Geographic MAP Modules

Transcription

1 3.3 GREATER EVERGLADES MODULE Overview of the Greater Everglades Module Approximately fifty percent of the Everglades habitat has been lost. The remaining portion of the GE ecosystem includes a mosaic of inter-connected freshwater wetlands and estuaries located primarily south of the Everglades Agricultural Area (EAA). This area makes up most of the GE Module (Figure 3-24). This module includes the littoral zones of Lake Okeechobee (which are the marsh areas of Lake Okeechobee) and the hydric pinelands and seasonal wetlands of the J.W. Corbett/Pal Mar/Dupuis Wildlife Management Area. A ridge and slough system of patterned, freshwater peatlands extends throughout the A.R.M. Loxahatchee National Wildlife Refuge (Refuge), WCAs 2, 3A and 3B into Shark River Slough within the ENP. The ridge and slough wetlands drain into tidal rivers that flow through mangrove estuaries into the Gulf of Mexico. Higher elevation wetlands that flank either side of Shark River Slough are characterized by marl substrates and exposed limestone bedrock. The marl wetland areas located to the east of Shark River Slough form the drainage basin for Taylor Slough, which flows through an estuary of dwarf mangrove forests into northeast Florida Bay. The Everglades marshes merge with the forested wetlands of Big Cypress National Preserve (BCNP) to the west of WCA 3 and ENP. Monitoring Changes Made Between 2004 and 2008 Given the strong interconnections among these regions, the integrated approach presented for the GE Module in MAP 2009 is based on the Total System Conceptual Ecological Model (Ogden et al. 2005) published in a special issue of the journal Wetlands. This is a change from MAP 2004 (RECOVER 2004) in which the GE Module was based on four regional CEMs, the Everglades Ridge and Slough (Ogden 2005), Southern Marl Prairies (Davis et al 2005), Everglades Mangrove Estuaries (Davis et al 2005), and Big Cypress Basin (Duever 2005; refer to Table 3-4). 3-86

2 Section 3 FIGURE 3-24: GREATER EVERGLADES MODULE BOUNDARY 2009 Revised CERP Monitoring and Assessment Plan 3-87 December 2009

3 3.3.2 Restoration Goals for the Greater Everglades Module The defining characteristics of the Everglades, as described in the Total System Conceptual Ecological Model (Ogden et al. 2005), included a unique combination of sheet flow, water depth patterns, oligotrophy, salinity distributions (in coastal estuaries), landscape patterns, and animal populations that together distinguished the Everglades from other large wetland systems. The restoration goals for the GE are based on those defining characteristics, and they identify a minimum set of criteria that must be achieved if CERP is to be considered successful in restoring the Everglades as a unique ecosystem. These goals are summarized from a longer list originally presented in MAP 2004, based on lessons learned from the Total System CEM, assessments of MAP results to date (Recover 2006 and 2007), and financial sustainability of a realistic, long-term MAP. The restoration goals for the GE are identified as follows: Sheet flow and water depth patterns consistent with outputs from the Natural System Hydrology Model (NSM v4.6.2 hereafter referred to as NSM) and with the conditions suggested by paleoecological studies Oligotrophic nutrient status as indicated by periphyton, soil, and water nutrient concentrations Landscape patterns of ridge and slough peatlands and adjacent marl prairies Wading bird nesting and freshwater predator/prey interactions American alligator populations Ecosystem characteristics of Everglades coastal wetlands. Freshwater inflows, hydrologic patterns, and salinity distributions Roseate spoonbill nesting and estuarine predator/prey interactions American crocodile juvenile growth and survival Mangrove forest community dynamics and soil accretion/subsidence The achievement of requisite restoration goals in the GE Module is targeted for an undivided ecosystem encompassing much of WCA 3A, WCA 3B, eastern BCNP, and ENP, where the potential exists for decompartmentalization combined with the resumption of a more natural volume, distribution, and timing of freshwater delivery and sheet flow (RECOVER 2006) Key Uncertainties Inherent uncertainties in each GE Module hypothesis cluster include scientific uncertainty regarding the causal relationships and uncertainty in the final design and operations of the CERP projects that will affect these relationships. Major uncertainties regarding the success of CERP in restoring the hydrological and ecological characteristics of the GE include scientific uncertainties inherent in each hypothesis cluster, water quality uncertainties, and the global uncertainties of climate change and exotic species as described in Section 1 of this document. 3-88

4 Scientific Uncertainties Two types of scientific uncertainty are inherent in each of the hypothesis clusters provided below. Although the causal relationships in the working hypotheses are based on a convergence of best scientific information, they are clearly hypothetical in that they have yet to be tested at the ecosystem-level scale of CERP, and at that scale they can only be tested through an AM approach. If the working hypotheses are supported by the MAP, there is another level of uncertainty regarding the final design and operation of CERP projects that are expected to restore the causal linkages of hydrology to ecological attributes adequately to achieve the restoration goals for the GE Module. These can only be tested through an AM approach Water Quality The importance of oligotrophy to all aspects of Everglades ecology emphasizes the need to restore water quality to impacted areas and maintain low nutrient conditions (with phosphorus the nutrient of primary concern) in the unimpacted areas of the Everglades ecosystem (FAC Water Quality Standards for Phosphorus Within the Everglades Protection Area; Noe and Childers 2007).. The 1994 Everglades Forever Act (Section , Florida Statutes [F.S.]) required the SFWMD to build and operate STAs as part of Everglades restoration to reduce TP levels in stormwater runoff from the EAA. The STAs were originally designed to achieve an outflow TP concentration of 50 ug/l (flowweighted mean) (Walker 1995). While substantial progress towards reducing phosphorus levels discharged into the Everglades Protection Area (EPA) has been made, additional measures are necessary to ensure that all discharges to the EPA meet water quality standards and the goals established in the EFA including compliance with the phosphorus criterion established in Rule , Florida Administrative Code (F.A.C.) (Burns and McDonnell 2003). There is a level of scientific uncertainty regarding the range of estimated level of performance of the STAs (Burns and McDonnell 2003). Restoration of water quality is dependent on several factors that include (1) continued use of source control (BMPs), (2) optimal operation of STAs, and (3) flux of historic phosphorus accumulations found within the sediments of impacted areas; each with inherent levels of uncertainty (Burns & McDonnell 2003;Newman et al, draft in review) Climate Change Since 1993, sea level has been rising at a rate of three millimeters per year, which was significantly higher than mean sea level the previous century (ICPP 2007, Brekke et al 2009). This level of sea rise is projected to significantly impact coastal wetland areas, especially coastal lowlands such as coastal Florida (Park et al 1989), resulting in coastal transgression involving the replacement of Everglades coastal wetlands with open water marine environments and the inland movement of coastal wetlands into interior areas that are presently freshwater environments (Davis et al. 2005a). There are uncertainties associated with the rate of coastal transgression, but the restoration of volume, timing and distribution of freshwater sheet flow through the remaining core area of GE (WCAs 3A and 3B, eastern BCNP, and ENP) with CERP implementation should have beneficial effects in slowing the 3-89

