Communities of parasites of freshwater fish of Jersey, Channel Islands

The parasite faunas of 12 species of freshwater fish from 17 localities on the island of Jersey were examined. Comparison of the species composition, number, diversity and equitability of the parasite fauna of each species of fish in each locality revealed that community diversity was always low, that most communities were dominated by a single species of parasite, and that community similarity between host species, and often between sites, was generally low. This was not related to unavailability or distribution of potential, invertebrate, intermediate host species, but appeared to be due to chance colonization events. With two exceptions, little exchange of parasites took place between host species, despite vacant niches in the parasite communities and the absence of competitors, and normal parasite specificity was maintained. Comparison of the parasite communities with those on other oceanic islands suggests that they are poorer than would be predicted by island biogeographical theory, and that this is not a very good predictor of parasite community richness on oceanic islands.