Diversity, consistency, and seasonality in parasite assemblages of two sympatric marine fish Pagrus pagrus (Linnaeus, 1758) and Pagellus bogaraveo (Brünnich, 1768) (Perciformes: Sparidae) off the coast of Algeria in the western Mediterranean Sea.

Abstract Various host characteristics (i. e., feeding habits, geographic distribution) and habitat characteristics (i.e., seasonality) influence the structure of parasite assemblages. To compare the parasite assemblages of hosts representatives of two genera of the same fish family, simultaneously occupying a geographic region, and to examine if seasonal variations influence parasite occurrence and abundance, we examined the parasite assemblages of two sympatric marine fish, Pagrus pagrus (n = 308) and Pagellus bogaraveo (n = 315) off the coast of Algeria in the western Mediterranean. Specimens were collected during summer and autumn over three consecutive years (2014–2016). Parasite assemblages were high in species richness and abundance. We compiled an inventory of 40 parasite taxa, including ectoparasitic monogeneans and crustaceans, and endoparasitic trematodes, cestodes, acanthocephalans, and nematodes. Endoparasite taxa primarily consisted of adult gastro-intestinal parasites and long lived larval helminths. Information on the parasite community structure and seasonal variations in parasite populations of these two hosts from the Mediterranean is here provided. Observed patterns of composition, diversity, dominance, and similarity indicate an overall consistency in assemblage structure. Although each host species harbored distinct parasite communities, they shared a high proportion of parasite species suggesting similar use of a common local pool of parasites. However, most shared species did not contribute to structuring the assemblages. Seasonal patterns in parasite abundance were observed for both hosts, with peak prevalence, abundance, and diversity in autumn. Results suggest that, regardless of a common pool of parasites being available to sympatric species, several ecological filters over time, led to distinct, independent variations in the parasite assemblages in each species.