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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 2 The Restoration in Context This chapter sets the stage for the second of this committee’s biennial assessments of restoration progress in the South Florida ecosystem. Background is provided for understanding the restoration project by defining the ecosystem decline, restoration goals, the needs of a restored ecosystem, and the specific activities of the restoration project. The Everglades and its restoration are also discussed in the larger context of human activities in South Florida and climate change. Finally, the chapter provides a view of important recent changes in the ecosystem, including tree islands, invasive species, and endangered bird populations. BACKGROUND The Everglades once encompassed about 3 million acres of slow-moving water and associated biota that stretched from Lake Okeechobee in the north to Florida Bay in the south (Figures 1-1a and 2-1a). The conversion of the uninhabited Everglades wilderness into an area of high agricultural productivity and cities was a dream of 19th-century investors, and projects begun between 1881 and 1894 affected the flow of water in the watershed north of Lake Okeechobee. By the late 1800s, more than 50,000 acres north and west of the lake had been drained and cleared for agriculture (Grunwald, 2006). These early projects included straightening the channel of the Kissimmee River and connecting Lake Okeechobee to the Caloosahatchee River and, ultimately, the Gulf of Mexico. In 1907 Governor Napoleon Bonaparte Broward created the Everglades Drainage District to construct a vast array of ditches, canals, dikes, and “improved” channels. By the 1930s, Lake Okeechobee had a second outlet, through the St. Lucie Canal, leading to the Atlantic Ocean, and 440 miles of other canals altered the hydrology of the Everglades (Blake, 1980). After hurricanes in 1926 and 1928 resulted in disastrous flooding from Lake Okeechobee, the U.S. Army Corps of Engineers (USACE) replaced the small berm that bordered
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 FIGURE 2-1 Water flow in the Everglades under (a) historical conditions, (b) current conditions, and (c) conditions envisioned upon completion of the Comprehensive Everglades Restoration Plan (CERP). SOURCE: Graphics provided by USACE, Jacksonville District. the southern edge of the lake with the massive Herbert Hoover Dike that now encircles the lake. The hydrologic end product of these drainage activities was the drastic reduction of water storage within the system and an increased susceptibility to drought and desiccation in the southern reaches of the Everglades (NRC, 2005). After further flooding in 1947 and increasing demands for improved agricultural production and flood control for the expanding population centers on the southeast Florida coast, the U.S. Congress authorized the Central and Southern Florida (C&SF) Project. This USACE project provided flood control with the construction of a levee along the eastern boundary of the Everglades to prevent flows into the southeastern urban areas, established the 700,000-acre Everglades Agricultural Area (EAA) south of Lake Okeechobee (see Box 2-1), and created a series of water conservation areas (WCAs) in the remaining space between the lake and Everglades National Park (Light and Dineen, 1994). The eastern levee isolated about 100,000 acres of Everglades ecosys-
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 BOX 2-1 The Everglades Agricultural Area Making the land in the Everglades Agricultural Area (EAA) (see Figure 1-3) suitable for agriculture was one of the original primary objectives of the C&SF Project (Lodge, 2005). Preliminary assessments in the late 1940s identified the peat soils just south of the southern rim of Lake Okeechobee as ideal for agriculture (Jones, 1948). Between 1950 and 1973, the USACE constructed a major dike on the east side of the agricultural area, established water delivery and drainage canals, and added pumps and control gates to manage water for agriculture. They also created the water conservation areas (WCAs) as temporary holding ponds that could accept surplus water during wet periods and provide additional water for agriculture during dry periods. Lake Okeechobee could also be managed to supply water in dry periods and accept excess water in wet periods. All of the EAA was designed for agricultural production, except for two fairly small wildlife management areas (WMAs): Rotenberger WMA and Holey Land WMA (Lodge, 2005). When the EAA was complete in the early 1970s, it subsumed 27 percent of the pre-drainage Everglades; for comparison, the WCAs occupy 37 percent, and Everglades National Park covers about 20 percent (Lodge, 2005; Secretary of Interior, 1994). By the 1990s, the EAA agricultural landscape had evolved into its present general form: about 85 percent of its area is devoted to sugar production, and 4 percent or less each is used for sod, vegetables, pasture, and non-specific general agriculture cultivation.a The peat soils (Histosols) of the EAA accumulated under marshy conditions, but drainage by the C&SF Project caused the soils to shrink, while oxidation further reduced their volume. These processes continue today, and the surface of the EAA subsides about 1 inch (2.5 cm) per year. Peak agricultural production in the EAA probably occurred in the 1980s, before subsidence of the soils began to take its toll on productivity (Snyder and Davidson, 1994). Sugar, the most important crop in the EAA, requires soil depths that are at least 3 feet (Jurenas, 1992). Preliminary soil surveys in the EAA showed that most of the soils were at least 5 feet deep in 1912, but by 2003 most soil depths had declined to depths less than 3 feet. In some cases, sugar cane was being grown on soils as thin as 1 foot, an unsustainable practice (Snyder, 2004). ahttp://www.florida-agriculture.com/agfacts.htm. tem, making it available for development (Lord, 1993). Urban and agricultural development has reduced the Everglades to about one-half its pre-drainage size (Davis and Ogden, 1994; Figure 1-1b) and has contaminated its waters with phosphorus, nitrogen, mercury, and pesticides. Associated drainage and flood-control structures, including the C&SF Project, have diverted large quantities of water to the coastal areas, thereby reducing the freshwater inflows and natural water storage that defined the ecosystem (see Box 2-2; Figure 2-1b). The profound hydrologic alterations were accompanied by many changes in the biotic communities in the ecosystem, including reductions and changes
