Species richness and diversity of macroparasite assemblages
were compared among American eels (Anguilla rostrata) from
Nova Scotia, European eels (A. anguilla) from the
United Kingdom (Kennedy, Bush & Aho, 1986; Esch et al. 1988;
Kennedy, 1990, 1993), and Australian eels (A. reinhardtii)
from Queensland (Kennedy, 1995). Community richness and
diversity of the macroparasite fauna of American and European eels
did not differ significantly for total parasite component
communities, intestinal parasite component communities, and
intestinal parasite infracommunities. The similarities in
richness and diversity between the parasite communities of American
and European eels are not surprising given the
common, recent origin of these sister species. However, differences
in species composition were noted between Nova
Scotia and the UK. Both species of eels were infected by a nearly
identical suite of specialists, but differences occurred
in the species number and composition of generalist parasites. In
addition, generalist species were rarely dominant in Nova
Scotia, but commonly so in the UK. These differences can be
attributed to the differences in the freshwater fish fauna
and their parasites that occur between Nova Scotia and the UK.
American and European eels are derived from a common
ancestor and, whereas they have carried with them a common suite
of specialist parasites during their brief period of
independence, they acquired different suites of generalists
apparently from their respective continental faunas after they
diverged. In contrast, parasite communities of American and
European eels were significantly less diverse and speciose
than those of Australian eels regardless of scale (total component
community, intestinal component community, intestinal
infracommunity). These results support the notion that parasite
communities have had more time to evolve and/or that
tropical conditions have promoted parasite speciation in Australian eels.