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Project Work Plan
Greater Everglades Science Program: Place-Based Studies
Project Work Plan FY 2003
A. GENERAL INFORMATION:
Project Title: Ecosystem History of the Southwest Coast-Shark River Slough Outflow Area
Other Investigator(s): Charles Holmes
Other Investigator(s): William Orem
Other Investigator(s): Gary Dwyer
Project Summary: One of the primary goals of the Central Everglades Restoration Plan (CERP) is to restore the natural flow of water through the terrestrial Everglades and into the coastal zones. Historically, Shark River Slough, which flows through the central portion of the Everglades southwestward, was the primary flow path through the Everglades Ecosystem. However, this flow has been dramatically reduced over the last century as construction of canals, water conservation areas and the Tamiami Trail either retained or diverted flow from Shark River Slough. The reduction in flow and changes in water quality through Shark River have had a profound effect on the freshwater marshes and the associated coastal ecosystems. Additionally, the flow reduction may have shifted the balance of fresh to salt-water inflow along coastal zones, resulting in an acceleration of the rate of inland migration of mangroves into the freshwater marshes. For successful restoration to occur, it is critical to understand how CERP and the natural patterns of freshwater flow, precipitation, and sea level rise will affect the future maintenance of the mangrove-freshwater marsh ecotone and the coastal environment. This project will provide 1) baseline data for restoration managers and hydrologic modelers on the amount and sources of freshwater influx into the southwest coastal zone and the quality of the water, 2) the relative position of the coastal marsh-mangrove ecotone at different periods in the past, and 3) data to test probabilities of system response to restoration changes.
Project Objectives and Strategy: The objectives of this project are to document impacts of changes in salinity, water quality, coastal plant and animal communities and other critical ecosystem parameters on a subdecadal-centennial scale in the southwest coastal region (from Whitewater Bay, north to the 10,000 Islands), and to correlate these changes with natural events and resource management practices. Emphasis will be placed on 1) determining the amount, timing and sources of freshwater influx (groundwater vs. runoff) into the coastal ecosystem prior to and since significant anthropogenic alteration of flow; and 2) determining whether the rate of mangrove and brackish marsh migration inland has increased since 20th century water diversion and what role sealevel rise might play in the migration.
First, the environmental preferences and distributions of modern fauna and flora are established through analyses of modern samples in south Florida estuaries and coastal systems. Much of these data have already been obtained through project work conducted in Florida Bay and the terrestrial Everglades starting in 1995. These modern data are used as proxies for interpreting the historical data from Pb-210 and C-14 dated sediment cores based on assemblage analysis. On the basis of USGS data obtained from cores in Florida Bay and Biscayne Bay, the temporal span of the cores should be at a minimum the last 150 years; this is in agreement with University of Miami data showing sedimentation rates in Whitewater Bay to be approximately 1cm/year. For the estuarine/coastal ecosystems, a multidisciplinary, multiproxy approach will be utilized on cores from a transect from Whitewater Bay north to 10,000 Islands. Biochemical analyses of shells and chemical analyses of sediments will be used to refine data on salinity and nutrient supply, and isotopic analyses of shells will determine sources of water influx into the system. Nutrient analyses will be conducted to determine historical patterns of nutrient influx. To examine the inland migration of the mangrove/coastal marsh ecotone, transects from the mouth of the Shark and Harney Rivers inland into Shark River slough will be taken. These cores will be evaluated for floral remains, nutrients, charcoal, and if present, faunal remains.
Potential Impacts and Major Products: The Comprehensive Everglades Restoration Plan (CERP) and the Critical Ecosystem Studies Initiative (CESI) have both identified the importance of understanding the natural patterns of freshwater flow through Shark River Slough and the changes incurred due to alterations in flow. This project directly addresses CESI Tasks CE3 and LP2 and CERP Tasks 3006-6, 3006-8, and 3050-11, developing a hydrodynamic model for the Gulf Coast estuaries and understanding the linkages between nearshore areas and inflow. This project will work closely with TIME (Tides and Inflows in the Mangroves of the Everglades), which is developing ground-water and surface water models for the region. Data from this project can be used as boundary conditions to test the TIME model. Output from this project will evaluate the potential impacts of restoration changes and will provide targets for restoration of historical flow through Shark River Slough. The Army Corps of Engineeers (ACOE), the South Florida Water Management District (SFWMD) and other agencies responsible for guiding CERP and CESI can use the information to develop performance measures and to establish mean-flow levels (the point beyond which no more water should be withdrawn from the slough). Ultimately restoration based on long-term historical data is more cost-effective and sustainable.
