Anguillicola, Yamaguti, 1935

Dangel, K. C., Keppel, M., Le, T. T. Y., Grabner, D. & Sures, B., 2015, Competing invaders: Performance of two Anguillicola species in Lake Bracciano, International Journal for Parasitology: Parasites and Wildlife 4 (1), pp. 119-124 : 120

2. Anguillicola in Lake Bracciano

Lake Bracciano is an almost round lake northwest of Rome, Italy, without in- or outlet. European eels are regularly introduced into the lake to maintain supplies for fishing ( Moriarty and Dekker, 1997). Swim bladder parasites of the genus Anguillicola were first recorded in Lake Bracciano by Paggi et al. (1982). The authors originally identified the species as Anguillicola australiensis , but Moravec and Taraschewski (1988) identified the species as A. novaezelandiae in their review on the genus Anguillicola . The nematodes were introduced to the lake in 1975 along with their original host species A. australis from New Zealand ( Welcomme, 1981; Paggi et al., 1982). While A. novaezelandiae established as a non-indigenous parasite of the indigenous European eel ( A. anguilla ) in Lake Bracciano and never spread outside the lake, a closely related species was introduced to Europe. In spring of 1982, A. crassus , an indigenous parasite of the Japanese eel ( A. japonica ) in Asia, was first recorded in European eels of the Weser-Ems-Region in Germany ( Neumann, 1985). Soon after this first record, the parasite began its rapid spread throughout the population of the European eel on the European continent as well as in North Africa as a consequence of natural eel movements and especially eel trade ( Kennedy and Fitch, 1990; Kirk, 2003; Moravec, 2006; Taraschewski, 2006; Jakob et al., 2009). But the triumph of A. crassus continued when the parasite was recorded in American eels ( Anguilla rostrata ) in North America in 1995 ( Johnson et al., 1995) and in three African eel species on the Island of Reunion in 2005 ( Sasal et al., 2008). The parasite raised attention as early as 1979, when Egusa (1979) noted that naïve European eels suffer more from an infection with A. crassus in Asian aquaculture than the Japanese eel as the original host. But the warnings of the author to prevent the introduction of the parasite to Europe went unheard and still the worldwide trade with live eels is going on.

In October 1993, A. crassus and A. novaezelandiae were both recorded in European eels of Lake Bracciano ( Moravec et al., 1994a). This was a very unique finding of two Anguillicola species in a single eel species, though no mixed infections in individual eels were found. Similarly, this was the last record of A. novaezelandiae in the lake. Between November 2002 and September 2004, Münderle (2005) sampled European eels of Lake Bracciano, but identified all Anguillicola individuals as A. crassus based on morphological features as well as on allozyme analyses, which suggests that A. novaezelandiae became extinct from the lake.