engleski

Distribution and molecular characterisation of Pomphorhynchus laevis, acanthocephalan parasite of Squalius cephalus from the Sutla River, Croatia

Pomphorhynchus laevis is an intestinal thorny-headed worm (phylum Acanthocephala) with a wide geographic and ecological range. Besides affecting fish health by introducing pathological changes in tissues, this parasite is important as a potential biological marker for environmental pollution due to accumulation of heavy metals in high concentrations. In this study, distribution and molecular characterisation of P. laevis from Squalius cephalus in the Sutla River (Croatia) was investigated. Total of 172 individuals of S. cephalus were examined from six locations during samplings in 2008 and 2009. Prevalence, mean abundance and intensity were calculated using data collected from different locations. For genetic variability, mitochondrial (COI) and two nuclear markers (ITS and 18S rRNA) were analysed. Total prevalence of P. laevis was 59.9% (95% confidence limits 52.14 to 67.28), mean abundance 5.64 (bootstrap 95% confidence limits 3.93 to 8.16) and mean intensity 9.42 (bootstrap 95% confidence limits 6.82 to 13.8). Significant difference (p<0.05) in prevalence, mean abundance and mean intensity of P. laevis infection in 2008 and 2009 was detected at one locality. Parasite prevalence showed significant locality-related difference (p<0.01) for samplings in 2009. Genetic variability of analysed P. laevis specimens was low. COI and ITS proved to be the most effective markers for genetic variability determination, while 18S rRNA sequence was identical between ten analysed parasite specimens. Phylogenetic analysis based on COI gene showed separate grouping of P. laevis from the Sutla River regarding other specimens available from GenBank. Our results showed stable P. laevis population with low genetic variability in S. cephalus from the Sutla River.

Pomphorhynchus laevis; Squalius cephalus; Sutla River; COI; ITS; 18S rRNA

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