5 rate of coastal transgression, and/or re-establishment of the ecological characteristics of a viable and productive coastal wetlands zone, albeit upstream of its present location. Reduced annual rainfall and longer dry periods resulting from global warming will probably equate to reduced water inputs and increased evaporation and transpiration water loss within the CERP boundaries. Depending on the magnitude of those changes, the currently planned distribution of water by CERP to remaining Everglades wetlands may result in reduced flow volumes, shortened hydroperiods, and increased frequency and intensity of fire. Alternatively, prioritization of water distribution to areas of the Everglades where restoration targets are most likely to be achieved, including the core area described above, may result in an increased likelihood of achieving hydrological and ecological restoration goals in those areas Exotic Species The extent of invasion by nonindigenous species of the south Florida ecosystem is staggering and has altered the ecosystem by the replacement of native species (Ferriter et al 2008). Clearly the presence of these species, individually or collectively introduces a level of uncertainty in any attempt to assess the effects of restoration efforts. The development of a general CEM for invasive species would provide the framework in which to address these uncertainties (Doren et al 2009). Melaleuca (Melaleuca quinquenervia (Cav.) S.T. Blake) and Old World climbing fern (Lygodium japonicum (Thunb.) Sw. and/or Lygodium microphyllum) are two exotic plant species that currently pose the greatest threat and uncertainty for Everglades restoration and are the focus of ongoing eradication programs. The melaleuca eradication program is successfully controlling this species within the boundaries of the GE (Ferriter et al 2009), and a major uncertainty regarding Everglades restoration is the question of sustained funding for that program. At this time, the Old World climbing fern represents the greatest uncertainty for Everglades restoration because of its rapid proliferation on tree islands, particularly in the Refuge, and the absence to date of an effective control agent. Without control, the Old World climbing fern has the potential to block the achievement of tree island restoration targets despite the restoration of natural sheet flow, hydroperiod and fire regimes in the Everglades Overview of Hypothesis Clusters Hypothesis clusters in the MAP represent the causal relationships among ecosystem components and describe how these relationships are expected to change with restoration. The restoration goals for the GE Module provide the basis for these hypotheses. Each cluster is depicted by a CEM that shows the minimum set of variables that must be monitored and understood if CERP is to achieve the restoration goal. 3-90

6 3.3.5 Sheet Flow and Water Depth Patterns Hypothesis Cluster Working Hypotheses The restoration of defining characteristics of the Everglades as an ecosystem requires the resumption of pre-drainage volume, timing, and distribution of sheet flow and resulting water depth patterns in a wetland system of large spatial extent and undivided by levees and canals (Figure 3-25). The NSM provides a best estimate of pre-drainage hydrologic conditions and hydrologic restoration targets for the GE Module. The core areas of remaining Everglades that retain the potential for large spatial extent, decompartmentalization, and restored sheet flow and water depth patterns through rainfall-driven water deliveries include WCA 3A South of I-75, WCA 3B, eastern BCNP, and ENP. FIGURE 3-25: GREATER EVERGLADES INTERRELATIONSHIPS OF SHEET FLOW, WATER DEPTH PATTERNS, OLIGOTROPHIC NUTRIENT STATUS, AND LANDSCAPE PATTERNS HYPOTHESIS CLUSTER DIAGRAM Key: blue squares=drivers, red ovals=stressors, green diamonds=ecological effects, orange hexagons=attributes 3-91

