Climate Clues in Diatoms


A University of Rhode Island oceanographer is studying microscopic organisms at the bottom of Narragansett Bay that could help determine how climate change is changing the bay’s ecosystem.

Rebecca Robinson’s research is on diatoms, single-celled organisms found in abundance in the oceans. Diatoms—a type of phytoplankton—are at the base of the food web, feeding everything from zooplankton to fish.

Getting a long-term historical view showing which diatoms are thriving and which ones are in decline could provide insight into the bay’s health in the face of global warming, says Robinson.

For many years, Robinson and her research team have collected sediment samples on the Bay’s floor. Back in her lab at URI’s Graduate School of Oceanography, the samples are put in a FloCam, equipment that allows her to rapidly image hundreds of diatoms in a few minutes.

The process allows Robinson and her team from GSO and Brown University to compare current diatom abundance in the water to sediments that go back 300-plus years.

Climate change is warming Narragansett Bay. GSO scientist Jeremy Collie says temperatures in the bay hit record highs and lows in 2015—the most extreme fluctuations since GSO started surveying the waters 56 years ago.

Indeed, since 1900 the Earth’s atmosphere has warmed by 1.5 degrees Fahrenheit, resulting in rising sea levels, lessening and intensifying rainfall amounts, and more ocean acidification from carbon emissions. Ocean temperatures worldwide are also changing.

Robinson is still in the preliminary stages of her research, but hopes eventually to determine if the “diatom community’’ is changing and possibly getting smaller—or if the changes are a natural shift in the ecosystem.

Diatoms are essential to the planet’s health. They are not only the base of the food chain, they also regulate the air people breathe by consuming carbon dioxide and releasing oxygen through photosynthesis.

Robinson is exploring whether the bay’s warmer waters are killing off diatoms—and also examining the impact of storm runoff and wastewater effluent on the organisms.

“We know the diatom community is changing,’’ says Robinson. “Out study will allow us to see how far out of the natural bounds these changes might be. If they’re significantly different from anything we’ve seen in the past, we should be ringing an alarm bell. The Bay’s health could be at stake.’’

Robinson’s research is supported by the Rhode Island Experimental Program to Stimulate Competitive Research—a National Science Foundation program—and a Rhode Island Science and Technology Advisory Council grant.

Pictured above: Rebecca Robinson, an associate professor in the University of Rhode Island’s Graduate School of Oceanography. Photo courtesy of Rebecca Robinson.

Media Contact: Elizabeth Rau, 401-874-2116