HR: 0800h
AN: PP31A-0171    [Abstracts]
TI: 300 Years of Run-off Changes in Subtropical Florida Forced by Solar Irradiance, Hurricanes, and Human Impact
AU: Gorissen, M
EM: p.m.gorissen@students.uu.nl
AF: Palaeoecology, Institute of Environmental Biology, Utrecht University, Laboratory of Palaeobotany and Palynology Budapestlaan 4, Utrecht, 3584 CD, Netherlands
AU: * Donders, T H
EM: t.h.donders@uu.nl
AF: Palaeoecology, Institute of Environmental Biology, Utrecht University, Laboratory of Palaeobotany and Palynology Budapestlaan 4, Utrecht, 3584 CD, Netherlands
AU: Sangiorgi, F
EM: f.sangiorgi@uu.nl
AF: Palaeoecology, Institute of Environmental Biology, Utrecht University, Laboratory of Palaeobotany and Palynology Budapestlaan 4, Utrecht, 3584 CD, Netherlands
AU: Wagner, F
EM: f.wagner@uu.nl
AF: Palaeoecology, Institute of Environmental Biology, Utrecht University, Laboratory of Palaeobotany and Palynology Budapestlaan 4, Utrecht, 3584 CD, Netherlands
AB: The coastal wetland ecosystems in Florida are highly sensitive to changes in fresh water run-off, and have experienced significant impacts from recent land use and sea level changes. In addition, the fresh water flow is likely influenced by variations in precipitation, which in Florida is partly related to El Nino-Southern Oscillation (ENSO) variability and tropical storm activity. We present a 300- year record of past changes in the hydrological cycle from a subtropical estuary (Rookery Bay) on the western shelf of Florida, Gulf of Mexico. Palynological and sedimentological analyses of a shallow sediment core reveal significant past changes in run-off and wetland development. Radiocarbon dating and first occurrences of exotic plant species provide a core chronology; age at 60 cm depth is approximately AD 1690. The onset and development of human impact in Florida is evident from high influx rates of Ambrosia pollen, which are indicative of land clearance, and reduced abundance of wetland taxa since AD 1900. Sedimentological analysis reveals several phases of high siliciclastic input, which are interpreted as phases with increased run-off, and are confirmed by higher wetland pollen abundance. High run-off phases consistently correlate to multi- decadal maxima in solar activity. Maximal run-off rates after AD 1900 also relate to increased land clearance and drainage, and correspondingly higher impact from hurricane landfalls in SW Florida. The record can help to reconcile different views on the impact of solar irradiance changes in subtropical Florida, as primarily responding to tropical pacific (ENSO) changes or North Atlantic forcing during the Little Ice Age period. In addition, information on pre-impact state of the coastal ecosystems will help wetland restoration efforts.
DE: 1632 Land cover change
DE: 1635 Oceans (1616, 3305, 4215, 4513)
DE: 1650 Solar variability (7537)
DE: 1834 Human impacts
DE: 4922 El Nino (4522)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting