Patterns of variation in parasite component communities and infracommunities of a littoral fish species from the northern coast of Chile

Abstract

The structure and similarity of the parasite communities of fish can be evaluated at the component community (CC) and infracommunity (IC) levels. Both hierarchical levels have been used to assess parasite variations in fish at large (biogeographic) scales. However, studies evaluating the consistency between these two hierarchical levels at smaller geographical scales are scarce. In this study, the parasite assemblages of 124 Paralabrax humeralis collected by local fishermen by spear fishing at four sites (El Fierro, EF; P. Angamos, PA; Santa María, ISM; San Jorge, BSJ) in northern Chile were compared to assess the variability (or similarity) of their CCs and ICs at a limited geographical scale using multivariate analysis. At the IC level, discriminant analyses showed that P. humeralis parasite communities varied significantly among sites; 70% of ectoparasite ICs were correctly assigned to each site, but only 55% of helminth parasite ICs were correctly classified. At the CC level, the composition of parasite communities as assessed by correspondence analyses varied significantly between sites. Tagia sp., Neobenedenia sp. and Philometra sp. were associated with BSJ, ISM and PA, respectively; Corynosoma sp. and most digeneans were associated with both ISM and EF. Analysis of similarities (ANOSIM) showed significant variations in the degree of similarity between P. humeralis CCs from different sites, but not between ICs. Variations between CCs from different sites reflect fish population processes (e.g., population age, reproductive segregation) and the particular conditions of their respective habitats, whereas ICs reflect individual host movements. This study demonstrated that, when examined at a limited geographical scale, IC is better than CC at capturing the local pool of parasite assemblages when host populations are spatially segregated. Therefore, in this study, it is demonstrated that at a small geographic scale, CC variations are not reflected by IC, when host population is spatially segregated.