Researchers to study whether sewer plants fueling invasive algae in Little Narragansett Bay

By Joe Wojtas 
The New London Day 4/4/2018

Stonington — A group of marine scientists from the University of Connecticut at Avery Point are preparing to begin a $225,000 study to determine if the discharge of nitrogen from the Westerly and Pawcatuck sewer plants is fueling the rapid growth of microalgae in Little Narragansett Bay.

The thick green algae, called Cladophora, is a voracious feeder that uses up oxygen and forces out other marine life, such as naturally occurring eel grass, which often is seen as an indicator of good water quality. The algae coats anything in its path.

“The solution is to identify where the nutrients are coming from and then determine what our options are,” said Julie Granger, an Avery Point assistant professor. She and faculty member Claudia Koerting are the study’s principal investigators.

They will be assisted by Avery Point graduate student Veronica Rollinson, who will analyze the data being collected. They also will work in conjunction with Stonington-based Clean Up Sound and Harbors, which does extensive water quality testing in the area. Local high school students, the state Department of Energy and Environmental Protection and the Rhode Island Department of Environmental Management also will be involved.

The project is one of five, two-year research projects focusing on marine life and water quality in Long Island Sound that this year is being funded by Connecticut Sea Grant, a partnership of UConn and the National Oceanic and Atmospheric Administration. The funding will pay for equipment, lab space and stipends.

Granger said the study’s presumption is that an abundance of nutrients, such as nitrogen and phosphorous, is contributing to the algae lowering oxygen levels and competing with eel grass and other marine life.

Koerting pointed out that clams, scallops, tube worms and other marine life once abundant in the sediment of the bay are not seen there anymore.

“The algae has killed off the natural mollusk community,” she added.

She said the algae has moved west into Mason’s Island and Pine Island, the latter of which is just a short distance from the Avery Point campus. She said she’s seen the algae while kayaking and paddleboarding and it’s been found on the docks at Avery Point. She said it is so hardy that, even when it dries out after being removed from the water, it comes back to life when water is added.

Granger and Jamie Vaudrey, also from the Avery Point Marine Sciences Department, have done some land modeling that shows some of the discharge comes from septic systems and farms along the river and the upstream Bradford Dyeing Co. But most of the nutrients come from point sources such as the two sewer treatment plants. She stressed that while these plants are operating within the discharge limits specified in their permits, addressing their discharge could have the most impact on water quality in the bay.

“They may be operating well within their permits but enough to cause a problem,” Koerting said.

Granger said that nitrogen discharges from different types of sources, such as septic systems and sewer plants, have their own signature, which allows them to be traced. While the nitrogen cannot be tracked to a specific plant, the researchers said the Westerly plant would produce more of an impact because it discharges more treated wastewater than the Pawcatuck plant.

They also point out that other factors in the shallow bay could be at work, such as rising water temperatures.

Koerting said that the researchers hope to have some answers in about 2½ years.

“Then we can start a conversation about what can be done,” she said.