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 BOX 2-2 Everglades Time Line: Significant Events in South Florida Ecosystem Management 1934 Everglades National Park is authorized. 1948 Congress authorized the Central and Southern Florida Flood Control Project to control the water flow in the Everglades. From 1949 to 1969, USACE and the Central and Southern Florida Flood Control District built and operated the project works. 1968 Biscayne National Park is established as a national monument; expanded to a national park in 1980. 1972 Florida Water Resources Act establishes fundamental water policy for Florida, attempting to meet human needs and sustain natural systems; puts in place a comprehensive strategic program to preserve and restore the Everglades Ecosystem. 1974 Big Cypress National Preserve is created. 1983 Florida Governor’s Save Our Everglades Program outlines a six-point plan for restoring and protecting the South Florida Ecosystem so that it functions more like it did in the early 1900s. 1987 Florida Surface Water Improvement and Management Act requires the five Florida water management districts to develop plans to clean up and preserve Florida lakes, bays, estuaries, and rivers. 1989 Modified Water Deliveries to Everglades National Park Project was authorized. 1990 Florida Preservation 2000 Act establishes a coordinated land acquisition program at $300 million per year for 10 years to protect the integrity of ecological systems and to provide multiple benefits, including the preservation of fish and wildlife habitat, recreation space, and water recharge areas. 1992 Federal and state parties enter into a consent decree on Everglades water quality issues in federal court. Under the agreement, all parties committed themselves to achieving both the water quality and quantity necessary to protect and restore the unique ecological characteristics of the Arthur R. Marshall Loxahatchee National Wildlife Refuge and Everglades National Park. Water Resources Development Act (WRDA) of 1992 authorizes the Kissimmee River Restoration Project and the C&SF Project Restudy, a comprehensive review study for restoring the hydrology of South Florida. 1994 Florida Everglades Forever Act enacted into state law the settlement provisions of federal-state water quality litigation and provided a financing mechanism for the state to advance water quality improvements in the Everglades by constructing over 44,000 acres of stormwater treatment areas (STAs) for water entering the Everglades Protection Area. The act also requires the South Florida Water Management District to ensure that best management practices (BMPs) are being used to reduce phosphorus in waters discharged into the STAs from the EAA and other areas. The rulemaking process by which the numeric total phosphorus criterion of 10 parts per billion (ppb) was proposed for the Everglades Protection Area also was established by this act.
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 1996 WRDA 1996 formally establishes the intergovernmental South Florida Ecosystem Restoration Task Force to coordinate the restoration effort among the state, federal, tribal, and local agencies. It authorizes the USACE to implement the critical restoration projects (see Box 2-3). Section 390 of the Farm Bill grants $200 million to conduct restoration activities in the South Florida Ecosystem. 1999 WRDA 1999 extends Critical Restoration Project authority until 2003; authorizes two pilot infrastructure projects proposed in the Comprehensive Everglades Restoration Plan (CERP). Florida Forever Act improves and continues the coordinated land acquisition program initiated by the Florida Preservation 2000 Act of 1990; commits $300 million per year for 10 years. 2000 WRDA 2000 authorized the CERP as a framework for modifying the Central and Southern Florida Project to increase future water supplies, with the appropriate timing and distribution, for environmental purposes so as to achieve a restored Everglades ecosystem, while at the same time meeting other water-related needs of the ecosystem. WRDA 2000 includes $1.4 billion in authorizations for 10 initial Everglades infrastructure projects, four pilot projects, and an adaptive management and monitoring program; also grants programmatic authority for projects with immediate and substantial restoration benefits at a total cost of $206 million; establishes a 50 percent federal cost share for implementation of the CERP and for operation and maintenance. Florida legislature passes the Lake Okeechobee Protection Act, a phased, comprehensive program designed to restore and protect the lake. 2003 Programmatic Regulations are issued which establish a procedural framework and set specific requirements that guide implementation of the CERP to ensure that the goals and purposes of the CERP are achieved. 2004 State of Florida unveils plan to expedite restoration of America’s Everglades (Acceler8). 2005 State of Florida announces the Lake Okeechobee Estuary Recovery Plan to help restore the ecological health of Lake Okeechobee and the St. Lucie and Caloosahatchee estuaries. 2007 The Florida state legislature authorized the Northern Everglades and Estuaries Protection Program which expanded the Lake Okeechobee Protection Act to strengthen protection for the Northern Everglades by restoring and preserving the Lake Okeechobee, Caloosahatchee, and St. Lucie watersheds, including the estuaries. WRDA 2007 authorizes three projects under the CERP: the Indian River Lagoon-South Project, Picayune Strand Restoration, and the Site 1 Impoundment Project. WRDA 2007 also increases funding limits for WRDA 1996 critical projects and for three WRDA 1999 authorized pilot projects. 2008 State of Florida announces that it will begin negotiations to acquire 187,000 acres of farmland in the EAA from U.S. Sugar Corporation for $1.75 billion for the purpose of restoration. SOURCES: SFERTF (2006); http://everglades.fiu.edu/reclaim/timeline/index.htm; http://www.washingtonpost.com/wp-dyn/content/article/2008/06/24/AR2008062401140.html.
