Bull. Eur. Ass. Fish Pathol., 31(1) 2011, 4

Digenean fauna of Cerastoderma glaucum (Veneroidae, Cardidae) from Tunisian coasts

L. Gargouri Ben Abdallah1*, R. Antar1, K. Hosni2, N. Trigui El Menif2 and F. Maamouri1

1 Reasearch Unit Animal Bio-Ecology and Systematic Evolutionary, Faculty of Sciences, Tunis, University of Tunis El Manar, 2092, Tunis, Tunisia; 2 Laboratory of Environment Bio-monitoring (LBE), Faculty of Sciences, Bizerte, University 7th November Carthage, 7021 Zarzouna, Bizerte,Tunisia

Abstract The study conducted on the cockle Cerastoderma glaucum from Tunisian coasts (Bizerte lagoon and Gulf of Gabes) showed the presence of two digenean species (sporocyst and cercaria of Bucephalus minimus and metacercaria of Meiogymnophallus strigatus). A description of these larvae and the behaviour of the naturally emerging cercaria are reported. The examination of the frequency of B. minimus and M. strigatus reveals some seasonal variation. This variation becomes more significant by comparing the sites. B. minimus has the highest frequency in the Bizerte lagoon, by contrast to that of M. strigatus which is the highest in the Gulf of Gabes. This variation is statistically significant. These results indicate that B. minimus and M. strigatus can be considered as biological indicators making it possible to predict the capture area of the cockle.

Introduction The cockle, Cerastoderma glaucum, which has process of regulating of the natural popula- a significant economic value, is commonly tions of marine organisms, is a theme which exploited in several European countries. In was the subject of little attention because of the Tunisia, in spite of its abundance in several durability of the relation parasite-host (Combes, sites, in lagoons as well as in the sea, this species 1995). Recently, De Montaudouin et al. (2000), still remains unexploited. This bivalve, slightly Mouritsen (2002), Desclaux (2003) and Desclaux hidden in the sandy-muddy sediment of the et al. (2002) studied the impact of Digenea on intertidal zone, is among the benthic organisms the cockle populations. These authors conclude most exposed to organic and chemical pollut- that digenean parasitism does not necessarily ants debouched in the receiving environment. explain the marked reduction in the molluscs, Studies carried out in the Bay of Saint Brieuc even if the presence of digeneans can indirectly by Le Mao et al. (2002), on some species of bi- increase the mortality rate of the cockle (Cerasto- valves, show a marked decrease of the cockle derma edule, Austrovenus stutchburyi) by reducing between 1988 and 2000. Various hypotheses their capacity for burrowing in the sediment. were proposed to explain this reduction, among A multifactorial effect is therefore suspected in which, we can cite intensive fishing, as well cockle mortalities. as pollution and parasitism. Parasitism, as a

* Corresponding author’s email: [email protected] Bull. Eur. Ass. Fish Pathol., 31(1) 2011, 5

