Distribution and prevalence of Anguillicola crassus (Nematoda) in eels Anguilla anguilla of the rivers Rhine and Naab, Germany

Würtz, Jürgen; Knopf, Klaus; Taraschewski, Horst

doi:10.3354/dao032137

Cited by 37 publications

(30 citation statements)

References 14 publications

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“…Therefore, our result suggests that transmission rates of A. crassus by paratenic hosts may be lower than by intermediate hosts in Mediterranean lagoons. This finding may not be a general trend in nematode transmission because other studies showed a positive (Thomas and Ollevier, 1992b;Lefebvre et al, 2002b;Audenaert et al, 2003) or no relationship (Würtz et al, 1998) between parasite abundance and the size of eels. Our results are consistent with those of Schabuss et al (1997) and Gargouri Ben Abdallah and Maamouri (2006), who showed a negative relationship between the two parameters.…”

Section: Salsesleucatementioning

confidence: 64%

Macroparasite communities in European eels,Anguilla anguilla, from French Mediterranean lagoons, with special reference to the invasive speciesAnguillicola crassusandPseudodactylogyrusspp.

Fazio

Sasal

Lecomte-Finiger

et al. 2008

Knowl. Managt. Aquatic Ecosyst.

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European eel parasites, in particular invasive species, are suspected to play a role in the decline in the populations of their host. The aims of this work were to describe the parasitic fauna of eels in French Mediterranean lagoons and to study the epidemiological trends of the invasive helminth species, the nematode Anguillicola crassus and the monogenean Pseudodactylogyrus spp., in regard to spatio-temporal dynamics, host biological characteristics and parasite community. A total of 418 eels was sampled in eight lagoons between March 2003 and June 2005. Our results revealed a total macroparasite richness of 23 species: 1 Monogenea, 13 Digenea, 2 Cestoda, 3 Nematoda, 2 Acantocephala and 2 Crustacea. We found no variation in A. crassus abundance in Salses-Leucate lagoon in the same month across years. However, the nematode abundance was higher in eels caught in summer than in those caught in winter. Pseudodactylogyrus sp. was not found in Salses-Leucate lagoon, except in July 2004. Comparisons between the lagoons on the same date showed that they could be separated into two groups for both species' abundance: Grau-du-Roi, Mauguio, Palavas and Vaccarès lagoons, where abundance was rather high, against Bages-Sigean, Pierre-Blanche, Salses-Leucate and Thau lagoons, where abundance was rather low or nil. We found significant negative relationships between A. crassus abundance and the length and age of eels. We also found a significant positive relationship between A. crassus and Pseudodactylogyrus sp. abundance. Finally, our results showed significant positive relationships between both A. crassus and Pseudodactylogyrus sp. abundance and the abundance of the digeneans Prosorhynchus aculeatus and Lecithochirium gravidum. We discuss the results in regard to the dynamics of invasions, the characteristics of the parasite life cycles and the ecology of eels.

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Section: Salsesleucatementioning

confidence: 64%

Macroparasite communities in European eels,Anguilla anguilla, from French Mediterranean lagoons, with special reference to the invasive speciesAnguillicola crassusandPseudodactylogyrusspp.

Fazio

Sasal

Lecomte-Finiger

et al. 2008

Knowl. Managt. Aquatic Ecosyst.

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“…Maximum values of prevalence, mean intensity and mean abundance were recorded each year in early summer and, to a lesser degree, in late winter. As previously mentioned, almost all investigations have failed to detect any seasonality (Kennedy & Fitch 1990, Möller et al 1991, Thomas & Ollevier 1992, Molnár et al 1994, Würtz et al 1998. Nevertheless, the existence of seasonal peaks has already been noted (Benajiba et al 1994, Hartmann 1994, Nagasawa et al 1994.…”

Section: Discussionmentioning

confidence: 83%

“…In fact, there are still some open questions about the temporal pattern of the infection in natural waters. Fluctuations in prevalence and intensity of the infection were generally observed across time, but for many reasons, most studies have failed to detect any seasonality (Kennedy & Fitch 1990, Möller et al 1991, Thomas & Ollevier 1992, Molnár et al 1994, Würtz et al 1998. It is not known, however, to what extent temporal variation in other factors such as eel length may influence the observed parasite count.…”

