Iran. J. Ichthyol. (December 2015), 2(4): 287–295 Received: August 27, 2015 © 2015 Iranian Society of Ichthyology Accepted: November 25, 2015 P-ISSN: 2383-1561; E-ISSN: 2383-0964 doi: http://www.ijichthyol.org Parasitic worms of the Persian sturgeon, Acipenser persicus Borodin, 1897 from the southwestern shores of the Caspian Sea Mohammad Reza NOEI1, Shaig IBRAHIMOV1, Masoud SATTARI2* 1Institute of Zoology, the Azerbaijan National Academy of Sciences, Baku, Azerbaijan. 2Department of Fisheries, Faculty of Natural Resources, University of Guilan, Sowmeh Sara, Iran. *Email: [email protected] Abstract: Although the Persian sturgeon, Acipenser persicus, is a commercially valuable sturgeon species of the Caspian Sea, but there are only few reports about its parasite fauna in the southern part of the Caspian Sea. In this study, a total of 209 individuals of Persian sturgeon were collected from two regions in the southwestern of Caspian Sea (Guilan Province, Iran) from March 2009 to May 2011. After recording their biometric characteristics, standard necropsy and parasitology methods were used for finding parasites. The nematodes were fixed in 70% ethanol and then cleared in lactophenol. The other worms were fixed in 10% buffered formalin and stained with aqueous acetocarmine. In this study, a total of 1396 worms belonging to six species, including two nematode species viz. Cucullanus sphaerocephalus and Eustrongylides excisus, two cestodes viz. Amphilina foliacea and Bothrimonus fallax, one digenean trematode, namely Skrjabinopsolus semiarmatus, and one acanthocephalan, namely Leptorhynchoides plagicephalus were found in 209 examined Persian sturgeons. Keywords: Acipenseriformes, Nematoda, Cestoda, Prevalence, Intensity. Introduction Specific parasitological information about The fishery of Persian sturgeon, Acipenser persicus A. persicus was not available, because this species Borodin, 1897 is of commercial importance in the had not been distinguished from A. gueldenstaedtii southwestern shores of the Caspian Sea (Emadi for a long time (Holcik 1989). Therefore, the species 1996). This species has a wide distribution range in composition and quantities of its parasites were Iranian shore and similar to the Russian sturgeon, presumed to be analogous to those of A. gueldenstaedtii Brandt & Ratzeburg, 1833, has a A. gueldenstaedtii. The first study on the parasite short, round and blunt snout (Berg 1948). Acipenser fauna of sturgeons in the Iranian shore of the Caspian persicus can be distinguished from A. gueldenstaedtii Sea (Mokhayer 1972) was carried out when by the somewhat smaller number of scutes and gill A. persicus was considered to be a subspecies of rakers, a relatively longer and lower head, more A. gueldenstaedtii. Therefore, only three parasite elongated body, and narrower and downward- species were reported from A. persicus (Gorogi curving and lighter colouration (Belyaev 1932; Marti 1996a) and in another study, nine parasite species 1940; Berg 1948; Mageramov 1972; Artyokhin were found in this fish (Sattari & Mokhayer 2006). 1979; Putilina 1983). The diet of A. persicus in the There are also other reports about the parasite fauna southern part of the Caspian Sea includes small fishes of sturgeons and other fish species in various areas of such as Clupeonella spp., gobiids, and Vimba vimba, the Caspian Sea (Dogiel & Bykhovskiy 1939; crustaceans such as shrimps and Balanus, and Dubinin 1952; Shulman 1954; Nechaeva 1964; polychaetes (Torrik 1994). Skryabina 1974; Sattari et al. 2008, 2009; Khara et 287 Iranian Journal of Ichthyology (December 2015), 2(4): 287-295 al. 2009; Mousavi Sabet & Sattari 2013; Daghigh Roohi et al. 2014; Khara & Sattari 2014). Hence, this study attempts to provide a comprehensive investigation on composition and quantities of parasites of A. persicus in the southwestern shores of the Caspian Sea with respect to their epizootiological status. Materials and Methods A total of 209 specimens of the Persian sturgeon were collected by gill net from March 2009 to May 2011. The samples consisted of the Persian sturgeons caught in fisheries regions 1 (region 1: western coast of Guilan Province) and 2 (region 1: eastern coast of Guilan Province) alongside a shore area of about 200km. The collected Persian sturgeons had a mean weight of 21.724kg (±8.452kg, range=3-43kg) and fork length of 150.99cm (±22.82cm, range=73- Fig.1. Electron photomicrograph of 197cm). Since the sampling of this study was C. sphaerocephalus (anterior part) from the Persian restricted by the governmental fishing program (i.e. sturgeon of the Caspian Sea (130X) showing its rounded head and slit-like oral opening. for artificial propagation and then exporting their flesh), therefore, age determination was not possible. of the abundance of all parasite species found After recording the biometric characteristics of (modified after Leong & Holmes 1981). Mean samples, standard necropsy and parasitology intensity of infection and abundance of the parasite methods (Bykhovskaya-Pavlovskaya 1985; Stoskopf species (with prevalence >10%) among seasons, 1993) were used for finding