Conscious of the ecological importance of distilled water and stained with boric carmine. the parasites, their action on the dynamics of After differentiation, the specimens were dehy- populations and the behaviour of the host, we drated in series of alcohol (70, 95, 100%), cleared investigated the digenean fauna of the cockle, in Gaulteria oil and mounted between slide and Cerastoderma glaucum and the spatiotemporal coverglass in Canada balsam. distribution of the parasites. Silversides collected from Kalaat El Andalous, Materials and methods a site known to be negative for the bucephalid The studied cockles (3200 specimens) were parasite, were exposed to cercaria released from sampled from the Bizerte lagoon (north-eastern C. glaucum to try the experimental infection. Tunisia) and the Gulf of Gabes (port of Sfax) (south-eastern Tunisia). The Bizerte lagoon, For histological preparations, cockles were fixed characterized by sandy-clay to clay-silt-sandy in Bouin’s fluid. After washing, samples were sediments, is rather deep (12 m) (Soussi et al., dehydrated through an ethanol series, treated 1983). In Bizerte Lagoon, the mean annual water with butyl alcohol, embedded in paraffin wax temperature is 18.28 ˚C and the mean annual and sectioned. The 5-µm sections were stained salinity is 34 ‰. In the Gulf of Gabes, charac- with Masson Trichrome (Martoja and Martoja- terized by sandy-muddy bottom sediments Pierson, 1967). (Amari, 1984), the annual mean temperature is 20.58 ˚C and the mean annual salinity is Illustrations and measurements of parasites 38.68‰. were made with the aid of Wild microscope drawing tube. The collected lamellibranchs were placed in small aquaria, which were examined daily with The nomenclature used in the analysis of the a binocular microscope to detect spontaneous frequencies of the larval-stage parasites accord- cercarial emergence. Each infected mollusc was ing to the seasons and sampling sites follows then kept in its own aquarium. The number Margolis et al. (1982) and Bush et al. (1997). of cercariae produced daily was counted. The experiment was subjected to natural lighting To test the significance of the variation of the conditions only, except during the period when values of the frequency according to the locali- cercariae were counted under artificial light. If ties of capture, X2 test was applied. these examinations appeared negative, after 15 days the molluscs were dissected to detect the Results and discussions possible presence of young sporocysts or meta- Examination of the cockle Cerastoderma glaucum cercariae. The site of infection and the number collected from the Bizerte lagoon and the Gulf of each parasite were noted. The parasites col- of Gabes (port of Sfax) reveal that this mollusc lected were either studied directly in vivo under is parasitized by the same digenean fauna in the stereomicroscope, or treated for a later ob- both localities. Two species of digenean belong- servation. The parasites were fixed in Bouin’s ing to two distinct families were recorded: the fluid between slide and coverglass, washed by sporocyst and cercaria of Bucephalus minimus Bull. Eur. Ass. Fish Pathol., 31(1) 2011, 6

(Stossich, 1887) Maillard, 1976 (Bucephalidae) Cercaria and the metacercaria of Meiogymnophallus stri- Morphology gatus (Lebour, 1908) Ching, 1965 (Gymnophal- The gasterostome cercaria (Figure 3), measur- lidae). ing, on average, 360 µm in length and 90 µm in width. Anterior extremity armed with an Bucephalus minimus organ of penetration, the rhynchus contain- Sporocyst ing numerous glandular cells. The posterior Branched sporocyst, white with constructions margin, ending with the tail, composed of a and containing, according to the degree of caudal bulb, prolonged by two long retractile maturation, either the germinal balls or the furca with numerous small transverse folds cercariae (Figures 1 a, b). Sporocyst occurring on surface. Glandular cells, present on caudal in gonads and digestive gland of the cockle. bulb and furca, secreting adhesive substance With histological analysis, it was possible to allowing the attachment of the cercaria to the confirm the presence of sporocyst in analyzed second intermediate host. Digestive tract of the tissue (Figure 2 a, b). As reported by Khamdan cercaria including an equatorial mouth followed (1998) and Desclaux et al. (2002), these larvae by a muscular pharynx (30 µm diameter), a caused severe disruption such as the castration short oesophagus and a saccular sac. The main of the gonadal tissue, function alteration of the excretory tubules, resulting from the union of digestive gland or death of the mollusc. The anterior and posterior collecting tubules, joining development of the larval stages was, therefore, the excretory vesicle at the level of the mouth. achieved at the expense of the parasitized host. Excretory vesicle, saccular, thin-walled, and The parasite diverts the metabolic activities measuring on average 60 µm in length. 72 flame of the mollusc for its own gain. The death of cells (36 on the right, 36 on the left) present in parasitized molluscs occurred before the total the following arrangement: emergence of the cercariae. 2[(6+6+6) + (6+6+6)] = 72

200 µm

a b

Figure 1. Sporocyst containing cercariae of Bucephalus minimus from Cerastoderma glaucum, a: Drawing, b: photo Bull. Eur. Ass. Fish Pathol., 31(1) 2011, 7

a b

Fig u re 2 . a: Histological section showing the presence of Bucephalus minimus sporocyst in gonads. b: Histological section showing the presence of Bucephalus minimus sporocyst in digestive gland. Sp: sporocyst.

