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Studying the Life Aquatic

Karen Sullam

9/28/2012 11:13:00 AM

Ecology Ph.D. student Karen Sullam’s got a thing for the underdog—particularly when it comes to the ichthyologic sort.

“It’s kind of funny because I started out studying sea turtles—they’re very big and charismatic—but I find myself drawn now to really, really small organisms and fish, which aren’t quite as charismatic to most, but I find them really interesting,” Sullam said with a laugh.

In fact, during her six years at Drexel, Sullam has immersed herself in all things aquatic. She is currently working to complete her dissertation on fish gut microbial communities with focus on Trinidadian guppies, which serve as a model system for evolutionary ecology in nature.

“The guppies are the kind you find in pet stores,” Sullam said. “Before I came along to Drexel, my labmates began to see differences in their diets. At that same time a lot of research was coming out about human gut bacteria, how that correlated with whether they’re lean or obese, and so I got to thinking about how gut bacteria can play a role [elsewhere] in nature.”

After realizing her interest in the guppies, Sullam wanted to learn as much as she could about the popular little fish. During her second year, she applied to a two-week summer school course in Switzerland about the intersection of ecology and evolution in aquatic systems. Despite the fact that the course was “meant for more experienced graduate students,” Sullam said, she was accepted to the program and left Philadelphia to study Swiss aquatic systems.

“It was an amazing experience to just be there and learn about all the research going on at other institutions,” Sullam said. “It made me really keen on coming back to that lab and learning more.”

So with the help of the Drexel Fellowships Office, Sullam later applied for and was honored with a prestigious Fulbright Scholarship, which led her back to the waters of Switzerland.

“I had applied for a Fulbright to work with the organizers of that same summer school course,” said Sullam, who participated in the 2011-12 program. “Once there, I also got to look at the gut bacteria of a different species of fish—sticklebacks.”

Sullam said that sticklebacks are particularly interesting because of the way their diets adapt to their main two environments—lakes or streams.

“If the [sticklebacks] live in a lake habitat, they tend to eat food that’s on the bottom of that lake like invertebrates,” Sullam said. “But if it’s a stream stickleback, they tend to eat more planktonic foods. As a result, it’s made me very interested in studying populations.”

Now that she’s back at Drexel, she’s focused on her dissertation—as well as an additional complimentary project being funded through a doctoral dissertation improvement grant from the National Science Foundation and a Guy Jordan Research Grant from the American Cichlid Association.

“I’m looking at gut bacteria in cichlids fish, but in this case the time scale for adapting is much longer than [that of] the guppies or sticklebacks,” Sullam said. “Their diets vary, and it’s a very cool system to study the evolution of potentially different communities.”

Sullam said she’s glad she made the switch from sea turtles to small fish—and said it’s the perfect time in science to do so.

“In the field of looking at bacteria and their interactions with other organisms, it’s a really cool time to be in this field because of all of the molecular approaches are coming more available and affordable. Ten years ago, a lot of it wouldn’t be possible,” Sullam said. “I think what I like about my project is that it not only focuses on organisms and their physiology, but how they interact, and I’m able to do that with the development of these tools and technologies. It’s definitely an exciting field to be in.”