Nutrient and Ecological Histories in Barnegat Bay, New Jersey: Research Project Summary
Date
2011-06
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Trenton, N.J. : New Jersey Department of Environmental Protection, Office of Science
Abstract
The primary objective of this project was to collect sediment cores from tidal regions of Barnegat Bay and determine the chronology of nutrient changes (i.e., nitrogen and phosphorus) and associated ecosystem level responses. Sediment nitrogen concentrations increased towards the surface in three of the 4 cores collected indicating an increase in nutrient loading from portions of the watershed. Sediment nitrogen accumulation rates increased twofold at the up-bay site starting in the mid-1950s. Algal diatoms indicate major shifts toward more eutrophic conditions starting in the 1940-1950s consistent with an increase in sediment nutrients and appear to indicate impacts from increasing population and land use in the northern part of Barnegat Bay, an area with urban and suburban land use. The southern site is situated in a rural or semi-rural area and was the least impacted. Wetlands in Barnegat Bay can sequester approximately 79 % of the nitrogen and 54 % of the phosphorus estimated to be entering the Bay from upland sources. This illustrates the important ecosystem services that marshes can perform and how important it is to maintain and enhance marshes within Barnegat Bay. Sedimentation rates on salt marshes are at, or just below, the rate of relative sea level rise in Barnegat Bay. These relatively low rates of accretion render the marsh vulnerable to inundation should the rate of sea level rise accelerate in the future. Overall, the irreversible shifts recorded by diatom species suggest that, despite the fact that the Barnegat Bay wetlands are protected by both federal and state laws, these sites remain impacted by anthropogenic disturbances and did not return to their natural, reference conditions. On the contrary, the most recent changes suggest an increase in habitat deterioration and pollution. Thus, the changes recorded in diatom species convey a strong message to identify and limit all sources of nutrients that contribute to the degradation of the estuary and its watershed.
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Keywords
New Jersey, New Jersey - Barnegat Bay