Helminth parasites in the alien Lepomis gibbosus (L.) (Centrarchidae) from the Lake Atanasovsko Wetlands, Bulgaria: survey of species and structure of helminth communities.
A helminthological survey of the alien Pumpkinseed Sunfish, Lepomis gibbosus (L.), from the Lake Atanasovsko Wetlands, Bulgarian Black Sea coast, is based on the examination of 107 host individuals studied in spring, summer and autumn of 2012 and 2013. Six helminth species are recorded: metacercariae of Posthodiplostomum centrarchi Hoffman, 1958 with prevalence (P) 8.41%, mean intensity (MI) 1.88 and mean abundance (MA) 0.16; monogeneans Onchocleidus similis Mueller, 1936 (P 31.78%, MI 4.41, MA 1.40) and O. dispar Mueller, 1936 (P 3.74%, MI 1.00, MA 0.04), both specific parasites of centrarchids; adult liver nematode Schulmanela petruschewskii (Shulman, 1948) (P 3.74%, MI 17.74, MA 0.66); larvae of nematodes Spiroxys contortus (Rudolphi, 1819) (P 10.28%, MI 2.90, MA 0.30) parasitic as adults in pond turtles and Contracaecum sp. (P 1.87%, MI 1.00, MA 0.02) parasitic as adults in fish-eating birds. Though L. gibbosus harbours three alien parasites (P. centrarchi, O. similis and O. dispar), there is no evidence for spillover infections in fishes in the Lake Atanasovsko Wetlands. However, its negative impact on native populations might be by parasite spillback (participation in life cycles of native parasites in fishes, reptiles and birds). Helminth component communities and infracommunities studied have lower species richness, diversity and abundance compared to those in the host's native range, which is consistent with the Enemy Release Hypothesis.