RICHNESS AND DIVERSITY OF HELMINTH PARASITE COMMUNITIES IN THE COMMONCARP AND IN 3 MORE RECENTLY INTRODUCED CARP SPECIES

It can be predicted that common carp Cyprinus carpio, as an introduced species, would harbour poor helminth infra-communities but that these would nevertheless re richer than those in three other species of car ps introduced into Europe in recent decades. These predictions were te sted by comparing the helminth infra-communities of common carp, Cteno pharyngodon idella, Hypophthalmichthys molitrix and Aristichthys nobil is reared under similar conditions in a fish farm. Data were presented on species richness of total helminth infra-communities, and on richn ess and diversity of gill, eye and intestinal infra-communities separa tely. These confirmed that common carp helminth infra-communities were poor and that they were no richer than those of the three other speci es of carp. This situation in the farm was considered to be representa tive of the situation in natural habitats in Europe. It is suggested t hat the poor infra-communities in common carp reflect the facts that t heir helminth communities are composed mainly of specialists, that the y are not readily susceptible io invasion by specialists of other fish hosts and that, as introduced species, they have not had sufficient t ime to acquire many generalist helminths from native species of fish. The difference in time between the introduction of common carp into Eu rope centuries ago and the introduction of the other three species of carps decades ago is not sufficient to produce any significant differe nces in the richness and diversity of their helminth infra-communities . (C) 1996 The Fisheries Society of the British Isles