Data on individual cores and modern monitoring work will be made available online following completion of analysis at the Ecosystem History Project website http://sofia.usgs.gov/flaecohist/. Relevant data will be provided to TIME for boundary conditions in the hydrologic models. Open-file reports on each core and a synthesis article for a scientific journal will be compiled. A special publication highlighting the research would be prepared for a non-scientific audience, including the stakeholders and the public, and could be made available at Everglades NP. In addition, results will be reported at scientific meetings, and to client agencies.
Cooperators and Collaborators:
B. WORK PLAN
Task Summary and Objectives: The primary purpose of the project is to determine the changes in salinity, freshwater influx, and water quality and over time and to determine what are the driving factors controlling salinity in the area. The objectives of this task are to obtain cores from the coastal zone, to develop modern proxies, and to determine decadal to sub-decadal changes in salinity and freshwater influx over the last several centuries. Specifically, we will 1) review previous work in the area, and conduct reconnaissance in order to locate potential coring sites along several transects; 2) investigate the current faunal and floral distribution of the area to establish proxies for downcore interpretations; 3) collect cores; 4) determine the age of the cores collected; and 5) determine the general salinity history of the coastal zone. Standard geochronologic (Pb-210 and where appropriate C-14) and paleoecologic methods (faunal assemblage analyses) will be used. Core location and collection will be coordinated with task 2, in order to obtain transects that cover the spectrum from upriver freshwater sites out to the marine coastal sites and a transect paralleling the coast from Whitewater Bay north to the 10,000 Island area. The first step is to obtain cores with good chronologies (i.e. the core has not been disrupted) and well-preserved faunal remains for analyses. If the core meets these criteria, then additional work can proceed. Review of earlier work in the area (Wanless, et al.) indicates obtaining good cores will not be a problem. The chronologic data will be used to interpret all additional analyses. Paleoecologic faunal assemblage analyses will be used to provide data on the general trends within the core in terms of salinity changes in water quality, nutrient supply, and the presence of subaquatic vegetation.
Work to be undertaken during the proposal year and a description of the methods and procedures: Work at the beginning of FY03 will focus on information gathering, reconnaissance, and developing modern proxies for the southwest coastal area. University of Miami Professor Hal Wanless and his students (C. Zarikian, T. Hood, P. Blackwelder, B. Bischof, S. Gelsanliter) have conducted a number of investigations in the area; we will review and evaluate their work as part of developing our own coring plan. In addition, we will gather information on outflow and salinity history from the water monitoring stations located throughout the area (SERC, J. Boyer). The information gathered will be compiled and reviewed to layout coring transects for the life of the project and in consultation with our client agencies (SFWMD, ACOE, ENP) we will determine the initial areas of concentration for coring in FY03 and FY04.
Fieldwork will be conducted to do reconnaissance of potential core sites, and modern benthic surveys and collections. Prior work in Florida Bay has established numerous proxy organisms among the molluscs, forams and ostracodes (data available at http://sofia.usgs.gov/flaecohist/) but the environment of the southwest coast is very different. We will need to refine, modify, and potentially establish new proxies for the southwest coastal area. Modern proxy data is critical, because it allows us to accurately interpret the downcore faunal assemblages. When the above steps are completed, we will begin to collect cores in the area, hopefully by the end of FY03.
Once the cores are collected they will be described, x-rayed, and cut into 2-cm intervals for processing. Samples will be processed using standard methods and all fractions will be retained for analyses. A portion of the less than 63-micron fraction will be used for Pb-210 geochronology. The greater than 63-micron fraction will be sorted for faunal analyses; ostracodes, molluscs and benthic forams will be picked, sorted and identified. Percent abundance will be calculated for the faunal data, and these data will be compared to the modern proxy data. The down-core faunal assemblages and the presence or absence of key indicator species will allow interpretation of trends in salinity, water quality and the presence of SAV at the site.
After the initial geochronologic and paleoecologic analyses are complete on each core, project scientists will determine if the core will be subjected to further analyses. If a core has a good chronology, and the faunal record shows evidence of distinctive changes, further analyses will be conducted (Task 3 and 4). A core with out a good geochronologic record will be discarded.
Planned Outreach: Data from cores will be compiled, analyzed, and presented as a poster or talk at the Florida Bay Science Conference and GEER. Additionally all data on individual cores and modern ecology will be made available online following completion of analysis at the Ecosystem History Project website http://sofia.usgs.gov/flaecohist/. An OFR will be produced on the core analyses and distributed to the clients and cooperators.
