Abstract from the 2002 AGU Spring Meeting.

The influence of 20th century water management practices and an historic 25cm sea-level rise on coastal ecosystems of northeastern Florida Bay were assessed through paleoenvironmental (floral and faunal) analysis of sediment cores. Short-lived radionuclides (Pb-210 and concentrations of anthropogenic lead) and radiocarbon dating were used to establish age-depth relationships for fifty sites in northeastern Florida Bay and the adjacent Everglades. Our results demonstrate that, prior to human alteration of water flow, active sediment accumulation in the bay was linked to variations in sea-level. In the Buttonwood Embankment fringing Florida Bay and adjacent wetlands, sea level fluctuations of up to 0.5 meters between 1,000 AD and 1800 AD influenced sedimentation and environments. Fresh-water supply from the Everglades during this time was sufficient to maintain an estuarine, hard-bottom ecosystem in the northeastern part of the bay. During the last 50 years, fresh-water diversion for urbanization and agricultural activities resulted in marine encroachement into the southernmost Everglades and changed the bay floor from a hard- to a soft-bottom carbonate mud ecosystem.

¹cholmes@usgs.gov, U.S. Geological Surevy, 600 Fourth Street South, St. Petersburg, FL 33701 United States

²dwillard@usgs.gov, U.S. Geological Survey, 12201 Sun Rise Valley Drive, Reston, Va 20192

³U.S. Geological Survey, 12201 Sun Rise Valley Drive, Reston, Va 20192

⁴mmarot@usgs.gov, U.S. Geological Surevy, 600 Fourth Street South, St. Petersburg, FL 33701 United States

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