Seventh Annual Long Island Natural History Conference





















Jamaica Bay Marshes as Archives of Past Vegetation, Sediment, and Pollution History in New York City

Dorothy M. Peteet, Ph.D.
NASA/Goddard Institute for Space Studies Senior Research Scientist and Adjunct Professor, Columbia University

Abstract: New York City is representative of many vulnerable coastal urban populations, infrastructure, and economies threatened by global sea level rise.  The steady loss of marshes in NYC’s Jamaica Bay is typical of many urban estuaries worldwide.  Essential to the restoration and preservation of these key wetlands is an understanding of their sedimentation. Here we present a reconstruction of the history of mineral and organic sediment fluxes in Jamaica Bay marshes over three centuries using a combination of density measurements and a detailed accretion model. Accretion rate is calculated using historical land use and pollution markers through a wide variety of sediment core analyses including geochemical, isotopic, and paleobotanical analyses. We find that since 1800 CE, urban development dramatically reduced the input of marsh-stabilizing mineral sediment. However, as mineral flux decreased, organic matter flux increased. While this organic accumulation increase allowed vertical accumulation to outpace sea level, reduced mineral content causes structural weakness and edge failure.  Marsh integrity now requires mineral sediment addition to both marshes and subsurface channels and borrow pits, a solution applicable to drowning estuaries worldwide. Integration of marsh mineral/organic accretion history with modeling provides parameters for marsh preservation at specific locales with sea level rise. 

Dr. Dorothy Peteet directs the Paleoecology Division of the New Core Lab at Lamont Doherty Earth Observatory of Columbia and in collaboration with LDEO geochemists and NASA/GISS climate modelers, is studying the Late Pleistocene archives of lakes and wetlands (peatlands, salt marshes, tidal freshwater marshes, bogs, fens). Past vegetational change documented using pollen and spores and macrofossils along with loss-on-ignition (LOI) and charcoal in conjunction with accelerator mass spectrometry (AMS) radiocarbon dating provides local and regional records of climate change and carbon sequestration.  Her research ranges from temperate eastern North America and Alaska to Siberia, and focuses recently on the Hudson River marshes.