The aim of the present study was to provide a current survey of metazoan parasites of the Mediterranean garfish Belone belone gracilis Lowe, 1839 off Tunisian coast and their potential use as biological tags for discr...The aim of the present study was to provide a current survey of metazoan parasites of the Mediterranean garfish Belone belone gracilis Lowe, 1839 off Tunisian coast and their potential use as biological tags for discriminate stocks. Parasitological analysis of 453 specimens of B. b. gracilis along the eastern Tunisian coast revealed the presence of ten species of metazoan parasites: one monogenean Axine belones Abildgaard, 1794;four digeneansLecithostaphylus retroflexus (Molin, 1859), Tergestia acanthocephala (Stossich, 1887) Stossich, 1899, Aponurus laguncula Looss, 1907 and Condylocotyla pilodora(metacercaria) Pearson et Prévot, 1985;one copepod Bomolochus bellonesBurmeister, 1835;two isopods Irona nana Schioedte et Meinert, 1884 andNerocila orbignyi (Guérin-Méneville, 1832);1 acanthocephalan Telosentis exiguus (Von Linstow, 1901) and one nematod Anisakid larvae. Discriminant analysis using parasites as biological tags, allowed identifying two stocks ofB. b. gracilis. Digenea L. retroflexus, A. laguncula and Anisakid larvae were the most important species in determining the position of sampled fishes from the central coast off Tunisia. Metacercaria C. pilodora characterized specimens from the Southern coast off Tunisia. These results were corroborated by comparing parameters of prevalence and mean abundance between zones. Discriminant analysis used for the separation of B. b. gracilis between seasons in both localities showed that a seasonal variation affected mainly specimens from the center suggesting seasonal move of fishes.展开更多
Although information about embryonic and larval development of garpike,Belone belone(Linnaeus,1761),is present in the published literature,the bulk of research concerns garpike from the northeastern Atlantic Ocean and...Although information about embryonic and larval development of garpike,Belone belone(Linnaeus,1761),is present in the published literature,the bulk of research concerns garpike from the northeastern Atlantic Ocean and the Baltic Sea.The present work describes the embryonic and larval development of garpike,Belone belone,from the Adriatic Sea,and methods used for incubation of fertilized eggs in aquarium conditions.Because garpike is,as suggested by some authors,divided into subspecies,we conclude that some differences in embryonic development could also be expected.In the present study,eggs were fertilized using the dry fertilization method and were incubated in a tank equipped with aeration and constant sea water flow.Salinity and content of dissolved oxygen were constant,and the temperature varied between 19.4 and 22.3°C.Eggs were spherical,measuring 3071.9±75.73μm in diameter.Yolk sacs were homogeneous and did not contain oil globules.The first larvae hatched 329 h and 47 min after fertilization.Absorption of the yolk sac occurred 17 h–48 h after hatching and the total length of newly hatched larvae was 9.78 mm.The peculiarities observed in the embryonic and early larval development are evidence of an exceptional plasticity and adaptive potential,which could be considered as helpful features in extending the natural range of occurrence of this species.展开更多
文摘The aim of the present study was to provide a current survey of metazoan parasites of the Mediterranean garfish Belone belone gracilis Lowe, 1839 off Tunisian coast and their potential use as biological tags for discriminate stocks. Parasitological analysis of 453 specimens of B. b. gracilis along the eastern Tunisian coast revealed the presence of ten species of metazoan parasites: one monogenean Axine belones Abildgaard, 1794;four digeneansLecithostaphylus retroflexus (Molin, 1859), Tergestia acanthocephala (Stossich, 1887) Stossich, 1899, Aponurus laguncula Looss, 1907 and Condylocotyla pilodora(metacercaria) Pearson et Prévot, 1985;one copepod Bomolochus bellonesBurmeister, 1835;two isopods Irona nana Schioedte et Meinert, 1884 andNerocila orbignyi (Guérin-Méneville, 1832);1 acanthocephalan Telosentis exiguus (Von Linstow, 1901) and one nematod Anisakid larvae. Discriminant analysis using parasites as biological tags, allowed identifying two stocks ofB. b. gracilis. Digenea L. retroflexus, A. laguncula and Anisakid larvae were the most important species in determining the position of sampled fishes from the central coast off Tunisia. Metacercaria C. pilodora characterized specimens from the Southern coast off Tunisia. These results were corroborated by comparing parameters of prevalence and mean abundance between zones. Discriminant analysis used for the separation of B. b. gracilis between seasons in both localities showed that a seasonal variation affected mainly specimens from the center suggesting seasonal move of fishes.
文摘Although information about embryonic and larval development of garpike,Belone belone(Linnaeus,1761),is present in the published literature,the bulk of research concerns garpike from the northeastern Atlantic Ocean and the Baltic Sea.The present work describes the embryonic and larval development of garpike,Belone belone,from the Adriatic Sea,and methods used for incubation of fertilized eggs in aquarium conditions.Because garpike is,as suggested by some authors,divided into subspecies,we conclude that some differences in embryonic development could also be expected.In the present study,eggs were fertilized using the dry fertilization method and were incubated in a tank equipped with aeration and constant sea water flow.Salinity and content of dissolved oxygen were constant,and the temperature varied between 19.4 and 22.3°C.Eggs were spherical,measuring 3071.9±75.73μm in diameter.Yolk sacs were homogeneous and did not contain oil globules.The first larvae hatched 329 h and 47 min after fertilization.Absorption of the yolk sac occurred 17 h–48 h after hatching and the total length of newly hatched larvae was 9.78 mm.The peculiarities observed in the embryonic and early larval development are evidence of an exceptional plasticity and adaptive potential,which could be considered as helpful features in extending the natural range of occurrence of this species.
