Parasitic infections in the Mediterranean needlefish Tylosurus acus imperialis(Teleostei:Belonidae)off Tunisian coast

Objective:To provide a current survey of parasitic infections in the Mediterranean needlefish Tylosurus acus imperialis(T.acus imperialis).The impact of host’s size and sex on some characteristics of the infection was also examined.Methods:Between 2004 and 2009,126 specimens of T.acus imperialis were necropsied to study their parasites.Results:Fifteen species of metazoan parasites were collected including 3 monogeneans(Aspinatrium gallieni,Nudaciraxine imperium and Axinoides sp.),4 digeneans(Lecithostaphylus tylosuri,Tetrochetus coryphaenae,Oesophagotrema mediterranea and Sclerodistomoides pacificus),1 cestode(Ptychobothrium sp.),3 copepods(Lernanthropus tylosuri,Caligodes laciniatus and Caligus sp.),1 isopod(Irona nana),1 acanthocephalan(Rhadinorhynchus sp.),1 nematode(anisakid larvae)and 1 annelid(piscicolid).Cestoda Ptychobothrium sp.was the most frequent species(72%).Prevalence and abundance of infection with Ptychobothrium sp.and Rhadinorhynchus sp.were positively correlated with the total length of the host.Host’s sex did not seem to affect the infection parameters of parasites in T.acus imperialis.Conclusions:This study provides first information on parasitic infections in the Mediterranean needlefish T.acus imperialis off Tunisia.Parasites can be used to understand phylogeny,biology and ecology of fish host and also as bioindicators of water quality.

Preliminary observations on the feeding habits of the Mediterranean needlefish Tylosurus acus imperialis(Teleostei:Belonidae)

Objective:To present the first information on the feeding habits of the Mediterranean needlefish Tylosurus acus imperialis(T.a.imperialis)of Tunisia and to examine the diet variation in relation to the fish size,maturity and sex.Methods:Gut contents of 92 specimens of T.a.imperialis,collected mainly from May 2004 to July 2006 off the Gulf of Gabès,Southeastern Tunisian coast,were analyzed.Results:The results showed that 55.4%of them had empty guts and 44.6%contained food in their guts.The emptiness index did not vary significantly according to size classes or sexes of T.a.imperialis.Basic food consisted of teleosts(Mugilidae,Gobidae and Belonidae)(59.63%)followed by crustaceans(40.24%),mostly decapods Sycionia carinata(5.42%).A decrease in the feeding rate at the peak of the spawning season was observed for both sexes.A diet variation among juvenile and adult specimens of T.a.imperialis was found.Conclusions:This study enhances our knowledge on the biology of the Mediterranean needlefish T.a.imperialis.This fish is an active predator and an opportunistic feeder but the feeding rate declines at the peak of the spawning season.

Diversity of monogenean parasites in belonid fishes off the Mediterranean Sea with redescription of Aspinatrium gallieni Euzet and Ktari,1971 and Axine belones Abildgaard,1794

Objective:To provide informations on the diversity of Monogenea parasitizing belonid fishes from the Mediterranean Sea.Monogenean species Aspinatrium gallieni Euzet and Ktari,1971(A.gallieni)and Axine belones Abildgaard,1794(A.belones)from belonids Tylosurus acus imperialis Rafinesque,1810(T.a.imperialis)and Belone belone Lowe,1839(B.belone)off Tunisian coast were redescribed.Methods:During the sampling period between 2004 and 2009,a total of 624 belonid fish belonging to three species,453 B.belone,45 Belone svetovidovi Collette and Parin,1970 and 126 T.a.imperialis were investigated for monogenean parasites.Results:Five Polyopisthocotylean monogenean parasites species were founded infected belonid fishes from Tunisian coast.These are,Nudaciraxine imperium Châari,Derbel and Neifar,2010,A.belones,Axine sp.,Axinoides sp.(Axinidae)and A.gallieni(Micrcotylidae).Among them,the most prevalent species A.gallieni from the inner gill cover and gill filaments of T.a.imperialis and A.belones from the gills of B.belone were redescribed.A.gallieni represented new host record for T.a.imperialis.A complete list of monogenean parasites found in belonid fishes from our study and those reported from the Mediterranean Sea was presented.Conclusions:This paper enhances the current knowledge of Monogenea infecting belonids off the Mediterranean Sea.It’s the first study on monogenean parasites of the overall belonid fishes off Tunisia.