Metapopulation and community dynamics of helminth parasites of eels Anguilla anguilla in the River Exe system

The possibility that much of the spatial and temporal variation in helminth communities in freshwater fish can he explained in terms of metapopulation theory. was tested by examining helminth component communities of eels sam pled from 3 localities in the River Exe and 5 of its tributaries on 2 occas ions at an interval of 3) ears. Four specific predictions of metapopulation theory in relation to community. dynamics were tested. The prediction that parasite species could be recognized as common and rare and that this was sensitive to scale was met. The prediction that core species would be more widely distributed and hale a higher dispersal ability was met only in part . The prediction that similarity between communities would increase with co nnectivity and decrease with distance apart was not met. The final predicti on that species would go locally extinct and be replaced by rescue effects was not met. There was evidence of local extinctions; not of eel specialist s but of species using other fish species as their principal definitive hos ts. Eel helminth communities were heavily dominated by 3 species of eel spe cialists which were relatively stable and responsible for most of the simil arity and its changes in space and time. It was concluded that metapopulati on theory did not provide a very satisfactory explanation for the changes i n the helminth communities in eels and reasons for this included the inhere nt difficult) of applying metapopulation theory to parasites and the fact t hat the helminth communities in eels in the River Exe were atypical in bein g dominated by eel specialists.