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An invasion record for the swimbladder nematode Anguillicoloides crassus in European eel Anguilla anguilla in a deep cold-monomictic lake, from invasion to steady state

Authors

  • D. Bernies,

    1. Fishery Research Station, Argenweg 50/1, 88085 Langenargen, Germany
    2. Institute of Parasitology, An den Tierkliniken 35, 04103 Leipzig, Germany
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  • A. Brinker,

    Corresponding author
    1. Fishery Research Station, Argenweg 50/1, 88085 Langenargen, Germany
    2. Ministry of Rural Area, Food and Consumer Protection of Baden-Württemberg, Kernerplatz 10, 70182 Stuttgart, Germany
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  • A. Daugschies

    1. Institute of Parasitology, An den Tierkliniken 35, 04103 Leipzig, Germany
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Errata

This article is corrected by:

  1. Errata: Corrigendum Volume 80, Issue 2, 471, Article first published online: 23 January 2012

Tel.: +49 7543 9308 324; email: alexander.brinker@lazbw.bwl.de

Abstract

This study is the first account of the establishment and development of the neozoic nematode parasite Anguillicoloides crassus in its host, the European eel Anguilla anguilla, in a deep, cold-monomictic lake. A 21 year study of A. crassus took place in Upper Lake Constance (ULC), Europe's second largest pre-alpine lake. The study included two extensive surveys, one in 1991 during the initial parasite invasion phase and the second in 2006 when the infection was well established. The subtropical swimbladder nematode A. crassus was first recorded in A. anguilla in ULC in 1989. Prevalence reached 60% in 1992 and remained at this level until 2007. In 2008, prevalence decreased to 48%. Infection intensity peaked in 1993 at a mean value of 16 adult parasites per host fish. Around 90% of all A. anguilla examined displayed swimbladder lesions, with a significant trend to increasing severity over time. Moreover, heavy swimbladder lesions were seen in c. 10% of A. anguilla ready to migrate to their spawning habitat. Both ruffe Gymnocephalus cernuus and sunfish Lepomis gibbosus serve as paratenic hosts for A. crassus in ULC. Gymnocephalus cernuus seems to be the main vector, and infection is especially frequent in spring possibly caused by reduced immune system efficacy of G. cernuus during winter. In 1991, hypochromic anaemia was prevalent in ULC A. anguilla acutely infected with A. crassus, whereas in 2006 blood values were indicative of chronic infection. The growth and survival rates of A. anguilla during their continental phase were not noticeably altered in infected fish, but damage to the swimbladder probably impairs migration potential and thus the subsequent breeding success of the oceanic phase.

Ancillary