Cladoceran Subfossils as indicators of ecosystem responses to multiple stressors in Lake Ontario (Canada) Coastal Wetlands

This thesis explores the use of Cladocera (Branchiopoda, Crustacea) subfossil remains preserved in sediment cores as potential ecological indicators of wetland health in three coastal wetlands of Lake Ontario (Canada). Great Lakes coastal wetlands are crucial for supporting wildlife and filtering pollutants and sediments from water. As watershed development intensifies, anthropogenic stressors impacting wetland health since European settlement in ~1850 remain a fundamental concern. Subfossil Cladocera were analyzed in McLaughlin Bay (Oshawa), Cootes Paradise (Hamilton), and Jordan Harbour (Lincoln). Subfossil Cladocera assemblage changes, particularly decreases in the abundances of littoral taxa, appeared to track declines in aquatic macrophyte coverage resulting from invasive carp, high turbidity, and poor water quality. Some evidence of recent ecosystem recovery was evident in Jordan Harbour, but not in McLaughlin Bay or Cootes Paradise. Overall, paleolimnological approaches can provide a historical context to guide future management and restoration of Great Lakes coastal wetlands.