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 The absence of A. crassus in lakes under Belpaire, C., De Charlcroy, D.and Thomas, K. (1987). Effects of restocking eels on the distribution of the nematode Anguillicola cras.1·a in Flanders, Belgium. Report EIFAC Working Party on the Eel, Bristol, Great Britain, 13-1 6 Apri I, 6. Benajiba, M.H. (1991). Les parasites de l'anguille eu ropeenne Anguilla anguilla, L., 1758 (Poisson, Teleostcen) dans la region du Languedoc: ultra structure, biologic et dynamique des populations. Doctoral, Univ. Blaise Pascal (Clermont Ferrand ll), 225 pp. Bonneau, S., Blanc, G. and Petter, A.J. (1991). Studies on the biology of the larval stages of Anguillicola crassus (Dracunculoidea, Nematoda): Specificity on the intermediate host and effect of temperature on rate of development. Rull. Fr. Peche l'iscic., 320, marine influence such as Bizerte, Char El Melli and Tunis can be explained by the fact that the nematode's development cannot take place in an environment with a salinity similar to that of sea water. The presence of this parasite on eels from the Ichkeul lake and from cued Sejnane indi cates favourable conditions for the progress of its biological cycle. It particularly implies the presence of an intermediate host, cope pod, cyclopidae or ostracod (Petter et al., 1989; Bonneau et al., 1991) and, may be, the presence of paratenical fish hosts (Haenen and Van Banning, 1990) favouring the pas sage from an infecting stage to the final host 1-6. Canest-i-Trotti, G. (1987). Occurrence of the Nematode Anguillicola crassa (Kuwahara, Niimi and ltagaki, 1974) in eels form the Po delta, Italy, ElFAC Bull. Eur. Ass. Fish Pathol., Workill!I Parry 011 Eel, Bristol, United Kingdom, 19(1),19, 1999. Mo, T.A. and Stcicn, S.H. (1994). First observation of eel swirnbladder nematode A11g11illicola eras.ms in 13- 16 April. Dupont, F. & Peuer, A.J. (1988). A11guillicola, une epi:wolie plurispecifique en Europe, apparition de A11f1uillicola crassa (Nematode, Anguillicolidae) Norway. Bull. Eur. Ass. Fish. Pat/101., 14, 163. Neumann, W. (1985). Schwimmblasenparasit A11guil/i cola bei Aalcn. Fischer 1111d Teichwirt, 36, 322. en Nieri, M., Sloeck, 0., Boudouresquc, C.F., Shili, A. et Camargue, sud de la France. Bull. Fr. Peche Pis Trabelsi, B. (1992). Contribution a L'etude de l'eco chcz l'anguille europeene Anguilla anguilla systeme du lac lchkeul (Tunisia). Les comparti cic., 308, 38-41. Haenen, O.L.M. and Van Banning, P., (1990). Detection ments llorc ct faune lagunaires. Fondation rationale of Larvae of A111:11il/ico/a crassus ( an Eel Swim de la rechcrche scientifique, Tunis Gis Posidonic, bladder Nematode) Marseille, 100 pp. Aquaculture, in Frchwater Fish Species. 87, 103-109. Koie, M. (1988 a). Parasites in eels, A11guilla a11guilla (L.) from cutrophic Lake Esrum (Denmark). Acta Parasit., 33, 89- 100. Koic, M. (1988 b). Parasites in European eel A11f!uilla w1guilla (L.) from Danish freshwater, brackish and marine localities. Opl1elia, 29, 93-118. Lecomte-Finiger, R. (1983 a). Conttibution a la con Peters, G., Hartman, F. (1986). Ang11illicola, a parasitic Nemalode of the swimbladdcr spreading among eel populalions in Europe. Dis. Aqua/. Org., 1, 229-230. Petter, /\.J., Cassone, J., Le Belle, N. (1990). Observa tions sur la biologic des premiers slades larvaires d' A11g11illicola cmssus, nematode parasite de l'angui llc. A1111. Parasit. Hu111. Co111p., 65, 28-31. naissance de l'eco-biologie de l'anguillc A111:uilla Petter, A.J., Fontaine, Y./\ et Le Belle, N. (1989). Etude anguilla L., 1758 des milieux lagunaires mediterra du developpement larvaire de Anguillicola cra.v.rns neens du golfc du Lion, Narbonne ct Roussillon. These Docl. Eiat, Univ. Pcrpignan, 203 pp. Lecomte-f'inigcr, R. (I 983 b). Regime alimentaire des civelles Cl anguille1tes (A11guilla cmguilla) dans trots etangs saumatres du Roussillon. Bull.Ecol., 14 (4), 297-306. (Dracunculoidca, Nematoda) chcz un cyclopidae de la region parisiennc. Ann. Parasit. Hu111. Comp., 64, 347-355.