On the banks of the Red Cedar: toward socio-ecologically robust riparian management in an iconic Michigan river

Abstract

Land use is continually evolving in river watersheds and riparian zones, particularly in areas containing dense human populations requiring infrastructure development. Land use planners in south-central Michigan, USA, are challenged to balance infrastructure needs with the ecological integrity of the iconic Red Cedar River, which flows through the Michigan state capital (Lansing) and surrounding suburban and rural areas and supports freshwater diatoms, mussels, fishes, and other organisms. Although land use goals in the Red Cedar River watershed include protecting riverine biodiversity, decision-makers need a systematic method for predicting and mitigating effects of land use change on the river ecosystem. We developed a framework for evaluating habitat associations of diatoms and native unionid mussels in the Red Cedar River using field collections and mixed-effects modeling to facilitate socio-ecologically informed riparian management. Diatoms were significantly more abundant and genus-rich in riffles and pools than runs, whereas mussels were more abundant in riffles than pools, with intermediate run abundance. Diatom relative abundance was most affected by pH (+ effect), depth (+), and water temperature (+), similar to diatom genus richness (pH and depth +). Mussel relative abundance was best explained by depth (–), pH (+), and percent forest cover (+), similar to mussel length (depth +, pH –). Results from this study underscore riparian management strategies for optimizing forest cover, depth, and pH to promote ecologically favorable conditions for diatoms and mussels in the Red Cedar River (e.g. stable, near-neutral pH; diverse tree species with ≥60% forest cover). Advancing understanding of aquatic biota and their habitats, this research provides a foundation for socio-ecologically balanced land use planning in the Red Cedar River and other riverine ecosystems.

Keywords

• Diatoms
• land use
• land use planning
• Red Cedar River
• unionid mussels