Gonadal maturation and histological observations of the grey triggerfish Balistes capriscus Gmelin,1789(Teleostei:Balistidae)in the Gulf of Gabès,Tunisia

Objective:To determine the spawning activity using gonadosomatic index(GSI)and gonad histology the Balistes capriscus(Teleostei:Balistidae)of the Gulf of Gabès(Southern Tunisia,Central Mediterranean Sea).Methods:The reproductive biology of the species,based on 756(480 females and 276 males),collected from commercial catches at several fishing ports including Chebba,Kerkennah and Zarzis at respective GPS coordinates(34°14'N,11°06'E),(34°45'N,11°17'E),(33°41'N,11°48'E)was studied over 28 months(January 2008-April 2010)using GSI and gonad histology.Sizes used in this study ranged from 11.30 to 45.60 cm in fork length.Results:Both GSI and gonad histology suggest that spawning activity occurred mainly between July and mid-September with a peak in July,coinciding with summer time.The first maturation occurred at 20.26 cm fork length for females and 21.30 cm fork length for males.The monthly values of hepatosomatic index and condition factor(K)indicated that the liver is the main organ responsible for the mobilization process of the energizing reserves during the sexual cycle.Conclusions:It is the first inventory of gonadal maturation and histological observations of the grey triggerfish Balistes capriscus Gmelin,1789(Teleostei:Balistidae)in the Gulf of Gabès,(Southern Tunisia,Central Mediterranean Sea).

Metals and metalloid bioconcentrations in the tissues of Typha latifolia grown in the four interconnected ponds of a domestic landfill site

The uptake of metals in roots and their transfer to rhizomes and above-ground plant parts（stems, leaves） of cattails（Typha latifolia L.） were studied in leachates from a domestic landfill site（Etueffont, France） and treated in a natural lagooning system. Plant parts and corresponding water and sediment samples were taken at the inflow and outflow points of the four ponds at the beginning and at the end of the growing season. Concentrations of As, Cd, Cr, Cu, Fe, Mn, Ni and Zn in the different compartments were estimated and their removal efficiency assessed, reaching more than 90% for Fe, Mn and Ni in spring and fall as well in the water compartment. The above-and below-ground cattail biomass varied from 0.21 to 0.85, and 0.34 to 1.24 kg dry weight/m^2, respectively, the highest values being recorded in the fourth pond in spring 2011. The root system was the first site of accumulation before the rhizome, stem and leaves. The highest metal concentration was observed in roots from cattails growing at the inflow of the system＇s first pond. The trend in the average trace element concentrations in the cattail plant organs can generally be expressed as： Fe 〉 Mn 〉 As 〉 Zn 〉 Cr 〉 Cu 〉 Ni 〉 Cd for both spring and fall. While T. latifolia removes trace elements efficiently from landfill leachates, attention should also be paid to the negative effects of these elements on plant growth.

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.

Influence of season,size and sex on the dynamic of gill metazoan parasite infesting the Balistes capriscus(Teleostei:Balistidae)of the Gulf of Gabès(Tunisia)

Objective:To investigate the effects of season,size and sex on the dynamic of gill metazoan parasite infesting the Balistes capriscus(Gmelin,1788)(Teleostei:Balistidae)(B.capriscus)of the Gulf of Gabès(Southern Tunisia,Central Mediterranean Sea).Methods:A parasitological survey of the grey triggerfish B.capriscus from the Gulf of Gabès(Southern Tunisia,Central Mediterranean Sea)was conducted monthly from June 2011 to June 2012.A total of 1080 fish were collected from commercial catches by pelagic trawl net at different fishing ports at Chebba(34°14'N,11°06'E),Kerkennah(34°45'N,11°17'E)and Zarzis(33°41'N,11°48'E).The weight,size,sex,date and area of capture of each specimen were recorded.Then,B.capriscus was examined to search for ectoparasites.For each parasite species,parasitological indices were calculated.Results:The parasite species are indentified as two copepods:Naobranchia variabilis,Taneacanthus ballistae and a monogenean:Ancyrocephalus balisticus.The parasitological indices depend significantly on seasonality;the highest prevalence of Naobranchia variabilis,Taneacanthus ballistae and Ancyrocephalus balisticus(28.89%,35.93%and 55.56%respectively)was recorded during summer season(June–August),while the lowest prevalence of each(6.3%,4.44%,8.15%)recorded during winter season(December–February).Furthermore the parasitological indices depend significantly on the host size but not on host sex.Conclusions:Our data suggest that the dynamic of gill metazoan parasite infesting B.capriscus is a result of a complex of biotic and abiotic factors.It is the first study on the effects of season,size and sex on the dynamic of gill metazoan parasite infesting B.capriscus(Teleostei:Balistidae)of the Gulf of Gabès(Southern Tunisia,Central Mediterranean Sea).