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 in the composition, distribution, and abundance of the populations of wading birds. Today, the federal government has listed 67 plant and animal species in South Florida as threatened or endangered, with many more included on state lists. Some distinctive Everglades habitats, such as custard-apple forests and peripheral wet prairie, have disappeared altogether, while other habitats are severely reduced in area (Davis and Ogden, 1994; Marshall et al., 2004). Approximately 1 million acres are contaminated with mercury (McPherson and Halley, 1996). Phosphorus from agricultural runoff has impaired water quality in large portions of the Everglades and has been particularly problematic in Lake Okeechobee (Flaig and Reddy, 1995). The Caloosahatchee and St. Lucie estuaries, including parts of the Indian River Lagoon, have been greatly altered by high and extremely variable freshwater discharges that bring nutrients and contaminants (Doering, 1996; Doering and Chamberlain, 1999). At least as early as the 1920s, private citizens were calling attention to the degradation of the Florida Everglades (Blake, 1980). However, by the time Marjory Stoneman Douglas’s classic book The Everglades: River of Grass was published in 1947 (the same year that Everglades National Park was dedicated), the South Florida ecosystem had already been altered extensively. Prompted by concerns about deteriorating conditions in Everglades National Park and other parts of the South Florida ecosystem, the public, as well as the federal and state governments, directed increasing attention to the adverse ecological effects of the flood-control and irrigation projects beginning in the 1970s (Kiker et al., 2001; Perry, 2004). By the late 1980s it was clear that various minor corrective measures undertaken to remedy the situation were insufficient. As a result, a powerful political consensus developed among federal agencies, state agencies and commissions, Native American tribes, county governments, and conservation organizations that a large restoration effort was needed in the Everglades (Kiker et al., 2001). This recognition culminated in the CERP, which builds on other ongoing restoration activities of the state and federal governments to create one of the most ambitious and extensive restoration efforts in the nation’s history. Ecosystem Restoration Goals for the Everglades Several goals have been articulated for the restoration of the South Florida ecosystem, reflecting the various restoration programs. The South Florida Ecosystem Restoration Task Force (hereafter, simply the Task Force), an intergovernmental body established to facilitate coordination in the restoration effort, has three broad strategic goals: (1) “get the water right,” (2) “restore, preserve, and protect natural habitats and species,” and (3) “foster compatibility of the built
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 and natural systems” (SFERTF, 2000). These goals encompass, but are not limited to, the CERP. The Task Force works to coordinate and build consensus among the many non-CERP restoration initiatives that support these broad goals. The goal of the CERP, as stated in the Water Resources Development Act of 2000 (WRDA 2000), is “restoration, preservation, and protection of the South Florida Ecosystem while providing for other water-related needs of the region, including water supply and flood protection.” The Programmatic Regulations (33 CFR 385.3; see Box 2-2) that guide implementation of the CERP further clarify this goal by defining restoration as “the recovery and protection of the South Florida ecosystem so that it once again achieves and sustains the essential hydrological and biological characteristics that defined the undisturbed South Florida ecosystem.” These defining characteristics include a large-areal extent of interconnected wetlands, extremely low concentrations of nutrients in freshwater wetlands, sheet flow, healthy and productive estuaries, resilient plant communities, and an abundance of native wetland animals (DOI and USACE, 2005). Although development has permanently reduced the areal extent of the Everglades ecosystem, the CERP hopes to recover many of the Everglades’ original characteristics and natural ecosystem processes. At the same time, the CERP is charged to maintain current levels of flood protection (as of 2000) and provide for other water-related needs, including water supply, for a rapidly growing human population in South Florida (DOI and USACE, 2005). Although the CERP contributes to each of the Task Force’s three goals, it focuses primarily on restoring the hydrologic features of the undeveloped wetlands remaining in the South Florida ecosystem, on the assumption that improvements in ecological conditions will follow. Originally, “getting the water right” had four components—quality, quantity, timing, and distribution. However, the hydrologic properties of flow, encompassing the concepts of direction, velocity, and discharge, have been recognized as an important component of getting the water right that had previously been overlooked (NRC, 2003c; SCT, 2003). Numerous studies have supported the general approach to restoration of getting the water right (Davis and Ogden, 1994; NRC, 2005; SSG, 1993), although it is widely recognized that recovery of the native habitats and species in South Florida may require restoration efforts in addition to getting the water right, such as controlling exotic species and reversing the decline in the spatial extent and compartmentalization of the natural landscape (SFERTF, 2000; SSG, 1993). The goal of ecosystem restoration can seldom be the exact re-creation of some historical or preexisting state because physical conditions, driving forces, and boundary conditions usually have changed and are not fully recoverable. Rather, restoration is better viewed as the process of assisting the recovery of a degraded ecosystem to the point where it contains sufficient biotic and abiotic
