A total number of 60 specimens of two different species of Scarus fish caught from the Red Sea coast at Jeddah (30) and Rabigh (30) cities in Saudi Arabia were examined to determine their metazoan parasitic fauna, the...A total number of 60 specimens of two different species of Scarus fish caught from the Red Sea coast at Jeddah (30) and Rabigh (30) cities in Saudi Arabia were examined to determine their metazoan parasitic fauna, their prevalences, and mean intensities. Collected parasites were identified as, Isopoda (praniza larva of Gnathia sp.), Copepoda (Hatschekia sp.) Monogenea (Diplectanum sp.) and Digenea (Lecithoclaster and Bucephalus spp). Out of 30 specimens of fish caught from Jeddah coast 13 (43.4%) were infested by 90 parasites comprising of two parasite species, praniza larva and Hatschekia sp., with prevalence of infestation 40% and 3.33%, and mean intensity 7 and 6 parasites per fish respectively. 19 (63.3%) of Scarus fish caught from Rabigh coast were infested by 205 parasites representing 4 parasite spp. Diplectanum sp. represents the most commonly encountered parasite with prevalence (53.3%) and mean intensity (10.94%), followed by (Lecithoclaster sp. then praniza larva, prevalances (16.66% and 13.3%) and mean inentisities (3.4. and 1.75) respectively. Bucephalus sp. showed the minor, prevalence (3.33%) and mean intensity (6). Generally Scarus fish species from Rabigh had higher prevalence and mean intensity (63.3% and 7.59%) than Scarus fish species from Jeddah (43.4% and 6.92%). Female fish from Jeddah showed no parasitic infestation, while males were infested (prevalence 65% and mean intensity 6.92). Female fish from Rabigh had higher prevalence (84.21) and lower intensity (6.43) than males which showed prevalence (27.27%) and intensity (19). Relationship between parasitic infestation and fish species and sex were also studied in the two different localities and discussed.展开更多
Although Caribbean mixed-species herbivorous fish groups are an important component to the reef community by helping to crop algae that often overgrow and kill corals, little is known of how they organize their foragi...Although Caribbean mixed-species herbivorous fish groups are an important component to the reef community by helping to crop algae that often overgrow and kill corals, little is known of how they organize their foraging groups. In spite of a highly flexible membership, the basic structure of these groups consists of a “core species,” that leads the group and often is either the striped parrotfish (Scarus iserti) or the ocean surgeon (Acanthurus tractus). These species lead their groups to open areas where they feed largely on low profile turf algae. Other members prefer macro algae and are termed “associate species,” of which the two common species we studied were the stoplight parrotfish (Sparisoma viride) and the redband parrotfish (Sparisoma aurofrenatum). In spite of the large difference in group sizes between Jamaica and Grand Cayman Islands, the relationships between movement patterns and compositional changes were largely consistent. There was no support for the hypothesis that these dramatic and continuous group changes were related to foraging success. Instead, we speculated that these group changes perhaps were designed to maintain cohesion among a membership that was spread over a wide area. We also examined if associates species may be more than just passive followers of core species but rather instigated the attracting or the building of core groups. Both associate species do attract striped parrotfish in open areas and thus appear active in initiating mixed-species groups. Finally, given that associate species seem to derive little foraging benefit from following core species, we tested the hypothesis that associate species joined core groups to gain protection against predators. Associate species do not selectively join the larger groups of striped parrotfish but appear to join core species randomly and the groups they joined resembled the wide assortment of core groups available in the area. Thus, while associates may be joining core groups for protection, this protection was not based on sizes of core groups.展开更多
文摘A total number of 60 specimens of two different species of Scarus fish caught from the Red Sea coast at Jeddah (30) and Rabigh (30) cities in Saudi Arabia were examined to determine their metazoan parasitic fauna, their prevalences, and mean intensities. Collected parasites were identified as, Isopoda (praniza larva of Gnathia sp.), Copepoda (Hatschekia sp.) Monogenea (Diplectanum sp.) and Digenea (Lecithoclaster and Bucephalus spp). Out of 30 specimens of fish caught from Jeddah coast 13 (43.4%) were infested by 90 parasites comprising of two parasite species, praniza larva and Hatschekia sp., with prevalence of infestation 40% and 3.33%, and mean intensity 7 and 6 parasites per fish respectively. 19 (63.3%) of Scarus fish caught from Rabigh coast were infested by 205 parasites representing 4 parasite spp. Diplectanum sp. represents the most commonly encountered parasite with prevalence (53.3%) and mean intensity (10.94%), followed by (Lecithoclaster sp. then praniza larva, prevalances (16.66% and 13.3%) and mean inentisities (3.4. and 1.75) respectively. Bucephalus sp. showed the minor, prevalence (3.33%) and mean intensity (6). Generally Scarus fish species from Rabigh had higher prevalence and mean intensity (63.3% and 7.59%) than Scarus fish species from Jeddah (43.4% and 6.92%). Female fish from Jeddah showed no parasitic infestation, while males were infested (prevalence 65% and mean intensity 6.92). Female fish from Rabigh had higher prevalence (84.21) and lower intensity (6.43) than males which showed prevalence (27.27%) and intensity (19). Relationship between parasitic infestation and fish species and sex were also studied in the two different localities and discussed.
文摘Although Caribbean mixed-species herbivorous fish groups are an important component to the reef community by helping to crop algae that often overgrow and kill corals, little is known of how they organize their foraging groups. In spite of a highly flexible membership, the basic structure of these groups consists of a “core species,” that leads the group and often is either the striped parrotfish (Scarus iserti) or the ocean surgeon (Acanthurus tractus). These species lead their groups to open areas where they feed largely on low profile turf algae. Other members prefer macro algae and are termed “associate species,” of which the two common species we studied were the stoplight parrotfish (Sparisoma viride) and the redband parrotfish (Sparisoma aurofrenatum). In spite of the large difference in group sizes between Jamaica and Grand Cayman Islands, the relationships between movement patterns and compositional changes were largely consistent. There was no support for the hypothesis that these dramatic and continuous group changes were related to foraging success. Instead, we speculated that these group changes perhaps were designed to maintain cohesion among a membership that was spread over a wide area. We also examined if associates species may be more than just passive followers of core species but rather instigated the attracting or the building of core groups. Both associate species do attract striped parrotfish in open areas and thus appear active in initiating mixed-species groups. Finally, given that associate species seem to derive little foraging benefit from following core species, we tested the hypothesis that associate species joined core groups to gain protection against predators. Associate species do not selectively join the larger groups of striped parrotfish but appear to join core species randomly and the groups they joined resembled the wide assortment of core groups available in the area. Thus, while associates may be joining core groups for protection, this protection was not based on sizes of core groups.
