Genetic diversity of Contracaecum rudolphii sp. A (Nematoda: Anisakidae) parasitizing the European Shag Phalacrocorax aristotelis desmarestii from the Spanish Mediterranean coast

Xavier Roca-Geronès; Roser Fisa; Isabel Montoliu; Margarida Casadevall; Carles Tobella; Josep M Bas; Marialetizia Palomba; Simonetta Mattiucci

doi:10.3389/fvets.2023.1122291

Genetic diversity of Contracaecum rudolphii sp. A (Nematoda: Anisakidae) parasitizing the European Shag Phalacrocorax aristotelis desmarestii from the Spanish Mediterranean coast

Front Vet Sci. 2023 Feb 2:10:1122291. doi: 10.3389/fvets.2023.1122291. eCollection 2023.

Authors

Xavier Roca-Geronès^{1

2}, Roser Fisa¹, Isabel Montoliu¹, Margarida Casadevall³, Carles Tobella³, Josep M Bas³, Marialetizia Palomba⁴, Simonetta Mattiucci²

Affiliations

¹ Secció de Parasitologia, Departament de Biologia, Sanitat i Medi Ambient, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain.
² Section of Parasitology, Department of Public Health and Infectious Diseases, Sapienza-University of Rome, Rome, Italy.
³ Department of Environmental Sciences, Faculty of Sciences, University of Girona, Girona, Spain.
⁴ Department of Ecological and Biological Sciences, Tuscia University, Viterbo, Italy.

Abstract

Sibling species of the Contracaecum rudolphii (s.l.) complex are habitual endoparasites of cormorants of the Phalacrocoracidae family, worldwide. In Europe, the two species, C. rudolphii sp. A and C. rudolphii sp. B, have been identified. However, information regarding the occurrence and distribution of these anisakids in cormorants from Spain is scarce. In the present study, 20 specimens of the European Shag, Ph. aristotelis desmarestii, from the western Mediterranean Spanish marine coast were parasitologically analyzed for the presence of nematodes. All hosts were found parasitized with Contracaecum specimens (n = 1,517). A representative subsample was genetically identified as C. rudolphii sp. A by sequence analysis of the mtDNA cox2 gene and the ITS1 and ITS2 regions of the rDNA. This represents the first report of C. rudolphii sp. A from the Spanish Mediterranean waters. Population genetic analysis was performed including other C. rudolphii sp. A specimens from the west Sardinian and the Tyrrhenian Sea. At the intraspecific level, a significant genetic differentiation (Fst ≈ 0.08, p < 0.00001) between the metapopulation from the Spanish Mediterranean coast and that from the Sardinian waters was observed; whereas, no differentiation was found between metapopulations of the parasite from the Spanish and the Tyrrhenian Italian coast. The findings highly support the hypothesis of the adaptation of the life cycle of C. rudolphii sp. A in brackish and marine ecosystems. Furthermore, the results on the population genetics of C. rudolphii sp. A suggest the possible role of the migration routes of wintering populations of cormorants in the Mediterranean Sea in influencing the parasite genetic structure.

Keywords: Contracaecum rudolphii sp. A; European Shag; Western Mediterranean; molecular identification; population genetics.

Grants and funding

This study was supported by the Grandi Progetti di Ricerca Ateneo of “Sapienza (2020)-University of Rome”; the Programa Pleamar of the Fundación Biodiversidad under the European Maritime and Fisheries Fund (EMFF) in the DESMARES III project of the University of Girona (UdG); the Generalitat de Catalunya Project 2017 SGR 1008; and the Margarita Salas grant for the training of young doctoral graduates under the call for the Requalification of the Spanish University system.