ENVIRONMENTAL EVALUATION OF MID-ATLANTIC COASTAL WETLANDS FROM PAIRED GEOCHEMICAL AND DIATOM ANALYSIS OF SEDIMENTS

Industrial and urban pollutants have been changing the ecosystems on which many organisms depend. This study focuses on the 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 silica shell that gets preserved and accumulates in bottom sediments, they are one of the most valuable tools to infer past environmental conditions from core sediments in both lacustrine and coastal environments. However, whilst some work has been done to develop diatom transfer functions in mid-Atlantic estuaries and marshes—namely, relating diatom species to ecological conditions—we still lack a robust understanding of how the abundances of the different species vary within the ecosystems. What’s more, there are still uncertainties in the transfer functions themselves, which calls for additional geochemical tracers to help constrain these relationships. Therefore, to help reduce these uncertainties we have analyzed the diatom assemblages from seven spatially distributed locations in New Jersey coastal wetlands which extend from Raritan Bay to the north, to Cape May to the south. To better assess the link between diatoms and ecological conditions, we also examined total phosphorus, nitrogen, and carbon, along with mineral grain size in the various locales across the NJ shoreline. 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 over the past few centuries. Such data are 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.