Determination of chlorophyll a concentrations and phytoplankton primary production in New England estuarine waters using ocean color remote sensing from low -flying aircraft

The response of coastal systems to the addition of nutrients (especially nitrogen) is generally to stimulate phytoplankton biomass, measured using the concentration of chlorophyll a as a surrogate. However, the concentration and distribution of chlorophyll in the aquatic environment is variable in space and time. Historically, random to systematic design strategies have collected samples from specific locations in space (i.e. a point measurement). These strategies also are limited in sampling intra-annual, seasonal, and episodic events. Therefore, in order to sample on all time scales of interest over large geographic areas, a large number of point measurements and resources are required. With their ability to provide extensive spatial and temporal coverage from watershed to global scales, satellites and aircraft are ideally suited to provide cost-effective temporal and spatial coverage to estimate chlorophyll concentrations. Previous research has shown that chlorophyll a concentrations in coastal and ocean surface waters could be estimated from aircraft- and space-based based sensors from the “color” of surface waters. The “color” of surface waters has been found to be principally dependent on water column optical properties. The concentration of colored dissolved organic matter (CDOM) is a primary factor affecting the absorption of incident sunlight in coastal and estuarine waters. In Chapter I, the temporal and spatial variability of CDOM absorption is characterized over an annual cycle in Narragansett Bay and Block Island Sound (Rhode Island). Results suggested that the magnitude of CDOM absorption is related to the seasonal input of freshwater from surrounding watersheds, the salinity regime of the bay, and new CDOM production from in situ biologic activity. In Chapter II, the chlorophyll concentrations predicted by several ocean color models were compared with field measurements concurrent with aircraft overflights to identify an algorithm which accurately modeled chlorophyll concentrations in Narragansett Bay. Results indicated that the SeaWiFS OC4v4 ocean color model had the best performance based on statistical and graphic criteria. In Chapter III, the magnitude and distribution of daily net phytoplankton primary production for Narragansett Bay were estimated by applying the Chesapeake Bay Production Model-1 (CBPM-1) to aircraft derived chlorophyll a and sea surface temperature data