Trophic Relationship between the Parasitic Isopod Ichthyoxenus japonensis and the Fish Carassius auratus auratus As Revealed by Stable Isotopes

ABSTRACT

Stable carbon and nitrogen isotope analysis was used to investigate the host-parasite trophic relationship between the parasitic isopod Ichthyoxenus japonensis and one of its freshwater fish host Carassius auratus auratus from Lake Fuxian, China. No significant differences in δ¹³C and δ¹⁵N were observed between the heterosexual pairs of I. japonensis in the same host. δ¹³C and δ¹⁵N of I. japonensis were significantly lower than those of its host fish, and the isotopic ratios of the isopod increased with the increase of host fish isotopic signatures. Unlike isotopic fractionation patterns generally observed among consumers and their diets, isopod parasite was ¹³C and ¹⁵N depleted relative to the muscle tissue of this host fish. Differential isotopic fractionation patterns in the isopod parasite and the fish may be attributed to differences in parasite and host metabolism.