Abstract
We investigated the relationship between the population densities of aquatic animals and environmental characteristics of abandoned ponds in Aina, Kobe-City, Hyogo Prefecture. The main results are as follows:
(1) The most abundant aquatic animal in this area is crayfish. Populations of crayfish in irrigation ponds are larger during winter compared to summer.
(2) As the surface area of each irrigation pond decreases, the ratio of the crayfish per square meter increases.
(3) The geographical range of crayfish in these irrigation ponds shows characteristics of the naturalization process.
