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(nematode, Anguillicolidae) in the Ichkeul Lake

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Bull. Eur. Ass. Fish Pathol.,
19(1),17, 1999.
OCCURRENCE OF ANGVILLICOLA CRASSUS (NEMATODE,
ANGUILLICOLIDAE) IN THE ICHKEUL LAKE (NORTH­
ERN TUNISIA)
1
1
1
F. MAAMOUR1 , L. GARGOURl M. OULD DADDAH AND G. Bounc 2
'
'
Department of Biology, Faculty of Science, Tunis, Tunisie. Parasitology and lrrununology, University Montpellier TI,
34095 Montpellier cedex 05, France.
Abstract
Investigations of fish pm·asitcs from the north of Tunisia revealed the presence of Anguillicola crassus in African waters.
The nematodes were found in lchkcul lake and in a river communicating with the lake, Oued Sejnane. The occurrence of
/\. crassus in fresh waters from Tunisia was discussed.
Introduction
Anguillicola
llagaki,
same host in the northern Tunisian Lake
crassus
Kuwahara,
Niimi
et
Ichkeul.
1974, a nematode parasile of the
swimbladder of the Japanese eel, was re­
Materials and methods
ported from Anguilla
several
The eels studied Anguilla angu.illa came
1985; Peters
and Hartman, 1986; Belpaire et al., 1987;
Canestri-Trotti, 1987; Koie, 1988 a and b;
Mo and Steien, 1994) and particularly, in the
from wild populations captured during Lhe
anguilla
in
European countries (Neumann,
soulh of France, in Camargue area (Duponl
and Petter,
J 988) and in Languedocian la­
year
1994-1995, in different lakes of the
north-east of Tunisia. (fight). Observations
344 specimens caughl in Lake Jch­
50 from the Lake Bizerte, 50 from
Lake Ghar El Melh and 100 from Lake Tu­
involved
keul,
1991). We re­
nis. We also examined some specimens from
port its presence, for the firsl Lime, on the
two rivers communicating with the Ichkeul
goon of Mauguio (Benajiba,
D 1994
limits of lchkeul park
dams
and
year of
opening
Figure 1. Localion of Lake Tchkeul
Bull. Eur. Ass. Fish Pathol.,
lake:
Cued
Joumine
(15
19(1),18, 1999.
specimens)
and
However, the questions are where does the
eel 's infection take place, in Oueds or in the
Oued Sejnane (5 specimens).
lake, and how did the parasite get there ?
Results
It is a known fact that eels recruitment takes
The eels from the lakes under marine influ­
place after a transatlantic migration of glass
ence (Bizerte, Ghar El Melh and Tunis) are
eels (or elvers) when they reach coastal wa­
not parasitised by A. crassus. On the other
ters of Europe or northern Africa and they
hand, in Lake Ichkeul, where salinity can
enter the continental waters where growth
reach 50% in autumn and 3% in spring
and
(mean rate of 14 to 16%) and where tem­
comte-Finiger, 1983 a and b) and where the
feeding
peratures vary from 29-30°C in summer to
infection
8-10°C in winter (Nieri et al., 1992), of 344
hypothesis
activity
take
probably occurs.
of
accidental
place
Therefore,
(Le­
the
introduction
specimens, 25 had l to 3 nematodes in their
through migrations of infested eels from the
swimbladder. Thir
occidental Meditenanean coasts, where A.
eight A. crassus were
found altogether. The global prevalence was
crassus intensity is clearly increasing, seem
7.26%, the abundance 0.11 and the mean
unlikely.
intensity 1.52.
The presence of this parasite in Lake Ichkeul
The size of the eels was between I 8 and 73
and Cued Sejnane is believed to be the result
cm. However, the parasites was found only
of an accidental introduction, either during
in specimens measuring from 23 to 68 cm
importation of fresh water fish from Europe
with low abundances (0.05 to 0.16) and with
when dams were stocked with fish, or with
a varying intensity of I to 2.
eels containing the adult nematode, or from
Monthly values of prevalence are relatively
intermediate or paratenical host carrying the
low. The highest rate was observed in Feb­
infesting stage and eaten by eels. Indeed,
ruary (17.6%). This prevalence was 12% i n
three of the six Oueds feeding Lake lchkeul
April and 10% i n November. For the other
have such dams. Joumine was opened in
months, it wavers between 7.8 and 5%. But,
1984, Ghezala in 1985 and Sejnane in 1994.
during June, July and August, no parasite
Environmental conditions (temperature and
was found on the 50 eels caught in these
salinity) and the presence of the intermediate
months.
host allowed the nematode cycle develop­
A. crassus was also found in one eel caught
ment. The parasite could be in a phase of
-
in Oued Sejnanc.
colonisation of new hosts populations<
Discussion
References
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