Meeting Abstract

P3-1   -   Combined effects of nutrient enrichment and sea level rise on salt marsh vegetation Robles, KD*; Chenoweth, K; Lloret, J; Valiela, I; Brown University, Providence, RI, USA; The Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA, USA; The Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA, USA; The Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA, USA karen_robles@brown.edu

Salt marshes serve a variety of important functions. Marshes filter pollutants before they reach the sea, sequester carbon, serve as a storm buffer, and prevent coastal erosion, among other services. Great Sippewisset Marsh is a local salt marsh in Cape Cod, MA that has been utilized as a study site for scientists at the Marine Biological Laboratory for more than fifty years. In an ongoing experiment that started in the 1970s, circular plots (10m-radius) have been fertilized with nitrogen and phosphorus every year to assess plant community response to nutrient enrichment. Nutrient enrichment is a common problem along coastal communities because sewage, wastewater treatment, and agricultural runoff often feed into salt marshes, altering their landscape. Sea level rise has also impacted the area, altering the structure of the plant community due to different species tolerance to salinity and submergence. Vegetation distribution and abundance within the experimental plots has been continuously recorded every year by field surveys, aerial images, and ground truth measurements. In this work we utilized GIS to digitize available maps of the experimental plots to analyze changes in vegetation over time (1976-2020). We compared differences in vegetation assemblages between control plots and plots fertilized with nitrogen (urea) and phosphorus. Our results show that fertilization has caused profound changes to the plant community composition. We have also observed that, over the past few decades, the plant community, in both fertilized and control plots, has shifted towards species with higher tolerance to salinity and increased submergence, in response to the rise in sea level.