Unlike other balistids, grey triggerfish Balistes capriscus occur in social groups in subtropical reef assemblages and have been noted to cooperate in capturing large crustacean prey. The objective of this study were ...Unlike other balistids, grey triggerfish Balistes capriscus occur in social groups in subtropical reef assemblages and have been noted to cooperate in capturing large crustacean prey. The objective of this study were to determine the structure of dominance hierarchies of these social groups and the factors that influence hierarchies of wild-caught grey triggerfish in a natu- ralistic setting. From observations of four groups of triggerfish （n = 19 fish） in both dyad and group （4 - 5 fish） settings, we provide a description of triggerfish behaviors and coloration patterns and an explanation of the social context in which suites of behaviors are used by dominant, middle-ranking, and subordinate fish. Sixteen behaviors and nine coloration patterns were noted for grey triggerfish. Grey triggerfish groups form linear hierarchies in both dyads and groups as measured by Landau＇s lndex of Linearity （h = 1.0 for Groups 1, 3, and 4 and h = 0.95 for Group 2 in dyads; h = 1.0 for all groups in group settings）. Dyadic hierarchies, however, were not necessarily good predictors of the hierarchies found in larger group settings, as they only predicted two of the four group hierarchies. Sex played no role in influencing status or behavior. Size had the greatest influence on domi- nance status, with larger fish being more dominant than smaller fish. An individual＇s dominance ranking influenced both body coloration and posture. These results suggest that color patterns and body postures may also be used by observers as an indicator of an individual＇s social status in groups [Current Zoology 56 （1）： 18-35, 2010].展开更多
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 T...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).展开更多
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 ...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.展开更多
基金funded by a Research Enhancement Grant to KLL from Southwest Texas State University, San Marcos,TX, USA
文摘Unlike other balistids, grey triggerfish Balistes capriscus occur in social groups in subtropical reef assemblages and have been noted to cooperate in capturing large crustacean prey. The objective of this study were to determine the structure of dominance hierarchies of these social groups and the factors that influence hierarchies of wild-caught grey triggerfish in a natu- ralistic setting. From observations of four groups of triggerfish （n = 19 fish） in both dyad and group （4 - 5 fish） settings, we provide a description of triggerfish behaviors and coloration patterns and an explanation of the social context in which suites of behaviors are used by dominant, middle-ranking, and subordinate fish. Sixteen behaviors and nine coloration patterns were noted for grey triggerfish. Grey triggerfish groups form linear hierarchies in both dyads and groups as measured by Landau＇s lndex of Linearity （h = 1.0 for Groups 1, 3, and 4 and h = 0.95 for Group 2 in dyads; h = 1.0 for all groups in group settings）. Dyadic hierarchies, however, were not necessarily good predictors of the hierarchies found in larger group settings, as they only predicted two of the four group hierarchies. Sex played no role in influencing status or behavior. Size had the greatest influence on domi- nance status, with larger fish being more dominant than smaller fish. An individual＇s dominance ranking influenced both body coloration and posture. These results suggest that color patterns and body postures may also be used by observers as an indicator of an individual＇s social status in groups [Current Zoology 56 （1）： 18-35, 2010].
基金Supported by the Faculty of Sciences,Sfax,Tunisia.
文摘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).
基金Supported by the Faculty of Sciences,Sfax,Tunisia.
文摘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.
