title: Non-native gobies facilitate the transmission of Bucephalus polymorphus (Trematoda).
abstract: BACKGROUND
  Introduced species can modify local host-parasite dynamics by amplifying parasite infection which can 'spill-back' to the native fauna, whether they are competent hosts for local parasites, or by acting as parasite sinks with 'dilution' of infection decreasing the parasite burden of native hosts. Recently infection by the trematode Bucephalus polymorphus has increased in several European rivers, being attributed to the introduction of intermediate host species from the Ponto-Caspian region. Using a combination of field and experimental data, we evaluated the competence of non-native and native fish as intermediate hosts for B. polymorphus and its role for parasite development in a definitive host.
  
  
  METHODS
  The density of 0+ juvenile fish (the second intermediate hosts for B. polymorphus) was measured in the River Morava, Czech Republic and fish were screened for natural metacercariae infection. The stomach contents of predatory fish that are definitive hosts of B. polymorphus were examined to assess the importance of non-native gobies for parasite transmission. In semi-natural conditions, parasite establishment, initial survival, and maturity rates in experimentally infected definitive hosts pikeperch Sander lucioperca were measured in flukes recovered from native white bream Abramis bjoerkna and non-native tubenose goby Proterorhinus semilunaris and round goby Neogobius melanostomus. Adult fluke size and egg production was also measured to evaluate the potential effect of intermediate host species on parasite fitness.
  
  
  RESULTS
  We detected high natural infection parameters of B. polymorphus in native cyprinids and non-native gobies compared to data from the period prior to goby establishment. Both fish groups are consumed by predatory fish and represent a major component of the littoral fish community. Parasite establishment and adult size in definitive hosts was equivalent among the second intermediate host species, despite a lower size of metacercariae recovered from round gobies. However, development in the definitive host of flukes recovered from gobies was reduced, showing higher mortality, delayed maturity and lower egg production, in comparison with parasites from native hosts.
  
  
  CONCLUSIONS
  Substantial 'spill-back' of B. polymorphus due to higher transmission rates after establishment of non-native gobies was partially buffered by decreased fitness of B. polymorphus that underwent development in gobies.
authors.affiliation: Institute of Vertebrate Biology, v.v.i., Academy of Sciences of the Czech Republic, Květná 8, 603 65, Brno, Czech Republic. audrey@sci.muni.cz.
authors.forename: Markéta
authors.initials: M
authors.lastname: Ondračková
authors.affiliation: Institute of Vertebrate Biology, v.v.i., Academy of Sciences of the Czech Republic, Květná 8, 603 65, Brno, Czech Republic. iveta.hudcova1@gmail.com.
authors.forename: Iveta
authors.initials: I
authors.lastname: Hudcová
authors.affiliation: Institute of Vertebrate Biology, v.v.i., Academy of Sciences of the Czech Republic, Květná 8, 603 65, Brno, Czech Republic. martinad@sci.muni.cz.|Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37, Brno, Czech Republic. martinad@sci.muni.cz.
authors.forename: Martina
authors.initials: M
authors.lastname: Dávidová
authors.affiliation: Institute of Vertebrate Biology, v.v.i., Academy of Sciences of the Czech Republic, Květná 8, 603 65, Brno, Czech Republic. adamek@ivb.cz.
authors.forename: Zdeněk
authors.initials: Z
authors.lastname: Adámek
authors.affiliation: Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37, Brno, Czech Republic. kasa@post.cz.|Department of Parasitology, Faculty of Science, Charles University in Prague, Viničná 7, 128 44, Prague, Czech Republic. kasa@post.cz.
authors.forename: Martin
authors.initials: M
authors.lastname: Kašný
authors.affiliation: Institute of Vertebrate Biology, v.v.i., Academy of Sciences of the Czech Republic, Květná 8, 603 65, Brno, Czech Republic. jurajda@brno.cas.cz.
authors.forename: Pavel
authors.initials: P
authors.lastname: Jurajda
mesh_terms: D000818:Animals; D005393:Fish Diseases / Q000469:parasitology / Q000635:transmission*; D058865:Introduced Species; D008018:Life Cycle Stages; D010473:Perciformes / Q000469:parasitology*; D045483:Rivers; D014200:Trematoda / Q000254:growth & development / Q000502:physiology*