Endohelminth fauna of barbel Barbus barbus (L. 1758) in the Serbian section of the Danube River, with dominance of acanthocephalan Pomphorhynchus laeavis

Infection of the barbel Barbus barbus (L. 1758) with endohelminths was observed in fish collected from eight localities in the Serbian part of the Danube River between September 2004 2009. Temporal variations in the number of parasites per fish sample were noted. A total of 194 fish specimens of different age, mostly males, were examined. The most prevalent parasitic species was the acanthocephalan Pomphorhynchus laevis, the dominant species of the intestinal component communities at all sampling sites which were recorded in 100% of the fish examined. * Corresponding author’s e-mail: [email protected] Introduction The barbel Barbus barbus is a large, powerful member of the carp family (Cyprinidae). It is a benthopelagic long-lived fish, growing up to 120cm and 12kg (Simonovic, 2001). Feeding is on benthic organisms, including crustaceans, insect larvae (mayfly and midge larvae), molluscs, crayfish and swan mussels, as well as small fish and eggs of other fishes (Vukovic and Ivanovic, 1971; Losos et al., 1980; Maitland and Campbell, 1992). Spawning normally takes place in very shallow, fastflowing waters, in riffles, from May to July, rarely until September when temperature reaches 15°C (Freyhof and Ko elat, 2008) a er the fish have migrated upriver. The area of it’s distribution extends in Western and Central Europe, from western France to the southwards to the drainage systems of the Rivers Rhone and Danube (Moravec et al., 1997). The barbel B. barbus was the subject of many ichthyological studies in Serbia (Djanic, 1979; Kiskaroly and Tafro, 1988; Cakic, 2002) contributed to the recognition of the ecology of this fish species and its populations in the Danube River Basin. Most data on helminth communities in the barbel in Central Europe are derived from the Danube basin and the Elbe (Kritscher, 1955; Ergens and Lucky, 1959; Molnar, 1970; Moravec and Scholz, 1991; Gelnar et al., 1996, 1997). Certain helminths of barbel, mainly acanthocephalans, can occur in high intensities of infection. Acanthocephalans of Bull. Eur. Ass. Fish Pathol., 30(6) 2010, 230 the genus Pomphorhynchus Monticelli, 1905 are common parasites of fishes. The type and the most abundant species of the genus, Pomphorhynchus laevis (Zoega in Müller, 1776) occurs predominantly in cyprinid and also in salmonid fishes with the Palaearctic distribution (Dudiňák and Šnábel, 2001; Nedeva et al., 2003). This species has a high morphological variability (Brown, 1987) as well as host variability (Rašin, 1928; Petrochenko, 1956; Yamaguti, 1963; Hine and Kennedy, 1974; Kennedy et al., 1989; Moravec and Scholz, 1991). In the present paper the results of a parasitological survey of the intestinal helminth fauna of Barbus barbus from the Serbian part of the Danube River are reported. Materials and methods A total of 194 large, medium-sized and small barbels were collected along the length of the Serbian part of the Danube River, from locality Stari Banovci (1.192 rkm) to downstream locality Prahovo (861 rkm) by bow nets in period September 2004 2009. Samples were taken from eight ecologically different sampling sites (Figure 1). Fish were transported to the laboratory and immediately examined for parasites. The total length, weight, sex and age were recorded for each fish specimen. The fish material was analyzed parasitological; particular attention was paid to helminth infections of the stomach and intestine. During the parasitological examination the intestines were cut open and examined under a stereomicroscope. Parasites found were bleached, stained, prepared and fixed for species identification and subsequent storage. Parasites were identified using identification keys (Bauer, 1987; Lom and Dykova, 1989; Moravec, 1994). Food items present in the gut were recorded. Statistical analysis ANOVA (Tukey test) and oneway test were used to determine the significant differences between number of parasites per individual and sampled site/month, apropos Fulton’s body conditional factor (factor of nourishment – CF) and normalised values of parasitic number per locality and month of sampling (statistical significant differences on level possibility of 5%), respectively.