News & Resources


Old Stream, New Stream - Au Sable Research Takes the Plunge in 2015

Jan 23, 2015

Like a bride’s dress, Au Sable research in northern Michigan streams will be something old and something new in 2015. For the eighth consecutive year, Institute faculty, staff and students will continue their evaluation of the effect of dam removal on stream macroinvertebrate communities in Michigan’s Boardman River. At the same time, a new study on the distribution and environmental tolerances of sculpin, a group of bottom dwelling species of stream fish will begin in the Manistee River.

The Boardman Study, designed and developed by Au Sable’s Associate Executive Director David Mahan and funded by the Conservation Resource Alliance, Trout Unlimited, and other local conservation organizations, has taken advantage of a unique natural experiment in the field of restoration ecology to answer the question: what are the differences between communities of stream insects and other invertebrates above and below a dam, and what happens to such communities when a dam is removed? Such invertebrate communities form the basis of food webs and food supplies for almost all stream organisms, as well as being the primary agents in ecological functions and services performed in the stream ecosystem, such as processing energy and shredding, collecting or removing material in and from the water. Moving water tends to have higher levels of oxygen and lower temperature, contributing to more diverse communities of stream invertebrates. Dams impede flow, resulting in lower oxygen levels and higher water temperatures immediately above and below the dam. Such impeded flow also tends to lead to a concentration of sediments and other pollutants above the dam. These conditions often lead to invertebrate communities with fewer species that are more tolerant of low quality water conditions.

Through its first seven years, the Boardman Study has revealed that, in fact, above-dam (within reservoir) invertebrate communities are of lower diversity and contain more pollution-tolerant species than communities associated with unimpeded flow below the dam. After dams are removed, however, former reservoir and immediately downstream areas recover quickly, transitioning to more diverse and environmentally sensitive species within one –to – three years after dam removal. Thus, the negative effects of dams on stream invertebrate communities need not be permanent if dams are removed, and streams like the Boardman River can see their invertebrate communities, and other species that depend on them, recover quickly under appropriate management.  Study leader Dave Mahan noted, “Our studies on the Boardman have confirmed the natural restorative ability of stream ecosystems after removal of a disturbance, something that should serve as a model for other stream restoration projects.” Au Sable expects to employ four student research assistants to continue this important effort in 2015.

While research continues on the Boardman, a new study will begin on the upper sections of the Big Manistee River in Kalkaska and Wexford Counties that will be focused on different species of sculpin, and especially the mottled sculpin. Sculpin are small, bottom-dwelling stream fish normally found in colder, highly oxygenated waters of high quality streams. The US Forest Service recently named the mottled sculpin as a “Management Indicator Species” for indicating high quality stream habitat on northern Michigan’s Manistee-Huron National Forest, but the designation raises important questions that need answers for the mottled sculpin to be a useful “indicator.” First, where, exactly, does the mottled sculpin occur in the Big Manistee and its tributary streams? Second, is it possible to accurately distinguish the mottled sculpin from a closely related species, the slimy sculpin, which also occurs within the watershed? Finally, what conditions contribute to the presence and abundance of mottled sculpin (what does the presence of the mottled sculpin “indicate” about environment conditions?).  Working with the expertise and financial support of the Little River Band of Ottawa Indians (LRBOI), the Au Sable sculpin study aims to provide answers to all of these questions, and so better enable stream managers to use the mottled sculpin more effectively to assess the quality of stream habitat. Marty Holtgren, Senior Fisheries Biologist for the LRBOI, described the value and importance of the study, and of the Tribe’s collaboration with Au Sable, this way, “We are enthusiastic about this new effort with Au Sable Institute. It will establish a partnership where we will develop a shared vision of river stewardship,  expertise and experiences as stewards of the river.  This partnership will provide us with a fuller understanding of the watershed and the options we may have for protecting it.”   Stephanie Ogren, Senior Aquatic Biologist for LRBOI, also is looking forward to working with the student research assistants to expand the stream monitoring program and better inform management decisions.

The sculpin study expects to employ four student research assistants, under the supervision of Institute staff and LRBOI scientists, to accomplish its goals in 2015. Fred Van Dyke, Executive Director of the Au Sable Institute, speaking of the significance of both studies, said, “All of us at Au Sable are honored to be continuing this long term study of the effects of dam removal on the Boardman River, as well as beginning a pioneering effort in evaluating the usefulness of the mottled sculpin as an indicator species. These studies do a number of great things all at once. They provide opportunity to give undergraduate students from colleges across the US and Canada direct experience in meaningful environmental research, which is a critical component to future professional success. They will, in the long run, provide important information for the scientific community to better understand these stream ecosystems and the species in them. And, perhaps most importantly, they allow the Institute to serve our local neighbors, like the Little River Band of Ottawa Indians and the members of the Conservation Resource Alliance, in areas that are important to them and to us. We’re grateful to have this opportunity to serve our neighbors and friends in this way.”

Students interested in being a part of these research teams can find instructions for applying at We’ll see you in the stream!