assessment: A distinct TP concentration gradient along the treatment flow-ways was observed at all periods of the flow events. However, average TP concentration reduction was higher for FW 1 than for FW 3. Soluble reactive P (SRP) accounted for a majority of the reduction in FW 1 while particulate P (PP) accounted for most of the reduction in FW 3. In FW 3, TP concentrations increased under stagnant condition following a period of high flow but not after low flow. The TP increase was largely due to increase in particulate P (PP), particularly at stations closer to the inflow. At the outflow region of both flow-ways, residual P was comprised mainly of PP and dissolved organic P (DOP). SRP was reduced early in the flow-way and reached minimum detection limit (2 µg/L) at the mid-region of both flow-ways.
- Flux Measurements: Vertical diffusive flux likely produced an internal load to water column P in the inflow and midflow regions, but not at the outflow region. However, the chambers measuring flux rates showed positive net fluxes in the outflow region. P flux declined from inflow to outflow. The sources of these fluxes, especially at the outflow regions have yet to be determined. Additional controlled flow event monitoring is underway in STA-2 FW 1.
- Microbial Assays: Trends in enzyme activity for two P-acquiring enzymes, one carbon (C)-acquiring enzyme and one N-acquiring enzyme were variable between the surface water and periphyton, between seasons and during flow or stagnant conditions for the flow events conducted in STA-2 FW 3 in 2016. Enzymatic activity in the periphyton for all enzymes was greater under stagnant conditions than flowing conditions, while enzymatic activity was less in the water column for stagnant conditions than flowing conditions. P and C enzyme activity in the periphyton increased along the nutrient gradient from inflow to outflow, but there was no consistent trend in surface water samples. For both surface water and periphyton, enzymatic activity was lowest in the summer compared to the spring and fall events.
- Vegetation Assessments: TP storage in the vegetation was substantially higher at the inflow region for EAV compared to SAV. TP concentration in vegetation tissues decreased from the inflow to the outflow of STA-2 FW 1 and FW 3. TP concentrations in SAV tissues at the inflow region of FW 3 were higher than in EAV tissues at the inflow region of FW 1, indicating higher P uptake by SAV; this trend reversed at the middle and outflow regions.
- Soil Characterization: High P enrichment of floc and soil were found near the inflows with concentrations decreasing toward the outflows. Enrichment of floc and recently accumulated soil in STA-2 FW 1 (EAV-dominated) was substantially higher and more spatially extensive than in STA-2 FW 3 (SAV-dominated). TP in the floc and recently accumulated soil from FW 1 was predominantly organic, while TP from FW 3 was primarily inorganic. P storage in FW 1 was higher than FW 3 due to higher bulk density of floc and accumulated material in FW 1. Spatial trends in floc and soil TP concentrations and storage in STA-3/4 Cell 3A (EAV) and Cell 3B (SAV) were similar to those observed in STA-2.
- Particulate Dynamics: Current and suspended sediment concentrations followed a diurnal pattern driven by peak winds in the afternoons in STA-2 FW 3. The effects of wind speed were greatest at the inflow where a long fetch and lack of vegetation in the water column allows for more wind-driven flows compared with the midflow and outflow. Sediments accumulating in STA-2 FW 3 show P sequestration with TP concentrations showing a declining gradient from inflow to outflow. Vertical traps and videos have shown particle settling, accumulation and resuspension in the water column. Sedimentation rates decreased from inflow to outflow and the particle size in the water column increased from the inflow to the outflow regions.
- Fauna Study: The STAs support substantial fish, waterfowl and invertebrate populations. The mean density of fish and invertebrates is greater in the STAs than in other similar wetland areas in the region (Shark River Slough and WCAs 3A and 3B). The effect of these high populations in the STAs can be significant. Based on bird population estimates and SAV consumption, approximately 4% of STA-1 West's TP external loading could be attributed to coot (a waterfowl) grazing on SAV thus affecting the overall P cycling in the STAs.
Reports and Publications
- Villapando, R and J. King. 2018 Appendix 5C-3: Evaluation of Phosphorus Forms. Flux, and Transformation Processes in the Stormwater Treatment Areas in Volume I 2018 South Florida Environmental Report.
Evaluation of the Influence of Canal Conveyance Features on Stormwater Treatment Area and Flow Equalization Basin Inflow and Outflow Phosphorus Concentrations
Description/ObjectiveDetermine if phosphorus (P) concentrations change when water is conveyed through Stormwater Treatment Area (STA) and Flow Equalization Basin (FEB) inflow or outflow canals and evaluate factors that could influence these changes.
The study includes two phases:
- Phase I – Review and analyze existing flow, stage and water quality data.
