Restoring Wetland Habitat and Function at the Shiawassee National Wildlife Refuge
Hydrologic connectivity is essential to maintaining coastal wetland services and functionality. Impounded wetlands often do not provide essential services such as flood mitigation and nutrient retention, nor can they be utilized as spawning and nursery habitat by important Great Lakes fishes. The Shiawassee National Wildlife Refuge manages hundreds of acres of historical coastal wetland habitat and began restoring hydrologic connectivity to the area in 2018. Pre- and post-restoration monitoring efforts by the USGS, University of Michigan, and other partners described the physical and biological effects of hydrologic connectivity and supported decision making by refuge staff as they continue managing for multiple priorities.
Study Area
The Shiawassee National Wildlife Refuge (SNWR) sits within the Shiawassee Flats about 20 miles inland from Saginaw Bay, Lake Huron. The Refuge is unique in that it sits squarely at the confluence of four tributaries to the Saginaw River (Flint, Cass, Tittabawassee, and Shiawassee) making it a highly dynamic coastal wetland with influences from both the rivers and the Bay.
Previous work at impounded coastal wetlands within the U.S. Fish and Wildlife Service Ottawa National Wildlife Refuge in Lake Erie guided the SNWR’s Restoration Plan, where hydrologic reconnections via water-control structures were found to aid in the restoration of key wetland functions including nutrient retention, flood mitigation, and access to habitat for aquatic species. In 2011, the SNWR received funding through the Great Lakes Restoration Initiative to restore historical wetland habitat within its boundaries to maximize services to the human population and increase functionality for fish and wildlife populations.
Restoration Monitoring Efforts
Pre-restoration monitoring efforts began at the refuge in 2012 and continued intermittently until the initial phase of hydrologic reconnection was completed in 2018. Pre-restoration research teams collected fish, macroinvertebrate, and vegetation community data, as well as performed a full hydrologic assessment of water flow and aggregation within the system. In 2018, a partnership between the U.S. Fish and Wildlife Service, USGS, and the University of Michigan’s School for Environment and Sustainability began in an effort to organize standardized post-monitoring protocols implemented over consecutive years. The monitoring protocols include intensive biological community assessments of fish, macroinvertebrates, and vegetation, as well as abiotic assessments (e.g., geospatial characteristics and water quality) within the newly restored wetland units and a historically reconnected unit. This approach supported analysis of trends during stages of restoration within the new wetland units and comparison to the historically reconnected unit.
From 2018 and 2022, SEAS Masters Project students assist SNWR and USGS researchers by collecting monthly field monitoring data from the restored wetland units. Sampling occurred monthly, from late Spring to early Fall, and included fyke netting, gill netting, and electrofishing (to assess fish community), dip-netting (to assess macroinvertebrate community), and a full vegetation survey. The project team also collected water quality data by way of in situ measurements of temperature, pH, dissolved oxygen, turbidity, and conductivity alongside every biotic sample. Additional water samples were collected and sent for processing to determine monthly dissolved nutrient levels from each wetland unit.
Altogether, the partnership resulted in a rich dataset collected over four years (2018-2022) that quantified the effects of restoration at the Shiawassee National Wildlife Refuge and are being used to inform management decisions there and across Great Lakes coastal wetland systems.
Sonar and Machine Learning Models to Assess Fish Habitat Use
In 2020, hydroacoustic sonars were placed at one of SNWR’s water-control structures to quantify fish movement and habitat use. Sonars are capable of collected continuous video data in low light conditions and in conditions that may be less suitable or unsafe for field teams (e.g., deep, high flow areas).
The sonar remained at the water control structure through 2022 and amassed a total of 70 TB of data. The team then built a cloud-hosted machine learning model (MLM) to process and analyze the hydroacoustic dataset, thus allowing the team to semi-autonomously derive quantitative fish passage data from hours of recordings. The MLM is capable of outputting bi-directional fish counts and individual fish length estimates. Fish spanning multiple size classes (small, schooling fish to large, spawning adults) were observed using the wetland. The sonar dataset will continue to provide insight into seasonal and diel differences in fish movement and size classes, as well as responses to known events (e.g., seiches, abrupt changes in flow or water quality).
