|| 要旨トップ | 目次 |||日本生態学会第63回全国大会 (2016年3月、仙台) 講演要旨
一般講演（ポスター発表） P2-464 (Poster presentation)
Contrary to a general rule of stable isotope trophic enrichment, parasites show great variation in isotope fractionation from isotope signatures of their host muscle tissues. One of possible mechanisms is that isotopic variation among host tissues may cause apparent deviation from the actual isotope fractionation between a parasite and a given host tissue consumed by the parasite. To test this possibility, we measured δ15 N and δ 13C for some fish parasites and a variety of their host tissues to estimate their actual trophic enrichment factors (Δ15Ν and Δ13C). All of trematodes investigated showed positive Δ15Ν and nearly zero Δ13C values. Cestodes and nematodes showed great variations in their Δ15Ν and Δ13C, which range from -3.27 to +3.45, when they were compared to a particular tissue/mucus. Acanthocephalans showed negative Δ15Ν and Δ13C in comparison with host intestinal mucus, and a crustacean had isotope ratios similar to those of host blood. Moreover, there were variations in Δ15Ν and Δ13C among taxa of intestinal parasites. These results suggested that atypical δ 15N and δ 13C enrichment of parasites is not caused by the variation of δ 15N and δ 13C among host tissues, but possibly by metabolic processes unique to parasites.