Volumen 45 - Número 2: 293-301 | 2010
Article

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Diet and parasites of the insular fish Scartichthys variolatus (Blenniidae) from Robinson Crusoe Island, Chile: How different is this from two continental congeneric species?

Pablo E. Díaz^1* and Gabriela Muñoz²

¹Departamento de Biología Marina, Facultad de Ecología y Recursos Naturales, Universidad Andres Bello, República 440, Santiago, Chile.

²Facultad de Ciencias del Mar y de Recursos Naturales, Universidad de Valparaíso, Casilla 5080, Viña del Mar, Chile

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This study analyzed the diet and parasites of an insular blenniid fish, Scartichthys variolatus, and then compared that with data published for two congeneric species from the South American Pacific coast, S. viridis and S. gigas. Fifty-two specimens of fish were collected during 2008 and 2009 from the intertidal zone of the Robinson Crusoe Island, about 700 km off the coast of central Chile. The most frequent food items in all the fish analyzed were algae. Just two specimens of S. variolatus (3.8%) were parasitized only by the nematode Pseudodelphis chilensis. Despite the fact that all Scartichthys spp. are herbivorous, and the diet was composed of similar species, there were differences in frequencies of some of the algae, maily in Chaetomorpha sp. and Polysiphonia sp. The low parasite species richness of S. variolatus contrasts with that of the continental congeneric species, S. viridis with 13 parasite species, and S. gigas with 13 species. Therefore, the diet of these fishes can not explain differences in their parasite composition, so it is possible that environmental conditions, and the distance between the location of Robinson Crusoe Island and the South American coast, had limited dispersal and distribution of hosts and parasites over time.

Key words: Juan Fernández Archipelago, parasite dispersion, Blenniid fishes, parasite species richness

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