HR: 0800h
AN: H51A-1106    [Abstracts]
TI: Deciphering the Role of Climate and Sea-Level Changes on Observed Decadal-Scale Variability in Salt-Marsh Sedimentation.
AU: * Kolker, A S
EM: akolker@ic.sunysb.edu
AF: Marine Sciences Research Center, Stony Brook University, Stony Brook, NY 11794-5000 United States
AU: Goodbred, S L
EM: sgoodbred@notes.cc.sunysb.edu
AF: Marine Sciences Research Center, Stony Brook University, Stony Brook, NY 11794-5000 United States
AU: Cochran, J K
EM: kcochran@notes.cc.sunysb.edu
AF: Marine Sciences Research Center, Stony Brook University, Stony Brook, NY 11794-5000 United States
AU: Beck, A
EM: beck@msrc.sunysb.edu
AF: Marine Sciences Research Center, Stony Brook University, Stony Brook, NY 11794-5000 United States
AU: Kroboth, T
AF: Marine Sciences Research Center, Stony Brook University, Stony Brook, NY 11794-5000 United States
AB: We are investigating the controls that climate and local oceanography exert on sedimentation patterns in 4 salt marsh-estuary complexes around Long Island, New York, USA. These systems encompass a variety of physical settings, including a range of tidal conditions, wave fetches, and human influences, but are all located within one climatic regime. Within these settings, we hypothesize that sedimentation patterns in limited-fetch, mesotidal salt marshes are influenced most strongly by sea-level changes, as the system is largely steady-state under high-energy conditions and sedimentation should track the longer-term sea-level transgression. Conversely, sedimentation in microtidal systems with large fetch should better track atmospheric forcings, because marsh-surface accretion largely occurs during episodic wind and storm events. To test this hypothesis, accretion rates (cm/yr) were determined by applying a constant-flux model to profiles of excess 210Pb, which reveals temporal variation in sedimentation. Additionally, we examined the rate of mineral sediment deposition (g/cm2/yr) and rate of organic matter accumulation (g/cm2/yr). These measures yielded a chronology of sedimentation patterns ~100 years long with a temporal resolution of 2-5 years, sufficient for resolving decadal-scale oscillations. Our proxies for sea-level change come from a variety of tide gauges; including the gauge at Battery Park, NYC which covers much of the past century, as well as local tide gauges with records spanning several decades. Proxies used for atmospheric forcings include mean annual winds for the past 50 years, storm histories and Hurrel's index of the North Atlantic Oscillation, which extends for over a century. Initial results reveal clear decadal-scale variability in marsh accretion, with variations ranging 2-3 fold about the long-term mean. These oscillations are very similar in timing and magnitude to those observed for the climate proxies and sea-level records. However, initial results reveal no significant correlation between local climate proxies and tide gauge records at the scale of this study. Therefore, we suspect that independent atmospheric and oceanic drivers of marsh sedimentation exist. The relative importance of these drivers in a particular embayment will likely depend on how characteristics such as the tidal regime, wave climate and human modifications, respond to changes in their physical forcings.
DE: 4860 Radioactivity and radioisotopes
DE: 4215 Climate and interannual variability (3309)
DE: 4556 Sea level variations
DE: 1833 Hydroclimatology
DE: 1851 Plant ecology
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting