engleski

MOLECULAR CHARACTERISATION OF THE METAZOAN PARASITES OF VARDAR CHUB (SQUALIUS VARDARIENSIS) FROM THREE RIVERS IN NORTH EASTERN MACEDONIA

Fish parasites with a complex life cycle, including intermediate and paratenic hosts, can be used as indicators of aquatic environmental stress. Their identification is however often difficult, due to the high level of intraspecific variability. The aim of the present study was to identify metazoan parasites found in Vardar chub (Squalius vardariensis) from three rivers in northeastern Macedonia under different mining impact. Parasite specimens were collected from the dissected Vardar chub (S. vardariensis) sampled in spring and autumn from the three rivers in northeastern Macedonia: Zletovica River and Kriva Rriver under mining activity impact and Bregalnica River which is non-impacted. Abdominal cavity cysts were observed in the fish from Bregalnica (spring and autumn) and Kriva River (spring) and cysts from two fish specimens were used for the identification. Intestinal parasites were observed in the fish from Bregalnica (spring and autumn) and Zletovica River (spring) and specimens from four different fish were used for identification. Morphological analysis of the parasitic cysts content was done by light microscope, while molecular identification was performed by sequence analysis of 18S rRNA region. Molecular identification of intestinal parasites was done by sequence analyses of three different DNA regions: 18S rRNA, ITS and COI gene. For the phylogenetic analysis of intestinal parasites based on partial COI sequence data, maximum likelihood as well as maximum parsimony method was applied by MEGA 6 software. Members of the two different parasitic phyla were determined from the examined Vardar chub: Myxozoa (Cnidaria) in the abdominal cavity and Acanthocephala in the intestine. Morphological analysis of myxozoan cysts indicated presence of Myxobolus sp., while molecular analysis based on 18SrRNA analysis confirmed this genus. Molecular analysis of acanthocephalans based on the 18S rRNA and ITS region confirmed two different species: Pomphorhynchus laevis and Acanthocephalus sp. most closely related to the A. anguillae (99.8% identity to the sequence from the GenBank). Phylogenetic analysis of P. laevis based on COI sequence data indicated separated clustering of Macedonian specimens in relation to the other European specimens available from the GenBank. Identification of Myxobolus sp. in Vardar chub is important as members of this genus are potentially dangerous to their fish host. Determination of acanthocephalans is important not just for their further phylogeographic studies, but also for the water contamination studies, as these parasites were suggested as a sensitive biological indicator of metal bioavailability in the river water.

parasites ; Myxozoa ; Acantochephala ; Myxobolus ; Vardar chub

nije evidentirano