Healthy Great Lakes coastal wetlands provide essential habitat for diverse native fishes, in addition to serving as a refuge for zooplankton and other invertebrates that are the base of the food web. However, ecosystem services provided by these wetlands have been degraded by cultural eutrophication as well as altered hydrology, which has facilitated colonization by invasive Typha species. Typha is known to alter biogeochemical processes and native species structure through the formation of dense mats that block access to occupiable habitat and create hypoxic and anoxic conditions for aquatic species. To combat this expansion and prevent future blockages from forming, the U.S. Army Corp of Engineers, in partnership with the EPA and U.S. Fish and Wildlife Service, excavated channels and potholes in Braddock Bay to create more accessible habitat. Similar initiatives were later taken to replicate this course of action at Buck and Cranberry Pond sites.
The goal of our research was to compare water quality, trophic state, and zooplankton abundance and composition in restored versus reference habitats in each of these 3 wetlands. In June and July of 2024, we used standardized protocols to sample water chemistry (e.g., temperature, dissolved oxygen, specific conductivity, pH, oxidative-reductive potential, chlorophyll a, total nitrogen and phosphorus) and zooplankton. We sampled 8-10 sites per wetland, with sites classified as “reference”; “restored” channels; “potholes”; and “open water”. We also deployed dissolved oxygen dataloggers to monitor fluctuations in concentrations over a 3-day period in restored, reference, and pothole sites at each wetland. In general, dissolved oxygen concentrations were highest in restored versus reference habitats across all 3 wetlands. We also observed lower mean total phosphorus and chlorophyll a concentrations in restored channels at Braddock Bay, relative to concentrations observed in Braddock Bay reference sites as well as for the other 2 wetlands. Preliminary results suggest restored channels play an important role in maintaining water quality and overall ecosystem health. Future analysis will compare zooplankton abundance and composition patterns across sites for each of the 3 wetlands.
