Waxing and waning slacks: The changing ecohydrology of interdunal wetlands/slacks in a Lake Michigan coastal dune complex during rising Lake Michigan-Huron levels

Since 2016 we have studied the largest interdunal wetlands/slack lying within a deflated parabolic dune east of Lake Michigan. Geologic cross-sections show ? 15 m sand and gravel beneath dunes , creating an aquifer hydraulically connecting Michigan-Huron (MH) with water table/shallow groundwater influencing slack. levels risen 1 from to 2020, increasing around slack m. Color-infrared images vegetation quadrat sampling appearing, then significantly expanding main upland/dune transitioning wetland in response this rise. Monitoring well data rise spring as MH rises. Levels drop growing season begins while continues through summer. Short-term level increases occur due local rain events, but significant declines follow evapotranspiration . Slack begin again late summer into fall end arrives, decreases, heavier, more frequent events occur. Together, these factors push their highest point year are decreasing. In fall–winter, concert levels. Climate change effects, increased transpiration higher temperatures, drought, greater variability lake fluctuations, may make it difficult maintain wet conditions for hydrophytic vegetation. Hence, climate poses risks existence imperiled ecosystem.