A new study published in the Journal of Helminthology by researchers from the Estonian University of Life Sciences and the Swedish University of Agricultural Sciences has found that migratory birds may carry fewer Diplostomum parasites between North Atlantic islands than previously thought. The research, conducted across Greenland and the Faroe Islands, challenges the belief that these birds effectively transport parasites over long distances.
Limited Dispersal of Diplostomum Parasites
The international research team explored the diversity and distribution of Diplostomum parasites infecting freshwater salmonids. Using modern DNA metabarcoding, they discovered that while infections were common in Arctic char and Atlantic salmon in Greenland, no infections were found in brown trout or Atlantic salmon from the Faroe Islands.
This stark contrast indicates that migratory birds are not always reliable vectors for parasite dispersal. The findings suggest that ecological factors and the complex life cycles of parasites may limit their spread across different ecosystems.
Implications for Parasite Ecology
The findings reveal a significant split between parasite communities in Greenland and those in North America, Iceland, and Northern Europe. As Alfonso Díaz-Suarez, the first author of the study, noted, "Given the extensive movements of migratory birds across the North Atlantic, we initially expected much greater overlap in parasite communities among North Atlantic islands." Instead, the research indicates limited exchange of parasites despite the presence of mobile hosts.
The researchers propose that a short transmission season, occurring only during the breeding season of avian hosts in the Arctic, may restrict opportunities for parasite colonization between islands. Specific migration routes and host distribution further contribute to this limited dispersal.
