, Volume 569, Issue 1, pp 237–257 | Cite as

Tracking rates of ecotone migration due to salt-water encroachment using fossil mollusks in coastal South Florida

  • Evelyn E. Gaiser
  • Angelikie Zafiris
  • Pablo L. Ruiz
  • Franco A. C. Tobias
  • Michael S. Ross


We determined the rate of migration of coastal vegetation zones in response to salt-water encroachment through paleoecological analysis of mollusks in 36 sediment cores taken along transects perpendicular to the coast in a 5.5 km2 band of coastal wetlands in southeast Florida. Five vegetation zones, separated by distinct ecotones, included freshwater swamp forest, freshwater marsh, and dwarf, transitional and fringing mangrove forest. Vegetation composition, soil depth and organic matter content, porewater salinity and the contemporary mollusk community were determined at 226 sites to establish the salinity preferences of the mollusk fauna. Calibration models allowed accurate inference of salinity and vegetation type from fossil mollusk assemblages in chronologically calibrated sediments. Most sediments were shallow (20–130 cm) permitting coarse-scale temporal inferences for three zones: an upper peat layer (zone 1) representing the last 30–70 years, a mixed peat-marl layer (zone 2) representing the previous ca. 150–250 years and a basal section (zone 3) of ranging from 310 to 2990 YBP. Modern peat accretion rates averaged 3.1 mm yr−1 while subsurface marl accreted more slowly at 0.8 mm yr−1. Salinity and vegetation type for zone 1 show a steep gradient with freshwater communities being confined west of a north–south drainage canal constructed in 1960. Inferences for zone 2 (pre-drainage) suggest that freshwater marshes and associated forest units covered 90% of the area, with mangrove forests only present along the peripheral coastline. During the entire pre-drainage history, salinity in the entire area was maintained below a mean of 2 ppt and only small pockets of mangroves were present; currently, salinity averages 13.2 ppt and mangroves occupy 95% of the wetland. Over 3 km2 of freshwater wetland vegetation type have been lost from this basin due to salt-water encroachment, estimated from the mollusk-inferred migration rate of freshwater vegetation of 3.1 m yr−1 for the last 70 years (compared to 0.14 m yr−1 for the pre-drainage period). This rapid rate of encroachment is driven by sea-level rise and freshwater diversion. Plans for rehydrating these basins with freshwater will require high-magnitude re-diversion to counteract locally high rates of sea-level rise.


mangroves sea-level rise salt-water encroachment paleoecology mollusks Everglades coastal wetlands 