parasites. Live locations, weight and length classes and sexes were nematodes were fixed in hot 70% ethanol and cleared tested using Kruskal-Wallis test (KW, multiple in lactophenol. Live trematodes and comparisons) and Mann-Whitney U test (MW, acanthocephalans were relaxed in distilled water at pairwise comparisons). The differences between the 4ºC for 1hrs and fixed in 10% hot buffered formalin. prevalence of the parasite in various groups were All specimens were fixed in 10% formalin, stained determined using Z test. The results were considered with aqueous acetocarmine, dehydrated and then significant at the 95% level (P<0.05). Data analysis mounted in permount. All the worms were identified were performed using the SPSS programme. using parasite identification keys (Yamaguti 1961; Avdeyev 1987; Moravec 1994) and then were Results deposited at the Laboratory of Fish Diseases, Faculty In this study, 1396 worms of six species, including of Natural Resources, University of Guilan (Iran). two nematode species, Cucullanus sphaerocephalus Statistical analysis: Classical epidemiological (Rudolphi, 1809) and Eustrongylides excisus variables (prevalence, intensity and abundance) were Jägerskiöld, 1909 larvae, two cestoda species, calculated according to Bush et al. (1997). The Amphilina foliacea (Rudolphi, 1819) and dominance of a parasite species (expressed as a Bothrimonus fallax Lühe, 1900, one digenean percentage) was calculated as N/N sum, where trematode, Skrjabinopsolus semiarmatus (Molin, N=abundance of a parasite species and N sum = sum 1858), and one acanthocephalan, Leptorhynchoides 288 Noei et al.-Parasitic worms of the Persian sturgeon from the Caspian Sea of Cobitis avicennae Fig.2. Electron photomicrograph of Fig.4. Electron photomicrograph of S. semiarmatus C. sphaerocephalus (head) from the Persian sturgeon (cirrus) from the Persian sturgeon of the Caspian Sea of the Caspian Sea (300X) showing its excretory pore. (400X) showing its powerful spinose cirrus. Fig.5. Leptorhynchoides plagicephalus (anterior part) from the Persian sturgeon of the Caspian Sea (100X) showing its extremely long proboscis, with 14 longitudinal hook rows, 22-24 per row. Fig.3. Electron photomicrograph of S. semiarmatus highest prevalence value (73.21%). The mean (anterior part) from the Persian sturgeonof the intensity of infection, abundance and dominance of Caspian Sea (120X) showing its spinose cuticle, small this parasites (7.54 and 5.52 and 82.22%, suckers, genital atrium and powerful spinose cirrus. respectively) were also more than the other parasites. plagicephalus (Westrumb, 1821) were found in 209 The prevalence of C. sphaerocephalus in autumn examined specimens (Figs. 1-10). and spring was significantly higher than that of The prevalence, mean intensity, range winter (Z test, P<0.05) (Table 2). The mean intensity (minimum and maximum number), abundance and of infection of C. sphaerocephalus in spring were dominance of the parasites are shown in Table 1. higher than that of autumn and winter, whereas, the Based on the results, C. sphaerocephalus had the differences between seasons were not significant 289 Iranian Journal of Ichthyology (December 2015), 2(4): 287-295 Fig.6. Leptorhynchoides plagicephalus (the tail of Fig.8. Bothrimonus fallax (head) from the Persian male) from the Persian sturgeon of the Caspian Sea sturgeon of the Caspian Sea (100X) showing its (100X) showing its copulating bursa. bottom divided into ventral and dorsal portions by low transverse septum. Fig.7. Bothrimonus fallax (anterior part) from the Persian sturgeon of the Caspian Sea (40X) showing its spherical head terminally bearing scyphoid suctorial hollow. Fig.9. Eustrongylides excisus larvae (anterior part) (KW, χ2=3.25, df=2, P=0.197). However, the from the Persian sturgeon of the Caspian Sea (100X) abundance of C. sphaerocephalus in seasons was showing its rounded head, provided with 12 papillae in two circles of 6 papillae each. significantly different (KW, χ2=9.255, df=2, P<0.05). The prevalence and mean intensity of df=2, P<0.05). The prevalence and mean intensity of S. semiarmatus in spring were higher than that of infection to L. plagicephalus in winter were higher autumn and winter, respectively, but the differences than that of spring and autumn, respectively, but the were not significant (Z test, P>0.05 for prevalence differences were not significant (Z test, P>0.05 for and KW, χ2=1.917, df=1, P=0.166 for mean intensity prevalence and KW, χ2=1.380, df=2, P=0.502 for of infection). The abundance of S. semiarmatus in mean intensity of infection). seasons was significantly different (KW, χ2=10.192, The prevalence and mean intensity of 290 Noei et al.-Parasitic worms of the Persian sturgeon from the Caspian Sea of Cobitis avicennae Table 1. The prevalence, mean intensity, range, abundance and dominance of some parasites in A. persicus. Parasite Prevalence (%) Mean intensity SD Range Abundance SD Dominance (%) C. sphaerocephalus 73.21 7.5410.86 1-89 5.529.87 84.22 N=1153 S. semiarmatus 6.22 7.5414.15 1-50 0.473.86 7.16 N=98 L. plagicephalus 8.13 5.536.63 1-19 0.452.38 6.73 N=94 E.