7 Monitoring Components and Sampling Design The EDEN is an integrated multi-agency network of real-time water level monitoring, ground elevation modeling, and water surface modeling that provides scientists and managers with ongoing (2000 to current) on-line water surface and water depth information for the freshwater wetlands of the WCAs, BCNP, and ENP. EDEN simulations are presented on a 400 meter by 400 meter grid spacing, and provide the ability to associate biological field data to the actual hydrology of the system, thus integrating hydrological and ecological functions. The freshwater surface is modeled across the Everglades using real-time data from a network of 256 water-level gages maintained by the USGS, the SFWMD, and the ENP. Using Geostatistical Analyst in ArcGIS 9.x (Johnston et al. 2001), radial basis function (RBF) interpolation with the multiquadric method was used to create a continuous mathematical representation of the water surface that was sampled further on a 400 meter by 400 meter grid spacing to record the interpolated values. These results are combined with a fixed digital elevation model (DEM) to obtain daily water depths (Jones and Price 2007). The 400 meter by 400 meter interpolated grid is stored in NetCDF format which allows rapid retrieval of geo-coded time-series data and import into ArcGIS. As the water-depth is the result of combining the fixed raster that represents ground surface and the variable water-surface raster, the overall error would be a combination of individual errors. Refinement of EDEN in order to more accurately describe the water surface in/around system boundaries is ongoing, and list of significant products and hydrologic tools, such as water depth, hydroperiod and surface water elevation are available on the EDEN website, sofia.usgs.gov/eden/ (USGS 2006) Predictive and Assessment Tools The South Florida Water Management Model (SFWMM) is a regional-scale, grid-based hydrologic model that simulates surface water and groundwater processes in the natural and manmade (canals, structures and reservoirs) systems from Lake Okeechobee to Florida Bay ( It is the primary planning tool for CERP. For all SFWMM simulations, water stages throughout the GE are projected at a daily timestep over a 36-year period of record. The uncertainty associated with estimated stages is generally described as +/- 6 inches. Alternative SFWMM simulations are based on a defined set of project designs and operations. Flow volumes across transects are also calculated. The SFWMM simulates the hydrologic conditions that are expected with every CERP alternative, and these hydrologic conditions data are processed in order to create many of the ecological models used in the GE Module to forecast the ecosystem responses to CERP. The large scale of the grid cells in the SFWMM domain (2x2 mile) is appropriate for regional water resource planning. However, assessment of the GE Module working hypotheses would take place at much smaller spatial scales. To compensate, ENP and USGS have collaborated in the production of a high resolution hydrology (HRH) model that utilizes the SFWMM input and the high resolution 400-square meter topographic information utilized in EDEN to produce the necessary finer scale hydrology. This process (which has been reviewed and approved by the Interagency Modeling Center [IMC], MSR 331), downscales the 2x2 mile projections of the SFWMM to a 500-square meter grid across the GE. This process would facilitate comparisons between the SFWMM projections and the field- 3-92

8 based observations of ecosystem responses to CERP, and would provide the hydrologic input necessary to drive ecological models over high resolution domains. The daily water depth maps provided by EDEN serve as the primary basis for the ecological assessment tools described below. These tools would be used to link hydrologic conditions to the ecological characteristics in the GE Module. Other models currently under development provide simulations of sheet flow in the ridge and slough habitat at small spatial scales ranging from one to ten square meters. An expanded discussion of these models can be found in the Decompartmentalization Physical Model Science Plan (Hagerthey et al 2009) which is being reviewed by the National Academies of Sciences. The Ridge and Slough Cellular Automata Landscape (RASCAL) model (Larsen and Harvey, in review) is designed to simulate flow/vegetation/sediment transport feedbacks at five square meter resolution, so that CERP participants can predict the outcome of a large number of landscape conditions flow velocity combinations through numerical simulations. The Ribbon Model (Saunders et al. in review) simulates transfers of phosphorus between the living and non-living compartments of the Everglades ecosystem and should allow CERP participants to explore the consequences of increased flow volumes moving through the system over decadal time spans. Finally, the Lattice-Boltzmann model is applied at very small scales (one square meter) to identify preferential flowpaths and assign flow resistance to different vegetation types (Sukop and Thorne 2006). The output of this model is used to parameterize the RASCAL and Ribbon Models when they are applied to different locations, and can be parameterized with SF 6 tracer studies in the location of interest. Longer term simulations of large areas can be driven with large-scale hydraulic gradients that are derived either from EDEN or from the SFWMM simulations. The objective of these models is to link the regional hydrologic conditions with the smaller-scale processes mediated by sheet flow, such as sediment transport, which are considered important in the formation and maintenance of the ridge, slough, and tree islands mosaic Oligotrophic Nutrient Status Hypothesis Cluster Working Hypotheses The dominance of direct rainfall as the primary source of water and phosphorus, in combination with sheet flow, resulted in an oligotrophic, phosphorus-limited nutrient state throughout the GE prior to drainage and development (Davis 1943, Davis and Ogden 1994, Noe et al. 2001, 2002, 2003, Figure 3-25). Increased phosphorus concentrations and loads in agricultural runoff water, and replacement of sheet flow with canal flows and point-source discharges, have produced phosphorus concentration gradients in surface water, soil and periphyton downstream of canal discharge structures and shifted wetlands from oligotrophic to eutrophic states (Walker, 1995; McCormick et al 1996). The importance of oligotrophy to all aspects of Everglades ecology emphasizes the need to monitor the nutrient status of the ecosystem. Research has shown that assessment of water column nutrient concentrations alone does not generally capture the level of ecosystem impact (restorative or deconstructive) that results from changes in nutrient loads over a period of time (McCormick and Stevenson 1998; Smith and McCormick 2001, Gaiser et al. 3-93

9 2004) because wetland water column nutrients are highly variable (Reddy et al 1999) with excess nutrients quickly assimilated by vegetation. The long-term fate of surface water quality nutrient concentrations are tied to how they are assimilated, including sequestration into the flocculent material (Koch and Reddy 1992; Kadlec and Knight 1995, Harwell et al 2008). This high spatial and temporal variability makes water column nutrient concentration a poor marker for assessing immediate changes in nutrient status, which is critical for applying AM principles. However, surface water quality assessment is valid for use as a long-term indicator of nutrient enrichment. Soil nutrient concentration is a long-term indicator of nutrient loading and, in the Everglades and is often associated with ecosystem change (Doren et al 1996; McCormick et al 1999; Craft and Richardson 1993; Newman et al 1997; Scheidt and Kalla 2007). Reddy et al. (1999) reports that sediment response to nutrient loading occurs over years (10 to 15 years) in the top ten centimeters of nutrient impacted wetlands. Research has shown that periphyton can provide a rapid (weeks to months) and accurate indication of water quality changes (McCormick et al. 1996; Reddy et al. 1999; Gaiser et al. 2004; Gaiser et al. 2005; Gaiser et al. 2006) making periphyton an excellent first responder signaling both restorative and deconstructive ecological responses to nutrient and hydrological changes if periphyton is monitored in the appropriate locations. Water quality data collected through other initiatives (i.e. EPA R-EMAP study, SFWMD permit and research surface water quality data, USGS PES and NSF LTER research) could be capitalized upon while pursuing the use of periphyton mat structure and community composition as an early responder used to detect system wide alterations in both hydrology and water quality. Phosphorus and nitrogen concentrations in periphyton mats integrate trends in surface water concentrations over time periods of weeks to months. The floating mat comprised of the periphyton complex and bladderworts provides critical support of the oligotrophic Everglades food web, both as a food source and as habitat for aquatic invertebrates that are consumed by small fish, crayfish and grass shrimp. However, as currently sampled, the periphyton monitoring network may be inadequate to fully capture the intent of MAP 2004; to specifically monitor the interior gradients of the system, MAP 2009 provides the many first steps toward this goal Monitoring Components and Sampling Design A holistic approach that integrates the assessment of the soil, periphyton, and surface water nutrient concentration data is needed to fully assess the oligotrophic status of the GE Wetlands ecosystem. This integration of all three data layers wouldl provide total predictive and assessment measures that are able to assess on both short and long spatial and temporal scales. 3-94

