Round & Tubenose Goby Parasites
Recent invasion theory has hypothesized that newly established exotic species may initially be free of their native parasites, augmenting their population success. Others have hypothesized that invaders may introduce exotic parasites to native species and/or may become hosts to native parasites in their new habitats. Our study analyzed the parasites of two exotic Eurasian gobies established in the Great Lakes since 1990: the round goby Neogobius malanostomus and the tubenose goby Proterorhinus semilunaris. We compared our results from the central region of their exotic ranges in Lakes Huron, St. Clair, and Erie with other studies in the Great Lakes and their Eurasian native and nonindigenous habitats. Results showed that goby-specific metazoan parasites were absent in the Great Lakes, and all but one species were larvae, suggesting that adults are presently poorly-adapted to the new gobies as hosts. Seven parasitic species are known to infest the tubenose goby in the Great Lakes, including our new finding of the acanthocephalan Southwellina hispida, and all are rare. We provide the first descriptions of four parasite species in the round goby and clarified two others, totaling 22 in the Great Lakes – with most being rare. In contrast, 72 round goby parasites occur in the Black Sea region. Studies reveal no overall increases in their Great Lakes parasitism over the past 1 ½ decades since the introductions. Trematodes are their most common parasitic group in the Great Lakes, as in their native Black Sea range and Baltic Sea introduction. Holarctic trematode Diplostomum spathaceum larvae were found in round goby eyes from all Great Lakes localities except Lake Huron proper, which are one of two widely-distributed species shared with Eurasia. In conclusion, the parasite “load” on the invasive round goby appears relatively low compared with that in native habitats, lending support to the “enemy release hypothesis”.
Neochasmus umbellus metacercaria. Round gobies in the Great Lakes are a new intermediate host for this species. However, they may be a dead end for the parasites, as they may not be able to complete their life cycle when using round gobies as a host.
Y. Kvach & C. A. Stepien. 2008b. Metazoan parasites of exotic round and tubenose gobies in the Great Lakes: Support for the "enemy release hypothesis". Journal of Great Lakes Research 34:23-35.