PELLSTON, Mich. — A large-scale, long-term research project involving hundreds of students and about a dozen scientists stationed at the University of Michigan Biological Station in northern Michigan describes changes to a river’s habitat as a result of removing a dam.
The work aims to help guide land managers and conservationists across the country regarding river restoration and recovery efforts when faced with the ramifications of removing aging dams.
The 10-year study at the more than 10,000-acre research and teaching campus just south of the Mackinac Bridge in Michigan’s Lower Peninsula was recently published in the journal Science of the Total Environment and led by Dr. Paul Moore, a researcher and instructor at UMBS who has been doing research at the UMBS Stream Lab along the Maple River for 28 years.
“Major changes in the water chemistry as well as the macroinvertebrate communities in the Maple River showed a significant impact from the removal of the dam,” said Moore, who also is a professor at Bowling Green State University. “Despite this impact, the ecology of the river stabilized after two years, but stabilized at a different set of conditions than prior to the dam removal.”
Researchers say today’s new habitat is driven by increases in flow and the nutrients ammonia, silica and phosphate as well as changes in the feeding group structure of the macroinvertebrate community, such as snails, crayfish, worms, beetles and leeches, which are a significant source of food for animals including birds, reptiles and fish.
Before, during and after the Lake Kathleen Dam was removed from the 26-mile Maple River in 2018 and 2019 due to crumbling infrastructure, researchers — including undergraduate and graduate students at UMBS —sampled physical, chemical and biological stream variables above and below the dam.
The dam was originally built in 1884 as part of an old hydroelectric plant.
Researchers identically sampled the Maple River’s chemistry and community once annually at five sites from 2012 to 2021.
“A data set this large had an equally large list of contributors over the decade-long data collection,” Moore said. “The brunt of the data collection was carried out by students in the Limnology course at UMBS that I teach. Students in other UMBS courses also participated in our efforts over the ten-year span, including General Ecology, Biology of Fishes, Biology of Insects, and Rivers, Lakes and Wetlands.”
“This study is one example of how our students are immersed in nature and scientific research at the U-M Biological Station,” said Dr. Aimée Classen, director of UMBS and a professor in the U-M Department of Ecology and Evolutionary Biology. “They get to work alongside scientists in the field and the laboratory. It’s an extraordinary opportunity for experiential learning and undergraduate student research.”
After the dam was removed, the team monitored an increase of erosion due to more water flow as the lake disappeared, likely causing an increase in ammonia, phosphate and silica, and a drop in pH.
Researchers say pH decreased at all sample sites, and ammonia showed a five-fold increase following dam removal at the two most upstream sites, while phosphate increased at all sites.
Within the biological community, the composition of macroinvertebrates changed at all sampling locations to include more filterers, which collect fine particulate organic matter, and shredders, which consume leaf litter that falls from trees.
Shredders like crayfish or caddis flies increased dramatically in the upstream sites whereas filterers like mussels or clams had the largest increase at the two main branch sites closest to the dam.
Researchers say the macroinvertebrate community is likely influenced heavily by nutrient dynamics and their influence on algal growth in the new streambed.
Two years after dam removal, Moore says the river has recovered but with a “different ecological set point.”
Read the full study, titled “Longitudinal study of stream ecology pre- and post- dam removal: Physical, chemical, and biological changes to a northern Michigan stream,” on the journal’s website.
Founded in 1909, the U-M Biological Station is one of the nation’s largest and longest continuously operating field research stations. Students and scientists live and work as a community to learn from the place in northern Michigan.
Laboratories and cabins are tucked in along Douglas Lake in Pellston to support long-term climate research and education.
Students, faculty and researchers from around the world have studied and monitored the impact of environmental changes on northern Michigan ecosystems for 115 years.
An estimated 10,500 students have passed through to be immersed in nature and engage in scientific discovery needed to understand and sustain ecosystems from local to global scales.
Learn about 2024 courses for the four-week spring and summer terms and fill out an application on the UMBS website.