10 Surface Water Nutrient Concentrations. Other collection initiatives can capitalize on water quality data (i.e. EPA R-EMAP study, SFWMD permit and research surface water quality data, USGS PES and NSF LTER research) Soil nutrient concentrations. A stratified random sampling design was used to produce maps of soil nutrient distributions across the freshwater wetlands of the Everglades in Methods and soil nutrient distribution maps were reported in the SSR 2006 (RECOVER 2007aA stratified random design is necessary for constraining the number of soil samples required to create a map for an area over 1000 square miles, but the magnitude of spatial variance associated with the 2005 data is being assessed in order to determine if the sample number and density is adequate to detect regional changes in soil phosphorus concentration. Refinement of the monitoring approach based on observed data is an objective, manageable, and cost-effective approach to refining this important component of the map, and the result of this study will be used to determine the sampling design and frequency for future monitoring of soil nutrients. Periphyton nutrient concentrations. Periphyton samples are collected concurrently with throw-trap samples for aquatic fauna prey populations using the sampling design described in the following section. See Gaiser (2006) and Gaiser et al. (2006) for details on methods and results Predictive and Assessment Tools RECOVER researchers developed a tool that provided a qualitative assessment of ecosystem response based on several periphyton attributes: a bundance, nutrient content and community composition (Doren et al. 2008). This tool is recognized as an important first step towards the development of quantitative assessment techniques and predictions of future conditions associated with CERP Landscape Patterns of Ridge and Slough Peatlands and Adjacent Marl Prairies in Relation to Sheet Flow, Water Depth Patterns and Eutrophication Hypothesis Cluster Working Hypothesis The loss of elongated patterns of ridges, sloughs, and tree islands in the direction of water flow in the ridge and slough landscape of the Everglades is attributed to disrupted sheet flow and related changes in water depth (Figure 3-25). Eutrophication and the spread of cattail further contribute to this loss. Spatial patterning and topographic relief of ridges and sloughs are directly related to the volume, timing and distribution of sheet flow and related water depth patterns, which drive processes of sediment accretion and loss (Ogden 2005). Resumption of sheet flow and related water depth patterns, in combination with maintenance or restoration of oligotrophic nutrient status, will stem and possibly reverse the degradation of the ridge, slough, and tree island landscape (SCT 2003). 3-95

11 Monitoring Components and Sampling Design The monitoring components and sampling design for this hypothesis cluster includes landscape monitoring and vegetation mapping. Landscape monitoring. The landscape monitoring design utilizes the Generalized Random Tessellation Stratified (GRTS) sampling approach of Stevens and Olsen (2004). It produces a spatially-balanced probability design tiling the ridge and slough landscape and adjacent marl prairies into two kilometer by five kilometer cells oriented along the directions of the ridges (Figure 3-26). The landscape sampling design maximizes the flexibility of subsequent analyses of the resultant monitoring data (Philippi 2007) and allows for flexibility in implementation to account for variable budget constraints. 3-96

12 FIGURE 3-26: MAP OF THE FIRST 80 PRIMARY SAMPLING UNITS IN THE GENERALIZED RANDOM TESSELLATION STRATIFIED DRAW Key: Colors indicate panels (years) solid colors illustrate the n=4 per year spatially-balanced subsets solid and outline combined show the n=16 per year subsets 3-97

13 The attributes to be monitored long-term would be determined based on the results of initial field work and from cost-benefit analyses. The systematic implementation of the landscape sampling design across the ridge and slough landscape and adjacent marl prairies began in The initial field work is as follows: Locate and mark corner boundaries of the 80 rectangular two kiliometers by five kilometers primary sampling units (PSUs), locating 16 units each year over five years Identify two to eight PSUs to be designated for additional intensive sampling Characterize the hydrology of each PSU primary sampling unit utilizing EDEN Establish additional Class B benchmarks for PSUs that are not located within a reasonable distance of existing benchmarks Establish two transverse transects in the upper and lower halves of each PSU, and record soil surface elevation, soil depth to bedrock, water depth, soil and vegetation type at intervals along the transects Characterize land surface elevation at multiple locations within each PSU Map and characterize each tree island within a given PSU, including forest structure (species and size composition), leaf area index, soil and tissue nutrient concentrations, and relative elevation Utilize the procedure documented by Wu et al. (2006) to calculate five landscape indices proposed for quantifying ridge and slough patterning Map and characterize the vegetation in each PSU in a manner consistent with the classification scheme developed for CERP vegetation mapping Vegetation mapping. The objective of the vegetation mapping monitoring component is to produce a spatially and thematically accurate pre-cerp reference condition vegetation map of the GE Module geographic area to be used in monitoring the spatial extent, pattern and proportion of plant communities within this region. Aerial photography is currently the best tool to produce dependable and accurate maps. Vegetation communities are being mapped with a 0.25-hectare (ha) minimum mapping grid unit (mmu) from 1:24,000 scale color infrared positive transparencies (23- by 23-centimeter format) that were flown in December The necessary geo-referencing and photo interpretation was performed on a Leica SD2000 analytical stereoplotter (Rutchey et al 2008). Then a 0.25 ha grid (50 meters by 50 meters) was created and superimposed over the entire set of stereo imagery, resulting in the designation of 227,429 individual grid cells (Rutchey and Godin 2009). Photo interpretation of each 0.25 ha grid cell is performed using the SD2000 by superimposing the twodimensional grid over the three-dimensional stereo imagery. Grids are labeled using PRO600 and Microstation software as part of the SD2000 stereo mapping system. All classification data are then migrated to softcopy workstations where QA/QC evaluations are performed and the final map accuracy assessments are completed. Each distinct vegetation community would be designated according to the Vegetation Classification System for South Florida Natural Areas (Rutchey et al. 2006; sofia.usgs.gov/publications/ofr/ /). All final data resides in ArcGIS geodatabase format. 3-98