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  1. Abbott, R. T. 1954American Seashells1Van Norstrand ReinholdNew York, NY541Google Scholar
  2. Appleby, P. G., Oldfield, F. 1978The calculation of lead-210 dates assuming a constant rate of supply of unsupported 210Pb to the sedimentCatena518CrossRefGoogle Scholar
  3. Binford, M. W. 1990Calculation and uncertainty analysis of 210Pb dates for PIRLA project lake sediment coresJournal of Paleolimnology3253267CrossRefGoogle Scholar
  4. Birks, H. J. B., Line, J. M., Juggins, S., Stevenson, A. C., Ter Braak, C. J. F. 1990Diatoms and pH reconstructionPhilosophical Transactions of the Royal Society of London B.327263278Google Scholar
  5. Boyer, J. N., Fourqurean, J. W., Jones, R. D. 1999Seasonal and long-term trends in water quality of Florida Bay (1989–97)Estuaries22417430CrossRefGoogle Scholar
  6. Brewster-Wingard, G. L., J.R. Stone & C.W. Holmes, 2001. Molluscan faunal distribution in Florida Bay, past and present: an integration of down-core and modern data. In Wardlaw, B. R. (ed.), Paleoecological Studies of South Florida. Bulletins of American Paleontology 361: 199–232.Google Scholar
  7. Childers, D. L., Day, J. W. 1990The dilution and loss of wetland function with conversion to open waterWetlands Ecology and Management119Google Scholar
  8. Church, J. A., Gregory, J. M., Huybrechts, P., Kuhn, M., Lambeck, K., Nhuan, M. T., Qin, D., Woodworth, P. L. 2001Changes in sea level. Chapter 11 of the Intergovernmental Panel on Climate Change Third Assessment Report, Science ReportCambridge University PressCambridge, UK638689Google Scholar
  9. Dufrene, M., Legendre, P. 1997Species assemblages and indicator species: the need for a flexible asymmetrical approachEcological Monographs67345366CrossRefGoogle Scholar
  10. Eakins, J. D., Morrison, R. T. 1978A new procedure for the determination of lead-210 in lake and marine sedimentsInternational Journal of Applied Radiation and Isotopes29531536CrossRefGoogle Scholar
  11. Egler, F. E. 1952Southeast saline Everglades vegetation, Florida, and its managementVegetatio Acta Geobotanica3213265CrossRefGoogle Scholar
  12. Ellison, J., Stoddart, D. R. 1991Mangrove ecosystem collapse during predicted sea-level rise: holocene analogues and implicationsJournal of Coastal Research7151165Google Scholar
  13. Ellison, J. C. 1993Mangrove retreat with rising sea-level, BermudaEstuarine, Coastal and Shelf Science377587CrossRefGoogle Scholar
  14. Feller, I. C. 1995Effects of nutrient enrichment on growth and herbivory of dwarf red mangrove (Rhizophora mangle)Ecological Monographs65477505CrossRefGoogle Scholar
  15. Gaiser, E. E., Wachnicka, A., Ruiz, P., Tobias, F., Ross, M. S. 2004Diatom indicators of ecosystem change in coastal wetlandsBortone, S. eds. Estuarine IndicatorsCRC PressBoca Raton, FL127144Google Scholar
  16. Intergovernmental Panel on Climate Change, 1998. The regional impacts of climate change: an assessment of vulnerability. Special Report of IPCC Working Group II. In Watson, R. T., M. C. Zinyowera & R. H. Moss (eds), Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, United Kingdom and New York, NY, 517 pp.Google Scholar
  17. Juggins, S. 2003C2 User guide: Software for Ecological and Palaeoecological Data Analysis and VisualizationUniversity of Newcastle, Newcastle upon TyneUKGoogle Scholar
  18. Leatherman, S. P., Zhang, K., Douglas, B. C. 2000Sea level rise shown to drive coastal erosionEos (Transactions American Geophysical Union)815557Google Scholar
  19. Maul, G. A., Martin, D. M. 1993Sea level rise at Key West, Florida, 1846–1992: America’s longest instrument record?Geophysical Research Letters2019551958Google Scholar
  20. McCune, B., Mefford, M. J. 1999Multivariate Analysis of Ecological Data. Version 4.17MJM SoftwareGleneden Beach, ORGoogle Scholar
  21. Meeder, J. F., P.W. Harlem, M. S. Ross, E. E. Gaiser & R. Jaffe, 2000. Southern Biscayne Bay Watershed Historic Creek Characterization. Final Report to the South Florida Water Management District.Google Scholar
  22. National Research Council1993Managing Wastewater in Coastal Urban AreasNational Academy PressWashington DCGoogle Scholar
  23. Nicholls, R. J., Hoozemans, F. M. J., Marchand, M. 1999Increasing flood risk and wetland losses due to sea-level rise: regional and global analysesGlobal Environmental Change9S69S87CrossRefGoogle Scholar
  24. Park, R. A., Trehan, M. S., Mausel, P. W., Howe, R. C. 1989Coastal wetlands in the twenty-first century: Profound alterations due to rising sea levelFisk, D. W. eds. Wetlands: Concerns and SuccessesProceedings of the American Water Resources AssociationTampa, FL, USA71800Google Scholar
  25. Parkinson, R. W., DeLaune, R. D., White, J. R. 1994Holocene sea-level rise and the fate of mangrove forests within the wider Caribbean regionJournal of Coastal Research1010771086Google Scholar
  26. Ross, M. S., O’Brien, J. J., Sternberg, L. da S. L. 1994Sea-level rise and the reduction in pine forests in the Florida KeysEcological Applications4144156CrossRefGoogle Scholar
  27. Ross, M. S., Meeder, J. F., Sah, J. P., Ruiz, P. L., Telesnicki, G. J. 2000The Southeast Saline Everglades revisited: a half-century of coastal vegetation changeJournal of Vegetation Science11101112CrossRefGoogle Scholar
  28. Ross, M. S., Gaiser, E. E., Meeder, J. F., Lewin, M. T. 2001Multi-taxon analysis of the “white zone”, a common ecotonal feature of South Florida coastal wetlandsPorter, J.Porter, K. eds. The Everglades, Florida Bay, and Coral Reefs of the Florida KeysCRC PressBoca Raton, FL205238Google Scholar
  29. Ross, M. S., J. F. Meeder, E. E. Gaiser, P. L. Ruiz, J. P. Sah, D. L. Reed, J. Walters, G. T. Telesnicki, A. Wachnicka, M. Jacobson, J. Alvord, M. Byrnes, C. Weekley, Z. D. Atlas, M. T. Lewin, B. Fry & Renshaw, 2003. The L-31E Surface Water Rediversion Pilot Project Final Report: Implementation, Results, and Recomendations. Report to South Florida Water Management District (SFWMD Contract C-12409).Google Scholar
  30. Teas, H. J., Wanless, H. R., Chardon, R. 1976Effects of man on the shore vegetation of Biscayne BayThorhaug, A.Volker, A. eds. Biscayne Bay: Past/Present/FutureMiamiFL133157University of Miami Sea Grant Special ReportGoogle Scholar
  31. Thompson, F. G. (2002). An Identification Manual for the Freshwater Snails of Florida. [Online]
  32. Wanless, H. R., Parkinson, R. W., Tedesco, L. P. 1994Sea level control on stability of Everglades WetlandsDavis, S. M.Ogden, J. C. eds. Everglades: The Ecosystem and Its RestorationSt. Lucie Press, St. LucieFL199222Google Scholar

Copyright information

© Springer 2006

Authors and Affiliations

  • Evelyn E. Gaiser
    • 1
    • 2
  • Angelikie Zafiris
    • 1
  • Pablo L. Ruiz
    • 2
  • Franco A. C. Tobias
    • 2
  • Michael S. Ross
    • 2
  1. 1.Department of Biological SciencesFlorida International UniversityMiamiUSA
  2. 2.Southeast Environmental Research CenterFlorida International UniversityMiamiUSA

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