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 resources to continue its functions without further assistance in the form of energy or other resources from humans (NRC, 1996; Society for Ecological Restoration International Science & Policy Working Group, 2004). In addition, in this report the committee sometimes uses the term ecosystem rehabilitation when the objective is to improve conditions in a part of the South Florida ecosystem to at least some minimally acceptable level to allow the restoration of the larger ecosystem to advance. This is particularly a focus in Chapter 5, “Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem.” Implicit in the understanding of ecosystem restoration is the recognition that natural systems are self-designing and dynamic and, therefore, it is not possible to know in advance exactly what can or will be achieved. Thus, ecosystem restoration is an enterprise with some scientific uncertainty in methods or outcomes that requires continual testing of assumptions and monitoring of progress. Additional challenges in defining and implementing restoration goals are discussed in the initial National Research Council (NRC) biennial review (NRC, 2007). What Natural System Restoration Requires Restoring the South Florida ecosystem to a desired ecological landscape requires reestablishment of the critical processes that sustained its historical functions. Although getting the water right is the oft-stated and immediate goal, the restoration will be recognized as successful if it restores the distinctive characteristics of the historical ecosystem to the remnant Everglades (DOI and USACE, 2005). Getting the water right is a means to an end, not the end in itself. The hydrologic and ecological characteristics of the historical Everglades serve as restoration goals for a functional (albeit reduced in size) Everglades ecosystem. The first Committee on Independent Scientific Review of Everglades Restoration Progress (CISRERP) review identified five critical components of Everglades restoration: Enough water storage capacity combined with operations that allow for appropriate volumes of water to support healthy estuaries and the return of sheet flow through the Everglades ecosystem while meeting other demands for water; Mechanisms for delivering and distributing the water to the natural system in a way that resembles historical flow patterns, affecting volume, depth, velocity, direction, distribution, and timing of flows; Barriers to eastward seepage of water so that higher water levels can be maintained in parts of the Everglades ecosystem without compromising the current levels of flood protection of developed areas as required by the CERP;
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 Methods for securing water quality conditions compatible with restoration goals for a natural system that was inherently extremely nutrient poor, particularly with respect to phosphorus; and Retention, improvement, and expansion of the full range of habitats by preventing further losses of critical wetland and estuarine habitats and by protecting lands that could usefully be part of the restored ecosystem. If these five critical components of restoration are achieved and the difficult problem of invasive species can be managed, then the basic physical, chemical, and biological processes that created the historical Everglades can once again work to create a functional mosaic of biotic communities that resemble what was distinctive about the historical Everglades. Even if the restored system does not exactly replicate the historical system, or reach all of the biological, chemical, and physical targets, the reestablishment of natural processes and dynamics should result in a viable and valuable Everglades ecosystem. The central principle of ecosystem management is to provide for the natural processes that historically shaped an ecosystem, because ecosystems are characterized by the processes that regulate them. If the conditions necessary for those processes to operate are met, recovery of species and communities is far more likely than if humans attempt to specify every constituent and element of the ecological system (NRC, 2007). Restoration Activities Several restoration programs, including the largest of the initiatives, the CERP, are now ongoing. The CERP often builds upon non-CERP activities (also called “foundation projects”), many of which are essential to the effectiveness of the CERP. The following section provides a brief overview of the CERP and some of the major non-CERP activities. Details of the progress in implementing the CERP projects are described in Chapter 3, and a few projects are discussed in more detail in Chapters 4–5. Comprehensive Everglades Restoration Plan WRDA 2000 authorized the CERP as the framework for modifying the C&SF Project. Considered a blueprint for the restoration of the South Florida ecosystem, the CERP is led by two organizations with considerable expertise managing the water resources of South Florida—the USACE, which built most of the canals and levees throughout the region, and the South Florida Water Management District (SFWMD), the state agency with primary responsibility
