Abstract
Trophic relationships between four taxa of fish parasite (Cestoda, Nematoda, Isopoda, Copepoda) and their hosts ( Gasterosteus aculeatus, Merlangius merlangus, Boops boops, Platichthys flesus ) were investigated using stable isotopes of carbon and nitrogen. δ 15 N differences between parasite and host were unlike those conventionally observed among consumers and their diets. In no case were parasites enriched in 15N with respect to the host organism; endoparasites were significantly and consistently depleted. In no case were parasites enriched in 15N with respect to the host organism; endoparasites were significantly and consistently depleted.