Infection of American Eels By the Invasive Swimbladder Parasite Anguillicoloides Crassus in South Carolina

A year-round survey of American eels, Anguilla rostrata, was performed in South Carolina (SC), USA 15 years after the first infection by the nematode Anguillicoloides crassus was reported from Winyah Bay, SC.  Prevalence, intensity, and abundance of A. crassus were determined. Overall, infection levels were higher than previous reports for eels in SC but comparable to more recent reports from other areas in North America.  An integrative analysis was performed to determine if infection parameters varied with biotic and abiotic factors including time of year, sampling locations, eel total length, and salinity.   The lack of seasonal effects on infection by the adult worm stage contrasts with studies from higher latitudes in North America and Europe and may be due to the warmer winter temperatures in southern latitudes. Significant variation in infection among localities reflects possible differences in abundance of intermediate and/or paratenic hosts and highlights the importance of identifying such hosts in North America.