The Bucephalid cercaria, named Bucephalus haimeanus by Lacaze-Duthiers in 1954, was collected in the oyster Ostrea edulis L. 1758 in the Balearic Islands and in Cardium glaucum Bruguiere, 1789 in France coasts (Sete). Mat- thews (1973) found this parasite in Cardium edule and succeeded in obtaining experimentally the metacercaria by infecting the goby, Poma- toschistus microps. Maillard (1975, 1976) never found a bucephalid cercaria in Ostrea edulis at Sete whereas Cardium glaucum was parasitized. He concludes that the bucephalid parasite of the oyster and that of the cockle constitute two distinct species. However, this author, only on the basis of morphological criteria, attributed the bucephalid collected from Cardium edule and that taken from Cardium glaucum to the species which he named Labratrema minimus. However, all previous designations were considered as a synonym of Bucephalus minimus (Overstreet and Curran, 2002; Bartoli et al., 2006). 100 µm Behaviour The cercaria left the mollusc and moved initially Figure 3. Cercaria of Bucephalus minimus. towards the water surface. The cercarial body Bull. Eur. Ass. Fish Pathol., 31(1) 2011, 8 was directed downwards and floats due to its two long filamentous furcae. In the absence of an intermediate host, the larva remained at the bottom of the small aquaria. It carried out slow movements by contracting the body and the filamentous furcae. Finally, the cercaria encysted within a thin transparent envelope. The cercariae were released diurnally from the mollusc. The emergence of the cercariae is related to the increase of the temperature. 100 µm Indeed, the mean number of emitted cercariae from parasitized mollusc, at temperatures of 15°C, 20°C and 25°C, is 45, 100, 250 individu- Figure 4. Metacercaria of Bucephalus minimus from Atherina boyeri. als per day, respectively. However, tempera- ture above 25°C shortens the longevity of the larvae (5 to 6 hours). The temperature of 15°C, on the other hand, maintains the life of the cercaria over 2 to 3 days. Graczyk and Fried (2001) suggest that the lifespan of the cercariae in water is determined by its glycogen reserves and water temperature. Higher temperatures involve an increased activity of the cercaria and thus a faster loss of its energy reserves, thus reducing its duration of survival (Evans and Gordon, 1983; Evans, 1985).

Experimental infections Previous research (Gargouri Ben Abdallah, 100 µm 2001) showed the presence of the metacercar- Figure 5. Adult of Bucephalus minimus from ia (Figure 4) in small teleost fishes (Atherina Dicentrarchus labrax. boyeri, Aphanius fasciatus, Gobius niger, Gobius paganellus and Pomatoschistus microps) and the which were emitting cercariae ofB. minimus. The adult parasite (Figure 5) in the sea bass, Dicen- cercariae attached to the fish by the filamentous trarchus labrax. The highest frequency of this furcae and bulb and penetrated by their apical metacercaria was recorded in the silverside (A. part. These fish were dissected, at a rate of 2 boyeri) which seems to be the preferred host specimens, at 2, 4, 10, 20 days post exposure. of this parasite. Accordingly, an experimental Two days post exposure, the liver of the fish infection using 8 specimens of silversides was was entirely invaded by the metacercariae of B. carried out. The fish were exposed, for one minimus. These larvae have enormous digestive day, to naturally infested Cerastoderma glaucum caeca, filled with hepatic and sanguineous cells, Bull. Eur. Ass. Fish Pathol., 31(1) 2011, 9 occupying the major part of the parasite body. sented by a compact mass of metacercariae. Four days after exposure, the anterior edge of the rhynchus forms protuberances, the volume The finding of the cercaria and the sporocyst of of the digestive caeca decreased and the excre- B. minimus, on the Tunisian coasts, allowed us tory vesicle increased in size. After ten days, to partially achieve the life cycle of this parasite the rhynchus carried, at its anterior margin, as already described by Maillard (1975). The life the well developed protuberances, while the cycle of this parasite was also achieved on the digestive caeca continued to regress, and the Portugal coasts (Pinna et al., 2009). However excretory vesicle to dilate to be filled with fine the first and the second intermediate hosts are granules. The silverside dissected after twenty respectively presented by Cerastoderma edule and days showed a metacercariae with immature Mugil cephalus. The larval and adult stage har- gonads. vested on Tunisian and Portugal coast present the same morphology. Only molecular analysis The number of larvae collected in autopsied fish will allow the confirmation of the attribution of varied from 20 to 35 specimens. These larvae the two sympatric parasites, harvested in differ- give the liver a white colour and a granular ent intermediate hosts, to the same species. aspect. Faliex (1991) and Faliex and Morand (1994), by studying the dynamics of the popu- Meiogymnophallus strigatus lations and the pathology of these larvae on Metacercaria body (Figure 6 a, b), with rounded the second host, concluded that the cercariae margin, measuring 406 µm in length and 279 consume the hepatic cells before encystment. µm in width and presenting a spinose tegument. When the infestation is intense, the liver is pre- Oral sucker (107 µm), subterminal, twice bread

