RESUMEN
Larval forms of the genus Anisakis were reported infecting several fish species from the North African coasts of central Mediterranean Sea. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was used to investigate the occurrence of larval forms of different Anisakis species in teleost fishes and squid from North African coasts of the Mediterranean Sea and to establish the geographical and host range of these parasites in this area. A total of 282 Anisakis larvae were identified by PCR-RFLP from 13 teleost fish species and one cephalopod species captured at different sites off the Algerian, Tunisian and Libyan coasts. The type I larvae were found with a frequency of 93.62% and were identified as belonging to the following species: Anisakis simplex s.str., Anisakis pegreffii, A. simplex s.str/A. pegreffii hybrids and Anisakis typica. The type II larvae were found to belong to Anisakis physeteris, with the frequency of 6.38%. The record of A. simplex s.str/A. pegreffii hybrids, previously recorded from the Spanish and Portuguese Atlantic coasts and the Alboran Sea, extends their geographic distribution to the Tunisian coasts. The occurrence of A. simplex s.str. and hybrids away from their known area of distribution may predict the successful use of Anisakis larvae for tagging Scomber scombrus fish stocks for fisheries management purposes. Moreover, the results reported provide valuable information regarding the diversity of Anisakis species in the study area, indicating that several Anisakis sibling and morphospecies coexist in the North African coasts of the Mediterranean Sea.
Asunto(s)
Anisakis/aislamiento & purificación , África del Norte , Animales , Anisakiasis , Anisakis/genética , Secuencia de Bases , Elementos Transponibles de ADN , ADN de Helmintos/genética , ADN de Helmintos/aislamiento & purificación , Ecosistema , Peces/parasitología , Geografía , Larva/genética , Región Mediterránea , Mar Mediterráneo , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de Restricción , Eliminación de SecuenciaRESUMEN
Two gadiform species with a successive bathymetric and an ecological and economical importance in the Mediterranean fishing industry, Phycis blennoides and Phycis phycis, were selected for the present study. A total of 592 fresh specimens belonging to the Gadiformes genus were obtained from local commercial fisheries. The investigation was centred on anisakid parasites of 272 specimens of the greater forkbeard (P. blennoides) and 320 of the forkbeard (P. phycis) captured off the Mediterranean coasts of Tunisia (eastern Mediterranean Sea). Four species of nematodes were identified: Anisakis simplex s.1., Anisakis physeteris, Hysterothylacium aduncum and Hysterothylacium fabri. The total prevalence was 53.75% in the forkbeard and 51.47% in the greater forkbeard. The highest values of prevalence (38.75%, 2-14), mean intensity (6.74+/-3.4) and mean abundance (2.61) were all obtained for H. fabri L4 in the forkbeard. The most frequent parasite in the greater forkbeard was H. aduncum L3 with 32.35% (1-3) prevalence and values of 1.21+/-0.58 and 0.39 for mean intensity and mean abundance, respectively. The infestation parameters were also analysed according to the host length, and prevalence was highest in P. blennoides longer than 35 cm in respect of all anisakid species. Whilst in P. phycis, the highest prevalence, conditioned by H. fabri parasitisation, was found in fish with length reaching a maximum of more than 40 cm. When the data were grouped seasonally, clear patterns were observed for P. blennoides and P. phycis species, with prevalence and mean intensity of all the anisakid species peaking in spring and summer.