Distance decay of similarity among parasite communities of three marine invertebrate hosts

David W. Thieltges, MacNeill A. D. Ferguson, Cathy S. Jones, Manuela Krakau, Xavier de Montaudouin, Leslie R. Noble, Karsten Reise, Robert Poulin

Research output: Contribution to journalArticlepeer-review

52 Citations (Scopus)


The similarity in species composition between two communities generally decays as a function of increasing distance between them. Parasite communities in vertebrate definitive hosts follow this pattern but the respective relationship in intermediate invertebrate hosts of parasites with complex life cycles is unknown. In intermediate hosts, parasite communities are affected not only by the varying vagility of their definitive hosts (dispersing infective propagules) but also by the necessary coincidence of all their hosts in environmentally suitable localities. As intermediate hosts often hardly move they do not contribute to parasite dispersal. Hence, their parasite assemblages may decrease faster in similarity with increasing distance than those in highly mobile vertebrate definitive hosts. We use published field survey data to investigate distance decay of similarity in trematode communities from three prominent coastal molluscs of the Eastern North-Atlantic: the gastropods Littorina littorea and Hydrobia ulvae, and the bivalve Cerastoderma edule. We found that the similarity of trematode communities in all three hosts decayed with distance, independently of local sampling effort, and whether or not the parasites used the mollusc as first or second intermediate host in their life cycle. In H. ulvae, the halving distance (i.e. the distance that halves the similarity from its initial similarity at 1 km distance) for the trematode species using birds as definitive hosts was approximately two to three times larger than for species using fish. The initial similarities (estimated at 1 km distance) among trematode communities were relatively higher, whereas mean halving distances were lower, compared to published values for parasite communities in vertebrate hosts. We conclude that the vagility of definitive hosts accounts for a high similarity at the local scale, while the strong decay of similarity across regions is a consequence of the low probability that all necessary hosts and suitable environmental conditions coincide on a large scale.

Original languageEnglish
Pages (from-to)163-173
Number of pages11
Issue number1
Early online date3 Feb 2009
Publication statusPublished - May 2009


  • faunal similarity
  • geographical distance
  • intermediate host
  • parasite
  • species richness
  • littorina-littorea
  • cerastoderma-edule
  • Baltic Sea
  • spatial heterogeneity
  • metazoan parasites
  • intertidal bivalve
  • larval trematodes
  • digenean larvae
  • West-Coast


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