摘要:Abstract Stable isotopes of carbon and nitrogen characterize trophic relationships in predator–prey relationships, with clear differences between consumer and diet (discrimination factor Δ 13 C and Δ 15 N). However, parasite–host isotopic relationships remain unclear, with Δ 13 C and Δ 15 N remaining incompletely characterized, especially for helminths. In this study, we used stable isotopes to determine discrimination factors for 13 parasite–host pairings of helminths in coral reef fish. Differences in Δ 15 N values grouped according to parasite groups and habitat within the host with positive Δ 15 N values observed for trematodes and nematodes from the digestive tract and variable Δ 15 N values observed for cestodes and nematodes from the general cavity. Furthermore, Δ 13 C values showed more complex patterns with no effect of parasite group or habitat within host. A negative relationship was observed between Δ 15 N and host δ 15 N values among different host-parasite pairings as well as within 7 out of the 13 pairings, indicating that host metabolic processing affects host-parasite discrimination values. In contrast, no relationships were observed for Δ 13 C values. Our results indicate that parasite group, habitat within host, and host stable isotope value drive Δ 15 N of helminths in coral reef fish while their effect on Δ 13 C is more idiosyncratic. These results call for use of taxon- or species-specific and scaled framework for bulk stable isotopes in the trophic ecology of parasites.
其他摘要:Abstract Stable isotopes of carbon and nitrogen characterize trophic relationships in predator–prey relationships, with clear differences between consumer and diet (discrimination factor Δ 13 C and Δ 15 N). However, parasite–host isotopic relationships remain unclear, with Δ 13 C and Δ 15 N remaining incompletely characterized, especially for helminths. In this study, we used stable isotopes to determine discrimination factors for 13 parasite–host pairings of helminths in coral reef fish. Differences in Δ 15 N values grouped according to parasite groups and habitat within the host with positive Δ 15 N values observed for trematodes and nematodes from the digestive tract and variable Δ 15 N values observed for cestodes and nematodes from the general cavity. Furthermore, Δ 13 C values showed more complex patterns with no effect of parasite group or habitat within host. A negative relationship was observed between Δ 15 N and host δ 15 N values among different host-parasite pairings as well as within 7 out of the 13 pairings, indicating that host metabolic processing affects host-parasite discrimination values. In contrast, no relationships were observed for Δ 13 C values. Our results indicate that parasite group, habitat within host, and host stable isotope value drive Δ 15 N of helminths in coral reef fish while their effect on Δ 13 C is more idiosyncratic. These results call for use of taxon- or species-specific and scaled framework for bulk stable isotopes in the trophic ecology of parasites.