Dr. George-Nascimento-Failla, Mario

We assessed compositional and aggregate properties of fish assemblages inhabiting rocky intertidal pools of the coast of central Chile. Its association to sampling regions, localities, tidepool volume or dominant substrate was examined. A total of 1502 individual fish representing 20 species were collected in 49 single-time sampled tidepools from 3 localities at Valparaíso and 5 from the Biobío region. The dissimilarity in composition of the fish assemblages was larger between regions than among localities within regions. The most abundant taxa in Valparaíso were Helcogrammoides chilensis and Scartichthys viridis. In Biobío were Calliclinus geniguttatus, Gobiesox marmoratus, Myxodes viridis and Ophiogobius jenynsi. There were significant and positive but not strong correlations between the volume of tidepools with the total fish number and species richness. There were no significant correlations with dominance, diversity and total fish biomass. Consequently, density in biomass, density in number of fishes, and in number of species decreased similarly and steeply with tidepool volume in Valparaíso and Biobío regions, indicating a strong size effect of tidepool volume in both regions. These results indicate that community composition variability is independent of aggregate community and that a biogeographical compositional transition occurs in this area.

The scarce information on the helminth fauna in otariids from the Southeastern Pacific comes mainly from stranded individuals or killed for that purpose. In this study, we compared the abundance and composition of enteroparasitic assemblages of Otaria flavescens using coprological techniques. Three sampling localities from north to south spanning 2,200 km off the Chilean coast were considered (Iquique, Viñ a del Mar, and Talcahuano). In all, 60 fecal samples were collected, and eggs belonging to 5 taxa were found in 91.6% of the samples. They were the anisakid nematodes Contracaecum and Pseudoterranova, the cestode Adenocephalus (syn. Diphyllobothrium), the trematode Ogmogaster, and the acanthocephalan Corynosoma. Samples from southern Chile (Talcahuano) showed the highest prevalence. Adenocephalus eggs had the highest prevalence and abundance in Iquique and Talcahuano, whereas Ogmogaster was the less prevalent and abundant in all sampling localities. Corynosoma eggs had similar prevalence and abundance among sampling localities, and Pseudoterranova eggs were absent in Iquique and with median prevalence values in Viñ a del Mar and Talcahuano. Thus, the composition of parasite egg assemblages was different between sampling localities. These differences between sampling localities may help to explain differential records of some zoonotic parasitoses such as pseudoterranovosis and diphyllobothriosis in Peru and Chile, where consumption of raw or marinated fish (ceviche) is common. For example, the lower diversity of parasite egg assemblages in the northern Chilean coast may be due to the absence or lower abundance of first intermediate/paratenic hosts of Pseudoterranova.