14 To date, vegetation maps for WCA 1 (Refuge) and WCA 2, WCA 3, and the Rotenberger Wildlife Management Area have been completed. It is anticipated that vegetation maps for the remainder of the GE Module area will be completed by the end of fiscal year (FY) It was originally estimated that the vegetation map could be completed in a five-year period, but experience has shown that due to a steep learning curve needed for training the required personnel, the time commitment to complete a pre-cerp reference condition map of the entire area will be about seven to eight years. Therefore, discussions are underway regarding the level of mapping that will be required for future maps and other technologies are being explored as they become available and refined Predictive and Assessment Tools The Everglades Landscape Model (ELM), while not funded by MAP, is a regional-scale, integrated ecological assessment tool designed to understand and predict the landscape response to different water management scenarios within the South Florida ecosystem. In simulating changes to habitat distributions, the ELM dynamically integrates hydrology, water quality, soils, periphyton and vegetation in the Everglades region (my.sfwmd.gov/elm). Currently, ELM s primary utility to CERP is to compare the consequences of different types of nutrient inflow distributions so that a clear, objective evaluation of the preferred inflow concentration can be made. Everglades researchers have recognized that understanding vegetation dynamics within the ridge and slough, and tree island landscape is critical to assess and predict the effects of hydrologic changes on ecosystem restoration. Several predictive models have been produced that have provided the foundation for future models. These models include a Tree Island HSI model, a vegetation succession model developed on the Across Trophic Level System Simulation (ATLSS) platform, and a Ridge and Slough HSI. The output of these models is best understood as hypotheses which can then be verified/refuted by monitoring. However, the conclusions that can be drawn from these models are limited by the relatively short period of record (36 years) over which the simulations are run. While small-scale, localized changes in vegetation can occur in just a few years in the Everglades as a result of altered hydrology or nutrient input, the development of large-scale ridge, slough and tree islands patterns in this ecosystem takes place over much longer time periods. Although the time involved in this process is uncertain, ridge and slough pattern formation processes may take hundreds of years. As a result, it is difficult to predict the developmental trajectories these systems will take with 36-year simulations. Everglades researchers recognize the need for process-based models of the ridge and slough habitat that link the processes of plant productivity, species competition, peat accretion, and sediment transport with fire frequency, sheet flow patterns, and water depths. The development of these types of models in the context of the Long Term Ecological Research program (LTER) funded by NSF, the Decomp Physical Model (DPM), and other work being funded by USGS are essential for reducing planning, implementation, and monitoring uncertainties for CERP. 3-99

15 3.3.8 Wading Bird Nesting in the Mainland and Coastal Everglades in Relation to the Aquatic Fauna Forage Base Hypothesis Cluster Working Hypotheses The collapse of wading bird nesting colonies in the southern Everglades is attributed to declines in wet season population densities and dry season concentrations of marsh fishes, crayfishes, and other aquatic prey organisms (Figure 3-27). Restoration of hydrologic conditions consistent with understanding pre-drainage conditions is expected to reestablish aquatic prey densities and concentrations across the landscape that in turn would support the return of large, successful wading bird nesting colonies to the southern Everglades. Wet season aquatic prey population. The wet season density and size structure of aquatic prey organisms are directly related to the time since the last dry-down and the length of time the marsh was dry. Aquatic prey populations are also affected by site nutrient status. Responses are non-linear and species specific. Dry season aquatic prey concentrations. The concentration of aquatic prey organisms into high-density patches where wading birds can feed effectively is controlled by the rate of dry season water level recession interacting with local topography and habitat heterogeneity. Wading bird super colonies. Unusually large aggregations of nesting wading birds (super colonies) consisting mostly of white ibis form after periods of drought in natural multi-year wet and dry cycles. The drought periods appear to cue pulses of production of prey organisms. The mechanisms by which these pulses are organized are poorly understood. Crayfish population surges, predatory fish population decline, and nutrient dynamics are likely involved. Roseate spoonbill nesting and predator-prey interactions in Everglades coastal wetlands. Successful nesting of roseate spoonbills on the northern boundary of Florida Bay requires a well-timed drying front progressing along the coastal wetland landscape between November and April. This drying front provides a reliable source of prey needed for nesting success. Water depths must drop to at least 12.5 centimeters as the dry season progresses in order to meet the spoonbill s depth threshold for effective foraging on concentrated populations of small fishes and other aquatic prey organisms. Years of low spoonbill nesting success occur when the drying front is abbreviated by too wet or dry conditions, or when water levels rise, rather than recede, during periods of the dry season (water level reversals). Another factor contributing to spoonbill nesting success is the buildup of prey populations of small marsh fishes during the wet season. Prey populations of marsh fishes that are available for concentration during the dry season are directly correlated to the duration of hydroperiod and inversely correlated to salinity

