On the Improvement of the Environmental Conditions of a Freshwater Wetland for the Conservation of Water Striders Habitat

Abstract

We investigated the relationships between five species of water strider (Gerridae) and the environmental conditions in 70 freshwater wetlands in the Kinki district. The environmental conditions measured were phisical structure on/near shoreline, plant coverage on/above water surface, and landcover of adjacent area. Furthermore, the differences in the preference for oviposition substrates and in the oviposition site among the five speceis of water strider were clarified in the laboratory. It was suggested that occurrence of G. insularis and G.gracillicornis were dependent on the relative abundance of woody area surrounding the wetland, the crown coverage above the water surface, and the erath and sand on/near shoreline. On the other hand, occurrence of A.paludum, G.latiabdominis, and G.nepalensis seemed to be dependent on the plant coverage above the water surface, and the grown types of herbs and grasses. Based on these results, we discussed about the direction of improvement of environmental conditions of freshwater wetland for conservation of habitat of gerridae from the viewpoint of landscape architecture.