- Phase II – Investigate canal sediment characteristics (e.g. sediment thickness probing, sediment core sampling, and sediment chemical and physical composition) and canal cross section surveys, if needed.
Activities Completed and Current Status
This project was completed in 2017.
Phase I evaluation included six STA canals: STA-1 Inflow Basin Canal, STA-1 West (STA-1W) Discharge Canal, STA-2 Supply/Inflow Canal, STA-2 Discharge Canal, STA-3/4 Supply/Inflow Canal and STA-1 East (STA-1E) Discharge Canal. Total P (TP), soluble reactive phosphorus, particulate phosphorus (PP), dissolved organic phosphorus, chloride and total suspended solids were evaluated for each canal. Phase II field characterization of the STA-2 Supply/Inflow Canal was completed in February 2017. Construction of the first two FEBs – A-1 FEB and L-8 FEB – was completed in 2015 and 2017, respectively. Subsequent operational monitoring and testing were ongoing through 2017, therefore the associated canals could not be evaluated in this current study. Given a few years of operation, these FEB associated canals could be evaluated if needed.
Results
The STA-1 Inflow Basin Canal was a source of TP during peak flows, primarily in the form of PP. With the implementation of an upstream Flow Equalization Basin (L-8 FEB), these peak flows are expected to decrease, reducing the potential for sediment transport/resuspension. After the L-8 FEB has been operational for at least three years, this canal should be re-evaluated to determine if TP export is still a concern.
The STA-1W Discharge Canal was a sink for TP, with much of the P being deposited as PP. Upon completion of STA-1W expansion construction, the STA-1W Discharge Canal will no longer serve as the discharge canal for the STA. Therefore, no further evaluation is recommended.
The STA-2 Supply/Inflow Canal could be a source or a sink for TP, depending on the source of flow. When S-6 flows dominated, the canal behaved as a sink. When G-337/G-328 flows dominated, the canal behaved as a source. A field survey indicated sediment buildup in the canal bottom and notable erosion from canal side-slope areas. Future surveys (e.g. every three to five years) are recommended.
The STA-2 Discharge Canal was neither a sink nor source of TP, while the STA-3/4 Supply/Inflow Canal was a TP and PP sink. No further evaluation is recommended on these canals. A review of the data for the STA-1E Discharge Canal indicated that TP concentrations did not increase in the canal; no further evaluation is recommended.
Reports and Publications
- Zhao, H. T. Piccone and S. Hill. 2016. STA-1 Inflow Basin Canal Final Report. Technical Report WR-2015-004. South Florida Water Management District. West Palm Beach, FL.
- Zhao, H. T., O. Diaz and T. Piccone. 2017. Stormwater Treatment Area 1 West Discharge Canal Evaluation Report Technical Report WR-2017-005. South Florida Water Management District. West Palm Beach, FL.
- Zhao, H. T., T. Piccone and O. Diaz. 2015. Supporting Information for Canal Evaluations Technical Report WR-2015-003. South Florida Water Management District. West Palm Beach, FL.
Development of Operational Guidance for Flow Equalization Basins and Stormwater Treatment Area Regional Operation Plans
Description/ObjectiveDevelop tools and methods to support operational guidance and regional operation plans to optimize Flow Equalization Basins (FEBs) and Stormwater Treatment Areas (STAs) to achieve the Water Quality Based Effluent Limits for Total Phosphorus (TP).
The study includes three tasks:
- Evaluate relevant information on STAs and conduct field tests to evaluate hydraulics and water quality.
- Define values for model equations needed to simulate hydraulics, hydrology and operational control of STAs.
- Develop local (STAs/FEBs) and regional operating strategies and rules and application of system optimization tools.
Activities Completed and Current Status
The study was completed in 2017.
Field measurements of waves propagated by inflow discharges to STA-3/4 Cell 3A were evaluated in relation to low, medium and high flow rates and water depth. Wave speeds and heights along flow paths were used to calculate vegetation resistance to flow. Maps of flow and resistance were created using the equations that described resistance at different flow rates. A total variation diminishing Lax-Friedrichs (TVDLF) method was used in a simple model to simulate flow-through hydraulic gradients of STA flow-ways based on real-time water elevation observations and flows. An inverse model (iModel) for Restoration Strategy Operational Protocol (RSOP) was developed to optimize flow rates along the Central Flow Path for proper flow attenuation and treatment with and without the FEB.
Results
Field tests improved water depth estimates and residence times in real-world applications leading to improved accuracy of physically based models of the STAs. The patterns of resistance produced from these applications reflected the general patterns of the vegetation distribution. The applications represented vegetation resistance, topography effects, resistance due to blockages, short-circuiting and turbulent behaviors. This information can assist project planning and design. The values in the model equations can determine if the flow behaves like porous-media flow or short-circuiting stream flow. The simple TVDLF method can forecast seven-day predictions of water depths under multiple management scenarios/flow regimes. At present this tool assists the management of the western flow-way of STA-3/4.
