Diversity and parasitological assessment of Digenea species in <i>Trachurus trachurus</i> (Teleostei, Carangidae) from the Algerian coast, Western Mediterranean

Summary A total of 820 specimens of Trachurus trachurus (Linnaeus, 1758) were collected from various locations along the Algerian coast between July 2023 and July 2024 and examined for digenean parasites. Among them, 27.68% were found to be infected. In total, 1,000 Digenea were retrieved, belonging to five species: Ectenurus lepidus Looss, 1907, Prodistomum polonii (Molin, 1859) Bray &amp; Gibson, 1990, Monascus filiformis (Rudolphi, 1819) Looss, 1907, Ancylocoelium typicum Nicoll, 1912, and Pseudopecoeloides chloroscombri (Fischthal &amp; Thomas, 1970) Bartoli, Bray &amp; Gibson, 2003. Notably, this study provides the first record of A. typicum in T. trachurus from Algeria. Among the identified parasites, M. filiformis exhibited the highest prevalence (19.63%) and mean abundance (0.66), whereas A. typicum and P. polonii showed the highest mean intensity (4.16 and 4.08, respectively). Statistical analyses revealed significant seasonal variations in the prevalence and abundance of most parasite species, except for P. chloroscombri . Regional differences were also observed, with significant variations in M. filiformis and A. typicum distributions. Additionally, the Spearman correlation test revealed a significant negative relationship between host weight and the mean abundance of several parasite species, as well as between host total length and the mean intensity of P. polonii . These results suggest that environmental factors, host size, and potentially feeding behavior play a critical role in shaping parasite distribution. Further research is needed to explore the ecological implications of these patterns and their potential effects on host population dynamics.