Date of Completion


Embargo Period



Penny Vlahos, Michael Whitney, Robert Mason

Field of Study



Master of Science

Open Access

Open Access


Long Island Sound (LIS) is an urbanized estuary that undergoes seasonal hypoxia in its western and central regions. Approximately 90% of the water exchange between LIS and the adjacent continental shelf, the Middle Atlantic Bight (MAB), occurs at the eastern LIS (ELIS) boundary. The contribution (import/export) of carbon (C), nitrogen (N) and phosphorous (P) from ELIS to the MAB has not been well constrained, though it is important for the management of LIS and coastal biogeochemical budgets. As a tidal estuary, sampling efforts are subject to a degree of natural variation that is currently not well quantified. To assess the significance of spatial, tidal and seasonal sampling variability on fluxes, a cross-section of ELIS was sampled over a complete tidal cycle during representative times of year. Results show that discrete sampling in tidal estuaries can lead to a significant spatial and tidal bias in C, N, and P concentrations. Uncertainties associated with dissolved and particulate organic C were 6-15% and 31-19%; total N, dissolved and particulate organic N were 24-7%, 11-36% and 12-19%; and phosphate were 15-11%, under high and low river flow conditions, respectively. These uncertainties are recommended for future sampling and modelling efforts of LIS to account for natural variations. By pairing measurements of C, N, and P with physical data, seasonal and annual fluxes were estimated. Tidally averaged fluxes indicate periods of both net import and export across seasons, which vary among constituents. Scaled values indicated a small net import of organic C in LIS for 2016.

Major Advisor

Penny Vlahos