Rebecca Robinson
URI Graduate School of Oceanography
Associate professor; oceanography

The research work of the Rhode Island NSF EPSCoR community spans the depth and breadth of the Ocean State’s coastal and off shore waters, from surface to sediment, and all manner of life and movement found in between.

Rebecca Robinson’s focus lies at the deepest point, in the particles that comprise the ocean floor. There, in the sediment, Robinson looks at diatoms, a single-celled organism distinctively known for its glass cell wall.

“In the last 50 years or so, the type of diatoms that were typically in Narragansett Bay are starting to decline,” Robinson says. “Some have surmised that this is in response to climate change. So, as the system warms up, it is possible the chemistry of the water is changing.”

In turn, that means change for the Bay’s marine life and ecosystem.

Diatoms are phytoplankton, a plant or algae, and exist at the base of the food web, the initial source of energy on which the whole ecosystem depends. The status of these microscopic organisms provides important insight to the Bay’s health and yields clues — indicators of sea ice to salinity — about the environment.

Using equipment at the Marine Science Research Facility (MSRF), a RI EPSCoR facility at the URI Bay Campus, Robinson examines cores of Narragansett Bay sediment. The research team is comparing diatom communities from the sediment to look at the deep past, from decades to centuries ago, to those from modern and to more recent times, using phytoplankton surveys by URI Graduate School of Oceanography scientists.

The flow cam, explains Robinson, is somewhat like a vacuum, pulling a stream of water past the lens. It takes a picture every fraction of a second and crops out particles as the sediment floats by. From this procedure, Robinson and her student, Neil Redmond, identify and build libraries of diatoms. She also measures temperature from the chemical signature of the sediment core.

“If the diatom community is changing and is really different than what Narragansett Bay has seen, if the organisms are being pushed outside of their normal limits, then maybe it’s an alarm bell.”

Worldwide, temperature changes appear to take place more rapidly in some areas while in others, change occurs more slowly. Robinson says there is not a wealth of coastal information, so the research work being done adds significantly to the database.

Tracing climate change in the Bay, given such factors as land use and wastewater influx in the upper Bay and surrounding watershed, poses a complicated challenge. Through shifts in diatom communities, sediment cores tell the story of what happens when such measures as wastewater treatment plants are built, helping to guide policy decisions and determine fiscal impact.

“We want to understand how to use this environmental data,” Robinson says. “If the diatom community is changing and is really different than what Narragansett Bay has seen, if the organisms are being pushed outside of their normal limits, then maybe it’s an alarm bell. But, if they’re within the natural limits, we can consider that as plans are made to adjust our management of the ecosystem.”

At this point of the research, after investing time to ensure accuracy of their procedures, the scientists are collecting data. The MSRF flow cam is instrumental in that it automates some of the long hours previously spent at the microscope — work, Robinson notes, made possible by a RI Science and Technology Advisory Council (STAC) grant and ultimately useful for multiple purposes well beyond Narragansett Bay.

Story and photo by Amy Dunkle | RI NSF EPSCoR