Spatial patterns in infection of cod Gadus morhua with the seal-associated liver worm Contracaecum osculatum sensu stricto from the Skagerrak to the central Baltic Sea
Fish serve as transport hosts to a range of parasites, with potential negative effects on fish health. In the Baltic Sea, the grey seal Halichoerus grypus (Fabricius) population has increased markedly since the early 2000s. H. grypus is the main final host to the liver worm Contracaecum osculatum (R...
| Published in: | Marine Ecology Progress Series |
|---|---|
| Main Authors: | , , , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
2018
|
| Subjects: | |
| Online Access: | https://orbit.dtu.dk/en/publications/542e74ae-922c-43eb-ad5b-d99990d18f05 https://doi.org/10.3354/meps12773 https://backend.orbit.dtu.dk/ws/files/161469210/Publishers_version.pdf |
| Summary: | Fish serve as transport hosts to a range of parasites, with potential negative effects on fish health. In the Baltic Sea, the grey seal Halichoerus grypus (Fabricius) population has increased markedly since the early 2000s. H. grypus is the main final host to the liver worm Contracaecum osculatum (Rudolphi, 1802), a parasitic nematode to which cod Gadus morhua (Linnaeus) is one of several transport hosts. Recent investigations have shown a marked increase in prevalence and abundance of infection of this parasite in livers of G. morhua inhabiting the central Baltic Sea. Yet no recent knowledge exists on levels of C. osculatum infection in G. morhua in adjacent areas. We investigated spatial differences in prevalence and abundance of this parasitic nematode in livers of G. morhua, covering a transect consisting of 9 areas from the Skagerrak to the eastern part of the central Baltic Sea. We further provide survey data of local abundances of H. grypus and harbor seal Phoca vitulina (Linnaeus) throughout this transect. Prevalence and abundance of C. osculatum sensu stricto in G. morhua livers differed significantly between east and west, with highest levels of infection occurring in the low-salinity central Baltic areas. Highly infected fish in the east had significantly lower condition factor than their westerly, less infected conspecifics. Spatial differences in local seal abundance and seal species, salinity and feeding ecology may explain the observed differences in C. osculatum infection between eastern and western G. morhua |
|---|