Daniel J. Hornbach

Daniel J. Hornbach serves as the John S. Holl Professor of Environmental Studies at Macalester College in St. Paul, Minnesota. He holds appointments in both the Environmental Studies and Biology Departments, with collaborative work extending to the Geology Department through his partnership with Professor Kelly MacGregor. His research focuses on aquatic ecosystems, particularly freshwater mussel conservation and stream ecology.

Hornbach earned his BS (1974) and MS (1976) from the University of Dayton, followed by a PhD from Miami University in Oxford, Ohio (1980). His academic journey has led to significant contributions in freshwater ecology and conservation biology.

Hornbach's research spans multiple areas of aquatic ecology, with particular emphasis on freshwater mussel biology and conservation. His work examines life-history evolution using fingernail clams, the physiology of freshwater mussels, impacts of zebra mussels on native species, effects of land use on aquatic ecosystems, seasonal variation in stream metabolism, and decomposition rates of native versus non-native plants. He has conducted extensive research on the St. Croix River, a National Wild and Scenic River, and more recently on the Minnesota River, which some environmental groups consider one of the most polluted rivers in the nation.

His publication record shows consistent research productivity through 2025, with recent work focusing on freshwater mussel population dynamics, ecosystem metabolism in ponds and streams, and the impacts of land use on aquatic ecosystems. His research demonstrates increasing interdisciplinary collaboration, with recent publications involving colleagues across multiple institutions and disciplines including biogeochemistry, fluid dynamics, and conservation policy.

• John S. Holl Professorship
• Dedication of the Dan Hornbach Environmental Studies Lab (October 2024)

Hornbach has mentored over 70 students in his research projects, with many former students co-authoring publications. His work has been funded by major agencies including the EPA, Fish and Wildlife Service, National Park Service, and the state of Minnesota. He has been involved with the Ecological Research as Education Network (EREN), an NSF-supported Research Coordination Network, serving as a Core Network Participant since its inception. Hornbach has also served on two Endangered Species Recovery Teams sponsored by the Fish and Wildlife Service.

Hornbach leads the Hornbach Lab, which conducts research on freshwater mussels in the St. Croix and Minnesota Rivers. His team collaborates with researchers at the University of Minnesota and other institutions, and has established long-term monitoring sites for studying ecosystem processes in various aquatic environments. The lab's work combines field research, laboratory analysis, and collaborative network science to address pressing conservation questions.