Bathymetry and water levels in lagoonal wetlands of the Apostle Islands National Lakeshore

Session: Poster Session

Shelly Ray, Mary Griggs Burke Center for Freshwater Innovation, [email protected]
Olivia Anderson, Northland College, Mary Griggs Burke Center For Freshwater Innovation, [email protected]
Matthew Cooper, Northland College, Mary Griggs Burke Center for Freshwater Innovation, [email protected]

Abstract

Lagoonal wetlands of the Apostle Islands in Lake Superior form within a dynamic coastal setting. Surface connections between the wetlands and Lake Superior vary from open river mouths to transient sand barriers that open and close periodically, to more stable sand barriers that remain closed for long periods. Accordingly, wetland hydrology is influenced to varying degrees by Lake Superior, direct precipitation, and groundwater inputs. To better understand water levels and inundation patterns in Apostle Island lagoons, we conducted bathymetric surveys and collected high temporal resolution water level data at seven wetlands throughout the summer and fall of 2017. Bathymetric data were interpolated to produce bathymetric maps over which wetland water level data were modelled.  Preliminary results suggest multiple water level regimes and inundation patterns driven primarily by the stability of lake-lagoon sand barriers as well as conductance through the barriers themselves. Understanding how wetland water levels and bathymetry influence inundation patterns could improve our understanding of how biotic communities are structured in these habitats.  Since Apostle Islands lagoons may serve as reference ecosystems to which other Lake Superior lagoonal systems are compared, understanding lake-wetland connections and inundations patterns is important.