Digenean parasites in saddled seabream Oblada melanurus (Teleostei, Sparidae) - first insights from Algerian waters

Abstract

In an attempt to contribute to the understanding of the biodiversity of Digenea in Algeria, we analysed for the first time the community structure of the digenean fauna of Oblada melanurus (Linnaeus, 1758). From June 2022 to July 2023, 172 specimens of O. melanurus were sampled from various locations off the Algerian waters and their digestive tracts were examined to collect the digenean parasites. We analysed the community structure by calculating the parasitological parameters. Also, a species accumulation curve (SAC) was generated to evaluate the sampling effort, and the Chi-square test was performed to evaluate the effects of seasonal variation on the prevalence of parasites. We collected 434 Digenea, which belonged to three species: Lepocreadium album (Stossich, 1890) Stossich, 1904 (Lepocreadiidae Odhner, 1905); Magnibursatus bartolii Kostadinova, Power, Fernandez, Balbuena, Raga & Gibson, 2003 (Derogenidae Nicoll, 1910) and Macvicaria dubia (Stossich, 1905) Bartoli, Bray & Gibson, 1989 (Opecoelidae Ozaki, 1925). Our findings include a new geographical record for M. dubia and the first report of L. album and M. bartolii from this particular host in Algeria. L. album had the highest prevalence and mean abundance values, while M. dubia had the highest mean intensity. According to the Chi-square test, significant differences in prevalence between seasons were observed only for L. album and M. bartolii. We offered the first insights into the Digenea fauna parasitizing O. melanurus in Algeria, enriching the knowledge of digenean biodiversity in Algerian marine fish. Additionally, we shed light on the seasonal variations in the prevalence of these digeneans. This study may serve as a valuable reference for future research on Digenea in other marine species and regions.