The beauty spot is part of the Berwyn Mountains site of special scientific interest, whose protected moors provide idealhabitat for rare birds such as the hen harrier and the black grouse.
Authorities have built a fence in the Fort Wayne area to prevent the carp from migrating from the Wabash to the headwaters of the Maumee River, a Lake Erie tributary regarded as ideal spawning habitat.
Dr Clay's reasoning is that changes made to the vegetation of the eastern United States over the past century have created a habitat that is ideal for cicadas.