URI student seeks answers to curious seaweed characteristic

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Jamestown resident says holes in sea lettuce help it attract nutrients

KINGSTON, R.I. – January 8, 2015 – Ivy Burns never imagined that she could become excited about seaweed. But the University of Rhode Island junior spent the last six months studying the marine algae, and now she can’t get enough of it.


“I was always that kid who would run around with a microscope looking at leaves, playing with spiders, always interested in the way things worked,” said the biological sciences major from Jamestown.


She had already spent time in a URI laboratory studying preying mantids and in another lab studying salt marsh plants. But when she took her first class about seaweed, she was hooked.


“I loved learning about the complex ecology of this thing that you would normally just walk right over,” Burns said. “It opened my eyes to this whole other facet of the world that most people ignore.”


Working with Professor Carol Thornber, she studied algae blooms in Narragansett Bay by focusing on the two most prolific bloom-forming species, Ulva compressa and Ulva rigida. Also called sea lettuce, they grow in thin green sheets and can reproduce by tearing bits off their blades.


“They’re very good at what they do,” said Burns, who was featured in a URI television advertisement last fall. “They’re very thin and grow really fast, and they absorb a lot of nutrients. They form mats of seaweed that block the sunlight from other algae on the bottom, and when the seaweed dies it releases chemicals that are bad for the environment and bad for the fish.”


Burns was curious about why rigida, the thicker of the two varieties, has holes in it while compressa typically does not. She wondered how and why holes might be a beneficial evolutionary strategy. So she conducted a series of tests to determine the strength of each species using engineering devices to stretch and penetrate the seaweeds.


The URI student found that rigida is more difficult to tear, so the holes may help in reproduction by making it easier to tear off bits of seaweed. While Burns said that’s a plausible explanation, she thinks something else is at work, too.


“What we think is really happening is that rigida, being thicker, might need help getting enough nutrients because it has less surface area due to the holes,” Burns said. “We think the holes cause a disturbance in the flow of water around it, allowing it to get more nutrients than if it didn’t have the holes.”


Although she has no data to prove it yet, Burns plans to continue her research in the coming year using a technique called digital particle image velocimetry, which uses a laser beam in a flow tank to measure how the water may flow differently over the different varieties of seaweed.


Burns’ research was conducted as part of URI’s Coastal Fellows program, a unique initiative designed to involve undergraduate students in addressing current environmental problems. Now in its 19th year, it is based at URI’s College of the Environment and Life Sciences. Students are paired with a mentor and research staff to help them gain skills relevant to their academic major and future occupations.


As if her coursework and research weren’t enough to keep her busy, Burns is also the president of two student groups: Secular URI, a discussion group she founded for non-religious students, and URI Students for the Advancement of Gender Equity, which provides a safe place for students to talk about gender-related issues. She also works as a peer educator at the URI Women’s Center and will be a cast member in URI’s upcoming performance of The Vagina Monologues.


Burns is also applying for summer research opportunities around the country to see if she – and her parents – can handle living far from home. And then she will be applying to graduate schools with the goal of becoming a college professor.


“I’m a plant person, I love ecology, and I like bugs and fungus,” she said. “I’m looking to be somewhere that I can research plants or fungus or bugs or a cross-section of those things. I can’t wait to get started.”


Photo courtesy of URI