16 FIGURE 3-27: GREATER EVERGLADES PREDATOR-PREY INTERACTIONS OF WADING BIRDS AND AQUATIC FAUNA FORAGE BASE HYPOTHESIS CLUSTER DIAGRAM Key: blue squares=drivers, red ovals=stressors, green diamonds=ecological effects, orange hexagons=attributes 3-101

17 Monitoring Components and Sampling Design The strategy for the assessment of wading bird and aquatic prey interactions is to annually track the production of aquatic prey populations during the wet season, the concentration of those populations during the subsequent dry season, and the distribution, size and timing of wading bird nesting colonies in response to the prey populations. Production of prey biomass. Aquatic prey populations during the late wet season (October- November) are monitored using one square meter throw traps (Jordan et al. 1997). Throw trap samples are collected in 149 primary sampling units in freshwater marshes across the Everglades in areas that were identified as feasible for throw-trap sampling by Trexler (2004) (Figure 3-28). Selection of primary sampling units follows guidelines from Philippi (2003, 2005) and is based on a spatially balanced recursive tessellation design (Stevens and Olsen 2004). Throw trap locations within a primary sampling unit are three fixed coordinates within a ten meter by ten meter cell drawn randomly from the habitat that can be sampled. Landscape estimates for standing crops of prey populations are interpolated via standard kriging across the sampling domain. The sampling design also recognized that sampling of non-slough areas is required in order to estimate changes in total fish biomass across the entire GE Module landscape. The high cost (estimated at approximately ten times more than sampling slough habitats) precluded inclusion of these areas into the routine annual monitoring design, but incorporated a recurring (approximately every three to five years) ancillary sampling effort with paired block-net sampling between a small subset of the slough sample points and adjacent ridge. A major strength of this sampling design in the context of CERP is its flexibility. Areas of the Everglades landscape can be re-configured to compare specific regions, such as those impacted by CERP projects, with other regions, and to add primary sampling units to specific regions without violating requirements for a random sampling design. Concentration of prey biomass. Aquatic prey concentrations in isolated pools during the dry season are monitored using throw traps. Random samples are collected from a subset of 32 of the primary sampling units used for wet season prey population sampling (Figure 3-28) (Botson and Gawlik 2006). The number and location of primary sampling units within that subset of 32 varies from year to year, depending on the distribution of drying patterns and the formation of isolated pools across the landscape. Wading bird colony location, size and timing in the mainland Everglades during the winter-spring nesting season. Wading bird nesting colonies in ENP, the WCAs, and Lake Okeechobee are monitored monthly each year between January and June using systematic aerial surveys (Frederick et al. 2006, Cook and Call 2006). East-west oriented transects spaced 1.6 nautical miles apart are monitored at a flight altitude of 800 feet above ground level (AGL), with observers on both sides of the aircraft. Additional north-south oriented transects result in overlapping coverage under a variety of weather and visibility conditions. The method has been used continuously since Wading bird species targeted for assessment based on aerial surveys include the wood stork, white ibis, great egret and snowy egret

18 Roseate spoonbill nesting and predator-prey interactions in Everglades coastal wetlands. Prey base fishes are collected using nine square meter drop traps (Lorenz et al. 1997) along the coastal wetlands from Biscayne Bay to Lostman s River (Figure 3-28). Drop trap samples are collected eight times per year (June, September, and monthly from November through April) to cover the spoonbill nesting period. The sites are grouped into four watersheds: Biscayne Bay, C-111 Basin, Taylor Slough and Cape Sable). Flat and creek habitats are sampled at each location. Flats are seasonally inundated peripheral wetlands that are flooded during the wet season, with each site experiencing different hydroperiod lengths depending on elevation. Creeks are wetted year round and serve as refugia for wetland fishes that are forced from the flats during drying events. For more details regarding data analysis, refer to the SSR 2007 (RECOVER 2007b)

19 Section '0"W 80 0'0"W 27 0'0"N 27 0'0"N Atlantic Ocean SFWMD Boundary Lake Okeechobee Gulf of Mexico 26 0'0"N 26 0'0"N Atlantic Ocean Gulf of Mexico Biscayne Bay Florida Bay 81 0'0"W Legend 80 0'0"W 2005 Dale Gawlik Aquatic Fauna Sampling Sites Jerry Lorenz Fish Sampling Sites 2006 Dale Gawlik Aquatic Fauna Sampling Sites Carol McIvor Forested Wetland Fish Samling Sites Shawn Liston Aquatic Prey Sampling Sites Joel Trexler FIU Biological Sampling Sites Bill Loftus Aquatic Refuge Sampling Sites John Volin FAU Crayfish Sampling Sites Miles 20 FIGURE 3-28: COMPREHENSIVE MAP OF SAMPLE SITE LOCATIONS OF AQUATIC FAUNA PREY POPULATIONS IN THE GREATER EVERGLADES 2009 Revised CERP Monitoring and Assessment Plan December 2009 Map Updated: April 19, 2007 Map Location: \\cerp\projects\gis\prgm_03\map_docs\map_docs\cmn4598_ssr_07maps\ge_comprehensiveaquatic_cmn4598.mxd Area of Interest

