For 10 years, students studied a portion of the Maple River near Pellston, close to the University of Michigan Biological Station, before, during, and after an old dam was removed.
Paul Moore is a professor with Bowling Green State University who works at the biological station. He led the dam removal research.
He said the construction of the dam in the late 19th century cut off two tributaries from the main river.
“And organisms in the main branch couldn’t get to the east branch or the west branch. So, essentially you that what’s supposed to be a single river, a single ecosystem, and you divide it into three.”
That causes habitat fragmentation. That means, if the bugs and organisms disappear in one part of the river, the population that survives downstream cannot replenish the population above the dam. Fish and everything on up in the food web are hurt.
“It can cause the entire ecosystem to go extinct, whereas a more connected river is more resilient. It’s more sustainable. So, from an ecological point of view, connected rivers are important,” Moore said.
When the rivers are free-flowing, the benthic community can thrive.
“So things like crayfish and dragonfly and caddis flies. So you have a much more diverse community on the bottom of that river than you what you would have in the water column, and because you have a diverse community, is more resilient,” Moore explained.
That’s especially important to rivers such as the Maple because it is a blue-ribbon trout stream populated with brown, brook, and rainbow trout.
He’s quick to note that there is also loss in removing the dam. Lake Kathleen was a place where people could catch pan fish and go canoeing or kayaking. However, the dam was costly to maintain and was dangerous when it was not maintained. There was a point in the 1950s when the dam partially collapsed right after a school bus crossed it.
“So, the question becomes, do we continually rebuild these dams and reinforce them? And how much money time does that cost versus do we restore the ecosystem to what it originally was a couple hundred years ago and then reap the benefits of that kind of ecosystem,” asked Moore, adding, “And to be honest, I don't think there is a right answer.”
The study, authored by Madison J. Wagner and Moore, was published in the journal Science of the Total Environment.