50 µm

a b

Figure 6. Metacercaria of Meiogymnophallus strigatus from Cerastoderma glaucum, a: Drawing, b: Photo. Bull. Eur. Ass. Fish Pathol., 31(1) 2011, 10 than ventral sucker (61 µm). Ventral sucker This larva was found by Rees (1939) in Cardium located, depending on the contraction, at the edule. Bartoli (1983) reported the presence of this posterior limit of the mid third or at the anterior metacercaria in several species of lamellibranchs limit of the posterior third of the body. Mouth, (Donax trunculus L., Donax semistriatus Poli., opening in the middle of the oral sucker, fol- Lentidium mediterraneum (Costa), Solen margina- lowed by a small pharynx (37 µm). Oesophagus tus Pennant, Ensis ensis (L.), Pharus legumen (L.), bifurcating into digestive caeca which reaching Spisula subtruncata (Da costa), Loripes lacteus (L.)) the level of the ventral sucker. from the coasts of the Camargue. The cercaria of M. strigatus was found in Tellina tenuis Da costa Immature gonads composed of two testes (80 and the adult in Melanitta nigra, and M. fusca µm), located in the area of the ventral sucker, (Pérès and Picard, 1964; Bartoli, 1983). near the lateral wall of the body and an ovary (65 µm) situated just anterior to the left testi- The metacercaria collected from the cockle from cle. Excretory system made of 16 flame cells the Tunisian coast, has an identical morphol- presented as the following formula: 2 [(2+2) + ogy to that described by Bartoli (1983) in the (2+2)] = 16. Bladder, with two branches, extend- Camargue. However, measurements of the ing to the level of the oral sucker and ending Tunisian specimens are slightly greater than in two lobes. those of the southern coasts of France. We also note that the anterior end of the testes, which The metacercaria of M. strigatus is gradually does not pass the middle of the ventral sucker enveloped by the pallial proliferations. It is in the specimens from the Camargue, reached located between the mantle and the shell of the or exceeds the anterior margin of the ventral host, on the surface of the pallium or placed sucker in the larvae of our coasts. This parasite inside the furrow periostracal bordering the is extremely close to Gymnophallus fossarum col- pallial lobes and generally, under the hinge. The lected on the Tunisian coast from Tapes decussata number of parasite per infested mollusc does (Trigui el Menif et al., 2004). Our observations not exceed 35. This parasite does not seem to show that these two species are characterized cause a disturbance at the host. This is undoubt- by the form of the body; G. fossarum is generally edly due to the lower number of the larvae so oval at and M. strigatus is round. The saccular their pathogenic effect can remain hidden. digestive caeca are more voluminous in M. strigatus. The size of the oral sucker, the form The metacercaria of M. strigatus, never encysted, and the width of the bladder constitute the was originally described as being a cercaria. It discriminating criteria of these two species. The was reported for the first time by Giard (1897) subterminal oral sucker, twice the size of the at Boulogne in Donax trunculus L., Tellina fabula ventral sucker at M. strigatus, is slightly broader Gronov, Tellina tenuis Da costa and Tellina solid- than the ventral sucker in G. fossarum. The an- ula L. Lebour (1908) attributed the name of terior end of the bladder is slightly forked and Cercaria strigita to this helminth. Dollfus (1912) does not pass the pharynx in G. fossarum, but it described this parasite again and specified that reaches the anterior limit of the oral sucker and it represents a metacercaria and not a cercaria. is divided into two lobes in M. strigatus. Bull. Eur. Ass. Fish Pathol., 31(1) 2011, 11