20 Roseate spoonbill nests are counted between November and April on 34 keys that have been used historically by spoonbills as nesting colonies in Florida Bay. Colonies are divided into five nesting sub-regions based on each colony s primary foraging location (Lorenz et al. 2001). Nest counts are performed by entering each active colony and searching for nests on foot. Nesting success is estimated for the four sub-regions through mark and revisit surveys of the most active colony within the sub-region. These surveys entail marking between 15 and 50 nests shortly after clutches have been laid and revisiting the nests on an approximate two-week cycle to monitor chick development. Supporting research. Monitoring and research to supplement the core monitoring components that are described above include the following: Sub-lethal effects of mercury on numbers of nesting white ibis. A three-year mercury exposure experiment using white ibis in a flight enclosure supported the hypothesis that suppressed initiation of nesting before 1999, compared to the marked increase in recent years, is related to reductions in tissue concentrations in the birds (Frederick and Adams 2006). This supporting research is completed and will not be continued. Crayfish population dynamics. A five-year study of crayfish population dynamics confirmed that throw trap sampling effectively sampled crayfish, and reported population densities across a variety of Everglades landscapes that were consistent with results from the wet season and dry season prey population sampling described above (Volin and Lott 2006). This supporting research is currently being concluded. Aquatic prey populations in forested wetlands. A study to compare sampling methods for monitoring aquatic prey populations in forested wetlands identified throw trap sampling as the most effective method in BCNP (Liston et al. 2006). A continuation of this study investigates statistical approaches to integrate a sampling design in BCNP with the probability-based design for sampling aquatic prey populations in the Everglades Predictive and Assessment Tools A number of models of fish and wading birds are in the development phase and the MAP monitoring data are being used to refine, calibrate and verify these models. These models are intended to assess the effects of current operations and restoration on marsh fish biomass and community structure, crayfish populations, wading bird populations and habitat suitability for spoonbills American Alligator Density and Body Condition in Relation to the Hydrologic Patterns and Artificial Canal Habitats in the Everglades Hypothesis Cluster Working Hypotheses Density and body condition of the American alligator in remaining Everglades wetlands are currently suppressed due to altered water depth patterns, salinity distributions and prey 3-105

21 abundance, which have resulted from compartmentalization and disrupted sheet flow (Figure 3-29). Canals further draw alligator populations from adjacent marshes and reduce the abundance and survival of juvenile alligators due to increased predation. Restoration of sheet flow and related water depth patterns consistent with the understanding of pre-drainage condition, in combination with the removal of canals, will result in a widespread increase in alligator density and body condition in the Everglades. Alligators are further expected to repopulate and resume nesting in the Rocky Glades and in the freshwater reaches of tidal rivers along the southern coastline of the Everglades. FIGURE GREATER EVERGLADES ALLIGATOR DENSITY AND BODY CONDITION IN RELATION TO THE HYDROLOGIC PATTERNS AND ARTIFICIAL CANAL HABITATS HYPOTHESIS CLUSTER DIAGRAM Key: blue squares=drivers, red ovals=stressors, green diamonds=ecological effects, orange hexagons=attributes 3-106

22 Monitoring Components and Sampling Designs As of 2008, adequate data have been collected to build alligator population models for use in CERP evaluations and assessments. Thus, a reduction in alligator monitoring effort will begin in The information collected on alligators is as follows: Alligator relative density. Alligators are counted via spotlight surveys along routes in six management units (Figure 3-30), following guidelines in the Alligator Survey Network Spotlight Survey Protocol (Rice and Mazzotti 2007, Appendix 1). Surveys are conducted twice in each area in both spring and fall, at least 14 days apart to achieve independent counts. Details of monitoring methods are given in Mazzotti et al. (2008). Relative density is calculated by dividing the total number of non-hatchling animals encountered on each survey by the total length, in kilometers, of the survey route, Alligator body condition. To determine body condition of alligator populations, semiannual capture surveys are performed in the same areas as described for spotlight surveys (Figure 3-30). A minimum of 15 alligators greater than one-meter total length are captured in the fall and spring of each year. Body condition, a ratio of body length to body volume, is determined using a Fulton s K condition factor (Zweig 2003) based on the ratio of lead length to weight Supplemental Monitoring and Supporting Research Surveys for alligator hole occupancy were conducted via systematic reconnaissance flights (SRF) in ENP during 2005 and Details of monitoring areas, methods and results are given in Rice et al. (2007)

23 FIGURE 3-30: MAP OF ALLIGATOR SPOTLIGHT SURVEY ROUTES IN SOUTH FLORIDA ( ) (Used for Monitoring American Alligator Relative Density and Body Condition [Rice et al. 2008]) Key: LNWR=Loxahatchee National Wildlife Refuge, BCNP=Big Cypress National Park, ENP=Everglades National Park, WCA=Water Conservation Area 3-108

24 Ecosystem Characteristics of Everglades Coastal Wetlands in Relation to Freshwater Inflows Hypothesis Cluster Working Hypotheses The volume, timing and distribution of freshwater flow to coastal wetlands of the Everglades from Barnes Sound to Lostmans Bay have been altered by upstream diversions of water, compartmentalization and disrupted sheet flow (Figure 3-31). Several hypotheses have been developed describing the cause-and-effect relationships between the alteration of freshwater flow and attributes of the coastal wetlands. Freshwater inflows, hydrologic patterns and salinity distributions. The volume, timing and distribution of sheet flow prior to drainage produced the following hydrology and salinity patterns in the coastal wetlands of the Everglades during most years: A freshwater pool upstream of the marsh-mangrove interface that persisted throughout most of the year and well into the dry season Freshwater flow into the mangrove estuaries that persisted throughout most of the year and well into the dry season A sequential drying front moving across the coastal wetland landscape that persisted into April during the dry season A wide and persistent zone of freshwater-to-oligohaline salinity in the coastal wetlands Oligohaline-to-mesohaline salinity ranges in the coastal basins of Florida Bay and the Gulf of Mexico as defined by the Venice System (Por 1972; Venice System 1959) Reduced volume and altered timing and distribution of sheet flow in the current managed system have resulted in the following changes in hydrology and salinity patterns in coastal wetlands of the Everglades during most years: Reduced annual duration of the freshwater pool upstream of the marsh-mangrove interface Reduced volume and duration of freshwater flow into the mangrove estuaries More rapid drying of the coastal wetland landscape during the dry season, interrupted by more frequent water level reversals resulting from upstream regulatory water releases Reduced spatial extent and duration of the zone of freshwater-to-oligohaline salinity in the coastal wetlands Seawater salinity ranges with periodic hypersaline events in the coastal basins Restoration of the volume, timing and distribution of sheet flow to conditions consistent with the best understanding of pre-drainage condition, would create hydrology and salinity patterns in coastal wetlands of the Everglades that more closely resemble conditions prior to drainage

