Sharing Is Caring?—Pathogens and Pathogen-Specific Antibodies in Arctic Endemic Seal Species and the Newly Sympatric Harbor Seals in Kongsfjorden, Svalbard

Abstract

Climate change associated transformations of Arctic marine ecosystems are having detrimental impacts on Arctic endemic marine mammals. However, warming conditions are providing new habitats for temperate marine mammals, some of which are expanding into Arctic regions, posing a threat of novel pathogen introduction and disease transmission. We analyzed swab samples for Influenza A, morbilli- (Phocine distemper virus, PDV), and herpesvirus nucleic acid and performed microbiological screenings and serological analyses for antibodies for the same viral pathogens, the bacterial agents Brucella spp. and Leptospira spp. and the protozoan parasite Toxoplasma (T.) gondii from ringed (Pusa hispida), bearded (Erignathus barbatus), and the newly established harbor seals (Phoca vitulina) in Kongsfjorden, Svalbard. Antibodies against Phocine Herpesvirus-1 or antigenetically related phocine herpesviruses (PhHV) were detected in all species. Antibodies against Influenza A were only found in one ringed seal and antibodies against PDV were found in two harbor seals. Twelve harbor seals and two ringed seals tested positive for Herpesvirus DNA by PCR. Brucella spp. and Leptospira spp. antibodies were detected in multiple harbor seals and a single bearded seal. Three harbor, two ringed, and one bearded seal had antibodies against T. gondii. Our results indicate an overlap and possible transmission of pathogens between all investigated seal species. The introduction of new pathogens to the Arctic through temperate species' range expansions could have fatal consequences for immunologically naive Arctic seal populations and should be further investigated.