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 for operating and maintaining this complicated water collection and distribution system. The CERP conceptual plan (USACE and SFWMD, 1999; also called the Yellow Book) proposes major alterations to the C&SF Project in an effort to reverse decades of ecosystem decline. The Yellow Book includes roughly 50 major projects consisting of 68 project components to be constructed at a cost of approximately $10.9 billion (estimated in 2004 dollars; DOI and USACE, 2005; Figure 2-2). Major components of the restoration plan focus on restoring the quantity, quality, timing, and distribution of water for the natural system. These major CERP components include the following: Conventional surface-water storage reservoirs, which will be located north of Lake Okeechobee, in the St. Lucie and Caloosahatchee basins, in the EAA, and in Palm Beach, Broward, and Miami-Dade counties, will provide storage of approximately 1.5 million acre-feet. Aquifer storage and recovery is a highly engineered approach that proposes to use a large number of wells built around Lake Okeechobee, in Palm Beach County, and in the Caloosahatchee basin to store water approximately 1,000 feet below ground; the approach has not yet been tested at the scale proposed. In-ground reservoirs will store water in quarries created by rock mining. Stormwater treatment areas (STAs) are constructed wetlands that will treat agricultural and urban runoff water before it enters natural wetlands.1 Seepage management approaches will prevent unwanted loss of water from the natural system through levees and groundwater flow; the approaches include adding impermeable barriers to the levees, installing pumps near levees to redirect lost water back into the Everglades, and holding water levels higher in undeveloped areas between the Everglades and the developed lands to the east. 1 Although some STAs are included among CERP projects, the USACE has recently clarified its policy on federal cost sharing for water quality features. A memo from the Assistant Secretary of the Army (Civil Works) (USACE, 2007d) states: “Before there can be a Federal interest to cost share a WQ [water quality] improvement feature, the State must be in compliance with WQ standards for the current use of the water to be affected and the work proposed must be deemed essential to the Everglades restoration effort…This determination must be based on some finding other than the project is a part of CERP and generally will aid the restoration effort.” The memo goes on to state, “the Yellow Book specifically envisioned that the State would be responsible for meeting water quality standards.” Therefore, it appears that until the water flowing into the project features meets existing water quality requirements or unless a special exemption is granted for projects deemed “essential to Everglades restoration,” the state is responsible for 100 percent of the costs of CERP water quality project features.
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 FIGURE 2-2 Major project components of the CERP. SOURCE: Courtesy of Laura Mahoney, USACE.
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 FIGURE 2-14 Estimates of the mean and 95 percent confidence interval for snail kite population size in Florida between 1997 and 2007. SOURCE: USFWS (2007) based on data supplied by W. Kitchens, University of Florida. factors (e.g., the AMO) have also led to deeper levels of inundation during the wet season in WCA-3A over the past decade compared to that which occurred between the mid-1960s and the early 1990s.9 These deeper water depths are also having negative effects on snail populations and are changing wetland plant species composition to less-favorable communities for kites and snails (Darby et al. 2008; Karunaratne et al., 2006). Apple snail (Pomacea paludosa) abundance appears to have declined substantially within WCA-3A (Darby et al., 2005). Cape Sable Seaside Sparrow The Cape Sable seaside sparrow (Ammodramus maritimus mirabilis; hereafter, simply CSSS), which was listed as an endangered species in 1968, is a morphologically, genetically, and ecologically unique subspecies of seaside 9 For more information, see water depth data from 1966 to the present at http://www.fgcu.edu/bcw/wca3a/wca3a.htm (sites 62, 64, and 65).
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 FIGURE 2-15 Locations of Cape Sable seaside sparrow subpopulations. Cape Sable is the landmass on the lower left (southwest) edge of the Florida peninsula. SOURCE: Courtesy of Pimm et al. (2002) . sparrow that is restricted to the Everglades ecosystem (Kushlan et al., 1982; McDonald, 1988). The CSSS is now distributed in what has been termed 6 subpopulations within the marl prairies (Figure 2-15), although presently only two of these areas support populations with more than 100 individuals (Hallac et al., 2007; Pimm et al., 2002; Walters et al., 2000). Large declines in the proportion
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 of area occupied by CSSSs within its range have been demonstrated across all the subpopulations between 1981 and 1992 (Cassey et al., 2007). During the past 5 to 10 years, the total number of CSSSs appears to have remained relatively stable (Figure 2-16), numbering around 3,000 individuals, but the number of subpopulations has declined from 6 to 4. Most individuals are in 2 subpopulations (B and E) that support 80–90 percent of the remaining individuals (SEI, 2007). Subpopulations B and E appear to have remained stable in recent years, but other subpopulations have declined. Most notable has been the precipitous decline of subpopulation A on the northwest side of Shark River Slough, which was estimated to have supported several thousand individuals in 1992 (Walters et al., 2000), 128 birds in 2003, and only 64 sparrows in 2007 (D. Hallac, NPS, personal communication, 2008). This decline occurred despite the attempts to reduce water flows across the S-12 structures from November FIGURE 2-16 Estimated number of Cape Sable seaside sparrows by subpopulation. SOURCE: Based on data received from D. Hallac, NPS, personal communication (2008).