25 Roseate spoonbill nesting and estuarine predator-prey interactions. Successful nesting of roseate spoonbills in northeast and northwest Florida Bay requires a temporal sequence of prey availability as the dry season progresses between November and April. Another factor contributing to spoonbill nesting success is the buildup of prey populations of small marsh fishes during the wet season, which is directly correlated to duration of hydroperiod and inversely correlated to salinity. For further details, refer to the Wading Bird Nesting in the Mainland and Coastal Everglades in Relation to the Aquatic Fauna Forage Base Hypotheses Cluster section above. American crocodile juvenile growth and survival. Growth and survival of juvenile American crocodiles increase when salinity fluctuates below 20 ppt in shoreline, pond and creek habitats of Everglades coastal wetlands. Reduced volume and altered timing and distribution of sheet flow to the coastal wetlands have increased salinity in areas where it previously fluctuated below 20 ppt, resulting in reduced growth and survival of juvenile crocodiles. Restoration of the volume, timing and distribution of sheet flow to conditions consistent with NSM outputs would decrease salinity to 20 ppt or less, and thereby increase growth and survival of juvenile crocodiles, throughout extensive areas of the coastal wetlands

26 FIGURE 3-31: GREATER EVERGLADES ECOSYSTEM CHARACTERISTICS OF EVERGLADES COASTAL WETLANDS PRIOR TO DRAINAGE HYPOTHESIS CLUSTER DIAGRAM Key: blue squares=drivers, red ovals=stressors, green diamonds=ecological effects, orange hexagons=attributes 3-111

27 Monitoring Components and Sampling Designs Freshwater inflows, hydrologic patterns and salinity distributions. Nine transects extending from freshwater to marine conditions have been established in coastal Everglades wetlands (Figure 3-32). As part of the Priority Ecosystems Science (PES) Program, the USGS has monitored a series of sites along several creeks and rivers since RECOVER supplemented this monitoring with ten additional sites adding recorders at the upstream ends of the transects (Woods and Zucker 2006). Water level, flow, salinity and temperature recorders at these sites provide data both for model development and calibration as well as to serve as a long-term hydrologic data set to assist in detecting change. In addition to the fixed monitoring network, moving boat surveys along the nine transects collect salinity, temperature and GPS data from boat-mounted sensors. Additional information regarding USGS coastal monitoring sites and the PES program is available at sofia.usgs.gov. Roseate spoonbill nesting and estuarine predator-prey interactions. Prey base fishes are collected using nine square meter-drop traps (Lorenz et al. 1997) along the coastal wetlands from Biscayne Bay to Lostmans River (Figure 3-32). Roseate spoonbill nests are counted between November and April on 34 keys that have been used historically by spoonbills as nesting colonies in Florida Bay. For further details, the Wading Bird Nesting in the Mainland and Coastal Everglades in Relation to the Aquatic Fauna Forage Base Hypothesis Cluster. American crocodile juvenile growth and survival. Juvenile growth is estimated by periodic recaptures in the fall of crocodiles that have been captured and marked during the previous summer. Assessments are based on capture areas in ENP (Buttonwood Canal) and the Refuge. Non-hatchling crocodiles greater than 50 centimeters in length are captured, weighed and measured for total length and snout-vent length. Average growth in centimeters per day during the first year of life is measured for juvenile animals less than or equal to 75 centimeters total length as the change in total length between the two capture events divided by the number of days between two capture events (refer to Rice et al. (2008) for details). Mangrove forest community dynamics and soil accretion/subsidence. Monitoring rates of soil accretion or subsidence in mangrove estuaries of the Everglades provides critical information about the capability of coastal wetlands to increase ground elevation so as not to be overtaken by current rates of sea level rise. The fate of coastal wetlands given current rates of sea level rise represents a major uncertainty in all working hypotheses pertaining to Everglades coastal wetlands

28 Section '0"W 1. Lostman's River 2. Broad River 3. Harney River 4. Ponce de Leon Bay 5. North River 6. McCormick Creek 7. Little Madeira - Taylor Slough 8. Joe Bay - C-111 Wetlands 9. Barnes South - South Dade Wetlands 26 0'0"N SFWMD Boundary Gulf of Mexico Area of Interest Shark River Slough Everglades National Park 1 Upstream Lostman's River 26 0'0"N USGS Coastal Gradient Transect WCA 3 Names Big Cypress National Preserve 2 Upstrream Broad River Gulf of Mexico Bottle Creek 3 Harney River 5 4 Upstream North River 9 Whitewater Bay Taylor Slough Wetland 6 Taylor Slough 8 Card Sound C-111 Wetland Manatee Bay 7 Seven Palm Lake 25 0'0"N 25 0'0"N Florida Bay 81 0'0"W Map Updated: April 9, 2007 Map Location: \\cerp\projects\gis\prgm_03\map_docs\map_docs\cmn4598_ssr_07maps\ge_coastal_gradients_cmn4598.mxd Atlantic Ocean Legend USGS CERP MAP Site USGS SET Site USGS PES Site USGS Generalized Coastal Transects Miles 12 FIGURE 3-32: LOCATION OF TRANSECTS AND MONITORING STATIONS FOR SALINITY GRADIENTS AND SEDIMENT ELEVATIONS IN THE COASTAL EVERGLADES 2009 Revised CERP Monitoring and Assessment Plan December