Early Infection of Newly Recruited American Eels By an Invasive Swimbladder Parasite in a South Carolina Estuary
This study examined A. crassus infection over a ten month period in more than 400 glass and elver eels collected from a dammed creek near Charleston, SC. Parasite prevalence varied significantly with eel size (total length) and time of year. From March to July, the smallest eels (~30 mm) were uninfected, but parasite prevalence increased to ~100% in eels greater than 130 mm. From August – December, when fewer eels were found, parasite prevalence was generally lower and it was less dependent on eel size (although the smallest eel sizes were uninfected, as before). In mid-summer, water temperatures rose above 30oC, which has been shown to be lethal for other infected Anguillid eels. At present, it is unknown whether the lower parasite prevalence later in the year was related to emigration of infected eels, mortality, or clearance of the parasite by host eels.