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DAO 56:223-233 (2003)
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Abstract
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Spatio-temporal dynamics of the parasitic nematode Anguillicola crassus in Flanders, Belgium
V. Audenaert1, T. Huyse1, G. Goemans2, C. Belpaire2, F. A. M. Volckaert2,*
1Laboratory of Aquatic Ecology, Katholieke Universiteit Leuven, Ch. 3000 de Bériotstraat 32, 3000 Leuven, Belgium
2Institute for Forest and Wildlife Management, A. 1560 Duboislaan 14, 1560 Hoeilaart-Groenendaal, Belgium
*Corresponding author. Email: filip.volckaert@bio.kuleuven.ac.be
ABSTRACT: Despite Egusa's earlier warning of the damage that the parasitic nematode Anguillicola crassus could inflict on the European eel Anguilla anguilla, its introduction in Europe was a fact in the early 1980s. Based on an elaborate
dataset on Anguillicola crassus infection of 11 river catchments, this paper presents the results of a detailed study on the dispersal of the parasite in Flanders, Belgium, and the host-parasite relationship. In addition, data from 1986 and 1997
are used for comparative purposes, providing a perspective on the temporal infection pattern over 15 yr. The presence of A. crassus in Flanders was first discovered in 1985; 2 yr later a survey revealed a prevalence of 34.1% and a mean infection
intensity of 5.5, based on adult nematodes only, and 10 yr later the parasite was present at all 11 sites sampled. Prevalence had increased to 62.5% but the mean infection intensity had decreased to 3.9 adults per infected eel. Finally, in the year 2000,
a third study revealed that A. crassus was present in 139 of 140 investigated sites; a further increase in prevalence to 68.7% and a decrease in mean infection intensity to 3.4 adults per infected eel was observed. When all larval stages were
taken into account, mean prevalence amounted to 88.1% and mean intensity to 5.5 adults. The high infection level in Flanders is thought to be the result of restocking with glass eel and yellow eel, both of which are susceptible to A. crassus. The
general infection parameters were similar in all 11 river catchments. It is possible that in Flanders both prevalence and mean infection intensity are stabilizing due to density-dependent regulation of the parasite infrapopulation. Fibrotic swimbladder
walls were observed, mainly in large eels, and 20% of the total number of nematodes consisted of encapsulated larvae in the surveys of 1997 and 2000; 8 cases of swimbladder regeneration were observed.
KEY WORDS: European eel · Exotic species · Host-parasite evolution · Mean intensity · Parasite · Prevalence
Full text in pdf format
Published in DAO Vol.
56, No. 3
(2003) on October 24
Print ISSN: 0177-5103; Online ISSN: 1616-1580.
Copyright © Inter-Research, Oldendorf/Luhe, 2003
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