Heavy metal concentrations inLiza aurata(Risso,1810)captured from the Kerkennah Islands(Gulf of Gabes)and associated health risks

Objective:To determine the concentration of heavy metals(Cd,Cu,Fe,Ni,Pb and Zn)in the liver,gills and muscle of Liza aurata(L.aurata)collected from the Kerkennah Islands.The target hazard quotient was also used as an indicator of human health risks associated with fish consumption.Methods:The sample was collected from Kerkennah Islands(Gulf of Gabes,Tunisia).Heavy metals in L.aurata tissues(gills,liver and muscle)were analysed with an atomic absorption spectrometer(PerkinElmer).Results:As expected,muscle always possessed the lowest concentrations of all metals.The maximum concentrations of Cd(0.52 mg/kg wet weight),Cu(5.43 mg/kg wet weight),Fe(115.27mg/kg wet weight)and Zn(112.20 mg/kg wet weight)were measured in the liver,while the highest Ni(1.54 mg/kg wet weight)and Pb(1.43 mg/kg wet weight)were recorded in gills.The target hazard quotient through consumption of fish and calculated by adding the inividual target hazard quotient was below 1,indicating that there was no significant potential health risk associated with consumption of L.aurata.Conclusions:L.aurata from the Kerkennah Islands may be suitable for human consumption.

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.

Spring phytoplankton variability along a south coast of Sfax at the water-sediment interface(Tunisia,Eastern Mediterranean Sea)

Objective:To compare the composition of the phytoplankton classes during the two spring studies,to study whether the spatial distribution of the phytoplankton is stable or not between spring 2010 and spring 2011 and to estimate the abiotic factor that mostly affects the structure and the richness of phytoplankton.Methods:Phytoplankton sub-samples were counted under an inverted microscope using the Utermöhl method.Phytoplankton identification was made from morphological criteria after consulting various keys.Results:Results showed a significant difference from spring 2010 to spring 2011 regarding nitrate/phosphate ratio,with high value in spring 2010(30.19±25.70).Relatively low nitrate/phosphate ratio(1.13±0.53)during spring 2011 might result from phosphogypsum.Phytoplankton was characterised by the proliferation of Bacillariophyceae(46%–78%of the total microphytoplankton)and by the large number of Euglenophyceae.Thirty two Bacillariophyceae species were identified at every station,represented essentially by Amphora sp.,Navicula sp.,Coscinodiscus sp.and Grammatophora sp.The results advise that Bacillariophyceae are usually adapted to particular ecological environment.Conclusions:This study shows that hydrological conditions in the south coast of Sfax present a high spatial and seasonal variability.The phytoplankton community distribution showed clear variations along the coastal stations during a spring cruises conducted in May 2010 and May 2011.The phytoplankton community found along the coast was dominated by opportunistic Bacillariophyceae species.

Parasitic inventory of Balistes capriscus(Teleostei:Balistidae)from the Gulf of Gabès(Southern Tunisia,Central Mediterranean Sea)

Objective:To investigate the parasitic inventory of Balistes capriscus(Teleostei:Balistidae)(B.capriscus)from the Gulf of Gabès(Southern Tunisia,Central Mediterranean Sea).Methods:A parasitological survey of the grey triggerfish B.capriscus(Gmelin,1788)from the Gulf of Gabès(Southern Tunisia,Central Mediterranean Sea)was conducted monthly from May 2007 to April 2009.A total of 480 fishes were collected from commercial catches by pelagic trawl net at different fishing ports at Chebba(34°14'N,11°06'E),Kerkennah(34°45'N,11°17'E)and Zarzis(33°41'N,11°48'E).The weight,the size,the sex,the date and the area of capture of each specimen were recorded.B.capriscus were then examined to search for ectoparasites and endoparasites.For each parasite species,parasitological indices were calculated.Results:Five species of parasites were identified,among which a new species of Digenea Hypocreadium caputvadum was discovered and two species of parasites were reported for the first time in the Mediterranean.Conclusions:It is the first inventory of the ecto and endoparasites of grey triggerfish collected from the Gulf of Gabès Mediterranean Sea.