Within-lake dynamics in the similarity of parasite assemblages of perch (Perca fluviatilis).

Although parasite communities have been studied extensively in recent years, spatial and temporal variation in factors affecting the communities has received less attention. This paper examined the similarity of parasite assemblages of perch (Perca fluviatilis) in 18 locations within a single lake in relation to geographical distance and temporal dynamics in the host and parasite populations. We expected that in the present study-scale where distinct but potentially interacting host subpopulations could occur, similarity of the assemblages could be affected by seasonal dynamics in host movements particularly during the spawning period. Parasite species showed differences in infection levels between the sampling locations and similarity of the assemblages of autogenic parasite species in winter, measured inversely as difference in parasite numbers, was negatively affected by geographical distance between the locations. However, no such relationship was observed in the allogenic species Ichthyocotylurus variegata. Furthermore, no relationship was found either in autogenic parasites when the locations were re-sampled in summer, after the spawning period of perch. We concluded that the effect of geographical distance on the similarity of parasite assemblages is a dynamic process, which is affected by seasonal dynamics in host and parasite populations.