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 Growth potential can affect timing of maturity in a long-lived semelparous fish

2018 ◽  
Vol 14 (7) ◽  
pp. 20180269 ◽  
Author(s):  
Kazuki Yokouchi ◽  
Françoise Daverat ◽  
Michael J. Miller ◽  
Nobuto Fukuda ◽  
Ryusuke Sudo ◽  
...  
Keyword(s):  
Anguilla Anguilla ◽  
Growth Conditions ◽  
Growth Potential ◽  
Individual Growth ◽  
Growth Trajectories ◽  
Female Size ◽  
European Eel ◽  
Growth And Survival ◽  
Silver Eels ◽  
Reproduction Cost

Many diadromous fishes such as salmon and eels that move between freshwater and the ocean have evolved semelparous reproductive strategies, but both groups display considerable plasticity in characteristics. Factors such as population density and growth, predation risk or reproduction cost have been found to influence timing of maturation. We investigated the relationship between female size at maturity and individual growth trajectories of the long-lived semelparous European eel, Anguilla anguilla . A Bayesian model was applied to 338 individual growth trajectories of maturing migration-stage female silver eels from France, Ireland, the Netherlands and Hungary. The results clearly showed that when growth rates declined, the onset of maturation was triggered, and the eels left their growth habitats and migrated to the spawning area. Therefore, female eels tended to attain larger body size when the growth conditions were good enough to risk spending extra time in their growth habitats. This flexible maturation strategy is likely related to the ability to use diverse habitats with widely ranging growth and survival potentials in the catadromous life-history across its wide species range.

The life cycle of Paraquimperia tenerrima: a parasite of the European eel Anguilla anguilla

2005 ◽  
Vol 79 (2) ◽  
pp. 169-176 ◽  
Author(s):  
J.A. Shears ◽  
C.R. Kennedy
Keyword(s):  
Life Cycle ◽  
Intermediate Host ◽  
Anguilla Anguilla ◽  
European Eel ◽  
Temperature Dependent ◽  
Free Living ◽  
Freshwater Invertebrate ◽  
Third Stage ◽  
History Of ◽  
Whole Life Cycle

AbstractPrevious studies on the life history of the nematode eel specialist Paraquimperia tenerrima (Nematoda: Quimperiidae) have failed to determine whether an intermediate host is required in the life cycle. In the laboratory, eggs failed to hatch below 10°C, hatching occurring only at temperatures between 11 and 30°C. Survival of the free-living second stage larvae (L2) was also temperature dependent, with maximal survival between 10 and 20°C. Total survival of the free-living stages (eggs and L2) is unlikely to exceed a month at normal summer water temperatures, confirming that parasite could not survive the 6 month gap between shedding of eggs in spring and infection of eels in early winter outside of a host. Eels could not be infected directly with L2, nor could a range of common freshwater invertebrate species. Third stage larvae (L3) resembling P. tenerrima were found frequently and abundantly in the swimbladder of minnows Phoxinus phoxinus from several localities throughout the year and were able to survive in this host in the laboratory for at least 6 months. Third stage larvae identical to these larvae were recovered from minnows experimentally fed L2 of P. tenerrima, and eels infected experimentally with naturally and experimentally infected minnows were found to harbour fourth stage larvae (L4) and juvenile P. tenerrima in their intestines. Finally, the whole life cycle from eggs to adult was completed in the laboratory, confirming that minnows are an obligate intermediate host for P. tenerrima.

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

Sources of Variation in Growth of the European Eel (Anguilla anguilla) Estimated from Otoliths

1994 ◽  
Vol 51 (3) ◽  
pp. 506-515 ◽  
Author(s):  
Jacques Panfili ◽  
Marie-Claude Ximénès ◽  
Alain J. Crivelli
Keyword(s):  
Somatic Growth ◽  
Growth Period ◽  
Anguilla Anguilla ◽  
Individual Variability ◽  
Fish Length ◽  
European Eel ◽  
Otolith Growth ◽  
Absolute Growth ◽  
Sources Of Variation ◽  
Natural Pond

Tetracycline labelling of otoliths was used for studying the growth of the European eel (Anguilla anguilla), which has strong individual variability. Two groups of eels were injected with tetracycline and released into a natural pond (Camargue, south of France) in spring 1989 and in autumn 1989. The marginal growth of otoliths between marking (tetracycline mark) and capture (otolith margin) was measured for all fish sampled until spring 1990. Comparisons of otolith growth rates were made according to fish size, age, sex, and growth period (ANCOVA). The results showed a great variability. After 15 mo of growth, the mean growth in length (back-calculated) was 6.6 cm. The three main factors tested, age, sex, and seasonal growth period, had a significant effect on otolith growth and therefore on somatic growth, since the relation between fish length and that of the otolith is highly significant (r2 = 0.802). There was also a very significant effect of size at marking on otolith growth. It is difficult to rank qualitative importance of these various factors, even though there are no interactions among them. The best absolute growth in Mediterranean lagoons could be attained by 2-yr-old female fish growing in the summer months.

scholarly journals Elemental composition of otoliths as a discriminator of life stage and growth habitat of the European eel, Anguilla anguilla

2005 ◽  
Vol 56 (5) ◽  
pp. 629 ◽  
Author(s):  
W. N. Tzeng ◽  
K. P. Severin ◽  
C. H. Wang ◽  
H. Wickström
Keyword(s):  
Elemental Composition ◽  
Environmental History ◽  
Life Stage ◽  
Anguilla Anguilla ◽  
Primary Component ◽  
European Eel ◽  
Yellow Eel ◽  
Minor Elements ◽  
Electron Probe Microanalyser ◽  
History Of

The hypothesis that elemental composition of otoliths of the eel (Anguilla spp.) changes with life stage and growth habitat was tested in the present study. The minor elements Cl, Na, K, Mg, Ca, Sr and P in otoliths of European eels (Anguilla anguilla) were examined by using an Electron Probe Microanalyser (EPMA) equipped with wavelength dispersive spectrometers (Cameca SX-50). Yellow-stage eels were collected from coastal waters and lakes of Sweden in 1987, 1988, 1991, and 1994, with ages ranging from 5 to 18 years old. Strontium maps and profiles of Sr : Ca ratio, as well as the elver check in otoliths, were used to classify life history stages of the eels as leptocephalus, and freshwater- and seawater-resident yellow eels. Canonical score plots of the otolith elemental compositions of the freshwater-resident yellow eel were completely separated from those of leptocephalus and seawater-resident yellow eel, but the latter two partially overlapped. Strontium is the primary component in determining the discrimination, but the nutrient-related (S and P), and the physiologically controlled elements (Na and Cl), may also play an important role in the discrimination. These results indicate that multiple-elemental information can provide additional insight into the migratory environmental history of diadromous fishes.

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.

Sign in / Sign up

Export Citation Format

Share Document