The iModel-RSOP was applied to four alternative scenarios of different FEB and Lake Okeechobee water delivery configurations. By rearranging flow to optimize TP removal, the iModel predicted lower TP concentration in discharge for all the scenarios compared to observed values. While the iModel results are encouraging, many difficulties were encountered to provide an accurate statistical prediction of TP concentration suggesting room for improvement.
Reports and Publications
- Ali, A. 2015. Multi-objective operations of multi-wetland ecosystem: iModel applied to the Everglades restoration. Journal of Water Resources Planning and Management 141(9).
- Ali, A. 2018. Appendix 5C-1 iModel for Restoration Strategy Operational Protocol Development. In: 2018 South Florida Environmental Report – Volume I, South Florida Water Management District, West Palm Beach, FL.
- Lal, A. M. W. 2017. Mapping Vegetation-Resistance Parameters in Wetlands Using Generated Waves. Journal of Hydraulic Engineering 143(9).
- Lal, A.M., M.Z. Moustafa and W. Wilcox, 2015. The use of discharge perturbations to understand in-situ vegetation resistance in wetlands. Water Resources Research 51:2477-2497; doi: 10.1002/2014WR015472.
Investigation of STA-3/4 Periphyton-based Stormwater Treatment Area Performance, Design and Operational Factors
Description/ObjectiveInvestigate performance, design elements, operation and biogeochemical characteristics that have enabled the 100-acre PSTA Cell to achieve ultra-low outflow total phosphorus (TP) concentrations.
This study includes monitoring and surveys within the cell, as well as mesocosm and microcosm experiments that supplement these studies. Continuous TP measurements at inflow and outflow locations of the cell were also conducted.
Activities Completed and Current Status
The study was completed in 2018.
Inflow and outflow concentrations of TP and flows into and out of the cell were monitored continuously. Grab surface water samples taken at the structures were analyzed for various P species. Other data measured periodically within the PSTA Cell included conductivity, pH, temperature, dissolved oxygen, chlorophyll a, turbidity, water depth, light and ion concentrations. Effects of pulse flows, season, time of day, water depth, inflow P concentration, flow rate and seepage on cell performance were evaluated. Enzyme assays were also conducted to evaluate the role of microbial activity. Sediment accrual and vegetation nutrient contents were also analyzed. Reports and manuscripts have been completed. Final analyses will be reported in the 2019 South Florida Environmental Report.
Results
The PSTA Cell achieved annual outflow flow-weighted mean TP concentrations ranging from 8 to 13 µg/L for the period of record (2008 to 2017). Pulse flow events and associated higher P loads had no adverse effect on treatment performance. Outflow TP concentrations were not affected by two different operational water depths (average of 0.39 m and 0.55 m) or the time of day. Generally, lower outflow TP concentrations were observed during the wet season. The optimal inflow TP concentrations to the PSTA Cell is 22 µg/L or less, which achieved outflow concentration of 13 µg/L or lower. Lateral seepage through the levee between the Lower Submerged Aquatic Vegetation (SAV) Cell and the PSTA Cell was the major source of seepage. The accumulated sediment in the cell is low in P and chemically stable, resulting in sustained P removal performance.
Reports and Publications
- James, R.T. 2015. Evaluation of Remote Phosphorus Analyzer Measurements and Hydrologic Conditions of the STA-3/4 Periphyton-based Stormwater Treatment Area. Technical Publication WR-2015-002. South Florida Water Management District, West Palm Beach, FL.
- James, R.T. 2017. Analysis of Effects of Sustained Moderate Flow at the STA-3/4 Periphyton-based Stormwater Treatment Area. Technical Publication WR-2017-003. South Florida Water Management District, West Palm Beach, FL.
- Zamorano, M. F. 2015. Effects of Pulse Flow Events on the STA-3/4 PSTA Cell's Phosphorus Treatment Performance. Technical Publication WR-2015-007. South Florida Water Management District, West Palm Beach, FL.
- Zamorano, M. F. 2017. Influence of Seepage on the STA-3/4 PSTA Cell's Treatment Performance. Technical Publication WR-2017-004. South Florida Water Management District, West Palm Beach, Florida.
- Zamorano, M. F., Grace, K., DeBusk, T., Piccone, T., Chimney, M., James, R. T., Zhao H., and Polatel, C. 2018. Appendix 5C-2: Investigation of Stormwater Treatment Area-3/4 Periphyton-based Stormwater Treatment Area Performance, Design, and Operational Factors. In: 2018 South Florida Environmental Report – Volume I, South Florida Water Management District, West Palm Beach, FL.
