Reclaiming the Shiawassee Flats: Monitoring During Hydrologic Restoration of the Shiawassee Flats Ecosystem

Abstract

In 2016, the US Fish and Wildlife Service (USFWS) completed the restoration of two new wetland units: Maankiki North (MN, opened in 2017) and Maankiki South (MS, opened in 2018) at the Shiawassee National Wildlife Refuge near Saginaw, Michigan. The Refuge sought to reconnect these units, formerly farmland, to the dynamic hydrology of the Shiawassee River, mimicking the function of this area’s historic floodplain complex. In early 2019, staff at the Shiawassee National Wildlife Refuge asked for support from students attending the University of Michigan School for Environment and Sustainability (SEAS) to aid in post-restoration monitoring of the biological conditions in the recently restored Maankiki units and Pool 1A, a wetland unit hydrologically reconnected to the Shiawassee River in 1958. Sampling in 2019 would complement pre-restoration research previously done by UM groups. Sampling techniques were modeled after the Great Lakes Coastal Wetland Monitoring Program and were used to create protocols to guide future studies. This report, organized by the abiotic and biotic factors investigated, represents the culmination of our team’s research. Water Quality describes the chemical, physical, and biological parameters used to measure the tolerance of the wetland units’ biological communities. ● Water quality varies by month, distance from the water control structure, vegetation type, and unit. ● Dissolved oxygen decreased throughout the season to levels unsafe for fish, likely due to warming temperatures. ● In the future, water quality monitoring should more closely reflect the GLCWMP methods, focus on nutrient testing, and more data collection from the Shiawassee River and Spaulding Drain. Vegetation identifies and compares the plant communities within and among wetland units and uses their diversity and abundance to evaluate wetland health. ● Calculations of importance values and dissimilarity indices show decreasing diversity from Maankiki South to Pool 1A to Maankiki North, which has a high abundance and density of invasive Typha. ● The Floristic Quality Assessment and Index of Biotic Integrity scored Maankiki South as ‘Medium Quality.’ Degradation increased from MS to Pool 1A to MN. ● Future research recommendations include the continued implementation of our monitoring protocol, managing the units’ flood duration and frequency to mimic the natural flow regime, and the harvesting of Typha biomass. Macroinvertebrates catalogs and compares indicator insect families in response to each unit’s water quality, vegetation types, and monthly variation. ● Communities changed throughout the summer following standard life-cycle trends. ● The majority of families found are known to be tolerant to the water quality conditions common to wetlands, such as high turbidity and low DO. ● Future management recommendations include the continued implementation of our monitoring protocol, the use of an elutriator while sampling, identifying individuals to genera, and more closely and accurately categorizing the unit’s substrates. Fish details the different gear types utilized to measure and compare the abundance, composition, and structure of fish communities and the environmental factors shaping these traits within and among units. ● Fish sampling included the use of multiple frame- and mesh-size fyke nets, gill nets, and electrofishing. ● The fish community contained no sensitive species. We found a mix of riverine and wetland species, in addition to abundant juvenile fish, that indicate the wetland units are used for spawning and refuge by species from both ecosystems. ● Future management recommendations include continued monitoring with multiple methods, tailoring methods to target species, and using minnow traps to catch smaller species and juveniles. We recommend continuous monitoring that incorporates the Shiawassee River and Spaulding Drain to understand how biological communities in the river are using the wetland units, and to provide a comparison of ecological function of restored wetlands to the river. Past, present, and future studies should be analyzed in combination to assist the Refuge in making science-based management decisions.