Task Status (proposed or active): Proposed
Task Summary and Objectives: During the 20th century, water management strategies resulted in reduced sheet flow across the Everglades, shifting the balance of fresh- to salt-water inflow along coastal zones. Although inland migration of the coastal marsh-mangrove ecotone was occurring before 20th century alterations to Everglades hydrology, it is possible that the rate of migration has accelerated since then due to reduced fresh-water flow. This task is designed to test three hypotheses: 1) natural, climatic processes, including sea-level rise, caused inland migration of the ecotone prior to the 20th century; 2) decrease in fresh-water flow from the Everglades due to water-management practices accelerated the transformation of freshwater wetlands to brackish/marine marshes and ultimately to mangrove forests; 3) restoration of predrainage water flow through the Everglades should stabilize regression of the ecotone to natural rates.
Work to be undertaken during the proposal year and a description of the methods and procedures: We will reconstruct the position of the coastal marsh-mangrove ecotone at selected time slices during the last few centuries, with the greatest detail provided for the last century. Reconstructions will be based on analysis of pollen, seeds, charcoal, and microfaunal assemblages from sediment cores collected in a transect along Shark River from fresh water marshes to mangroves at the river mouth. (Location of transects will be coordinated with Task 1.) These sites correspond to existing vegetation and SET sites SH1-5 and some water monitoring sites that are part of the Tides and Inflows in the Mangrove Ecotone (TIME) project. Cores also will be collected at Big Sable Creek. Cores will be described sedimentologically before paleoecological analyses.
Based on previous radiometric dating of peat cores from the Everglades (Willard et al, 2001a, b, in press), sampling intervals of 1 - 2 cm should provide adequate temporal resolution to identify vegetational and environmental changes on sub-decadal scales for the 20th century. Geochronology will be established using a combination of cesium-137 and lead-210, which provides good age control over the last 100 years, and radiocarbon dating, which provides age control over centennial to millennial time scales.
The natural variability of the system will be established through analysis of pre-drainage sediments. Globally documented climatic events may have elevated temperature as much as climate models predict for the 21st century, and an understanding of the past response of the system to such perturbations will provide important information to policymakers in designing restoration plans that incorporate expected climate variability.
Data on the timing and extent of salinity changes at the freshwater wetland-mangrove marsh ecotone will be used for calibration and verification of the TIME Project hydrodynamic and transport model being developed for the entirety of Everglades National Park. Historical salinity predictions will enable scientists conducting the TIME model development to compare the results of numerical simulations of salinity fluxes to past evidence of changes and thereby adjust critical process parameters in order to increase the accuracy of model predictions. Accurate predictions of the effects of upland water-management decisions on coastal salinities and estuarine habitat are needed to ensure the success of CERP.
Planned Outreach: Data from cores will be compiled, analyzed, and presented posters or talks at scientific meetings and meetings with clients. Results of this task will be compiled with results from other tasks for a journal article and a general interest publication.
Task Summary and Objectives: Determine salinity history of the southwest coastal zone for the period prior to and following the CS&F projects using salinity proxies from sediment cores collected in transects from the coastal marsh ecotone out into the marine environment and from Whitewater Bay north to the 10,000 Islands (task 1). Relate salinity variability to changes in fresh water flow due to land-use changes and natural variability in rainfall, freshwater runoff and water temperature (evaporation) and determine the extent to which water diversion disrupted natural patterns of salinity. Task will build on previous work in Florida Bay and ongoing work in Biscayne Bay using ostracode, foram, and mollusc shell chemistry to reconstruct salinities and water sources. Oxygen isotope ratios in foraminifers, and possibly molluscs, will be used as proxies for past salinity and/or temperature changes. Carbon isotope ratios will be used to reconstruct sources of the water. The sediment core records of paleosalinity and paleotemperature will be compared and "spliced" together with instrumental records of rainfall, salinity and temperature obtained from water monitoring. The reconstructed record of physical and biological conditions of the southwest coast will be compared to the history of water quality obtained by W. Orem (task 4). Data from task 3 will be compiled with data from task 1, and eventually will be compared to records from Florida and Biscayne Bays to examine regional trends for south Florida.
