scholarly journals Comparative imaging of European eels (Anguilla anguilla) for the evaluation of swimbladder nematode (Anguillicoloides crassus) infestation

2015 ◽  
Vol 39 (6) ◽  
pp. 635-647
Author(s):  
K Frisch ◽  
A Davie ◽  
T Schwarz ◽  
JF Turnbull
Keyword(s):  
Anguilla Anguilla ◽  
Anguillicoloides Crassus

Infection of European eel, Anguilla anguilla (L.), with the nematode Anguillicoloides crassus (Kuwahara, Niimi et Itagaki, 1974) in Polish waters

2012 ◽  
Vol 15 (2) ◽  
pp. 253-257 ◽  
Author(s):  
R. Popielarczyk ◽  
S. Robak ◽  
K. Siwicki
Keyword(s):  
Infection Intensity ◽  
Anguilla Anguilla ◽  
Mean Value ◽  
European Eel ◽  
Szczecin Lagoon ◽  
The Mean ◽  
The Individual ◽  
Anguillicoloides Crassus ◽  
Anatomical Pathology

Infection of European eel, Anguilla anguilla (L.), with the nematode Anguillicoloides crassus (Kuwahara, Niimi et Itagaki, 1974) in Polish waters The aim of this study was to determine the degree of Anguillicoloides crassus infection in European eel inhabiting Polish waters based on selected parasitic descriptors and on anatomical pathology of the swimbladder using macroscopic methods. In all, 154 European eel specimens were sampled from eleven sites in Poland and A. crassus was present in the swimbladder of 114 fish. The intensity of A. crassus infection in all the eel specimens ranged from 1 to 62 parasites at a mean value of 7.5. High values of mean infection intensity were noted in samples from Pomeranian lakes Bukowo, Łebsko, and Jamno. The health of the swimbladder was evaluated using the swimbladder degenerative index (SDI). The mean value of the SDI for all of the eel examined was 3.3, and extensively degenerated swimbladders were observed mainly in samples in the Szczecin Lagoon and from lakes. According to the individual SDI ratings, 9.1% of the eel specimens did not exhibit pathological symptoms of the swimbladder (SDI-0) and an extremely damaged (SDI-6) swimbladder was noted in 11.7% of the fish examined. In the case of eel infected with A. crassus, higher SDI values were reflected in initially increasing shares in subsequent categories. In fish that were not infected with the nematode, only 20% (8 individuals) of the swimbladders showed no symptoms of pathology (SDI-0).

Infection by Anguillicoloides crassus in a riverine stock of European eel, Anguilla anguilla

2010 ◽  
Vol 17 (6) ◽  
pp. 485-492 ◽  
Author(s):  
S. COSTA-DIAS ◽  
E. DIAS ◽  
J. LOBÓN-CERVIÁ ◽  
C. ANTUNES ◽  
J. COIMBRA
Keyword(s):  
Anguilla Anguilla ◽  
European Eel ◽  
Anguillicoloides Crassus

scholarly journals Is the continental life of the European eel Anguilla anguilla affected by the parasitic invader Anguillicoloides crassus ?

2013 ◽  
Vol 280 (1754) ◽  
pp. 20122916 ◽  
Author(s):  
François Lefebvre ◽  
Géraldine Fazio ◽  
Béatrice Mounaix ◽  
Alain J. Crivelli
Keyword(s):  
Reproductive Potential ◽  
Adaptive Immune Response ◽  
Anguilla Anguilla ◽  
Individual Variability ◽  
Growth Potential ◽  
Size Increase ◽  
European Eel ◽  
History Of ◽  
Internal Marker ◽  
Anguillicoloides Crassus

Quantifying the fitness cost that parasites impose on wild hosts is a challenging task, because the epidemiological history of field-sampled hosts is often unknown. In this study, we used an internal marker of the parasite pressure on individual hosts to evaluate the costs of parasitism with respect to host body condition, size increase and reproductive potential of field-collected animals for which we also determined individual age. In our investigated system, the European eel Anguilla anguilla and the parasitic invader Anguillicoloides crassus , high virulence and severe impacts are expected because the host lacks an adaptive immune response. We demonstrated a nonlinear relationship between the severity of damage to the affected organ (i.e. the swimbladder, our internal marker) and parasite abundance and biomass, thus showing that the use of classical epidemiological parameters was not relevant here. Surprisingly, we found that the most severely affected eels (with damaged swimbladder) had greater body length and mass (+11% and +41%, respectively), than unaffected eels of same age. We discuss mechanisms that could explain this finding and other counterintuitive results in this host–parasite system, and highlight the likely importance of host panmixia in generating great inter-individual variability in growth potential and infection risk. Under that scenario, the most active foragers would not only have the greatest size increase, but also the highest probability of becoming repeatedly infected—via trophic parasite transmission—during their continental life.

scholarly journals A mechanical approach to understanding the impact of the nematode Anguillicoloides crassus on the European eel swimbladder

2020 ◽  
Vol 223 (17) ◽  
pp. jeb219808
Author(s):  
Helen A. L. Currie ◽  
Nicholas Flores Martin ◽  
Gerardo Espindola Garcia ◽  
Frances M. Davis ◽  
Paul S. Kemp
Keyword(s):  
Mechanical Damage ◽  
Severe Infection ◽  
Anguilla Anguilla ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
European Eel ◽  
Sargasso Sea ◽  
Mechanical Integrity ◽  
The Impact ◽  
Anguillicoloides Crassus