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 through April to increase nesting success of sparrows in subpopulation A. Several of the other subpopulations have also exhibited recent population declines, and subpopulations D and F had no birds detected in 2007 (Figure 2-16). Water management is integrally linked to the survival of the CSSS (Nott et al., 1998). Nests of these sparrows are susceptible to inundation if water levels rise quickly (Nott et al., 1998), and recent work suggests that nest predation may also be linked to water levels, as rates appear to increase under both high and low conditions (Baiser and Lockwood, 2006; Lockwood et al., 2006). Moreover, water level conditions that permit multiple brooding appear to be very important if CSSS populations are to increase (Walters et al., 2000). A change in habitat suitability as a result of shifts in hydrologic characteristics may have resulted in the drastic decline of subpopulations A and D (Pimm et al., 2002; SEI, 2007). Wood Storks and Other Wading Birds Although most wading birds are not listed under the Endangered Species Act, with the exception of the wood stork (Mycteria americana), they are considered important indicators of Everglades ecosystem functioning. The total number of wading birds using Everglades National Park and WCA-3A has increased over the past 5 years from about 330,000 to 500,000, although their distribution has changed. Four of seven species of wading birds (great egrets, great blue herons, wood storks, and white ibis) have shown an annual increase over the past 5 years, and a larger number of wood storks were identified in 2006 and 2007 than had been documented in the previous 40 years in the United States (Cook and Herring, 2007). However, large colonies of wading birds are now found in more northern areas, particularly northeastern WCA-3A, rather than in the southern Everglades where they historically occurred (Crozier and Cook, 2004). Only one species—the great white heron, which primarily resides in Florida Bay—has shown a decline (Alvarado and Bass, 2007). Restoration Delays Further Endanger Everglades Birds While wading birds responded favorably to environmental conditions in the Everglades over the past 5 years, endangered Everglades birds have not recovered. Recovering endangered species requires identifying and ameliorating the causes of population decline. Declines in endangered Everglades bird populations often are not gradual; instead, they occur after some catastrophic event (e.g., drought or flooding, hurricanes, fires). All populations are subject to these effects, but when populations decline to a few hundred or a few thousand individuals, their resiliency to recover from natural perturbations is greatly
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 reduced, further increasing their risk of extinction due to natural climate and environmental variations. A panel of independent experts (SEI, 2007) who reviewed the current situation of endangered birds in the Everglades recently concluded that the status quo of flow conditions and water schedules in the WCAs and Everglades National Park “is not an option if the goal is to restore the ecosystem and prevent the extinction of critically endangered species. Incomplete implementation of emergency measures and failure to complete more major plans in a timely way increases the risks to endangered species. Moreover it makes it more difficult and more expensive to recover them.” Ongoing delays in the Mod Waters project (see Chapter 4) not only have postponed improvements to the hydrologic conditions but has allowed ecological decline to continue. As discussed previously, recent water management strategies (i.e., the IOP) have not produced conditions that are conducive to restoring the sparrow and appear to be negatively impacting the kite (SEI, 2007). The recent Sustainable Ecosystems Institute’s (SEI’s) avian ecology panel (SEI, 2007) stated that “continuing degradation of the ecosystem has reached the point that there is immediate concern about both of these species (CSSS and Snail Kite) rather than just the former.” That same SEI panel also stated that completing Mod Waters is critical to maintaining healthy avian populations in the Everglades. Fortunately, none of the endangered bird species exists in such small numbers that they are in immediate danger of extinction. There is still time to rectify the situation through restoration activities, even if some populations are impacted as a necessary consequence of the early transitions of restoration. Nevertheless, positive ecosystem changes may take years or decades to occur once restoration activities are enacted. Further loss of numbers and habitat deterioration due to delays in completing Mod Waters reduces the opportunity for adaptive management, may preclude allowing some incidental take, and increases the chance that an extreme weather event (e.g., hurricane or drought) could imperil the existing populations. Lake Okeechobee Lake Okeechobee has been profoundly altered by the combination of diking and connection to the coastal estuaries (St. Lucie to the east and Caloosahatchee to the west). The changes have affected not only the amounts and flows of water but also water quality, especially the overload of phosphorus. As a result, the biotic communities in the lake and in the estuaries also have undergone significant changes (SFWMD and FDEP, 2005, 2008a) (see Chapter 5 for a more detailed discussion). For example, the goal for shoreline water clarity in Lake
