Parasite assemblages of crucian carp (Carassius carassius)--is depauperate composition explained by lack of parasite exchange, extreme environmental conditions or host unsuitability?
Recent studies on parasite communities have considered the factors which contribute to variability in parasite infections among populations of one host species. This paper examined parasite assemblages of crucian carp (Carassius carassius) in a natural set-up of two distinctive environments inhabited by the same host species and differing in respect to composition of other fish species: ponds, where extreme conditions prevent other fish species from occurring and lakes, where crucian carp coexist with other fish species. Our aim was to evaluate the significance of parasite exchange, environmental conditions and host suitability for the depauperate parasite assemblages observed in pond crucian carp. As predicted, crucian carp had more diverse parasite species composition in lakes, which supports the hypotheses of increased opportunities for parasite exchange with other fish species and better environmental conditions for the parasites. However, for instance, diplostomids were found only from few fish individuals in very low numbers. Experimental exposure trials with the eye fluke Diplostomum spathaceum in the laboratory indicated that crucian carp were totally resistant to infection, which is exceptional and suggests that the low number of these parasites in crucian carp was due to physiological unsuitability of the host. To obtain a better understanding on the mechanisms underlying the formation of parasite assemblages in these fish, further studies on the relationships between the unique physiology of crucian carp and infection success by other parasite species are needed.
Karvonen
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A
Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland. anskarv@bytl.jyu.fi
Bagge
A M
AM
Valtonen
E T
ET
D000049:Acanthocephala / Q000502:physiology; D000818:Animals; D002347:Carps / Q000469:parasitology*; D003445:Crustacea / Q000502:physiology; D003710:Demography; D017753:Ecosystem; D005387:Finland; D005393:Fish Diseases / Q000469:parasitology*; D006790:Host-Parasite Interactions; D008974:Mollusca / Q000502:physiology; D009348:Nematoda / Q000502:physiology; D015995:Prevalence; D014200:Trematoda / Q000502:physiology