NARRAGANSETT — On Wednesday afternoon, local scientists, shellfishermen and graduate students gathered at the University of Rhode Island to listen to a series of lectures from researchers who have been studying the aquatic environments of Narragansett Bay. Professor of Oceanography Chris Kincaid first presented his work at the event, organized by Rhode Island Sea Grant, on water circulation in the bay and its impact on nutrient distribution.
“On my first day of work, [former Professor of Oceanography] Scott Nixon came into my office and said ‘look, there are three things I want you to answer,’” said Kincaid. “I want you to answer counter clockwise flow in Narragansett Bay, the difference of flow in the East Passage and West Passage, and the deep source of nutrients in Narragansett Bay.”
Thus Kincaid’s research began, developing computer models and doing physical research through monitoring systems throughout Narragansett Bay. In the bay, the inward flow of water passes through the East Passage, takes a turn at the Providence River, and returns to flow out towards the ocean in the West Passage.
“We use Acoustic Doppler Current Profilers (ADCPs), which give us a really good spatial picture of what the water is doing,” said Kincaid. “When the sound comes back to the instrument, we can figure out the speed and movement of the water in the water column.”
“We do 14-hour surveys on a motorboat and, what we find with ADCPs is that we see very stable flow structures, very repeatable, lateral flow structures, in Narragansett Bay,” he added.
The purpose of studying the water circulation in Narragansett Bay rests in understanding how nutrients, from natural sources as well as man-made, aggregate and flush according to the flow of the bay. The input of nitrogen, for example, in Narragansett Bay’s waters has the potential to suffocate certain species in the water column.
Kincaid and his colleagues have employed what is called a Regional Ocean Modeling System (ROMS), which is a three-dimensional modeling system that calculates all the individual impacts upon the water column, such as wave flow, temperature and wind.
“In the models, we have dyed 16 different rivers and wastewater treatment systems throughout the bay, and we watch where those dyes go,” said Kincaid. “One of the things we are motivated by is there was a major fish kill in 2003 and a summary was written up. One point it made was low oxygen was the cause, and the main discussion was about circulation and it carrying northern [chemical] sources into Greenwich Bay.”
“Northern chemical sources often bypass Greenwich Bay, and it is the southern chemical sources that have a greater impact, which is what we found,” he continued.
What Kincaid has ultimately found, although his research is ongoing, is that wind has a greater impact on the flow of chemicals in the Narragansett Bay water column than previously known.
The second speaker, URI Graduate School of Oceanography Ph.D. candidate, Jeff Mercer, presented his most recent work on the distribution of quahog offspring throughout Narragansett Bay, activity which is highly dependent on the flushing patterns throughout the bay.
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