Abstract

Background:
The Libyan Mediterranean coast supports diverse marine fish assemblages; however, parasitological data remain fragmentary, especially regarding the spatial distribution and infection patterns in the southern Mediterranean basin. Understanding these host–parasite interactions is essential for fisheries management and ecosystem health assessment.

Aim:
To fill geographical gaps in Libyan waters, this study provides a preliminary characterization of the metazoan parasite assemblages of the salema porgy (Sarpa salpa) and the little tunny (Euthynnus alletteratus) across three coastal regions (Tripoli, Misurata, and Susa).

Methods:
During the sampling season of 2025 (March–August), 45 fish specimens (E. alletteratus n = 23; S. salpa n = 22) were collected. The parasitological examinations followed standard necropsy protocols, with taxonomic identification based on morphological and morphometric analysis. Statistical indices, including prevalence (P%) and mean intensity (MI), were analyzed using Chi-square (χ2) and Kruskal–Wallis (H) tests, with precise p-values and degrees of freedom reported.

Results:
The survey identified five metazoan parasite taxa: Monogenea, Digenea, Nematoda, Copepoda, and Isopoda. E. alletteratus (sampled only in Misurata) showed a 100% prevalence (MI = 4.5 ± 2.1), which was significantly higher than S. salpa (χ2 = 15.4, df = 2, p < 0.001). In S. salpa, prevalence ranged from 40% in Tripoli to 58.3% in Susa, with a significantly higher mean intensity in the eastern region (MI = 19.3 ± 8.5; H = 1.1, p = 0.58). Specific parasites included Atrispinum salpae, Neohexostoma euthynni, and zoonotic Anisakis type I larvae, with the latter highlighting potential seafood safety risks.

Conclusion:
Parasite communities along the Libyan coast exhibit patterns influenced by host-specific ecological traits and potential geographic gradients. Given the small sample size and asymmetric sampling design, these findings provide a preliminary rather than a robust baseline, emphasizing the need for future molecular confirmation and environmental monitoring to validate the use of these parasites as biological indicators.

Key words: Bioindicators; Fish health; Preliminary survey; Southern Mediterranean; Zoonotic risk.