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Quantifying contributions to light attenuation in estuaries and coastal embayments: Application to Narragansett Bay, Rhode Island
Abdelrhman, M. Quantifying contributions to light attenuation in estuaries and coastal embayments: Application to Narragansett Bay, Rhode Island. Estuaries and Coasts. Estuarine Research Federation, Port Republic, MD, 40(4):994-1012, (2017).
An innovative normalization for light attenuation is presented to validate comparison between water clarity of the same or different systems in space and time. The methods developed can be used to study the effect of various environmental and management scenarios on the recovery efforts for seagrass beds in estuarine and coastal systems. Seagrass beds are important nursery areas and feeding grounds for a variety of recreational and commercial valuable fish and wildlife.
In Narragansett Bay, light attenuation by total suspended sediments (TSS), colored dissolved organic matter (CDOM), and phytoplankton chlorophyll-a (chl-a) pigment is 129, 97, and 70%, respectively, of that by pure seawater. Spatial distribution of light attenuation indicates higher values in the upper Bay, where rivers with sediment and nutrient-rich waters enter and elevate TSS, CDOM, and chl-a concentrations. The temporal trends of light attenuation during the summer months (July–August) differed at various locations in the Bay, having the highest values in July. For the same period, spectral methods overestimated attenuation throughout the Bay. These findings quantify the behavior of light attenuation in space and time, providing information that can guide decisions related to improving water clarity and help understanding the effects of various environmental and management scenarios on it.