Seasonal frequencies of digenean larvae Metacercaria of M. strigatus presents generally The seasonal prevalences of the sporocysts of low values of frequencies. These values which B. minimus show a perennial infestation in the are more important in Sfax, are cancelled in cockle from Bizerte lagoon with maximum autumn in the two prospected localities. The values in autumn which decrease gradually in development of the metacercaria starts in winter winter then in spring and becoming minimal reaching a maximum in spring to be reduced in summer. These values are zero in summer again in summer (Figure 8). The diminution of in the Gulf of Gabes (port of Sfax) and do not this frequency during the summer is, undoubt- exceed 3% in spring (Figure 7). The absence edly, due to the mortality of the cockle following of this bucephalid in summer at Sfax can be the increase of the temperature of water. The explained by the increase of the temperature lack of infestation during the autumn can be which can be lethal for infested mollusc, ex- explained by the non emission of the cercaria hausted by the energy spoliation caused by the during the summer season or by the fast death parasite, or for the infecting miracidial stage. of these larvae, following the rise in the tem- The highest frequencies noted in Bizerte lagoon perature, before reaching the second host. The may be due to the nature of the harvested area; space variability of the infestation is probably indeed, the lagoon of Bizerte, qualified as con- related to the environmental conditions of the fined environment, with high densities of or- sites and the frequency of the other hosts inter- ganisms, represents a privileged endemiotope vening in the life cycle. for the digeneans, thus allowing the successful completion of the life cycle of B. minimus. The Examination of the frequencies of B. minimus hydrodynamism, more important at Sfax, plays and M. strigatus reveals a low seasonal vari- a fundamental role in the dispersion of the ability. The variation becomes more noticeable infective stages thus restricting their chances when we compare the sites. Indeed, B. minimus of the meeting with their hosts. This variation is more frequent in the Lagoon of Bizerte and M. can also be related with salinity and frequency, strigatus is more common in the Gulf of Gabes. in the prospected area, of the intermediate and The variations of the distribution according the final hosts allowing the completion of the to sampling localities are statistically signifi- heteroxenic life cycle of this parasite. However, cant (X2=3.84, dl=1, p<0.05) for the two species. Maillard (1976) noted that the emergence of the These results make it possible to consider B. cercaria of B. minimus, in the ponds of Prevot, minimus and M. strigatus as biological indica- Vic and Arnel, is observed during the summer tors of cockles stocks. We think that parasitic then decrease in autumn and disappears in fauna could be used to predict the harvesting winter. The development of the cercaria begins area for unknown samples. This natural method again in spring. The lag, of one season, of para- of marking was used in the countries of the sitic frequency peak between the Tunisian and northern Mediterranean coast for distinction of French coasts and the absence of this larva in fish stocks (Arthur and Albert, 1993; Margolis, winter in the latter locality are, undoubtedly, 1993; Mackenzie, 2002; Power et al., 2005; Timi, because the water temperature in France is 2007). In Tunisia, a similar approach was used lower. to discriminate stocks of triglids (Chelidonicthys Bull. Eur. Ass. Fish Pathol., 31(1) 2011, 12

25

Bizerte Sfax 20

15 % ce Prevalen 10

5

0 SummerAutumnWinterSpring Seasons

Figure 7. The seasonal variation of prevalence of Bucephalus minimus according to sampling localities

12

Bizerte Sfax 10

8 % ce 6 Prevalen

4

2

0 SummerAutumnWinterSpring Seasons

Figure 8. The seasonal variation of prevalence of Meiogymnophallus strigatus according to sampling localities Bull. Eur. Ass. Fish Pathol., 31(1) 2011, 13