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 Okeechobee (100 percent visibility to the lake bed from May through September) was met less than 10 percent of the time during the past 5 years (SFWMD and FDEP, 2008a). Submerged aquatic vegetation declined substantially, and other components of the vegetation experienced large changes (SFWMD and FDEP, 2008a). The zooplankton and fish also experienced changes in recent years, particularly in response to four hurricanes in 2004 and 2005. In general, piscivorous fishes declined, while omnivores and planktivores increased, with marked declines in the fish species of greatest recreational and commercial interest, particularly largemouth bass and various species of sunfish (Johnson et al., 2007). The changes in water quantity and quality in Lake Okeechobee have been accompanied by declines in most of the water bird populations, although the cause-effect mechanisms are not well understood for all the species (e.g., Beissinger and Snyder, 2002; Rodgers, 2007). Exotic and Invasive Species Invasive, nonindigenous (nonnative) species are a large and expanding threat to the South Florida ecosystem. There are at least 32 invasive nonindigenous plant species and over 150 nonindigenous animals found in the South Florida ecosystem. Although many invasive species are widespread and occupy large areas (e.g., Brazilian pepper [Schinus terebinthifolius]), some of the most damaging invasive plants have been brought under control through a combination of vigorous control efforts and introduction of biocontrol agents (Ferriter et al., 2008). The most striking success is for Melaleuca; only 7,000 acres are currently heavily infested—down from nearly 500,000 acres in 1993 (TAME Melaleuca, 2004)—although approximately 270,000 acres remain under maintenance control (Ferriter et al., 2008; Morgan and Allen, 2007). Despite effective control mechanisms for some invasive, nonindigenous plant species and $21 million per year spent on exotics control, both the number and the abundance of invasive species continue to increase (e.g., Figure 2-17). However, few quantitative data are available to adequately track changes in the number, abundance, and distribution of invasive species, especially invasive animals. None of the eight physiographic regions within the South Florida ecosystem is currently free of exotic species invasion, and three are predicted to decline in quality over the next 1–2 years due to the expansion of invasive nonindigenous plant species (Table 2-2; Ferriter et al., 2008). Recent proposals to develop biofuel plantations growing giant reed (Arundo donax), a known invasive species near the Everglades, have sparked concern that a new source of problematic species is developing in the region (Rosenthal, 2008). Even if Ever-
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 FIGURE 2-17 Number of Burmese pythons removed from the Greater Everglades region between 1979 and 2007. Increase largely reflects the result of reproduction, dispersal, and establishment in the park and on adjacent lands, with some increase in reporting effort. SOURCE: S. Snow, NPS, personal communication (2008). glades hydrology is effectively restored, the continuing introduction and spread of damaging species could threaten the restoration of ecological integrity. Current Trends and Regime Shifts The observed patterns of species and habitat decline and increasing threats from invasive nonindigenous species need to be understood within the context of regime shifts (also called alternate stable states). The ability of an ecosystem to resist change in its configuration, given a disturbance or change in environmental conditions, is referred to as ecological resilience (Gunderson, 2000; van Nes and Scheffer, 2004). However, given sufficient environmental changes, the ecosystem can undergo a relatively rapid transition to a new configuration of species and processes, which in turn remains stable over a wide range of environmental conditions (Beisner et al., 2003; Carpenter and Gunderson, 2001; Gunderson, 2000; Mayer and Rietkerk, 2004; Scheffer and Carpenter, 2003; Scheffer et al., 2001). Both model analysis and observational studies show that as the threshold condition for regime shift is approached, it may require only a small additional change to precipitate a large change in the system configuration, as it assumes
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 TABLE 2-2 Invasive Nonindigenous Plant Indicator Status for Components of the South Florida Ecosystem Florida Keys Southern Estuaries Greater Everglades Big Cypress Northern Estuaries West Northern Estuaries East Lake Okeechobee Kissimmee River 2006 Overall Status 2007 Overall Status 1-2 Year Prognosis Number of Plant Species Rated “Yellow-Red” Or “Red” 3 3 3 5 12 6 2 7 Number of Serious Animal Species 5 3 8 5 4 3 7 8 NOTE: A stoplight indicator system (see below) integrates these components of invasive species impact, considering: (1) number of exotic plant species present; (2) number, abundance, and frequency of new exotic species; (3) abundance of established invasive species in new locations; (4) location and density of invasive exotic plants; (5) rate of spread; and (6) effectiveness of control actions/programs, measured as reduction in spatial extent. Red (R)= Severe negative condition, or one is expected in near future. Red/Yellow (R | Y ) = Currently a negative condition but there are reasonable control efforts under way. However, without continued efforts this species may revert to a severe situation. Yellow/Red (Y | R) = Problem was previously localized or not too severe but appears to be progressing. Condition generally due to inaction. Without attention and resources, the situation may develop or become red. Yellow (Y ) = Situation is improving and either is stable or moving toward stabilizing, or the species is still very localized. Yellow/Green (Y | G) = Significant progress is being made and situation is moving toward good maintenance control and is expected to continue improving as long as resources are maintained. SOURCE: Ferriter et al. (2008).
