Abstract
We analyzed carbon stable isotope ratio (σ13C) of spiders (Arachnida) which were caught nearby farm ditches and a levee in a paddy field at hill bottom (katsuda) with their life types.σ13C of web-builder spiders was 26.0%0, which indicated that they have been greatly affected by insects emerged from the ditches that had depended on the organic matter supplied from village forest (Satoyama).σ13C and its distribution of long jawed water spiders (Tetragnatha maxillosa) was approximately equal to silver vlei spiders (Leucauge magnica). That suggested that both of spiders depended on the same food resources. Although σ13C of phytophilous hunting spiders was close to the web-building type, the standard deviation was higher than that.σ13C of epigaeic hunting spiders was 22.2%0, which indicated that C4 plants rose σ13C value of the spiders. It was suggested that σ13C of epigaeic hunting spiders lay in close relation with the rate of C4 plants to the hole plants on the levee and approximately one third of carbon in their bodies was derived from C4 plants. We revealed diversity of material flow in creatures by carbon stable isotope ratio in the area of Iatsuda ditches, which is the ecotone between Satovanur and a paddy field.