Cerastoderma edule (Mollusque bivalve) lastoviza, C. lucerna and C. obscurus) from the en milieu lagunaire macrotidal. Thèse de Gulfs of Gabes and Hammamet by using a doctorat. Université Bordeaux I. 253pp. differential space frequency of Monogenea Desclaux C, De Montaudouin X and Bachelet (Plectanocotyle sp, P. major, Trochopus pini and G (2002). Cockle emergence at the sediment Triglicola obscurum) (Neifar, 2008). surface: ‘favourization’ mechanism by digenean parasites? Diseases of Aquatic Organisms 52, 137-149. References Amari A (1984). Contribution à la connaissance Dollfus RP (1912). Une métacercaire hydrologique et sédimentologique de la margaritigène parasite de Donax vittatus Da plate forme des Kerkennah. Thèse 3ème cycle. Costa. Contribution à l’étude des trématodes Faculté des Sciences de Tunis, Université de marins du Boulonnais. Mémoires de la Société Tunis II. 263 pp. Zoologique de France 24, 85-144. Arthur JR and Albert E (1993). Use of parasites Evans NA (1985). The influence of environmental for separating stocks of Greenland halibut temperature upon transmission of the (Reinhardtius hippoglossoides) in the canadian cercariae of Echinostoma liei (Digenea: northwest Atlantic. Canadian Journal of Echinostomatidae). Parasitology 90, 269- Fisheries and aquatic Sciences 50 (10), 2175- 275. 218. Evans NA and Gordon DM (1983). Experimental Bartoli P (1983). Les stades larvaires de studies on the transmission dynamics of the Meiogymnophallus strigatus (M.V. cercariae of Echinoparyphium recurvatum Lebour, 1908) n. comb. (Trematoda: (Digenea: Echinostomatidae). Parasitology Gymnophallidae). Annales de Parasitologie 87, 167-174. Humaine et Comparée 58(3), 227-242. Faliex E (1991). Ultrastructural study of the Bartoli P, Bray RA and Gibson DI (2006). host parasite interface after infection of two Four closely related but forgotten species species of teleosts by Labratrema minimus of Rhipidocotyle Diesing, 1858 (Digenea: metacercariae (Trematoda, Bucephalidae). Bucephalidae) in fishes from European seas. Diseases of Aquatic Organisms 10, 93-101. Systematic Parasitology 65, 129–149. Faliex E and Morand S (1994). Population Bush AO, Lafferty KD, Lotz JM and Shostak dynamics of the metacercariel stage of the AW (1997). Parasitology meets ecology on Bucephalid trematode, Labratrema minimus its own terms: Margolis et al. Revisited. The (Stossich, 1887) from Salses-Leucate lagoon Journal of Parasitology 83, 575-583. (France) during the cercarial shedding period. Journal of Helminthology 68, 35-40. Combes C (1995). Interactions durables. Ecologie et évolution du parasitisme. Gargouri Ben Abdallah L (2001). Les trématodes Ouvrage publié avec le concours du centre parasites de deux poissons d’intérêt national du livre. 524 pp. commercial le loup Dicentrarchus labrax (Linnaeus, 1758) et l’anguille Anguilla De Montaudouin X, Kisielewski I, Bachelet anguilla (Linnaeus, 1758). Etude comparative G and Desclaux C (2000). A census of et cycles évolutifs des espèces du genre macroparasites in an intertidal bivalve Bucephalus. Thèse de Doctorat. Université community, Arcachon Bay, France. de Tunis El Manar. Faculté des Sciences de Oceanologica Acta 23, 453-468. Tunis. 226 pp. Desclaux C (2003). Interaction hôte parasite : Giard A (1897). Sur un distome (Brachycoelium diversité ; mécanisme d’infestation et impact sp.) parasite de Pélécypodes. Comptes rendus des trématodes digènes sur les coques de la société de Biologie Paris 49, 956-957. Bull. Eur. Ass. Fish Pathol., 31(1) 2011, 14

