A 4000-YEAR ENVIRONMENTAL EVALUATION OF MID-ATLANTIC COASTAL WETLANDS FROM PAIRED GEOCHEMICAL AND DIATOM ANALYSIS OF SURFICIAL AND DOWN-CORE SEDIMENTS

Industrial and urban pollutants have been changing the ecosystems on which many organisms depend. This study focuses on the long term effects modern anthropogenic activities have had on mid-Atlantic coastal wetlands. Pollution and other environmental factors that alter an ecological system are readily preserved in the water and sediments, along with the organisms that inhabit the wetland. For example, diatoms are microscopic siliceous algae widely used as indicators of environmental conditions in aquatic ecosystems. Because of their high ecological sensitivity and their potential for preservation in bottom sediments, they are a valuable tool to infer past environmental conditions in both lacustrine and coastal environments. Whilst some work has been done to develop diatom transfer functions in mid-Atlantic estuaries and marshes, we still lack a robust understanding of how the abundances of the different species vary within the ecosystems. Additionally, there are still uncertainties in the transfer functions themselves, which calls for additional geochemical tracers to help constrain these relationships. To help reduce these uncertainties analysis of diatom assemblages from seven spatially distributed locations in the New Jersey coastal area have been undertaken. Diatom assembledges have also been analyzed from two marine sediment cores from Tuckerton and Silver bay, located along the NJ coastline. To better assess the link between diatoms and ecological conditions, geochemical properties of Phosphorous, Carbon, Hydrogen, and Nitrogen composition as well as sediment grain size and percent organics were taken from the sediments. Each core was also carbon dated at multiple transects to create an age model of geochemical parameters and diatom assemblages going back as far as four thousand years. The results from this study will not only improve the diatom transfer functions, but also allow us to trace the diatom composition over time and identify reference assemblages that existed in the bay area over the past few centuries. Such data is not only important for understanding how the structure and function of biological communities is changing as a result of human impacts, but are also useful for establishing biological indicators of ecosystem health.