Health and Resiliency of Salt Marshes in Jamaica Bay
J. Kirk Cochran, Stony Brook University; Qingzhi Zhu, Stony Brook University
Salt marshes serve important ecosystem roles as habitat, nurseries for marine organisms, filters for contaminant inputs to coastal waters and buffers against the impact of storms on the coastal environment. However, salt marsh loss is a worldwide phenomenon and this is especially evident in Jamaica Bay, with losses in acreage of ~63% between 1951 and 2003. Marsh loss may be due to numerous factors. Stresses on Jamaica Bay marshes include rising sea levels, changing configuration of the bay through activities such as dredging of the Bay bottom, and eutrophication of the Bay system. This research focuses on several aspects of marsh loss and the constraints on resiliency. The approach is to collect marsh peat cores from selected marshes for analysis. By characterizing the sediment distribution and geochemistry of these cores, this project will help to advance our understanding of the ability of salt marshes to cope with enhanced rates of sea level rise and continued loadings of nutrients and resultant organic matter production in the Bay.
Sea level rise is a key constraint on salt marsh resiliency. Under some conditions, a marsh may keep up with sea level rise by accreting sediment and therefore maintaining growth. In other cases, a loss of sediment associated with sea level rise may degrade the base of a salt marsh. Improving our understanding of accretion rates in Jamaica Bay’s marshes is critical to evaluating and managing their current and long-term health, particularly in the context of accelerated rates of sea level change associated with climate change. This project will collect samples of marsh peat to determine rates of accretion over time in select salt marshes. Marsh accretion chronologies will be determined based on 210Pb (and 137Cs) distributions in cores of marsh peat.
This project will also better test the investigators’ hypothesis that excessive nutrient loading and resultant organic matter production contribute to plant die-off and to the risk of marsh collapse. This is a particular threat in Jamaica Bay, where nutrient loading associated with releases from Combined Sewerage Overflows (CSOs) heightens production of labile organic matter in the estuary, which is deposited on salt marshes via tides. The decomposition of organic matter creates hydrogen sulfide, which acts as a toxin to marsh plants such as Spartina alterniflora. This project will characterize the build up of phytotoxins in marsh pore water. Pore water geochemistry will be characterized via discrete sampling (sippers) and chemical sensors. The project will also characterize drainage via determination of pore water “residence times” using naturally occurring radium isotopes (223,224Ra).
Funding: Department of Interior, National Park Service
Project Period: November 2014 – October 2016