- Zamorano, M., Piccone, T. and Chimney, M.J. 2018. Effects of short-duration hydraulic pulses on the treatment performance of a periphyton-based treatment wetland. ecological engineering 111(1): 69-77.
- Zhao, H., T. Piccone, and M. Zamorano. 2015. STA-3/4 Periphyton-based Stormwater Treatment Area (PSTA) Cell Water and Total Phosphorus Budget Analyses. Technical Publication WR-2015-001. South Florida Water Management District, West Palm Beach, FL.
Evaluation of Sampling Methods for Total Phosphorus
Description/ObjectiveDetermine if current sampling and monitoring techniques accurately measure total phosphorus (TP) concentrations, and if not, evaluate factors that influence results.
Activities Completed and Current Status
The study was completed in 2017.
Various sampling methods were evaluated. Cameras were used to observe physical and biological disturbances that could affect sample quality. Methods were compared based on analytical results and sampling efficiency. Sample sets using different methods, including, Grab sampling, flow-proportional composite autosamplers (ACF) and discrete autosamplers based on time (ADT), were collected. These sets were compared with measurements from a remote phosphorus analyzer (RPA) deployed within the Stormwater Treatment Areas (STAs). Additionally, water quality sondes were deployed to measure conductivity, pH and turbidity.
Results
Data comparisons suggest that Grab and ADT collection methods are more reliable than ACF methods. Under some conditions, the ACF method may be biased and not meet the completeness (percent of acceptable samples collected based on planned number of samples to be collected) target of 90%. Completeness estimates differ, depending on whether they are based on time coverage and/or flow representation. Reverse, low or poorly defined flows interfere with ACF sampling and can lead to non-representative samples, particularly at sites with small water level differences from up to downstream. Data from the RPA method indicated a mid-day peak in TP concentrations.
Infrastructure and levees can function as habitat for wildlife and could be potential sources of TP. Some animals such as anhingas and turtles were observed interfering directly with sampling systems. Masses of submerged aquatic vegetation were also observed to accumulate often at the sample intake screens, but the influence of these events on TP results was not clear.
It is recommended that flow proportionality of autosamplers and comparison of ACF versus ADT at multiple locations be further investigated. The use of ACF method at structures with small water level differences from up to downstream should be discouraged. Evaluating the completeness of collection should be based on the amount of flow represented, rather than time. Also, methods for limiting wildlife impacts on surface water sampling should be studied further.
Publications
- Rawlik, Peter 2017 Results from Project REST Remote Environmental Sampling Test. Technical Report WR-2017-002. South Florida Water Management District, West Palm Beach, FL.
Investigation of Rooted Floating Aquatic Vegetation in Stormwater Treatment Areas
Description/ObjectiveDetermine if rooted floating aquatic vegetation (rFAV) enhance low-level phosphorus (P) removal in back-end submerged aquatic vegetation (SAV) communities of Stormwater Treatment Areas (STAs).
The study includes two phases:
- Phase I – Evaluate P in the water column of rFAV and SAV patches to determine if differences exist.
- Phase II – Determine if Phase I findings are consistent among the STAs. Examine the mechanisms that account for the differences between patches.
Activities Completed and Current Status
The study was completed in 2018.
Phase I included water chemistry measurements to examine spatial within patch variability and temporal differences between rFAV and SAV patches. Expanded temporal sampling of additional patches was conducted to verify findings from primary patches. Measurements of soil characteristics and porewater from all patches, and sonde measurements, were conducted to determine factors that could explain patch differences.
Results
Water column P concentrations are different between rFAV and SAV areas for two of the three species evaluated. Water column P concentrations in white water lily and American lotus patches were higher than their corresponding SAV patch, while water column P concentrations in a spatterdock patch were not different from SAV patch. Soils in white water lily patches were lower in bulk density, higher in organic content and lower in calcium content compared to its paired SAV patch. This low bulk density soil may be prone to resuspension and could be contributing to the higher particulate P concentrations in the water column. Dissolved oxygen and pH measurements indicate greater aquatic metabolism in the SAV patch relative to the rFAV patch. Greater aquatic metabolism results from increased photosynthetic rate in the water column, which leads to higher pH during the daylight hours. This higher pH may enhance co-precipitation of P with calcium resulting in more P removal. The soil from American lotus patches has a higher organic content than SAV patches but were similar otherwise.
Reports and Publications
- Powers, M. 2018. Role of Rooted Floating Aquatic Vegetation, in 2018 South Florida Environmental Report – Volume I Chapter 5C: Restoration Strategies Science Plan Implementation (D. Ivanov, T. Piccone, T. James, and J. McBryan Eds.). South Florida Water Management District, West Palm Beach, FL.