Upper Midwestern Amphibian Populations Fish introductions affect amphibian populations by making historical amphibian breeding sites, such as permanent wetlands, uninhabitable. Aquacultural practices adversely affect amphibian populations.
Weirs allow fishes direct access to fringing wetlands.
Introduced bullfrogs affect populations of smaller vertebrates, including other amphibians. Dredging and aeration of basins facilitate colonization of wetlands by fishes, over and above direct introductions. Applications of the herbicide aquazine favor algal-dominated ecosystems and affect the community structure of both the algal and the invertebrate prey base. This distinction has ecological consequences. Fishes prey preferentially on red zooplankton and therefore contribute to a decrease in zooplankton abundance, invertebrate species diversity, and overall wetland productivity.