Marney Pratt '97 Named Coastal Studies Center Visiting Scholar
Story posted October 01, 2003
Marney Pratt, the new scholar-in-residence at the Coastal Studies Center, arrived in Maine about a month before her trip back to North Carolina to defend her dissertation at Duke, two months before her wedding and three months before much of the wildlife on which her research depends dies off in the cold that will soon hold the gulf of Maine in its clutches.
She's in for a busy fall semester, but itís one she is looking forward to. She is one of Bowdoin's own, returned, this time as a scholar and a colleague to her former teachers and advisors.
"I'm really excited to be back at Bowdoin," she said. "I'm especially looking forward to the chance to start new research, teach an advanced biology course, and mentor undergraduates. Being able to live and work at the Coastal Studies Center is a fantastic opportunity."
Pratt is, in a sense, returning to something of her own making: She was the student representative on the committee that helped create the Coastal Studies Center.
"At that point we debated a lot about who we wanted to be out here," she said. The committee considered a fulltime caretaker who would live at the Center, but eventually decided that they wanted someone more involved in the intellectual life of the campus. A few years later the scholar-in-residence program was born and Pratt is the latest recipient of the title.
The work at the Center is designed to be interdisciplinary, so any department can request a position for the scholar in residence. Since the program began, an environmental historian, a painter, a marine biologist, and a photographer have all worked at the Center. Pratt, a biologist, jumped at the chance to return to Maine to teach and perform research.
"It was really fun just to come back for the interview. So much has changed, so many buildings have been built, and the biology department has almost doubled in size," she said. "The only unfortunate thing is that it's only for a year, and that's a really short time to get research going." One of Pratt's strengths, however, is that she already knows the area, so she hopes to be able to get her research up and running more quickly than she would in a completely new place.
Pratt studies colonial invertebrate animals called bryozoans. The colonial animals most familiar to many people are corals and sponges, but all colonial animals are made up of a replicated unit. Most colonial animals reproduce sexually to form new colonies, but colonies grow by asexual "budding" that replicates the essential unit in different directions. To explain, Pratt compared the bryozoans to Legos.
"You can build pretty much everything out of Legos, and bryozoans can bud in any direction and form just about any kind of shape," she said.
In many ways bryozoans are more like plants than animals - they are mostly stationary, and they also appear static to the naked eye, but a look through a microscope reveals a shivering and pulsing community.
For her dissertation, Pratt studied the effect of water velocity on the bryozoans' colony formation. She discovered that one particular species of bryozoan seemed to out perform other species. Membranipora membranacea had a higher feeding rate, a higher growth rate, a higher survival rate, and was also the most abundant species.
Membranipora membranacea has now brought Pratt back to the Maine coast, where the species is invasive. The Coastal Studies Center position will allow her to study the species more closely for clues to its ability to thrive.
Membranipora was first discovered in the Gulf of Maine in 1987. The larvae by which bryozoans form new colonies can survive in water for up to two months and might have been brought to the Gulf in ships' ballast water. Within two years of its discovery Membranipora was a dominant species in the kelp beds on which it lives, and it has now spread up the coast of Maine and into Nova Scotia.
While "invasive" is technically neutral, referring to a non-native species that has been introduced, has established itself and is starting to spread, the connotation and usually the real-life results are negative. (Though humans, Pratt reminded, are the champion invasive species: "We do that all the time...we're probably one of the worst introduced species. Wherever we go, we bring chaos," she said.)
It's doubtless that Membranipora isaffecting the ecosystem of the Gulf, but the specific effects aren't clear. Bryozoa will live attached to algae, rocks, shells, docks. Membranipora, however prefers large flat seaweed, such as kelp, and a kelp bed is an extremely productive environment, the temperate equivalent of a rainforest, according to Pratt. Sea urchins, in particular, love to eat kelp and will sometimes eat up an entire kelp bed leaving what is known as an urchin barren. For years there has been a symbiotic relationship between the two with a healthy turnover of kelp bed to urchin barren and back. Now, colonies of Membranipora are covering the kelp. This may not in and of itself interfere with the urchin feeding, but the Membranipora-covered kelp seems to be more brittle and easily broken than other kelp, so kelp is lost before urchins are able to feed on it. In addition, the breaking of the kelp seems to leave the way open for a new, invasive form of algae to move in and thrive.
"There's all kinds of dynamic things going on, and they seem to be changing over time," Pratt said. Scientists have been investigating the issue, but few have focused on the bryozoa as Pratt will.
Membranipora doesn't much care for mud, so it isn't abundant on the mud flats near the marine lab, but Pratt has found plenty of Membranipora colonies at the end of Bailey Island, near the Giant Steps. Membranipora's adaptability is especially intriguing to Pratt. While it usually grows in flat sheets, she's found it on Bailey Island growing on very thin strands of algae and on eel grass, something she's rarely seen before.
"It just amazes me," she said, "It'll grow on whatever it can, in whatever way it can. This species seems able to grow on anything."
In addition to her research, Pratt will be teaching "Intertidal Ecology" during the spring semester. The land covered at high tide and exposed at low tide is well studied, but it's an environment Pratt finds fascinating. In some intertidal areas, the organisms must contend with furiously crashing waves. "It's like us living in a hurricane all the time," she said. In other locations, intertidal organisms deal with extremes of heat and dryness or cold. In Washington, where Pratt conducted research, low tide often falls in the heat of the day, while in Maine, intertidal zones are buried in winter ice and snow. When the weather warms up in the spring, Pratt plans to take the class on weekly field trips to different intertidal areas.
Pratt views the scholar-in-residence position as a unique opportunity to do post-doctoral research and be able to teach as well - something rare in post-doc positions. Pratt also hopes to get students involved in her research at the Coastal Studies Center. She knows from personal experience how much undergraduate research and mentoring can shape the future.
Amy Johnson encouraged Pratt when she was a student at Bowdoin, first to excel in her classes, then to perform an independent study, and finally, to pursue a doctorate. In fact, it was while doing research for one of Johnson's courses that Pratt first became interested in bryozoans.
"I think mentoring is so crucial in encouraging people to go on," Pratt said. "I just want to be one of those people."
Pratt graduated from Bowdoin summa cum laude with honors in biology. She earned her doctorate in biology from Duke University. While at Duke she also earned a teaching certificate in college biology. She has taught at Guilford College and performed research at the University of Washington's Friday Harbor Laboratories.
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