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The shoemaker spinefoot Siganus sutor (Valenciennes, 1835) in the marine waters of Iraq: second appearance and the northernmost record in the northern Indian Ocean

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Jawad L. , Abed J. , Resen A. K. , Al-Yassein R. , Kulw A. M.

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tom Vol. 52, No. 2

166--171

EN

A new record of Siganus sutor from inland artificial marine extension Shatt al-Basrah canal, south of Iraq, is reported.Two specimens were collected during an ichthyologic survey on 2 November 2021. The specimens are 127 and 129 mm in total length. This record from Iraqi waters represents the species’ second and northernmost appearance in thenorthern Indian Ocean.

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First substantiated record of a Lessepsian migrant–the dusky spinefoot, Siganus luridus (Actinopterygii: Perciformes: Siganidae), in the Adriatic Sea

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Dulcic J. , Dragicevic B. , Grgicevic R. , Lipej L.

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tom 41

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nr 2

EN

One specimen of the dusky spinefoot, Siganus luridus (Rüppell, 1829) (♀, total length = 17.3 cm, total weight = 87.61 g), a lessepsian migrant, was captured in the Mljet Channel (Southern Adriatic, Croatian coast) on 15 November 2010. This is the second record of this species from the Adriatic, but first well documented and based on the captured specimen. First record occurred earlier in the Northern Adriatic, but was based solely on underwater observations.

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Ecological comments on the intestinal helminths of the rabbitfish Siganus rivulatus [Teleostei, Siganidae] from the Northern Red Sea

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Hassanine R. M. E.-S. , Al-Jahdali M. O.

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nr 3

EN

Between May and September 2006, 640 specimens of the rabbitfish Siganus rivulatus Forsskål (Teleostei, Siganidae) were examined for infections with intestinal helminths. These fishes were caught in the Red Sea off the coast of Sharm El-Sheikh, South Sinai, Egypt, examined in a field laboratory and separated into three size groups of regular length intervals. Only three species of helminths were recovered: the trematode Gyliauchen volubilis Nagaty, 1956 (Gyliauchenidae Fukui, 1929), the acanthocephalan Sclerocollum rubrimaris Schmidt et Paperna, 1978 (Cavisomidae Meyer, 1932) and the nematode Procamallanus elatensis Fusco et Overstreet, 1979 (Cucullanidae Cobbold, 1864). The distribution of these helminths along the intestine of S. rivulatus, in all patterns of single and concurrent infections and the corresponding prevalences and intensities of infection in the different size groups of the fish were recorded. In single infections, each parasite species was found distributed in a well-defined fundamental niche along the intestine of Siganus rivulatus, and a distinct partial overlap between the niches of G. volubilis and Sclerocollum rubrimaris was observed. In concurrent infections with these two species, their fundamental niches were significantly reduced, probably being affected by interactive site segregation and individuals of each species were found segregated in a restricted realised niche. In all other patterns of concurrent infections, each parasite species was normally found in its original fundamental niche. The prevalences of these parasites in the fish examined were relatively low and somewhat similar. In all patterns of single and concurrent infections, the intensity of infection was directly related to fish size. In concurrent infection with G. volubilis and S. rubrimaris, a significant decline was observed in the intensities of both species in the different size groups of the fish, but, in all other patterns of concurrent infections, no significant change in intensity was observed. These observations suggest that the interaction between G. volubilis and S. rubrimaris is probably a negative and symmetrical one. The mode of transmission of these parasites to the fish is also discussed.

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Fecundity and condition of successful invaders: Siganus rivulatus and S. luridus (Actinopterygii: Perciformes: Siganidae) in the Eastern Mediterranean Sea

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Bariche M. , Sadek R. , Azzurro E.

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nr 1

EN

Background. Rabbitfishes, Siganus rivulatus and S. luridus, are among the most successful invaders in the Mediterranean Sea but population parameters in their new environment are barely known. Fecundity and condition are key parameters of fish populations and their assessment is very important for exotic species; this information is needed to properly evaluate their reproductive and invasive potential. The current is study contributes to fill this gap by exploring fecundity and condition of those two fish species. Materials and Methods. About 1000 individuals of Siganus rivulatus and S. luridus were processed from off the Lebanese coasts over a 20-month period. Fecundity and condition index were estimated and compared. Regression analyses tested the dependence of fecundity on fish length, mass, and gonad mass. Results. Fecundity values were assessed for S. rivulatus and for S. luridus: Fabs = 272 043 ± 144 666 (SD), Frel = 2123 ± 808 oocytes · g-1 for S. rivulatus and Fabs = 245 273 ± 164 211, Frel = 1584 ± 627 oocytes · g-1 for S. luridus. The relation between Fabs and gonad mass [g] was y = 14 339x + 59 297 for S. rivulatus and y = 9245x + 62 140 for S. luridus. Condition exhibited a clear seasonal trend for the two rabbitfishes. It increased in spring prior to the reproduction period and again in autumn before the decrease of seawater temperature, and remained low during the cold period. Its values were significantly higher for S. luridus than to S. rivulatus. Conclusion. S. rivulatus displayed a higher fecundity while S. luridus showed a better condition in the Eastern Mediterranean. Gonad mass was the best predictor of fecundity for both species while condition exhibited a clear seasonal trend in both rabbitfishes.