Graczyk TK and Fried B (2001). Helminth Matthews RA (1973). The life cycle ofBucephalus biology, adaptation, transmission, and haimeanus Lacaze-Duthiers, 1854, from survival. Recent Research and Development Cardium edule L. Parasitology 67, 341-350. of Microbiology 5, 171-185. Mouritsen KN (2002). The parasite-induced Khamdan SAA (1998). Occurrence of Bucephalus surfacing behaviour in the cockle sp. Trematode in the gonad of the pearl Austrovenus stutchburyi : a test of an oyster, Pinctada radiata. Environnement alternative hypothesis and identification international 24, 117-120. of potential mechanisms. Parasitology 124, 521-528 Lacaze-Duthiers FJH (1954). Mémoire sur le Bucéphale haime (Bucephalus haimeanus) Neifar L (2008). Les Plathelminthes parasites helminthe parasite des Huîtres et des de poissons : Biodiversité et implications Bucardes. Annales des Sciences Naturelles pratiques. Habilitation à diriger des de Paris (Zoologie) 4, 1 (5), 294-302. recherches. Université de Sfax, Faculté des Sciences de Sfax. 83 p. Lebour MV (1908). Trematodes of the Northumberland coast, n°II. Trans- National Overstreet RM and Curran SS (2002). History Society North-umberland 3, 28-45. Superfamily Bucephaloidea Poche, 1907. In Keys to the Trematoda, Vol. 1, D. I. Le Mao P, Retiere C et Plet M (2002). Les Gibson, A. Jones, and R. A. Bray (eds.). CAB peuplements benthiques intertidaux de International Publishing and The Natural la baie de Saint-Brieuc, Ifremer-museum History Museum, London, U.K., 67–110. d’histoire naturelle-dinard-diren Bretagne, 23p+ annexes. Pérès JM and Picard J (1964). Nouveau manuel de bionomie benthique de la mer Mackenzie K (2002). Parasites as biological tags Méditerranée. Recueil des Travaux Station in population studies of marine organisms: marine d’Endoume. 31, 5-137. an update. Parasitology 124, 153-163. Pinna S, Barandela T, Joao Santos M, Russel- Maillard C (1975). Labratrema lamirandi (Carrère, Pinto F and Rodrigues P (2009). Identification 1937) (Trematoda, Bucephalidae) parasite and description of Bucephalus minimus de Dicentrarchus labrax. Création du genre (Digenea, Bucephalidae) life cycle in Labratrema. Cycle évolutif. Bulletin du Portugal: Morphological, Histopathological, Muséum National d’Histoire Naturelle. Paris, and Molecular data. Journal of Parasitology 283, Zoologie 193, 69-80. 95, 353-359. Maillard C (1976). Distomatose de poissons Power AM, Balbuena JA and Raga T (2005). en milieu lagunaire. Doctorat es-Sciences Parasite infracommunities as predictors of naturelles. Université des Sciences et harvest lacation of bogue (Boops boops L.): Techniques de Languedoc. Montpellier, a pilot study using statistical classifiers. 383 pp. Fisheries Research 72, 229-239. Margolis L (1993). A case of forensic parasitology. Rees G (1939). Cercaria strigata Lebour from Journal of Parasitology 79, 461-462. Cardium edule and Tellina tenuis. Parasitology Margolis L, Esch GW, Holmes JC, Kuris AM 31, 458-463. and Schad GA (1982). The use of ecological Soussi N, Levy A and Zaouali J (1983). La lagune terms in parasitology. Journal of Parasitology de Bizerte : Sédimentologie et écologie des 68, 131-133. Foraminifères et Mollusques. Notes de service Martoja R and Martoja-Pierson M (1967). Géologique de la Tunisie 47, 27-40. Initiation aux techniques de l’histologie Timi JT (2007). Parasites as biological tags for animale. Masson et compagnie, Editeurs., stock discrimination in marine fish from 345 p. Bull. Eur. Ass. Fish Pathol., 31(1) 2011, 15

South American Atlantic waters. Journal of Helminthology 81, 107-111. Trigui El Menif N, Gargouri Ben Abdallah L and Le Pennec M (2004). Parasitisme et anomalie de calcification de la coquille observés chez la palourde européenne Ruditapes decussatus prélevées dans la région de Sfax. Rapport de la Commission Internationale de la Mer Mediterranée 37, 448.