Work to be undertaken during the proposal year and a description of the methods and procedures: Work for FY03 will be focused on collection of modern proxy data (related to task 1) to determine current water and shell chemistry data. Water samples and live ostracodes, molluscs, and forams will be collected during fieldwork in task 1 for the following purposes: (1) to calibrate the oxygen isotopic composition of foraminiferal shells to water isotope ratios and salinity for application to sediment core forams; (2) to determine the local radiocarbon "correction" for the southwest coastal zone. These modern calibration sites will be located along one or more salinity transects and will correspond to the modern ecology sites established in Task 1 for the benthic faunal surveys. If any living large shelled clams (eg. Mercenaria) or oysters are collected during fieldwork, these will be analyzed for trace elements and stable isotopes. Some of these animals may live for over a decade, so they would provide a record of recent changes that can be calibrated to water chemistry data recorded by water monitoring stations in the area. Successful reproduction of the modern salinity record in the shell record would provide levels of confidence for interpretation of the same species downcore. These species if present in the cores will provide a potentially continuous record of seasonal salinity changes during their lifetime. The molluscan chemistry work will build on work done in Florida Bay (Wingard, Wardlaw, et al.) and in the Naples area (D. Surge, U. Mich.).
Primary work for this task will not begin until initial cores have been collected, processed, and an age model developed (task 1), which will be late FY03 or the beginning of FY04. Proxy methods include 1) oxygen isotope analyses of benthic foraminifera, 2) trace elemental (magnesium/calcium ratios) of ostracodes, 3) morphological indicators of temperature (shell size), 4) analyses of trace elements and isotopic ratios in molluscan shell layers; and 5) relative proportions of species of forams, ostracodes and molluscs indicative of specific salinity ranges (i.e. oligohaline, mesohaline, etc.)(related to task 1 assemblage analyses). The stable isotopic and trace elemental analyses will be carried out with cooperators using mass spectrometry and direct current plasma emission spectrometry at University of Miami and Duke University, respectively. The use of paired analyses of stable isotopes of forams and Mg/Ca ratios in ostracodes should allow the quantification of changes in salinity and temperature and the impact of these changes could then be assessed from the faunal analyses of benthos from the same samples. Selected intervals identified as representing extreme salinity conditions will be studied for seasonal salinity variability using molluscan shell chemistry (related to Paleosalinity as a Key for Success Criteria in South Florida Restoration Project; Wingard, Wardlaw and others).
Planned Outreach: In addition to reports listed in Task 1, the following will be done: presentations to Everglades National Park personnel and South Florida Water Management District, work with TIME Project (Tides and Inflows in the Mangroves of the Everglades, R. Schaffranek) providing data on historical salinities for their models.
Task Status (proposed or active): Proposed
Task Summary and Objectives: Nutrients from agricultural and urban runoff are causing eutrophication and microalgal blooms in many of the estuaries in south Florida. High nutrients have been reported for the southwest coastal zone, but the source of phosphate is unknown. Debates about phosphorous limitation in eastern Florida Bay and nitrogen limitation in western Florida Bay are ongoing. The influence of Shark River slough waters on the southwest coast, and western Florida Bay, however, is not fully understood. It is important to examine both the current influx of nutrients and the historical patterns of nutrient influx into the southwest coastal zone. The effects of this excess nutrient input on biotic assemblages in this region may be substantial. Eutrophication and microalgal blooms may be responsible for seagrass dieoff in Florida Bay, which occurred primarily in western and west-central Florida Bay. Linking eutrophication to these changes in the biotic community, however, is a difficult problem.
Our major objectives are to determine the historical record of eutrophication of the southwest coastal zone and to evaluate the linkage between eutrophication and changes in the biotic community. The approach we will take in this task is to examine the historical record of nutrients from dated sediment cores. Results will also be compared to water flow records to determine if known changes in the water control system of south Florida may correspond to distinct nutrient changes within the cores. Historical changes in sulfur content of the cores will also provide information on historical changes in salinity related to construction of canals within the Everglades. We will also examine organic geochemical markers of seagrass and microbial communities in the cores to determine historical changes in these biota. Work on this project will build on results from the Integrated Biogeochemical Studies in the Everglades (Orem and Krabbenhoff). The results from this task will be compiled with faunal and floral data from tasks 1 and 3. Comparing the timing of changes in nutrient input to that of changes in the biological community will allow a determination of whether eutrophication of the coastal zone and changes in biota are directly linked.
Work to be undertaken during the proposal year and a description of the methods and procedures: Work in FY03 will be limited to research, reconnaissance, and participation in planning coring transects. Work will begin in full in FY04, after cores have been collected and a good chronologic age model developed.
Planned Outreach: Data and results will be presented at workshops, public forums, and meetings in south Florida, and ultimately will be compiled with data from other tasks to produce a journal article and general interest publications aimed at the resource managers.