Tidal Marsh Record of Nutrient Loadings in Barnegat Bay, New Jersey

Abstract

Velinsky, D.J.; Paudel, B.; Belton, T.J., and Sommerfield, C.K., 2017. Tidal marsh record of nutrient loadings in Barnegat Bay, New Jersey. In: Buchanan, G.A.; Belton, T.J., and Paudel, B. (eds.), A Comprehensive Assessment of Barnegat Bay-Little Egg Harbor, New Jersey.Sediment and nutrient burial in tidal marshes of Barnegat Bay was investigated using age-dated sediment cores collected along a north-to-south transect. Measurements of radionuclides (210Pb and 137Cs) and stable isotopes (13C and 15N) were accompanied by nutrient and organic matter concentrations. Sediment accumulation rates, measured using 210Pb and 137Cs chronology, ranged from 48 to 81 mg cm2 y−1, whereas corresponding accretion rates ranged from 0.16 to 0.30 cm y−1. Sediment nitrogen (N) accumulation rates increased twofold at an upper bay site, starting in the mid-1950s, whereas at other locations, only small to no increases were seen with time. Phosphorus (P) accumulation was minimal with time. N and P accumulation rates were higher between the 1940s to 1950s at stations BB-1 and BB-3, while higher accumulation rate in the down-bay (BB-4) was identified in the early 1990s. Results indicate that bay marshes can sequester approximately 79 ± 11% of N and 54 ± 34% of P entering the Bay from upland sources; thus, these marshes perform an important ecosystem service in the form of nutrient sequestration. Marsh accretion rates at the coring sites fall at, to just below, rates of relative sea-level rise recorded by nearby tide gauges. These relatively low rates of accretion render the marsh vulnerable to inundation should the rate of sea-level rise accelerate in the future.