Perspective of the effect of caesium on nitrogen transport in the aquatic insect body of Kamimuria tibialis (Plecoptera) and Epeorus latifolium (Ephemeroptera)

Cs is absorbed into the insect body in a manner similar to K. However, the degree of Cs absorption and its physiological activity in the insect body differ from those of K. Following the Fukushima nuclear power plant accident, radiocaesium was eluted and accumulated in streams. Consequently, aquatic insects exhibited uptake of radiocaesium; such contamination may have affected their body construction. In this study, δ¹³C and δ¹⁵N values were compared between legs and heads of two aquatic insect species, Kamimuria tibialis and Epeorus latifolium, sampled in radiocaesium-contaminated and non-contaminated habitats. At the non-contaminated site, δ¹⁵N differed between legs and heads in both species, whereas at the contaminated site, δ¹⁵N values did not differ in K. tibialis. The disparity in δ¹⁵N between body parts in K. tibialis differed among sites and the difference was significant between contaminated and non-contaminated sites. The amino acid symport mechanism appears to differ between species and may be altered by the presence of Cs in K. tibialis, possibly because of their behavior, foraging modes, and the mobility of other contaminants in stream. The correlative results of this study may provide insight into the effects of radiocaesium on amino acid transport in the aquatic insect body.