Section: Introductionmentioning

confidence: 96%

“…It is not known, however, to what extent temporal variation in other factors such as eel length may influence the observed parasite count. Generally, the number of parasites steadily increases along with the increasing host size (Thomas & Ollevier 1992, Molnár et al 1994, Baruš et al 1996, but other data do not support a linear relationship (Peters & Hartmann 1986, Würtz et al 1998). In fact, most studies have investigated separately the importance of these factors, whereas interactions between them may generate confounding effects.…”

Section: Introductionmentioning

confidence: 99%

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Spatial and temporal variation in Anguillicola crassus counts: results of a 4 year survey of eels in Mediterranean lagoons

Lefebvre¹,

Contournet²,

Priour³

et al. 2002

Dis. Aquat. Org.

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We present the results of a survey of anguillicolosis in the Rhône River delta. From January 1997 to December 2000, a total of 13 319 eels (Anguilla anguilla from elver to silver phase) were examined, in which we found 22 227 swimbladder nematodes (Anguillicola crassus adults and preadults). A generalised linear model (GLM) framework was used to explore the relative contribution of various factors to the occurrence, intensity and abundance of the parasite. We reveal a major influence of the month of sampling, and we document the existence of a seasonal pattern with regular peaks in early summer and late winter. In contrast, the year of sampling is of secondary importance, and no particular trend in the development of the infection can be detected. More than a decade after the first record of A. crassus in the Rhône River delta, anguillicolosis has thus attained a constant infection rate of nearly 50%, with a mean number of 3 or 4 macroscopic lumen worms per infected eel. The eel length strongly influences the intensity and the abundance of the nematode, but has little if any effect on the probability of being infected. There exists a linear relationship between eel size and the number of parasites, but not between eel size and prevalence. We observe a decrease in the proportion of infected individuals among elver eels. We discuss this result in relation to the possible mortality of heavily infected individuals and/or a change in the eels' alimentary diet.

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“…From the few relevant studies hitherto available, it has been suggested that the infection spread might stabilize (Van Willingen & Dekker 1989, Ashworth 1994, Würtz et al 1998, Lefebvre et al 2002b, even though the nematode possesses many attributes of a successful invasive colonizer (Kennedy & Fitch 1990).…”

Section: Anguillicolosis In European Eels Anguilla Anguillamentioning

confidence: 99%

Anguillicolosis: dynamics of the infection over two decades

Lefebvre¹,

Crivellì²

2004

Dis. Aquat. Org.

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The dynamics of the infection of the European eel Anguilla anguilla L. by the Asian nematode Anguillicola crassus Kuwahara, Niimi and Itagaki, 1974 (i.e. anguillicolosis) was monitored over 2 decades in an oligohaline canal in southern France (Camargue, Mediterranean coast). Since the first mention of the parasite in this canal in 1985, which was also the first record in France, prevalence of pre-adult and adult forms has risen from 32 to 73%. However, during the last 7 yr (1997 to 2003), prevalence seems to have stabilized around values of 60 to 70% and parasite load, though inter-annual variation is substantial, shows no sign of increase (intensity for the last 5 yr: min. = 3.70, max. = 9.66, mean = 6.01). Our results thus confirm the dynamic pattern observed elsewhere in Europe, i.e. a rapid spread following the introduction of the parasite in a water system and then stabilization around ceiling levels. We review possible mechanisms that may explain such a leveling off in the infection spread. We particularly document the possibility that repetitive infections may render the infected organ, i.e. the swimbladder, unsuitable for further A. crassus establishment. In support of this hypothesis, we showed that the infection rate is lower among eels with severely damaged swimbladders.

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Distribution and prevalence of Anguillicola crassus (Nematoda) in eels Anguilla anguilla of the rivers Rhine and Naab, Germany

Cited by 37 publications

References 14 publications

Macroparasite communities in European eels,Anguilla anguilla, from French Mediterranean lagoons, with special reference to the invasive speciesAnguillicola crassusandPseudodactylogyrusspp.

Macroparasite communities in European eels,Anguilla anguilla, from French Mediterranean lagoons, with special reference to the invasive speciesAnguillicola crassusandPseudodactylogyrusspp.

Spatial and temporal variation in Anguillicola crassus counts: results of a 4 year survey of eels in Mediterranean lagoons

Anguillicolosis: dynamics of the infection over two decades

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