BACKGROUND: Recently, human intervention enabled the introduction of Barbus barbus from the Rhône River basin into the Barbus meridionalis habitats of the Argens River. After an introduction event, parasite loss and lower infection can be expected in non-native hosts in contrast to native species. Still, native species might be endangered by hybridization with the incomer and the introduction of novel parasite species. In our study, we aimed to examine metazoan parasite communities in Barbus spp. populations in France, with a special emphasis on the potential threat posed by the introduction of novel parasite species by invasive B. barbus to local B. meridionalis. METHODS: Metazoan parasite communities were examined in B. barbus, B. meridionalis and their hybrids in three river basins in France. Microsatellites were used for the species identification of individual fish. Parasite abundance, prevalence, and species richness were compared. Effects of different factors on parasite infection levels and species richness were tested using GLM. RESULTS: Metazoan parasites followed the expansion range of B. barbus and confirmed its introduction into the Argens River. Here, the significantly lower parasite number and lower levels of infection found in B. barbus in contrast to B. barbus from the Rhône River supports the enemy release hypothesis. Barbus barbus × B. meridionalis hybridization in the Argens River basin was confirmed using both microsatellites and metazoan parasites, as hybrids were infected by parasites of both parental taxa. Trend towards higher parasite diversity in hybrids when compared to parental taxa, and similarity between parasite communities from the Barbus hybrid zone suggest that hybrids might represent "bridges" for parasite infection between B. barbus and B. meridionalis. Risk of parasite transmission from less parasitized B. barbus to more parasitized B. meridionalis indicated from our study in the Argens River might be enhanced in time as higher infection levels in B. barbus from the Rhône River were revealed. Hybrid susceptibility to metazoan parasites varied among the populations and is probably driven by host-parasite interactions and environmental forces. CONCLUSIONS: Scientific attention should be paid to the threatened status of the endemic B. meridionalis, which is endangered by hybridization with the invasive B. barbus, i.e. by genetic introgression and parasite transmission.

• Keywords
• Biological invasion, Cyprinid fish, Hybridization, Metazoan parasite communities,
• MeSH
• Biodiversity * MeSH
• Chimera classification   genetics   growth & development   parasitology   MeSH
• Cyprinidae classification   genetics   growth & development   parasitology   MeSH
• Microsatellite Repeats MeSH
• Parasite Load MeSH
• Parasites classification   isolation & purification   MeSH
• Rivers MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• France MeSH

The seasonal dynamics of Gyrodactylus rhodei, a monogenean ectoparasite of bitterling (Rhodeus sericeus), was studied from June 2000 to May 2001 in the Kyjovka River, Czech Republic. A negative relationship between prevalence and intensity of infection of G. rhodei and water temperature was found. Metrical variability of the hard parts of the parasite haptor was studied throughout the sampling season. A negative relationship between water temperature and the size of the hard parts of the G. rhodei haptor was evident in the measurements of the total length of the marginal hooks, the sickle length of marginal hooks, anchors, anchor point and root, the width of the ventral bar and the membrane processes. Sequences of the partial ITS (rDNA) of specimens collected during the cold and warm seasons were analysed. Sequences of all studied parasite specimens were identical and there was no evidence of intraspecific variability in the sequenced region.

• MeSH
• Cyprinidae parasitology   MeSH
• DNA, Helminth analysis   MeSH
• Genetic Variation MeSH
• Trematode Infections epidemiology   parasitology   veterinary   MeSH
• DNA, Ribosomal Spacer analysis   MeSH
• Fish Diseases epidemiology   parasitology   MeSH
• Seasons * MeSH
• Sequence Analysis, DNA MeSH
• Trematoda * anatomy & histology   classification   genetics   isolation & purification   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• DNA, Helminth MeSH
• DNA, Ribosomal Spacer MeSH