Partners (not separate tab)
Hydrologic connectivity is essential to maintaining coastal wetland services and functionality. Impounded wetlands often do not provide essential services such as flood mitigation and nutrient retention, nor can they be utilized as spawning and nursery habitat by important Great Lakes fishes. The Shiawassee National Wildlife Refuge manages hundreds of acres of historical coastal wetland habitat and began restoring hydrologic connectivity to the area in 2018. Pre- and post-restoration monitoring efforts by the USGS, University of Michigan, and other partners described the physical and biological effects of hydrologic connectivity and supported decision making by refuge staff as they continue managing for multiple priorities.
Study Area
The Shiawassee National Wildlife Refuge (SNWR) sits within the Shiawassee Flats about 20 miles inland from Saginaw Bay, Lake Huron. The Refuge is unique in that it sits squarely at the confluence of four tributaries to the Saginaw River (Flint, Cass, Tittabawassee, and Shiawassee) making it a highly dynamic coastal wetland with influences from both the rivers and the Bay.
Previous work at impounded coastal wetlands within the U.S. Fish and Wildlife Service Ottawa National Wildlife Refuge in Lake Erie guided the SNWR’s Restoration Plan, where hydrologic reconnections via water-control structures were found to aid in the restoration of key wetland functions including nutrient retention, flood mitigation, and access to habitat for aquatic species. In 2011, the SNWR received funding through the Great Lakes Restoration Initiative to restore historical wetland habitat within its boundaries to maximize services to the human population and increase functionality for fish and wildlife populations.
Restoration Monitoring Efforts
Pre-restoration monitoring efforts began at the refuge in 2012 and continued intermittently until the initial phase of hydrologic reconnection was completed in 2018. Pre-restoration research teams collected fish, macroinvertebrate, and vegetation community data, as well as performed a full hydrologic assessment of water flow and aggregation within the system. In 2018, a partnership between the U.S. Fish and Wildlife Service, USGS, and the University of Michigan’s School for Environment and Sustainability began in an effort to organize standardized post-monitoring protocols implemented over consecutive years. The monitoring protocols include intensive biological community assessments of fish, macroinvertebrates, and vegetation, as well as abiotic assessments (e.g., geospatial characteristics and water quality) within the newly restored wetland units and a historically reconnected unit. This approach supported analysis of trends during stages of restoration within the new wetland units and comparison to the historically reconnected unit.
From 2018 and 2022, SEAS Masters Project students assist SNWR and USGS researchers by collecting monthly field monitoring data from the restored wetland units. Sampling occurred monthly, from late Spring to early Fall, and included fyke netting, gill netting, and electrofishing (to assess fish community), dip-netting (to assess macroinvertebrate community), and a full vegetation survey. The project team also collected water quality data by way of in situ measurements of temperature, pH, dissolved oxygen, turbidity, and conductivity alongside every biotic sample. Additional water samples were collected and sent for processing to determine monthly dissolved nutrient levels from each wetland unit.
Altogether, the partnership resulted in a rich dataset collected over four years (2018-2022) that quantified the effects of restoration at the Shiawassee National Wildlife Refuge and are being used to inform management decisions there and across Great Lakes coastal wetland systems.
Sonar and Machine Learning Models to Assess Fish Habitat Use
In 2020, hydroacoustic sonars were placed at one of SNWR’s water-control structures to quantify fish movement and habitat use. Sonars are capable of collected continuous video data in low light conditions and in conditions that may be less suitable or unsafe for field teams (e.g., deep, high flow areas).
The sonar remained at the water control structure through 2022 and amassed a total of 70 TB of data. The team then built a cloud-hosted machine learning model (MLM) to process and analyze the hydroacoustic dataset, thus allowing the team to semi-autonomously derive quantitative fish passage data from hours of recordings. The MLM is capable of outputting bi-directional fish counts and individual fish length estimates. Fish spanning multiple size classes (small, schooling fish to large, spawning adults) were observed using the wetland. The sonar dataset will continue to provide insight into seasonal and diel differences in fish movement and size classes, as well as responses to known events (e.g., seiches, abrupt changes in flow or water quality).
Partners (not separate tab)