Deconstructing dams

MARQUETTE – Life near waterfalls might change your body type, if you were a fish. That’s what Kayla Knoll, a graduate student in biology at Northern Michigan University, is researching for her master’s thesis.

Knoll is looking at the effects of dams and other barriers, particularly waterfalls, on fish morphology, which deals with basic body shape.

“I’m interested is seeing how these barriers are affecting these fish, and no one’s really looked at waterfalls, so that’s what I’m really interested in,” Knoll said. “We have awesome waterfalls to look at all around.”

Most of the waterfalls she’s examining, she said, are in Marquette and Alger counties, but she’s traveled to other areas, although they have to be in the Lake Superior watershed.

Traveling to spectacular waterfalls probably is one of the better parts of her study, although Knoll acknowledged there is at least one major challenge.

“The mosquitoes are so terrible this year,” she said. “There’s so much standing water.”

Since many smaller dams in the Upper Peninsula don’t have ladders so fish can get around them, Knoll said she ‘s interested in those dams, particularly those with lamprey barriers and how they affect native fish populations, she said.

Knoll said she expects to see changes among fish being separated for long periods of time, especially above and below the barriers. With smaller populations, changes can occur pretty quickly, she said.

Knoll fished when she was growing up, but was not interested in studying fish until later.

“I’ve always been into aquatic biology, but I was never specifically into fish until grad school and I started studying them, and now I’m hooked,” she said.

So what “hooked her,” so to speak? After all, fish don’t have what many people might consider the same appeal as a river otter, trumpeter swan or monarch butterfly, although fish too are true animals.

“Just the biology aspect of fish,” Knoll said. “They’re just really interesting animals. I really like studying the community fish, the smaller minnows that a lot of people don’t really care about because they don’t have the fisheries value behind them, but I like to study the smaller fish that no one has really looked into as much.”

Knoll and the volunteers she’s taken on for her thesis have already caught many species of fish, including creek chubs, blacknose dace, darters, sticklebacks, sculpins and brook, brown and rainbow trout.

The sculpin, a bottom-dwelling scaleless fish with wing-like pectoral fins and a broad, flat head and a body that tapers to a narrow tail, is Knoll’s favorite.

“They’re really evolved to live on the bottom of the streambed, and they’re just funny-looking, warty guys,” she said.

Knoll said she and her volunteers take samples within 100 meters above or below a barrier with a backpack electroshocker. Fish are scooped up, and length and weight measurements are taken. Fish, which also are photographed, then are returned to the water.

Knoll said she hasn’t yet developed any definite results.

“It’s too early to tell, but I’m hoping to see differences in body shape above and below the barrier from them being isolated for hundreds of years, or even with waterfalls – it’s been tens of thousands of years that these populations haven’t been interbreeding,” she said.

A body shape, Knoll explained, can tell a lot about a fish’s lifestyle.

Knoll said she hopes to have her thesis completed within a year.

Knoll’s advisor at NMU, biology professor Jill Leonard, said in an email Knoll’s work is important because it allows the evaluation of effects of human-made structures on native species using a relatively underused approach with species that are rarely the subject of study.

“As our understanding of the natural world increases, it is ever more important to consider the entire ecosystem, including all its species, as we try to understand the impacts of human alterations to the environment,” Leonard said. “The project also allows us to look at evolutionary changes in native fish species in the wild that result from human activities.”

What practical applications can be taken away from Knoll’s thesis?

“Hopefully, I think it can give us an understanding on how the smaller dams can affect the fish,” Knoll said. “Small dams are all across the U.P., and really, everywhere. We don’t have any idea if it’s affecting the fish in any way, and a morphology’s a really good way to approach it without having to get into the DNA analysis, which can be really costly.”