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 an alternate state which is stabilized by a new set of feedback relationships (van de Koppel et al., 2004). Furthermore, there can be a pronounced hysteresis, in which reestablishment of the initial environmental conditions fails to move the system back to its original state due to the stabilizing feedbacks present in the alternate state (Beisner et al., 2003). The response of each ecosystem regime to environmental change is highly nonlinear (Mayer and Rietkerk, 2004) and can show time lags and unexpected, even surprising, patterns of change (Groffman et al., 2006). There are important implications of a system of multiple dynamic regimes for the Everglades restoration effort. Theory and observation suggest that even a small environmental change could create an alternate ecosystem configuration that could prove very difficult to reverse even if managers “get the water right,” and such changes could occur very rapidly. With the current system showing declines and losses of resilience in many components, together with increasing threats from invasive species—as described in this section—there is concern that further environmental changes could result in a degraded system that could be very difficult to restore. CONCLUSIONS AND RECOMMENDATIONS The Everglades ecosystem is one of the world’s greatest ecological treasures, but for more than a century it has been subject to widespread changes resulting from the installation of an extensive water control infrastructure. Culminating in the C&SF Project completed in the 1970s, canals, dikes, and gates to control flows have changed the geography of South Florida and have facilitated extensive agricultural and urban development. These changes have had profound ancillary effects on regional hydrology, vegetation, and wildlife populations, resulting in an extensive decline in the vitality of all components of the ecosystem, including not only the central “River of Grass” but also Lake Okeechobee and the coastal estuaries. The CERP, a joint effort led by the state and federal governments and authorized in 2000, seeks to reverse the general decline of the ecosystem in the midst of a changing human and environmental context. Population growth and associated development will make restoration more difficult. Increasing water demands from an expanding, more densely settled population in Florida could create competition with ecosystem restoration when supplies are limited. Agriculture and other undeveloped lands face an uncertain future in South Florida. The EAA in particular intervenes directly in the flow of water between Lake Okeechobee and Everglades National Park and influences the movement of water, sediment, and nutrients for the rest of the system. The use of “smart growth” principles that integrate the needs of environmental restoration
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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 with human demographic changes can lessen the negative impacts of population growth, if cities, counties, the state, and CERP planners are all involved. Human-induced climate change is likely to impact the effectiveness of CERP projects, and CERP planners should assess and factor into planning and implementation the most recent projections of the impacts of climate change in South Florida. Precipitation, evapotranspiration, and the intensity of rainfall events in South Florida are expected to change during the current century due to climate change. Impending climate change should not be an excuse for delay or inaction in the restoration, but instead provides further motivation to restore the resilience of the ecosystem. The CERP Guidance Memorandum on climate change recommends consideration of sea-level rise and changes in precipitation quantity, distribution, and evapotranspiration in all CERP planning, but new analysis of impacts based on higher sea-level rise assumptions are needed. Among those possible changes that should be assessed and factored into planning and implementation are: changes in the water budget, including increasing human demands for water; changes in the return frequency and intensity of hurricanes; the effects of climate change on the distribution of biota in the Everglades ecosystem; and impacts of projected sea-level rise on the hydro-geomorphology of the estuaries and the mangrove zone. Ongoing delay in South Florida ecosystem restoration has not only postponed improvements to the hydrologic condition but also has allowed ecological decline to continue. Recent water management strategies have not produced conditions that are conducive to restoring the Cape Sable seaside sparrow and appear to be negatively impacting the snail kite. Tree islands have undergone a multidecadal decline in both number and surface area—a trend that appears likely to continue until significant CERP and non-CERP restoration progress has been made. In the past decade, Lake Okeechobee has experienced continued water quality and habitat degradation. Meanwhile, the number and area of influence of invasive species are increasing and represent very real challenges to restoration efforts. In the face of these numerous challenges, Everglades restoration efforts are even more essential to improve the condition of the South Florida ecosystem and strengthen its resiliency as it faces additional stresses in the future. If ecological resilience is not restored, the possibility exists that environmental changes could precipitate rapid and deleterious state changes that might be very difficult or impossible to reverse. Unless near-term progress is achieved on major restoration initiatives, including CERP and non-CERP efforts, opportunities for restoration may close with further loss of species numbers and habitat deterioration, and the Everglades ecosystem may experience irreversible losses to its character and function.
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