URI ecologist: Abundant seaweed, algae in Narragansett Bay makes 2005 a typical summer
Todd McLeish, 401-874-7892
KINGSTON, R.I. -- August 23, 2005 -- Rhode Island boaters and beachgoers have had plenty to think about this summer, including concerns about red tide, masses of seaweed accumulating on beaches, and occasional algae blooms in Narragansett Bay.
“There are many factors contributing to why we’re hearing more about algae this year, but these events aren’t particularly unusual,” said Carol Thornber, assistant professor of biological sciences at the University of Rhode Island who studies macroalgae (seaweed).
The red tide algae is frequently found off the New England coast, but the winds and currents last spring shifted just enough to bring it closer to the coastline, Thornber said. Seaweed accumulations – a significant problem at Easton’s Beach in Newport this year -- are also a common problem encountered at beaches every year as waves dislodge native seaweed from rocks and push it on shore.
It may get worse over time, she warns, because as water temperature increases due to global warming, some algae will grow faster. Nutrients from sewage and fertilizers flowing into the bay also increase concerns about algae. But for now, the marine ecologist isn’t worried about what some residents see as an out-of-control problem.
“Algae aren’t a bad thing,” reminds Thornber, a resident of Westerly. “They are the base of the food chain and provide food and habitat for a wide variety of other species. If you like to eat seafood, you’re going to have to put up with a little algae because without algae, you won’t have any of your favorite foods.”
That’s not to say that it can’t be a problem. It can foul boat props, clog lobster pots and become lodged in fishing nets. “If you go to your favorite beach and find it covered in decomposing algae, it smells bad and makes you want to stay away. I love algae, but it’s still pretty disgusting when it’s decomposing.”
Thornber grew up in New Jersey with an interest in marine biology, “and I never grew out of it,” she said. After earning degrees from Stanford University and the University of California at Santa Barbara, she joined the faculty at URI in 2004.
In cooperation with the R.I. Department of Environmental Management, Thornber is assessing the quantity and species of algae washing up on shore around Greenwich Bay. This baseline data can be compared to data collected in future years to determine if the problem is growing.
Thornber is also collecting samples of two species of green algae at several sites around Narragansett Bay and analyzing their nitrogen content.
“Nitrogen from different sources has a different chemical signature, so by doing a chemical analysis of algae from different places around the bay, I’ll be able to estimate the amount of nitrogen coming from human sources, like sewage overflows and fertilizers, and nitrogen from natural oceanic sources,” Thornber said.
She expects that more of the nitrogen in algae found in the northern part of the bay will come from human sources, while the nitrogen in algae found closer to Rhode Island Sound will be primarily from natural sources.
“There have been a lot of studies done on mussels and barnacles and other creatures living in rocky intertidal areas, but very little research on the macroalgae living right next to them,” Thornber said. “I hope with my research to provide a more complete picture of the marine setting.”
Carol Thornber (left) and research assistant Amanda Chester sample algae near Oakland Beach in Warwick.
URI News Bureau Photo by Michael Salerno Photography.