ABSTRACTOne of the most detrimental factors in the drastic decline of the critically endangered European eel (Anguilla anguilla) was the inadvertent introduction of the invasive nematode Anguillicoloides crassus. Infection primarily affects the swimbladder, a gas-filled organ that enables the eel to control its depth in the water. A reduction in swimbladder function may be fatal for eel undergoing their spawning migration to the Sargasso Sea, a journey of over 5000 km. Although the physiological damage caused by this invasive parasite is well studied through the use of quantifiable gross pathological indices, providing a good measure of the swimbladder health status, they cannot separate the role of mechanical and morphological damage. Our study examined the appropriateness of three commonly used indices as a measure of mechanical damage by performing uniaxial tensile tests on swimbladder specimens obtained from an infected eel population. When the test results were compared with the gross pathological indices it was found that thickness correlated most strongly with mechanical damage, both confirming and, more importantly, explaining the counterintuitive findings of earlier work. In a damaged swimbladder, the immune response leads to a trade-off; increasing wall thickness raises the pressure required for organ rupture but decreases strength. The results indicate that for moderate infection the mechanical integrity of the swimbladder can be maintained. For severe infection, however, a reduction in mechanical integrity may reach a tipping point, thereby affecting the successful completion of their oceanic migration.

scholarly journals Swim Bladder Nematodes (Anguillicoloides crassus) Disturb Silvering In European Eels (Anguilla anguilla)

2012 ◽  
Vol 98 (4) ◽  
pp. 695-705 ◽  
Author(s):  
Géraldine Fazio ◽  
Pierre Sasal ◽  
Gabriel Mouahid ◽  
Raymonde Lecomte-Finiger ◽  
Hélène Moné
Keyword(s):  
Anguilla Anguilla ◽  
Swim Bladder ◽  
Anguillicoloides Crassus

scholarly journals In-situ non-lethal rapid test to accurately detect the presence of the nematode parasite, Anguillicoloides crassus, in European eel, Anguilla anguilla

2020 ◽  
Author(s):  
M. De Noia ◽  
R. Poole ◽  
J. Kaufmann ◽  
C. Waters ◽  
C. Adams ◽  
...  
Keyword(s):  
Rapid Test ◽  
Anguilla Anguilla ◽  
Nematode Parasite ◽  
European Eel ◽  
In Situ Extraction ◽  
Predictive Values ◽  
Non Invasive ◽  
Specificity And Sensitivity ◽  
Anguillicoloides Crassus

AbstractAnguillicoloides crassus is an invasive nematode parasite of the European eel, Anguilla anguilla, and one of the primary drivers of eel population collapse. The presence of the parasite has been shown to impact many features of eel physiology and life history. Early detection of the parasite is vital to limit the spread of A. crassus. However, until recently, accurate diagnosis of infection could only be achieved via terminal dissection. To support A. anguilla fisheries management in the context of A. crassus we developed a rapid non-lethal and non-invasive environmental DNA method to detect the presence of the parasite in the swim bladder. Screening of 131 wild eels was undertaken between 2017 and 2019 Ireland and UK to validate the procedure. DNA extractions and PCR were conducted using both a Qiagen Stool kit at Glasgow University and in situ using Whatman qualitative filter paper No. 1 and a miniPCR DNA Discovery System™. Primers were specifically designed from the cytochrome oxidase mtDNA gene region. In situ extraction and amplification takes approx. 3h for up to 16 individuals with higher specificity and sensitivity compare to the laboratory Qiagen kit extraction. The local diagnostic procedure demonstrated Positive Predictive Values at 96% and Negative Predictive Values at 87%. Our method will be a powerful tool in the hands of fisheries managers to help protect this iconic but critically endangered species. It will allow a non-invasive monitoring of the A. crassus dispersion across the European waters.

The impact of Anguillicoloides crassus (Nematoda) on European eel swimbladder: histopathology and relationship between neuroendocrine and immune cells

Parasitology ◽  
2021 ◽  
pp. 1-11
Author(s):  
Bahram Sayyaf Dezfuli ◽  
Chiara Maestri ◽  
Massimo Lorenzoni ◽  
Antonella Carosi ◽  
Barbara J Maynard ◽  
...  
Keyword(s):  
Polyclonal Antibodies ◽  
Central Italy ◽  
Anguilla Anguilla ◽  
European Eel ◽  
Gland Cells ◽  
Bony Fishes ◽  
Mucosal Layer ◽  
Gas Gland ◽  
The Impact ◽  
Anguillicoloides Crassus

Abstract The swimbladder functions as a hydrostatic organ in most bony fishes, including the European eel, Anguilla anguilla. Infection by the nematode Anguillicoloides crassus impairs swimbladder function, significantly compromising the success of the eel spawning migration. Swimbladders from 32 yellow eels taken from Lake Trasimeno (Central Italy) were analysed by histopathology- and electron microscopy-based techniques. Sixteen eels (50%) harboured A. crassus in their swimbladders and intensity of infection ranged from 2 to 17 adult nematodes per organ (6.9 ± 1.6, mean ± s.e.). Gross observations of heavily infected swimbladders showed opacity and histological analysis found a papillose aspect to the mucosa and hyperplasia of the lamina propria, muscularis mucosae and submucosa. Inflammation, haemorrhages, dilation of blood vessels and epithelial erosion were common in infected swimbladders. In the epithelium of parasitized swimbladders, many empty spaces and lack of apical junctional complexes were frequent among the gas gland cells. In heavily infected swimbladders, we observed hyperplasia, cellular swelling and abundant vacuolization in the apical portion of the gas gland cells. Numerous mast cells and several macrophage aggregates were noticed in the mucosal layer of infected swimbladders. We found more nervous and endocrine elements immunoreactive to a panel of six rabbit polyclonal antibodies in infected swimbladders compared to uninfected.

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